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CHAPTER 9: SAFETY ASSESSMENT FOR THE POST-CLOSURE PERIOD

Number of pages: 253

Reference: 1373-02-00018-NT-09-900-5

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5 12.03.2012 Revised version



2 28/02/2010 Revised version

1 31/01/2010 Revised version

0 31/01/2010 Initial edition

Index Date Description of amendments

DOCUMENT LEVEL V. LEFTEROV C. GHITA A. STOYANOVA

I. STANEV

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Safety Assessment Report

for siting the near surface radioactive waste disposal facility in Saligny Chapter 9

Page 2 of 253

T A B L E O F C O N T E N T S

9. SAFETY ASSESSMENT FOR THE POST-CLOSURE PERIOD .......................................................... 14

9.1. OBJECTIVE AND PURPOSE OF THE UPDATED SAFETY ASSESSMENT FOR THE POST-CLOSURE

PERIOD ............................................................................................................................................................. 14

9.2. ENSURING THE SAFETY DURING THE POST-CLOSURE PERIOD ....................................................... 15

9.3. METHODOLOGY FOR THE POST-CLOSURE SAFETY ASSESSMENT .................................................. 18

9.4. IDENTIFICATION OF FEATURES, EVENTS AND PROCESSES .............................................................. 21

9.5. CONTAMINANT TRANSPORT PATHWAYS ......................................................................................... 22

9.6. DEFINITION OF SCENARIOS ................................................................................................................ 23

9.6.1. GENERAL CONSIDERATIONS ............................................................................................................. 23

9.6.2. METHODOLOGY FOR SELECTION OF SCENARIOS ......................................................................... 25

9.6.3. DEFINITION OF THE SCENARIOS FOR THE POST-CLOSURE PERIOD .............................................. 25

9.6.4. DEFINITION OF THE SCENARIOS FOR THE ACTIVE INSTITUTIONAL CONTROL DURING THE

POST-CLOSURE PERIOD ....................................................................................................................................... 26

9.6.4.1. DEFINITION OF THE REFERENCE SCENARIO ....................................................................................26

9.6.4.2. DEFINITION OF THE ALTERNATIVE SCENARIOS ...............................................................................29

9.6.5. DEFINITION OF THE SCENARIOS FOR THE PASSIVE INSTITUTIONAL CONTROL DURING POST-

CLOSURE PERIOD ................................................................................................................................................. 32



9.6.6. DEFINITION OF THE SCENARIOS FOR THE POST-CLOSURE PERIOD AFTER 300 YEARS ............... 39



9.6.7. DESCRIPTION OF THE SELECTED SCENARIOS FOR THE POST-CLOSURE PERIOD ........................ 47

9.6.7.1. ACTIVE INSTITUTIONAL CONTROL DURING POST-CLOSURE PERIOD ...........................................47

9.6.7.1.1. REFERENCE SCENARIO .....................................................................................................................47

9.6.7.1.2. ALTERNATIVE SCENARIOS .................................................................................................................49

9.6.7.2. PASSIVE INSTITUTIONAL CONTROL DURING POST-CLOSURE PERIOD .........................................50



9.6.7.3. POST-CLOSURE PERIOD AFTER 300 YEARS ......................................................................................51



9.7. DESCRIPTION OF THE APPLIED COMPUTER CODES ....................................................................... 61

9.8. SAFETY ASSESSMENT FOR THE POST-CLOSURE PERIODS ................................................................ 61

9.8.1. PERIOD OF ACTIVE INSTITUTIONAL CONTROL AFTER THE CLOSURE ............................................ 67

9.8.1.1. DOSES FOR THE OPERATORS ............................................................................................................67

9.8.1.1.1. REFERENCE SCENARIO – INSPECTION OF DRAINAGE GALLERIES ...............................................67


9.8.1.1.2.1. DOSE FOR THE OPERATOR FOR SCENARIOS 1A) FAILURE OF A ROOF CLOSURE AND 2A)

FAILURE OF THE GROUND SLAB ...........................................................................................................................69



Page 3 of 253

9.8.1.1.2.2. DOSE FOR THE OPERATOR IN SCENARIO 3A) FAILURE OF THE DRAINAGE SYSTEM ..................70

9.8.1.2. MODELS OF THE SOURCE TERM .......................................................................................................72

9.8.1.2.1. CALCULATIONS FOR THE REFERENCE SCENARIO .........................................................................72

9.8.1.2.2. CALCULATIONS FOR THE ALTERNATIVE SCENARIOS .....................................................................72

9.8.1.3. MODELS OF THE PROCESSES IN THE UNSATURATED ZONE ...........................................................73



9.8.1.4. MODELS OF THE PROCESSES IN THE SATURATED ZONE ................................................................78



9.8.1.5. DOSES FOR THE POPULATION ..........................................................................................................85

9.8.1.6. EVALUATION OF THE IMPACT ON THE ENVIRONMENT .................................................................86

9.8.2. PERIOD OF PASSIVE INSTITUTIONAL CONTROL AFTER THE CLOSURE .......................................... 86




9.8.2.2. MODELS OF THE PROCESSES IN THE UNSATURATED ZONE ...........................................................88





9.8.2.3.1.1. PORFLOW INPUT DATA .....................................................................................................................93

9.8.2.3.1.2. DESCRIPTION OF THE MODEL...........................................................................................................95

9.8.2.3.1.3. RESULTS ...............................................................................................................................................95

9.8.2.3.1.4. ANALYSIS OF THE RESULTS .................................................................................................................98



9.8.2.4.1. DOSES FOR THE POPULATION DURING THE REFERENCE SCENARIO ...........................................102

9.8.2.4.2. DOSES FOR THE POPULATION DURING THE ALTERNATIVE SCENARIOS ......................................102

9.8.2.4.2.1. DOSE FOR THE POPULATION FOR ALTERNATIVE SCENARIOS 1) FAILURE OF THE ROOF

CLOSURE SYSTEM AND 2) FAILURE OF THE GROUND SLAB ..............................................................................102

9.8.2.4.2.2. DOSE FOR THE POPULATION FOR ALTERNATIVE SCENARIO 3) BATH TUBING EFFECT ...............103


9.8.2.5.1. EVALUATION OF THE IMPACT FOLLOWING THE REFERENCE SCENARIO ....................................106

9.8.2.5.2. EVALUATION OF THE IMPACT FOLLOWING THE ALTERNATIVE SCENARIOS ...............................107

9.8.3. POST-CLOSURE PERIOD AFTER 300 YEARS ...................................................................................... 107


9.8.3.1.1. DESCRIPTION OF THE MODEL...........................................................................................................107

9.8.3.1.2. INPUT DATA ........................................................................................................................................108

9.8.3.1.3. ASSUMPTIONS AND BOUNDARY CONDITIONS ..............................................................................111

9.8.3.1.4. RESULTS FROM THE CALCULATIONS OF “DUST MS DM BREAK” MODEL .....................................112

9.8.3.1.5. ANALYSIS OF THE RESULTS FOR THE REFERENCE SCENARIO ........................................................119

9.8.3.2. MODELS OF THE PROCESSES IN UNSATURATED ZONE ..................................................................119

9.8.3.2.1. 3D MODEL OF SALIGNY SITE UNSATURATED ZONE ........................................................................120

9.8.3.2.1.1. INPUT DATA ........................................................................................................................................120



Page 4 of 253

9.8.3.2.1.2. ASSUMPTIONS ....................................................................................................................................120

9.8.3.2.1.3. GEOMETRICAL MODEL .....................................................................................................................121

9.8.3.2.1.4. 2D MODEL REPRESENTING THE TRANSPORT OF THE RADIONUCLIDES IN LATERAL

DIRECTIONS ............................................................................................................................................................123

9.8.3.2.1.4.1. Model validation ........................................................................................129

9.8.3.2.1.4.2. Results and analysis....................................................................................131

9.8.3.2.1.4.3. Conclusions .................................................................................................145

9.8.3.2.2. CALCULATION OF RADIONUCLIDES’ TRANSPORT CONSIDERING THE SOIL'S HYDRAULIC

DATA FROM [7] ......................................................................................................................................................145


9.8.3.3.1. INPUT DATA ........................................................................................................................................151

9.8.3.3.2. ASSUMPTIONS ....................................................................................................................................153

9.8.3.3.3. DESCRIPTION OF THE MODEL...........................................................................................................153

9.8.3.3.4. BOUNDARY CONDITIONS .................................................................................................................153

9.8.3.3.5. RESULTS ...............................................................................................................................................157

9.8.3.3.6. ANALYSIS AND CONCLUSIONS .......................................................................................................168


9.8.3.4.1. DOSE FOR THE POPULATION DURING THE REFERENCE SCENARIO .............................................168

9.8.3.4.1.1. INPUT DATA ........................................................................................................................................169

9.8.3.4.1.2. CONSTRUCTION OF A FARM ON THE REPOSITORY .......................................................................172

9.8.3.4.1.3. FARM ON THE REPOSITORY ..............................................................................................................175

9.8.3.4.2. DOSES FOR THE POPULATION DURING THE ALTERNATIVE SCENARIOS ......................................180

9.8.3.4.2.1. ALTERNATIVE SCENARIO 1) FARM ON THE REPOSITORY - RESIDENCE SCENARIO ON

TOTALLY DEGRADED WASTE ................................................................................................................................180

9.8.3.4.2.2. ALTERNATIVE SCENARIO 2) ARCHAEOLOGICAL INVESTIGATION OF THE SITE ..........................186

9.8.3.4.2.3. ALTERNATIVE SCENARIO 3) GEOLOGIST INTRUSION .....................................................................193

9.8.3.4.2.4. ALTERNATIVE SCENARIO 4) ROAD CONSTRUCTION .....................................................................197


9.8.3.5.1. EVALUATION OF THE IMPACT ACCORDING TO THE REFERENCE SCENARIO ............................200

9.8.3.5.2. EVALUATION OF THE IMPACT ACCORDING TO THE ALTERNATIVE SCENARIOS .......................206

9.8.3.5.2.1.1. Archaeological investigation of the site .................................................206

9.8.3.5.2.1.2. Road construction .....................................................................................210

9.9. UNCERTAINTY AND SENSITIVITY ANALYSIS ........................................................................................ 212

9.9.1. PURPOSE .............................................................................................................................................. 212

9.9.2. REGULATORY REQUIREMENTS AND RECOMMENDATIONS .......................................................... 212

9.9.2.1. ROMANIAN REQUIREMENTS AND RECOMMENDATIONS .............................................................212

9.9.2.2. IAEA REQUIREMENTS AND RECOMMENDATIONS .........................................................................213

9.9.3. REVIEW OF THE PERFORMED CALCULATIONS ................................................................................ 213

9.9.4. STRATEGY FOR UNCERTAINTY EVALUATION ................................................................................... 214

9.9.5. REVIEW OF RESULTS FROM CALCULATIONS OF ALTERNATIVE SCENARIOS ................................ 214

9.9.5.1. DUST-MS ..............................................................................................................................................214

9.9.5.2. HYDRUS ...............................................................................................................................................215

9.9.5.3. PORFLOW ...........................................................................................................................................216

9.9.5.4. RESRAD ...............................................................................................................................................217



Page 5 of 253

9.9.5.5. MERCURAD ........................................................................................................................................217

9.9.5.6. CONCLUSIONS FOR SCENARIO UNCERTAINTIES ...........................................................................217

9.9.6. MATRIX OF SENSITIVITY CALCULATIONS .......................................................................................... 218

9.9.6.1. REVIEW OF INPUT DATA RANGE ......................................................................................................218

9.9.6.1.1. DUST-MS ..............................................................................................................................................218

9.9.6.1.2. HYDRUS ...............................................................................................................................................219

9.9.6.1.2.1. CHANGE OF LAYER TYPES ................................................................................................................219

9.9.6.1.2.2. EXISTENCE OF SAND LAYER ..............................................................................................................219

9.9.6.1.3. PORFLOW ...........................................................................................................................................221

9.9.6.1.4. RESRAD ...............................................................................................................................................221

9.9.6.1.5. MERCURAD ........................................................................................................................................221

9.9.6.2. CALCULATIONS .................................................................................................................................221

9.9.6.2.1. DUST-MS ..............................................................................................................................................222

9.9.6.2.1.1. MOISTURE CONTENT ..........................................................................................................................222

9.9.6.2.1.2. WASTE DENSITYF .................................................................................................................................222

9.9.6.2.1.3. DENSITY OF CONCRETE ....................................................................................................................223

9.9.6.2.1.4. DARCY FLOW .....................................................................................................................................223

9.9.6.2.1.5. MATERIAL DIFFUSION COEFFICIENT .................................................................................................225

9.9.6.2.2. HYDRUS ...............................................................................................................................................226



9.9.6.2.3. PORFLOW ...........................................................................................................................................228

9.9.6.2.4. RESRAD ...............................................................................................................................................229

9.9.6.2.5. MERCURAD ........................................................................................................................................230

9.9.6.3. CALCULATIONS SUMMARY ..............................................................................................................230

9.9.6.3.1. DUST-MS ..............................................................................................................................................231

9.9.6.3.2. HYDRUS ...............................................................................................................................................232



9.9.6.3.2.3. SUMMARY OF THE RESULTS FROM HYDRUS SENSITIVITY STUDY ....................................................234

9.9.6.3.3. PORFLOW ...........................................................................................................................................234

9.9.6.3.4. RESRAD ...............................................................................................................................................235

9.9.6.3.5. MERCURAD ........................................................................................................................................236

9.9.6.4. SENSITIVITY STUDY – REVIEW AND CONCLUSIONS ........................................................................236

9.9.6.4.1. DUST-MS ..............................................................................................................................................237

9.9.6.4.2. HYDRUS ...............................................................................................................................................237

9.9.6.4.3. PORFLOW ...........................................................................................................................................237

9.9.6.4.4. RESRAD ...............................................................................................................................................238

9.9.6.4.5. MERCURAD ........................................................................................................................................238

9.10. CONCLUSIONS ..................................................................................................................................... 238

9.11. REFERENCES .......................................................................................................................................... 245

APPENDIX 9.1 – INTERACTION MATRIXES FOR POST-CLOSURE PERIOD ......................................... 248



Page 6 of 253

L I S T O F T A B L E S

Table 9-1 List of scenarios for the post-closure period .........................................................................47

Table 9-2 Contaminant release mechanisms .......................................................................................59

Table 9-3 Computer codes ......................................................................................................................61

Table 9-4 Description of the scenarios in the post-closure period .....................................................62

Table 9-5 Concentrations for the active institutional control period for the reference scenario ..72

Table 9-6 Concentrations for the active institutional control period for the alternative scenario 73

Table 9-7 Tritium concentration for the reference scenario ................................................................82

Table 9-8 Tritium concentration for the alternative scenarios.............................................................85

Table 9-9 Concentrations for the passive institutional control period ...............................................87

Table 9-10 Concentrations for the passive institutional control period .............................................87

Table 9-11 Tritium concentration for the reference scenario..............................................................98

Table 9-12 Tritium concentration for the alternative scenarios.........................................................101

Table 9-13 Expected inventory within repository in year 2080 [19] ...................................................111

Table 9-14 Maximal concentration according to DUST calculations and limits according to [35]

...................................................................................................................................................................119

Table 9-15 Hydraulic parameters of the unsaturated geological formations of the Saligny site 124

Table 9-16 Distribution coefficients of the radionuclides in the geological formations of the

Saligny site kd (m3/kg) [50] .....................................................................................................................126

Table 9-17 Half Life(years)/ Decay constant (y-1) of the considering radionuclides .....................127

Table 9-18 PH01 unsaturated zone parameters ..................................................................................146

Table 9-19 PH03 unsaturated zone parameters ..................................................................................147

Table 9-20 PH01 Van Genuchten parameters of the unsaturated zone ........................................147

Table 9-21 PH03 Van Genuchten parameters of the unsaturated zone ........................................148

Table 9-22 Soil hydraulic properties of the unsaturated zone ...........................................................170

Table 9-23 Radionuclide mass activity for the non-compactable waste .......................................173

Table 9-24 Radionuclide mass activity .................................................................................................175

Table 9-25 Total activity with decay for 300 years ..............................................................................187

Table 9-26 Dose conversion factors according to [36]: .....................................................................188

Table 9-27 Doses for the archaeologists ..............................................................................................189

Table 9-28 Comparison between the calculations in cases a) and b) ...........................................192

Table 9-29 Total activity with decay for 300years ...............................................................................195


Table 9-31 Doses for the geologists .......................................................................................................196

Table 9-32 Total activity with decay for 300 years ..............................................................................198



Page 7 of 253


Table 9-34 Doses for the workers constructing the road ....................................................................199

Table 9-35 Comparison between maximum limits of the contaminants in the drinking water with

the maximum well water concentration .............................................................................................206

Table 9-36 Radionuclide concentration in the air above the road construction zone ................211

Table 9-37 Computer codes used for the safety assessment ...........................................................213

Table 9-38 DUST-MS Scenario uncertainties for the post-closure period .........................................215

Table 9-39 HYDRUS Scenario uncertainties for the post-closure period ..........................................216

Table 9-40 PORFLOW Scenario uncertainties for the post-closure period ......................................216

Table 9-41 RESRAD Scenario uncertainties for the post-closure period...........................................217

Table 9-42 Range of sensitivity parameters for DUST MS ....................................................................218

Table 9-43 Range of sensitivity parameters for HYDRUS .....................................................................219

Table 9-44 Parameters of the geological layers considered in the HYDRUS sensitivity scenario .220

Table 9-45 Range of sensitivity parameters for PORFLOW .................................................................221

Table 9-46 Range of sensitivity parameters for RESRAD .....................................................................221

Table 9-47 Range of sensitivity parameters for MERCURAD ..............................................................221

Table 9-48 - DUST-MS sensitivity study summary for the post-closure period ...................................231

Table 9-49 – Summary of the HYDRUS sensitivity study – Silty loess change ....................................232

Table 9-50– Summary of the HYDRUS sensitivity study – Upper clayed loess change ...................233

Table 9-51 – Summary of the HYDRUS sensitivity study – Silty loess change ....................................234

Table 9-52 – Summary of the PORFLOW sensitivity study results ........................................................235

Table 9-53 – Sensitivity study results for the post-closure reference scenario RESRAD model ......236

Table 9-54 MERCURAD sensitivity study summary for the operational period ................................236

Table 9-55 Calculated doses for the active institutional period .......................................................243

Table 9-56 Calculated doses for the passive institutional period .....................................................243

Table 9-57 Calculated doses for the post-closure period after 300 year ........................................243

L I S T O F F I G U R E S

Figure 9-1 General sequence of the safety analysis ............................................................................20

Figure 9-2 Potential pathways for transport of contaminants .............................................................22

Figure 9-3 Classification of scenarios ......................................................................................................24

Figure 9-4 Conceptual model of reference scenario for critical group (leaching) .......................49

Figure 9-5 – Conceptual model of Bath tubing scenario ...................................................................51

Figure 9-6 Conceptual model of scenario “Building a residence on the degraded site –

reference scenario after 300 years” .......................................................................................................54



Page 8 of 253

Figure 9-7 Conceptual model of scenario “Building a residence on totally degraded site –

alternative scenario after 300 years” .....................................................................................................56

Figure 9-8 Conceptual model of “Geologist intrusion” scenario.......................................................57

Figure 9-9 Conceptual model of “Archaeological investigation” scenario .....................................58

Figure 9-10 Conceptual model of “Road construction” scenario .....................................................58

Figure 9-11 H-3 volumetric specific activity distribution in the unsaturated zone ............................74

Figure 9-12 H-3 volumetric activity in the unsaturated – saturated zone boundary – side area of

the repository (linear scale) .....................................................................................................................74


the repository (logarithmic scale) ...........................................................................................................75

Figure 9-14 H-3 volumetric activity in the unsaturated – saturated zone boundary – the region

below the center of the repository .........................................................................................................75

Figure 9-15 H-3 volumetric activity distribution in the unsaturated zone ...........................................76







Figure 9-19 PORFLOW model of the saturated zone ............................................................................79

Figure 9-20 Results from HYDRUS – PORFLOW boundary condition ....................................................79

Figure 9-21 Tritium concentration for group a/ nodes .........................................................................80

Figure 9-22 Tritium concentration for group b/ nodes .........................................................................80

Figure 9-23 Tritium concentration for group c/ nodes .........................................................................81

Figure 9-24 Tritium concentration for group d/ nodes .........................................................................81

Figure 9-25 3H concentration on bottom layer .....................................................................................83

Figure 9-26 3H concentration in group a/nodes ..................................................................................83

Figure 9-27 3H concentration in group b/nodes ..................................................................................84

Figure 9-28 3H concentration in group c/nodes ...................................................................................84

Figure 9-29 3H concentration in group d/nodes ..................................................................................85


Figure 9-31 H-3 volumetric activity in the unsaturated – saturated zone boundary – side region of


Figure 9-32 H-3 volumetric activity in the unsaturated – saturated zone boundary – side region of









Page 9 of 253





Figure 9-38 Tritium concentration results from HYDRUS ........................................................................93

Figure 9-39 Tritium concentration in group a/nodes ............................................................................96

Figure 9-40 Tritium concentration in group b/nodes ............................................................................96

Figure 9-41 Tritium concentration in group c/nodes ............................................................................97

Figure 9-42 Tritium concentration in group d/nodes ............................................................................97

Figure 9-43 3H concentration on bottom layer .....................................................................................99

Figure 9-44 3H concentration in group a/nodes ..................................................................................99

Figure 9-45 3H concentration in group b/nodes ................................................................................100

Figure 9-46 3H concentration in group c/nodes .................................................................................100

Figure 9-47 3H concentration in group d/nodes ................................................................................101

Figure 9-48 DUST MS model ....................................................................................................................107

Figure 9-49 Concentration of 14C ..........................................................................................................113

Figure 9-50 Concentration of 36Cl ..........................................................................................................114

Figure 9-51 Concentration of 60Co ........................................................................................................114

Figure 9-52 Concentration of 137Cs .......................................................................................................115

Figure 9-53 Concentration of 3H /tritium/ .............................................................................................115

Figure 9-54 Concentration of 129I ...........................................................................................................116

Figure 9-55 Concentration of 93mNb ......................................................................................................116

Figure 9-56 Concentration of 59Ni ..........................................................................................................117

Figure 9-57 Concentration of 63Ni ..........................................................................................................117

Figure 9-58 Concentration of 241Pu .......................................................................................................118

Figure 9-59 Concentration of 90Sr ..........................................................................................................118

Figure 9-60 3D model of Saligny site unsaturated zone for HYDRUS ................................................122

Figure 9-61 Saligny site repository area ................................................................................................122

Figure 9-62 Cross section of Saligny site unsaturated zone ...............................................................123

Figure 9-63 2D model, presenting the repository and lateral area ..................................................123

Figure 9-64 Validation of 3D model of the repository unsaturated zone ........................................130

Figure 9-65 C14 volumetric activity in the unsaturated-saturated zone boundary, considering

different properties of the second natural layer .................................................................................130

Figure 9-66 Sr90 volumetric activity (the properties of compacted loess layer are assumed to be

equal to those for silty loess) ..................................................................................................................131

Figure 9-67 Sr-90 volumetric activity in the unsaturated-saturated zone boundary ......................131

Figure 9-68 C-14 volumetric activity (the properties of compacted loess layer are assumed to be




Page 10 of 253

Figure 9-69 C-14 volumetric activity in the last layer (the boundary between unsaturated and

saturated area of Saligny site) in different regions .............................................................................133


saturated area of Saligny site) in different regions, for the first 2500 years .....................................133

Figure 9-71 C-14 Volumetric activity distribution in lateral and transversal direction (2D model)

...................................................................................................................................................................134

Figure 9-72 C-14 volumetric activity in the central and lateral points of the unsaturated –

saturated zone boundary beneath the repository ............................................................................134

Figure 9-73 H-3 volumetric activity (the properties of compacted loess layer are assumed to be

equal to those for red clay on the left graphic and to those for silty loess on the right graphic)

...................................................................................................................................................................135

Figure 9-74 H-3 volumetric activity in the last layer – the FS1 area (the boundary between

unsaturated and saturated area of Saligny site) ................................................................................135

Figure 9-75 H-3 volumetric activity in the last layer (the boundary between unsaturated and

saturated area of Saligny site), performed with the 2D model ........................................................136


saturated area of Saligny site), performed with the 2D model ........................................................136

Figure 9-77 Cs-137 volumetric activity (the properties of compacted loess layer are assumed to

be equal to those for red clay on the left graphic and to those for silty loess on the right) ........137

Figure 9-78 Cs-137 volumetric activity in the last layer – FS1 area (the boundary between


Figure 9-79 I-129 volumetric activity (the properties of compacted loess layer are assumed to be


Figure 9-80 I-129 volumetric activity in the unsaturated – saturated zone boundary in the first

1000 years (the properties of compacted loess layer are assumed to be equal to those for the

silty loess) ..................................................................................................................................................138

Figure 9-81 I-129 Volumetric activity distribution in lateral and transversal direction at different

times (2D model) .....................................................................................................................................139

Figure 9-82 I-129 volumetric activity in the central and lateral point of the unsaturated –

saturated zone boundary beneath the repository ............................................................................140

Figure 9-83 Ni63 volumetric activity (the properties of compacted loess layer are assumed to be


Figure 9-84 Ni63 volumetric activity in the last layer – the FS1 area (the boundary between




Figure 9-86 Ni-59 volumetric activity in the last layer – the FS1 area (the boundary between


Figure 9-87 Cl-36 volumetric activity in the last layer – the FS1 area (the boundary between

unsaturated and saturated area of Saligny site .................................................................................142

Figure 9-88 Am-241 volumetric activity (the properties of compacted loess layer are assumed to

be equal to those for silty loess) ............................................................................................................144



Page 11 of 253

Figure 9-89 Am-241 volumetric activity in the last layer – FS1 area (the boundary between


Figure 9-90 PH01 soil composition .........................................................................................................146

Figure 9-91 PH03 soil composition .........................................................................................................147

Figure 9-92 2D model of Saligny site unsaturated zone according to [7]– region PH01 – (different

colors represent different soil layers) ....................................................................................................149

Figure 9-93-Comparison of the results for C-14 concentration in the unsaturated – saturated

zone boundary ........................................................................................................................................150

Figure 9-94- Carbon concentration – HYDRUS results .........................................................................154

Figure 9-95 Iodine concentration – HYDRUS results ............................................................................154

Figure 9-96 Strontium concentration – HYDRUS results .......................................................................155

Figure 9-97 Tritium concentration – HYDRUS results ............................................................................155

Figure 9-98 Nickel concentration – HYDRUS results .............................................................................156

Figure 9-99 Chlorine concentration – HYDRUS results .........................................................................156

Figure 9-100 Iodine concentration for group a/ nodes .....................................................................157

Figure 9-101 Iodine concentration for group b/ nodes .....................................................................158

Figure 9-102 Iodine concentration for group c/ nodes .....................................................................158

Figure 9-103 Iodine concentration for group d/ nodes .....................................................................159

Figure 9-104 Carbon concentration for group a/ nodes ...................................................................159

Figure 9-105 Carbon concentration for group b/ nodes ...................................................................160

Figure 9-106 Carbon concentration for group c/ nodes ...................................................................160

Figure 9-107 Carbon concentration for group d/ nodes...................................................................161

Figure 9-108 Strontium concentration for group c/ nodes ................................................................161

Figure 9-109 Strontium concentration for group d/ nodes ................................................................162

Figure 9-110 Tritium concentration for group a/ nodes .....................................................................162

Figure 9-111 Tritium concentration for group b/ nodes .....................................................................163

Figure 9-112 Tritium concentration for group c/ nodes .....................................................................163

Figure 9-113 Tritium concentration for group d/ nodes .....................................................................164

Figure 9-114 Ni-59 concentration for group b/ nodes ........................................................................164

Figure 9-115 Ni-59 concentration for group c/ nodes ........................................................................165

Figure 9-116 Ni-59 concentration for group d/ nodes ........................................................................165

Figure 9-117 Cl-36 concentration for group a/ nodes .......................................................................166

Figure 9-118 Cl-36 concentration for group b/ nodes .......................................................................166

Figure 9-119 Cl-36 concentration for group c/ nodes .......................................................................167

Figure 9-120 Cl-36 concentration for group d/ nodes .......................................................................167

Figure 9-121 RESRAD OFFSITE model for the reference scenario ......................................................169

Figure 9-122 Dose per person, all nuclides summed, all pathways summed .................................174



Page 12 of 253

Figure 9-123 Dose per person, all nuclides summed, all pathways summed .................................174

Figure 9-124 Dose for the human – all radionuclides summed, all pathways summed ................177

Figure 9-125 Dose for the human – I-129, all pathways summed .....................................................178

Figure 9-126 Dose for the human –Cl-36, all pathways summed .....................................................178

Figure 9-127 Dose for the human – C-14, all pathways summed .....................................................179

Figure 9-128 Dose for the human – all radionuclides summed, all pathways summed ................179

Figure 9-129 Dose for the human – all pathways summed ...............................................................190

Figure 9-130 Dose for the human – component pathways ...............................................................191

Figure 9-131 Dose for the human – all pathways summed ...............................................................191

Figure 9-132 Dose for the human – component pathways ...............................................................192

Figure 9-133 C-14 concentration in well water ...................................................................................200

Figure 9-134 C-14 concentration in plants ...........................................................................................201

Figure 9-135 C-14 concentration in meat ............................................................................................201

Figure 9-136 C-14 concentration in milk ...............................................................................................202

Figure 9-137 I-129 concentration in well water ...................................................................................202

Figure 9-138 I-129 concentration in plants ...........................................................................................203

Figure 9-139 I-129 concentration in meat ............................................................................................203

Figure 9-140 I-129 concentration in milk ...............................................................................................204

Figure 9-141 Cl-36 concentration in well water ...................................................................................204

Figure 9-142 Cl-36 concentration in plants ..........................................................................................205

Figure 9-143 Cl-36 concentration in meat ...........................................................................................205

Figure 9-144 Cl-36 concentration in milk ..............................................................................................206

Figure 9-145 C-14 concentration in the air above the primary contamination .............................207

Figure 9-146 C-14 concentration in the air above the offsite dwelling ...........................................207

Figure 9-147 C-14 concentration in the offsite dwelling surface soil ................................................208

Figure 9-148 C-14 concentration in plants ...........................................................................................208

Figure 9-149 C-14 concentration in meat ............................................................................................209

Figure 9-150 C-14 concentration in milk ...............................................................................................209

Figure 9-151 Cs-137 contamination in the contaminated soil (time variation) ..............................210

Figure 9-152 Cs-137 concentration in the offsite dwelling surface soil ............................................210

Figure 9-153 2D model, presenting the repository and lateral area ................................................220

Figure 9–154 14C concentration Figure 9–155 60Co concentration ...........................................222

Figure 9–156 137Cs concentration ..........................................................................................................222

Figure 9–157 90Sr concentration Figure 9–158 36Cl concentration ...............................................223

Figure 9–159 14C concentration Figure 9–160 137Cs concentration .............................................223

Figure 9–161 14C concentration Figure 9–162 36Cl concentration ...............................................224



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Figure 9–163 137Cs concentration Figure 9–164 129I concentration ..............................................224

Figure 9–165 59Ni concentration ...........................................................................................................225

Figure 9–166 129I concentration Figure 9–167 36Cl concentration ................................................225

Figure 9–168 59Ni concentration ...........................................................................................................226

Figure 9–169 3H concentration – 2 m Figure 9–170 3H concentration – 10 m .............................226

Figure 9–171 - 14C concentration Figure 9–172 - 14C concentration – peak zoom in ................227

Figure 9-173 Comparison of C-14 concentration ...............................................................................227

Figure 9-174 C-14 Volumetric activity distribution in lateral and transversal direction, considering

one meter of sand (2D model)..............................................................................................................228

Figure 9–175 3H concentration dependence on clay effective porosity........................................228

Figure 9–176 3H concentration dependence on Darcy flow ...........................................................229

Figure 9–177 Dose rate dependence on “Fruits, grains and non leafy vegetables” consumption

...................................................................................................................................................................229

Figure 9–178 Dose rate dependence on “Water Ingestion”.............................................................230

Figure 9–179 MERCURAD scene for calculations ................................................................................230



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9. SAFETY ASSESSMENT FOR THE POST-CLOSURE PERIOD

9.1. OBJECTIVE AND PURPOSE OF THE UPDATED SAFETY ASSESSMENT FOR THE POST-

CLOSURE PERIOD

The safety assessment for the post-closure period is a result of the implementation of Activity

4 “Analysis and completion of the safety assessment documentation for siting a near

surface radioactive waste disposal facility in Saligny” of PHARE project RO 2006/018-

147.05.01. The safety assessment is developed in accordance with the requirements of the

Technical Specification [1] and the authorization conditions of [2].The safety assessment for

the post-closure period of Saligny repository is performed considering the requirements of

Romanian regulations NDR 05 [3] and NSR-01 [4].

The recommendations of the report of IAEA Mission WATRP/2006 for verifying the Technical

and Safety Documentation necessary for the authorization of Saligny site for DFDSMA [5]

and the Report of the Mission of Experts IAEA no. IAEA-TCR-03852 [6] are used as a base for

the performance of the post-closure safety assessment.

During the performance of the post-closure safety assessment the following main sources of

data are used:

Final assessment report of the Saligny site performance [7];

Saligny Data base (08.04.2009) [28];

Updated waste inventory [19] developed under the scope of Activity 5 of PHARE

project RO 2006/018-147.05.01;

Waste acceptance criteria [25] developed under the scope of Activity 5 of PHARE

project RO 2006/018-147.05.01;

Reviewed conceptual design [38] developed under the scope of Activity 3 of PHARE

project RO 2006/018-147.05.01;

The following IAEA documents are applied during the performance of the post-closure

safety assessment:

INTERNATIONAL ATOMIC ENERGY AGENCY, Disposal of Radioactive Waste, IAEA, Safety

Standards Series, IAEA, Vienna (draft-DS 354)[8];

IAEA, Safety Standard Series, The safety case and safety assessment for radioactive

waste disposal (draft DS 355), IAEA, Vienna, 2008 [9];

Improvement of Safety Assessment Methodologies for Near Surface Disposal Facilities.

Volume I: Review and Enhancement of Safety Assessment Approaches and tools. IAEA-

ISAM-1, Vienna, 2004 [10];

Near Surface Disposal of Radioactive Waste, IAEA Safety standards Series No.WS-R-1,

Vienna 1999 [11];

Safety Assessment for Near Surface Disposal of Radioactive Waste, IAEA Safety Guide

No. WS-G-1.1, Vienna, 1999 [12];

INTERNATIONAL ATOMIC ENERGY AGENCY, Fundamental Safety Principles. Safety

Fundamentals No. SF-1, IAEA, Vienna, 2006 [24];

IAEA Safety standard, Safety assessment for facilities and activities, GSR Part 4, May

2009 [13];



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IAEA TECDOC 1255, Performance of engineered barrier materials in near surface

disposal facilities for radioactive waste, November 2001 [20];

IAEA TECDOC 1256, Technical considerations in the design of near surface disposal

facilities for radioactive waste, November 2001 [18];

IAEA TECDOC-1372, Safety indicators, 2003 [40]

IAEA TECDOC 1380, Derivation of activity limits for the disposal of radioactive waste in

near surface disposal facilities, IAEA, Vienna, December 2003 [36]

The methodology used for the post-closure safety assessment is based on the Improvement

of Safety Assessment Methodologies for Near Surface Disposal Facilities [10].

The purpose of this Chapter is to present in detail the development of reference and

alternative scenarios for the post-closure period of Saligny repository, the elaboration of

conceptual models for the near filed, unsaturated area, saturated area and biosphere, the

selection of computer tools, the development of the mathematical models, the

performance of the calculations, the uncertainty and sensitivity analysis and the

interpretation of results.

All results from the performed calculations are compared to the selected safety indicators

for Saligny site (presented in Chapter 2) in order to evaluate the safety margins of Saligny

repository.

9.2. ENSURING THE SAFETY DURING THE POST-CLOSURE PERIOD

The function of Saligny radioactive waste repository is to protect the public and

environment from the dangers, coming from the waste, during the time such dangers exist.

This is performed by the collection of the waste in isolated volumes (modules and cells). The

repository operator shall interrupt all the human interventions, closely watch the

maintenance of good condition of the repository and eliminate eventual breaches of

restrictions. The radioactive decay provides for a natural decrease of the waste radiation

and limits the period of necessary active monitoring over the repository area.

After a period which is equal to 10 times the radioactive decay half time, the harmful effect

of the waste will be reduced by the factor 1000, and the residual quantity of the

radionuclides with long period of life shall not exert an unacceptable human and

environment influence. Therefore, as concerns beta and gamma radioactivity, the disposal

of waste with short or middle life radionuclides of weak or middle activity per unit of mass

may be accepted for final surface disposal. For such wastes, Cesium 137 may be

considered representative isotope, having a decay half time of approximately 30 years.

Therefore, it is necessary to provide a reliable organization of the companies and the

institutions which will monitor the repository and keep record of the history for a period of

about 300 years.

The design of Saligny repository ensures that the releases will not exceed applicable

regulatory limits during the operational and post-closure periods and will be as low as

reasonably achievable (ALARA) taking into account the relevant economic and social

factors.

The radiological safety of the operators, population and environment is ensured in

designing Saligny repository by strict application of the principle of radiation exposure

limitation. According to this principle, exposure to unacceptable risks of ionizing radiation

must be completely prevented. Consequently, the risk of exposure and the expected

doses, resulting from a possible exposure are the main safety indicators of Saligny repository

design.



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From technical point of view, the radiological protection is ensured by application of three

basic methods: protection (of people and environment), optimization (of repository systems

and operation procedures) and limitation (of the risk for exposure).

The repository design provides materials, systems and procedures, which bring the possible

exposure to ionizing radiation in conformity with the dose limits established for the operators,

population and environment according to the Romanian legislation and IAEA

recommendations.

According to the international practice, the post closure period is divided in the following

sub-periods:

o Active institutional Control Period – 100 years: the active institutional control is

designed to physically control access to the disposal facility. It consists in three

types of controls:

- proprietary institutional controls which are put in place by the property

owner, as physical protection;

- governmental institutional controls, which are based on a government's

authority or police powers, such as zoning, water well-use restrictions, and

building permit requirements;

- physical controls such as fences, markers, earthen covers, and radiological

monitoring and maintenance for such controls.

Active maintenance is also required to maintain wastes’ radioactivity

containment structures (enveloping).

o Passive institutional control period – 200 years:

- Administrative restriction of land use

- The safety of the facility is ensured by the remaining life time of the

engineered barriers.

o Post-Closure Period after 300 years:

- No protection activities are performed.

- During this period, physical access controls to the disposal site are assumed

to be lost, containment structures have failed, and the site surveillance has

ceased.

- It is assumed that general knowledge of the disposal facility location and

previous use of the site are lost.

- Wind and water erosion, as well as other phenomena, may expose the

wastes.

- Radionuclides may migrate along the air, surface water, and groundwater

pathways.

- Inadvertent human intrusion is considered as a possible spreading pathway

for contaminating elements.

Institutional control is a control of a radioactive waste site by an authority or institution

designated under the law. This control may be active – monitoring, surveillance, remedial

works or passive (land use control) and is a factor in the design the near surface repository.

Monitoring is the measurement of the dose or contamination for reasons related to the

assessment or control of exposure to radiation or radioactive substances and the



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interpretation of the results. The monitoring of the facility will allow corrective actions to be

taken when monitoring indicates unacceptable performance.

Additional reassurance is achieved by monitoring of the repository environment for eventual

releases of radionuclides.

During operation and closure of the repository, as well as after its closure, maintenance will

be provided to ensure that the isolating of the waste/controlling of the releases, and

minimizing of the impacts objectives are still observed. The objective during all stages is to

achieve the necessary degree of safety through the use of passive rather than active

control systems.

The long term post-closure safety of the population and environment is ensured by:

- protection from direct radiological exposure (in case of human activities);

- protection from radioactivity release with soil, air, water and other fluids;

- protection from intake of radio-active particles by breathing, food or water.

The long term safety of Saligny near surface repository is achieved through a combination

of favorable site characteristics, engineered design features, appropriate form and content

of the wastes, operating procedures and institutional controls (monitoring).

This activity includes the continued surveillance of the site for a period of 100 years after the

closure of the repository and during this period such surveillance represents an important

safety factor.

The safety in the period when active institutional control is no longer maintained, or it is

assumed that this control is not fully effective, the so called passive institutional control

period (200 years) is ensured by demonstration of conformity with safety requirements

depending on present assessments of the robustness and future performance of the

repository.

The final disposal concept proposed for Saligny repository - a surface repository with

multiple barriers, is developed in detail in the document “Safety concept for DFDSMA” [44]

and presented as well in Chapter 2. The concept is selected according to the waste

categories commonly resulted from the operation and decommissioning of CANDU type

reactors. The French and other international experience are considered in the process of

selection of the disposal concept, as well. Chapter 2 presents the definition of the safety

objectives, safety principles, defense in depth principles and the confinement (isolation)

strategy.

Saligny repository will continue to present a potential hazard to human health during the

post-closure period. Due to this fact an attention has to be oriented towards potential doses

and potentially exposed groups.

Radiological safety criteria for the post-closure phase are defined in the form of dose

criteria. The dose limits for population prescribed in Romania norm NDR-05 [3] shall be

applied during the post-closure phase of the repository.

At a deeper level of safety consideration the design of Saligny repository observes specific

dose constraints, which are more conservative than the dose limits and ensure safety

margins that are available for eventual occurrences of very low probability. These

constraints are developed by application of the ALARA principle: “Radiation exposure for

the professionally exposed people and for the population, caused by Saligny repository

shall be kept as low as reasonably achievable, considering the current economic and

social factors”.



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The object of post-closure safety assessment is to evaluate the design values of the safety

indicators and by comparison to the dose limits and dose constraints to define the safety of

the repository on a long term.

The process of selection of the safety indicators for Saligny repository is presented in detail in

the report “Safety Concept for DFDSMA” [44].

Dose limits and dose constraints comparison between the Romanian regulations [3] and [4],

European practice and French experience is performed and also presented in [44].

Document [44] also includes the safety objectives as concerns the exposure of population

and personnel under normal conditions and in case of accident, as well as the dose limits

and constraints for the population and personnel, applicable in case of Saligny repository.

They comply with the ones defined in the Romanian regulation NSR-01[4], also complying

with the international practices.

The dose limits and constraint for Saligny repository presented in [44] are the following:

1. The limit of an effective dose for occupational exposed workers is of 20 mSv per year.

2. The limit of effective dose for population is of 1 mSv per year.

3. The effective dose constraint for the population during the post-closure period of

Saligny repository is of 0,3 mSv/year.

4. The effective dose constraint for the personnel during the post-closure period of

Saligny repository is of 5 mSv/year.

Document [44] also defines complementary safety indicators in order to evaluate and

confirm the long-term safety of Saligny repository. For very long time (more than 10 000

years) the maximum concentrations of radionuclides in the drinking water are considered

complementary safety indicators for Saligny repository.

The maximum limits of the contaminants in the drinking water (evaluated for an estimated

effective dose of 0,1 mSv/a) according to [35] are as follows:

Radionuclide Bq/l

Cs 137 1.1E+01

Sr 90 1.9

I-129 9.6E-01

C-14 2.3E+02

H-3 7.6E+03

Ni-59 1.1E+03

Directive 98/83 [45] establishes the maximum concentration of tritium in the drinking water

at 100 Bq/l and the total indicative dose – 0.10 mSv/y.

International Commission for radiological protection in Publication 30 [15] establishes the

maximum concentration of tritium and tritium oxide in the air at respectively 540 µCi/m3 and

21 µCi/m3.

9.3. METHODOLOGY FOR THE POST-CLOSURE SAFETY ASSESSMENT

The purpose of the quantitative safety analysis is to evaluate the consequences from:

direct exposure on the personnel;



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indirect irradiation to the population;

impact on the biosphere, hydrosphere, geo-sphere.

The purpose of quantitative safety analysis and the sequence of related activities are

clearly defined as a basis for performance of the safety assessment of Saligny repository.

The safety assessment of the post-closure period of Saligny repository is made based on the

current methodologies in the field, recommended by CNCAN.

The method of post-closure safety assessment is based on the ISAM methodology [10], the

applicable IAEA documents and French experience.

The main steps of the methodology for the post-closure safety assessment of Saligny

repository are as follows:

Definition of legislative framework – review of Romanian regulatory framework, the

applicable IAEA documents and good international practice;

Review of the design features of Saligny repository – conceptual design, site

characterization data, safety documentation, description of disposal and transport

operations;

Definition of safety assessment content for the post-closure period;

Definition of the safety objective, safety principles and safety requirements;

Definition of safety criteria - main and complementary safety indicators applicable to

the post-closure period;

Definition of main safety functions for the post-closure period;

Analysis of the multiple barrier system considering all types of potential pathways

achieving the defense in depth;

Identification of the contaminant transport pathways;

Development and justification of Features, Events and Processes (FEP) list for the post-

closure period;

Development and justification of the scenarios – reference and alternative scenarios for

the post-closure period;

Development of conceptual models – near field model, unsaturated zone model,

saturated zone model and biosphere model;

Development of computer models for the reference and alternative scenarios;

Quantitative assessment of the reference and alternative scenarios;

Comparison of the results to the defined safety criteria for Saligny repository;

Interpretation of the results and drawing of conclusions concerning the safety of Saligny

repository during the post-closure period.

Figure 9-1 General sequence of the safety analysis presents the general sequence of the

safety analysis.



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Figure 9-1 General sequence of the safety analysis

Safety Assessment contents

Development of physical

models

Calculations, Sensitivity and

Uncertainty analysis

Development of the computer

models

Interpretation of the results

Elaboration of conclusions

Development and justification

of the scenarios

Design of the repository systems

Comparison to

safety criteria

Acceptance

YES NO Review and modifications

Definition of features, events

and processes



Page 21 of 253

9.4. IDENTIFICATION OF FEATURES, EVENTS AND PROCESSES

The FEP list for the post-closure period is based on the requirements of the Romanian

regulations and international practice in the field.

The FEP list for the post-closure period is presented in detail in document “Report regarding

the existing FEP list and proposal for an updated FEP list” [42].

FEP list contents and structure comply in detail with the generic list of FEPs given in [37].

The FEPs are classified into four groups, according to the classification in [10]:

0. Assessment Context

1. External Factors;

2. Internal Factors;

3. Contaminant factors.

According to [10] each FEP is classified by its specific identification number. The number

consists in three digits:

– first digit presents the FEP layer;

– second digit presents FEP category;

– third digit presents FEP number in the respective category.

The post-operational phase FEP list is sub-divided into two additional parts – for the institution

control phase and for the post-institution control phase.

Requirements regarding the FEP list elaboration according to the Romanian legislation and

the applicable IAEA requirements are presented in [42]. Comparison of Saligny repository

FEP list to the IAEA FEP list is performed and presented as well.



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9.5. CONTAMINANT TRANSPORT PATHWAYS

The main pathways of contaminant transport are defined and presented in Figure 9-2.

Figure 9-2 Potential pathways for transport of contaminants

1. Repository to unsaturated zone

2. Unsaturated zone to saturated zone;

3. Unsaturated zone to surface water;

4. Unsaturated zone to surface soil;

5. Saturated zone to underground water;

6. Underground water to drinking water;

7. Underground water to surface;

8. Surface soil to air;

9. Surface water to drinking water;

10. Surface water to fish;

11. Surface soil to surface water;

12. Surface water to surface soil;

13. Surface soil to plants;

14. Underground water to surface water;



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15. Surface water to air;

16. Plants to food;

17. Plants to animals;

18. Animals to food;

19. Underground water – external exposure;

20. Drinking water – internal exposure;

21. Fish – internal exposure;

22. Air – internal/external exposure;

23. Food – internal exposure;

24. Exposure from repository gamma sources.

9.6. DEFINITION OF SCENARIOS

9.6.1. General considerations

Definition of the term “scenario”: A scenario is a hypothetical sequence of processes and

events chosen from a set, destined to illustrate the range of future behavior and states of a

repository system, for the purposes of evaluating the safety concept [10].

Scenarios are description of alternative, but internally consistent, future evolutions and

conditions of the waste disposal system, sequences of events and accepted limiting

conditions [10].

The main purpose of scenario elaboration in the safety assessment of Saligny repository is

therefore to use scientifically-informed expert judgment to guide the safety evaluation of

the disposal system and its future behavior.

Scenario generation is important to the safety assessment for several reasons:

Scenarios provide the context in which safety assessments are performed. The analysis

of the long term performance of a radioactive waste disposal system cannot be

performed without considering future conditions of the site;

Scenarios allow to quantify the performances of the disposal and to verify the good

dimensioning of the barriers;

Scenarios influence model development and data collection efforts;

Scenarios provide an important area of communication between repository developers

and regulators, and other stakeholders with an interest in repository safety;

Scenarios are a very important aspect in building confidence for the post-closure safety

assessment and therefore also a focal point of independent reviewers of the

assessment.

Scenarios depend on the environment and system characteristics, as well as on events and

processes which could either initiate the release of radionuclides from waste or influence

their transport to humans and the environment. The choice of appropriate scenarios and

associated conceptual models is very important and strongly influences subsequent analysis

of the waste disposal system.

The following initiating events/activities shall be considered during scenarios’ development:

natural processes and events;

waste and disposal facility characteristics and operational activities;



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non-operational human activities.

Some of these events can be considered as not relevant to quantitative analysis because

of their low probability, or due to their magnitude and consequences specific for the site.

Figure 9-3 presents the general classification of the scenarios.

Figure 9-3 Classification of scenarios

The selected scenarios provide an appropriately comprehensive picture of key aspects of

the system, their possible evolution pathways, critical events and system robustness. In this

context, it is extremely important to have a systematic scenario generation approach and

to document all steps while generating the scenarios. This allows the analysis of a

reasonable set of scenarios that can be used to ensure that the system will remain safe in

the future.

A single reference scenario is developed for initial consideration. The “Reference“ scenario

represents how the system might be expected to behave assuming the design operates as

planned.

“Alternative” scenarios are then developed to investigate the impact of scenarios that

differ from the reference scenario. The reference scenario is considered to be the most likely

scenario for the safety assessment; it is considered to be a benchmark scenario against

which the impact of alternative scenarios can be compared.

The scenario development method consists of:

analysis of the established FEPs list;

defining the main FEPs to be considered in the assessment of the scenarios, and their

associated states;

building the combinations/sequences of the defined states;

review and grouping of the scenarios into categories.

The following basic requirements are used during the systematic scenario generation:

Transparency, including documentation and handling of expert judgment;

Comprehensiveness – all possible FEPs, which significantly influence the disposal

system and the release of radionuclides are considered;

Description of the relevant future evolutions;

Identification of the critical issues;

Investigation of the robustness of the system.



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9.6.2. Methodology for selection of scenarios

The set of scenarios is generated based on the review and analysis of the FEPs list and the

applicable IAEA recommendations [8], [11], [12], [13] and [36]. The observations of IAEA

mission reports [5] and [6] were considered during the preparation of scenarios. The chapter

presents a brief description of each scenario as well as the conceptual models and ways of

exposure.

The methodology applied for the development of the scenarios for Saligny repository is

based on ISAM methodology [10].

The scenario development methodology consists in the following main steps:

Review of the FEPs list in order to identify FEPs and their potential relevance to the

repository during the post-closure period.

Categorization of FEPs in order to identify contributions to scenario development.

Evaluation of relationships between FEPs.

Development of interaction matrixes for each repository life period.

Identification of the reference scenarios based on the interaction matrix and the FEPs

describing the normal operation of the repository in different periods of repository’s

operation.

Identification of the alternative scenarios for each period based on the interaction

matrix and a failure analysis, identification of their likelihood and identification of the

type of process, features and events relevant.

Definition of the contaminant transfer pathways – the pathways which will be analyzed

in order to prove the protection of the entire population from releases of radioactivity in

the air, soil, groundwater, surface water, plant uptake and exhumation by animals.

Development of the conceptual models for reference and alternative scenarios for all

life periods of the repository.

The application of this approach has resulted into the development of the reference

scenario and alternative scenarios for the post-closure period.

9.6.3. Definition of the scenarios for the post-closure period

The FEPs defined in FEPs list were analyzed, being selected and presented the FEPs related

to scenarios development in the post-closure period. The identification of the selected FEPs

complies with the numbering defined in FEPs list.

The interaction matrix presenting the possible transportation paths of the radionuclides and

the human exposure during the post-closure period is presented in Appendix 9.1.

In order to define the reference and alternative scenarios for the post-closure period the

following grouping of FEPs is applied:

• Initial and boundary conditions:

FEPs defining the assessment assumptions;

FEPs defining the internal factors;

FEPs defining the external repository factors;

FEPs defining the external human actions;

FEPs defining the data on population and staff’s habits.



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• Normal development (for reference scenario)+ FEP related to the definition of the events

that lead to initiating repository development scenarios (for alternative scenario);

• Contamination consequences.

Based on the FEPs defining the conditions of the repository and interaction matrixes for the

post-closure period, reference and alternative scenarios are selected.

9.6.4. Definition of the scenarios for the active institutional control during the post-

closure period

The FEPs defined in FEP list [42] are reviewed and the FEPs related to scenarios development

in the active institutional control during the post-closure period are selected and presented

below. The identification of the selected FEPs is in accordance with the numbering defined

in the FEPs list.

The interaction matrix presenting the possible radionuclides transport paths and human

exposure means during the active institutional control of post-closure period is presented in

Appendix 9.1.

9.6.4.1. Definition of the reference scenario

Initial and boundary conditions

FEPs related to the definition of the Initial and boundary conditions for the reference

scenario in the active institutional post-closure period are as follows:

FEPs defining the assessment assumptions:

o 0.1Assessment endpoints

o 0.2 Timescales of concern

o 0.3 Spatial domain of concern

o 0.4 Repository assumptions

o 0.5 Future human action assumptions

o 0.6 Future human behavior (target group) assumptions

o 0.8 Assessment purpose

o 0.9 Regulatory requirements and exclusions

o 0.10 Model and data issues

FEPs defining the internal factors:

o 1.1.6 Records and markers, repository

o 1.1.8. Quality control

o 1.1.10 Administrative control, repository site

o 1.1.11 Monitoring of repository

o 2.1.1 Inventory, radionuclide and other materials

o 2.1.2 Waste form materials, characteristics and degradation processes

o 2.1.3 Container materials, characteristics and degradation/failure processes

o 2.1.4 Buffer/backfill materials, characteristics and degradation processes

o 2.1.5 Engineered barrier system characteristics and degradation processes

o 2.1.6 Other engineered features materials, characteristics and degradation

processes



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o 2.1.7 Mechanical processes and conditions (in waste and engineered

barriers)

o 2.1.10. Biological/biochemical processes and conditions (in waste and

engineered barriers)

o 2.3.1 Topography and morphology

o 2.3.2 Soil and sediments

o 2.3.3 Aquifers and water-bearing features, near surface

o 2.3.4 Lakes, rivers, streams and springs

o 2.3.7 Atmosphere

o 2.3.8 Vegetation

o 2.3.9 Animal populations

o 2.3.10 Meteorology

o 2.3.11 Hydrological regime and water balance (near-surface)

o 2.3.12 Erosion and subsidence

o 2.3.13 Ecological/biological/microbial systems

FEPs defining the external repository factors:

o 1.2.2 Anorogenic and within-plate tectonic processes (elastic, plastic or

brittle deformation)

o 1.2.3 Seismicity

o 1.2.7 Erosion and sedimentation

o 2.2.2 Host lithology

o 2.2.3 Lithological units, others

FEPs defining the external human actions:

o 1.4.10 Water management (wells, reservoirs, dams)

o 1.4.11 Social and institutional developments

FEPs defining the data for population and staff’s habits:

o 2.4.1 Human characteristics (physiology, metabolism)

o 2.4.2 Adults, children, infants and other categories

o 2.4.3 Diet and fluid intake

o 2.4.4 Habits (non-diet-related behavior)

o 2.4.5 Community characteristics

o 2.4.6 Food and water processing and preparation

o 2.4.8 Wild and natural land and water use

o 2.4.9 Rural and agricultural land and water use (incl. fisheries)

o 2.4.10 Urban and industrial land and water use

Institutional control

FEPs related to the definition of the normal operation of the facility during the active

institutional control are as follows:



Page 28 of 253





Contamination consequences

FEPs related to the estimation of the consequences resulted from contamination of the

facility during the active institutional control of post-closure period are as follows:

o 2.1.12 Gas sources and effects (in waste and EBS)

o 2.1.13 Radiation effects (in waste and EBS)

o 2.2.5 Contaminant transport paths’ characteristics (in geosphere)

o 2.2.7 Hydraulic/hydrogeological processes and conditions (in geosphere)

o 3.1.1 Radioactive decay and in-growth

o 3.1.4 Volatiles and potential for volatility

o 3.1.5 Organics and potential for organic forms

o 3.1.6 Noble gases

o 3.2.1 Dissolution, precipitation and crystallization, contaminant

o 3.2.2 Speciation and solubility, contaminant

o 3.2.3 Sorption/de-sorption processes, contaminant

o 3.2.4 Colloids, contaminant interactions and transport with colloids

o 3.2.7 Water-mediated transport of contaminants

o 3.2.8. Solid-mediated transport of contaminants

o 3.2.9 Gas-mediated transport of contaminants

o 3.2.10 Atmospheric transport of contaminants

o 3.2.12 Human-action-mediated transport of contaminants

o 3.2.13 Food chains, uptake of contaminants

o 3.3.1 Drinking water, foodstuffs and drugs, contaminant concentrations

o 3.3.2 Environment, contaminant concentrations

o 3.3.3. Non-food products, contaminant concentrations

o 3.3.4 Exposure modes

o 3.3.5 Dosimetry (exposure impact factors for the human body)

o 3.3.6 Radiological toxicity/effects

o 3.3.7 Non-radiological toxicity/effects

o 3.3.8 Radon and radon daughter exposure

Based on the FEPs defining the conditions of the facility during the active institutional control

and interaction matrix for this period the following reference scenarios are selected:

For the operators - direct exposure to radon or gamma radiation of staff performing

the control of the water tanks’ monitoring in the collecting system’s gallery



Page 29 of 253

For the critical group – Consumption and use of the groundwater in small farms

outside of the facility considering the indirect irradiation to the population; the

critical group is considered to consist in the inhabitants of a small farm situated on

the site. Contaminated water is supposed to be used at the farm.

For the environment – evaluation of the impact on the biosphere, hydrosphere,

geosphere:

o offsite accumulation of contaminants:

- surface soil;

- surface water;

- plants;

- animals;

- aquatic food.

9.6.4.2. Definition of the alternative scenarios


FEPs related to the definition of the Initial and boundary conditions for the alternative

scenarios in the active institutional post-closure period are as follows:






















processes



Page 30 of 253


barriers)




o 2.3.2 Soil and sediment



o 2.3.7 Atmosphere

o 2.3.8 Vegetation






FEPs defining the external repository factors:

o 1.2.2 Anorogenic and within-plate tectonic processes (deformation,

elastic, plastic or brittle)

o 1.2.3 Seismicity



o 2.2.3 Lithological units, other

FEPs defining the external human actions:

o 1.4.5. Un-intrusive site investigation



o 1.4.14 Explosions and crashes

FEPs defining the data for the population and staff habits:


o 2.4.2 Adults, children, infants and other variations








Initiating events



Page 31 of 253

FEPs related to the definition of initiating events during the active institutional control are as

follows:

o 1.2.3 Seismicity





processes





facility during the active institutional control period are as follows:

o 2.1.12 Gas sources and effects (in waste and EBS)

o 2.1.13 Radiation effects (in waste and EBS)

o 2.2.5 Contaminant transport path characteristics (in geosphere)





o 3.1.6 Noble gases












o 3.3.2 Environmental media, contaminant concentrations








Page 32 of 253


Based on the FEPs defining the initiating events and the interaction matrix for the active

institutional control the following alternative scenarios are selected for the preliminary

screening:

Failure of a closure roof element - upper concrete slab of a cell or multi-layer cover

panel;

Direct accidental release of radioactive water of the collecting system into the

storm basin and then into the groundwater;

Failure of the ground slab;

Cell bath tubing effect - not applicable due to the availability of active institutional

control and measures to discover the leak and drain the cell;

Earthquakes – not considered as initiating events but, due to the fact that their

effect is covered by other scenario, they have not been selected for the detailed

analysis (justification is presented at point 8.6.3.2, Chapter 8);

Events caused by severe meteorological phenomena- not selected for the detailed

analysis (justification is presented in it. 8.6.3.2, Chapter 8);

Explosions and crashes - not selected for the detailed analysis (justification is

presented in it. 8.6.3.2, Chapter 8).

As a result of the preliminary screening of the considered scenarios the following alternative

scenarios for the active institutional control during post-closure period are selected:

Failure of a roof closure element;

Direct accidental release of radioactive water of the collecting system into the

storm basin and then into the groundwater;

Failure of the ground slab.

These scenarios are subject to detailed quantitative analysis for the active institutional

control during post-closure period.

9.6.5. Definition of the scenarios for the passive institutional control during post-

closure period

The FEPs defined in FEP list [42] were reviewed and the FEPs related to scenarios

development for passive institutional control during the post-closure period are selected

and presented below. The identification of the selected FEPs is in accordance with the

numbering defined in the FEPs list [42].

The interaction matrix presenting the possible radionuclides transport paths and human

exposure during the passive institutional control of post-closure period is presented in

Appendix 9.1.




scenario in the passive institutional control during the post-closure period are as follows:






Page 33 of 253












o 2.1.1 Inventory, radionuclide and other material






processes


barriers)

o 2.1.8 Hydraulic/ hydrogeological processes and conditions (in waste and


o 2.1.9 Chemical/geochemical processes and conditions (in waste and








o 2.3.7 Atmosphere

o 2.3.8 Vegetation






FEP defining the external repository factors:



Page 34 of 253

o 1.2.2 Anorogenic and within-plate tectonic processes (Deformation,


o 1.2.3 Seismicity




FEP defining external human actions:

o 1.4.2 Motivation and knowledge issues (inadvertent/deliberate human

actions)

o 1.4.3 Drilling activities (human intrusion)





FEP defining data for the population and staff habits:










o 2.4.11 Leisure and other uses of environment

Passive control

FEPs related to the definition of normal operation during the passive institutional control are

as follows:






facility during the active institutional control of post-closure period are as follows:

o 2.1.12 Gas sources and effects (in waste and engineered barriers)

o 2.1.13 Radiation effects (in waste and engineered barriers)





Page 35 of 253




o 3.1.6 Noble gases



















Based on the FEPs defining the conditions of the repository during the passive institutional

control and interaction matrix for this period the following reference scenarios are selected:

For the operators – not applicable

For the critical group – Consumption and use of the groundwater in the small farm

outside of the facility considering the indirect irradiation to the population;


geosphere:

o accumulation of contaminants in offsite:

- surface soil;

- surface water;

- plants;

- animals;

- aquatic food.





Page 36 of 253


scenarios in the passive institutional control period are as follows:





















processes


barriers)

o 2.1.8 Hydraulic/hydrogeological processes and conditions (in waste and










o 2.3.7 Atmosphere

o 2.3.8 Vegetation




Page 37 of 253





FEP defining the external repository factors:



o 1.2.3 Seismicity




External human actions:


actions)

o 1.4.5 Un-intrusive site investigation





Data for the population and staff habits:











Initiating events

FEPs related to the definition of initiating events during the passive institutional control are as

follows:

o 1.2.3 Seismicity







Page 38 of 253



processes





facility during the active institutional control during post-closure period are as follows:








o 3.1.6 Noble gases



















Based on the FEPs defining the conditions of the repository during the passive institutional

control and interaction matrix the following alternative scenarios are selected for the

preliminary screening:

Failure of several closure system elements;



Page 39 of 253


Cell bath tubing effect (accumulation of water);

Earthquakes – considered initiating events, but not selected for the detailed analysis

(justification is presented in it. 8.6.3.2, Chapter 8);


analysis (justification is presented in it. 8.6.3.2, Chapter 8);


presented in it. 8.6.3.2, Chapter 8).


scenarios for the passive institutional control during post-closure period are selected:

Failure of several closure system elements;


Cell bath tubing effect (accumulation of water);

These three scenarios are subject to detailed quantitative analysis.

9.6.6. Definition of the scenarios for the post-closure period after 300 years

The FEPs defined in FEP list [42] are reviewed and the FEPs related to scenarios development

in the post-closure period after 300 years are selected and presented below. The

identification of the selected FEPs is in accordance with the numbering defined in the FEPs

list [42].

The interaction matrix presenting the possible radionuclides transportation paths and

human exposure during the passive institutional control of post-closure period is presented in

Appendix 9.1.




scenario in the post-closure period after 300 years are as follows:











FEP related to the definition of the Initial status of the facility:

Internal Factors:





Page 40 of 253

o 2.1.3 Container materials, characteristics and degradation/failure

processes


o 2.1.5 Engineered barrier system characteristics and degradation

processes

o 2.1.6 Other engineered features materials, characteristics and

degradation processes


barriers)

o 2.1.8 Hydraulic/hydrogeological processes and conditions (in waste and







o 2.3.2 Soil and sediment



o 2.3.7 Atmosphere

o 2.3.8 Vegetation

o 2.3.9Animal populations





External repository factors:



o 1.2.3 Seismicity



o 2.2.3 Lithological units, other

FEP related to the definition of the human behavior:



actions)





Page 41 of 253

o 1.4.6 Surface excavations

o 1.4.8 Site development

o 1.4.9 Archaeology















FEP related to the normal conditions during the post-closure period after 300 years





processes

FEP related to the estimation of the contamination consequences:




o 2.2.7 Hydraulic/hydro-geological processes and conditions (in geosphere)




o 3.1.6 Noble gases








Page 42 of 253














Based on the FEPs defining the conditions of the facility during the post-closure period after

300 years and interaction matrix for this period the following reference scenarios are

selected:

For the operators – not applicable

For the critical group – Consumption and use of the groundwater in the small farm

onside of the facility considering the indirect irradiation of the population; the critical

group is considered to consist in the inhabitants of a farm located on repository site.

The farm shall use contaminated water.


geosphere:

o accumulation of contaminants in offsite:

- surface soil;

- surface water;

- plants;

- animals;

- aquatic food.




scenarios in the post-closure period after 300 years are as follows:









Page 43 of 253





FEP related to the definition of the Initial status of the repository:

Internal Factors:

o 2.1.1 Inventory, radionuclide and other material


o 2.1.3 Container materials, characteristics and degradation/failure

processes


o 2.1.5 Engineered barrier system characteristics and degradation

processes

o 2.1.6 Other engineered features materials, characteristics and

degradation processes


barriers)

o 2.1.8 Hydraulic/hydro-geological processes and conditions (in waste and










o 2.3.7 Atmosphere

o 2.3.8 Vegetation




o 2.3.12 Erosion and deposition


External repository factors:



o 1.2.3 Seismicity




Page 44 of 253



FEP related to the definition of the human behavior:



actions)





o 1.4.9 Archaeology















FEP related to the definition of the initiating events:

o 1.2.3 Seismicity





o 1.4.9 Archaeology



processes


FEP related to the estimation of contamination’s consequences:




Page 45 of 253



o 2.2.7 Hydraulic/hydro-geological processes and conditions (in geosphere)




o 3.1.6 Noble gases



















Based on the FEPs defining the initiating events and the interaction matrix for the post-

closure period after 300 years the following alternative scenarios are selected for the

preliminary screening:

Farm on the repository - Residence scenario on totally degraded wastes (repository

disruption) failure of backfill, fracture formation in concrete, failure of closure cover

system;

Archaeological investigation on site;

Geologist intrusion – investigation of samples collected from the site;

Road construction (realistic profile without tunnel) - creation of a contaminated

dust cloud.

Earthquakes – not selected for the detailed analysis (justification is presented in p.

8.6.3.2, Chapter 8);



Page 46 of 253


analysis (justification is presented in p. 8.6.3.2, Chapter 8);


presented in p. 8.6.3.2, Chapter 8).


scenarios for the post-closure period after 300 years are selected:

Farm on the repository - Residence scenario on totally degraded wastes (disposal

facility disruption) failure of backfill, fracture formation in concrete, failure of closure

cover system - water consumption + 1 hour per day of exposure to radionuclides in

the cellar;

Archaeological investigation on site; the critical group shall consist in archeologists

participating to investigations;

Geologist intrusion – investigation of samples collected from the site; the critical

group shall consist in geologists participating to investigations;

Road construction (realistic profile without tunnel) - creation of a contaminated

dust cloud; the critical group shall consist in workers building the road.

These scenarios are subject to detailed quantitative analysis.

Table 9-1 List of scenarios for the post-closure period presents the list of the reference and

alternative scenarios for the post-closure period selected for the detailed quantitative

analysis.



Page 47 of 253

Table 9-1 List of scenarios for the post-closure period

Period Scenarios

Post-closure period – active institutional control (100 years)

Reference

scenario

For the operators - direct exposure to radon or gamma radiation of staff

performing the control of the monitoring water tanks in the cell water

drainage system gallery

For the critical group – Consumption and use of the groundwater in a

small farm outside of the facility considering the indirect irradiation to

the population;

For the environment – evaluation of the impact on the biosphere,

hydrosphere, geosphere.

Alternative

scenarios

Failure of the roof closure system covering the repository;


Failure of the drainage system;

Post-closure period – passive institutional control (200 years)

Reference

scenario


small farm outside of the facility considering the indirect irradiation to

the population;



Alternative

scenarios

Failure of the roof closure system covering the repository;


Cell bath tubing effect (water accumulation);

Post-closure period – no control after 300 years

Reference

scenario


small farm onside of the facility;



Alternative

scenarios

Farm on the repository - Residence scenario on totally degraded wastes

(disposal facility disruption) failure of backfill, fracture formation in

concrete, failure of closure cover system;

Archaeological investigation on site;

Geologist intrusion – investigation of samples collected from the site;

Road construction (realistic profile without tunnel) - creation of a

contaminated dust cloud during 6 months.

9.6.7. Description of the selected scenarios for the post-closure period

9.6.7.1. Active institutional control during post-closure period

9.6.7.1.1. Reference scenario

The following reference scenarios are selected:

For the operators - direct exposure to radon or gamma radiation of staff performing the

control of the monitoring water tanks in the collecting system gallery

For the critical group – Consumption and use of the groundwater in a small farm




Page 48 of 253


geosphere.

Reference scenario for the operator:

During the active institutional control period the zone will be secured (fenced/enclosed),

monitored and reduced in order to prevent the unauthorized access of persons and

animals. The final cover system will be monitored and the possible damages will be

remedied. Even if the cover system is designed to reduce the infiltration rate, small

quantities of water will however infiltrate inside the repository. The drums corrosion process

as well as the waste degradation will also start during this period and gas releases (tritiated

water vapors and C-14) will occur. During this period the site will be marked and registered

in the official documents.

For the first period after the cell closure when it is considered that the cell, the modules and

the long term cover layers are operational, the radionuclides will decay and migrate by

diffusion on short distances into the concrete matrix inside the module and in the module’s

wall. There was also considered that during this period, as long as inside the modules the

water will not percolate, and only the residual moisture of the concrete matrix will exist, the

radionuclides leaching process will be low.

The dose from the direct exposure to radon or gamma radiation of staff performing the

control of the monitoring water tanks in the collecting system gallery will be estimated.

Reference scenario for the evaluation of the impact on the environment:

Evaluation of the impact on the biosphere, hydrosphere, and geosphere will be performed

by calculating the concentration of the offsite accumulated contaminants in:

surface soil;

surface water;

plants;

animals;

aquatic food.

Reference scenario for the critical group:

The scenario for the critical group considers consumption and use of the groundwater in the

small farm outside of the repository. The conceptual model of this scenario is presented in

Figure 9-4 Conceptual model of reference scenario for critical group.



Page 49 of 253

Figure 9-4 Conceptual model of reference scenario for critical group (leaching)

9.6.7.1.2. Alternative scenarios

Many factors influence concrete degradation, including chemical attack, physical stress

and microbial action. Chemical attack processes include Sulphate attack, calcium

hydroxide leaching (extraction by dissolution), alkali-aggregate reaction, salt crystallization

and metal corrosion. Degradation caused by physical stress is due to freezing and thawing,

damping and drying. Microbial action includes the effects of sulphur-oxidising and nitrifying

bacteria and heterotrophic organisms. These factors cause the change of concrete

properties in time: surface degrades, rebar corrodes and cracks develop and propagate to

surface, calcium hydroxide leaching (extraction by dissolution) changes bulk properties of

concrete; live and dead loads cause progressive cracking and final deterioration.

The following alternative scenarios are selected:

Failure of the closure system;

The event is a crack at the bottom of the cover system. All the rain which fall on the roof

surface run down and infiltrates directly on the concrete roof of the disposal cell, short

Precipitation

Waste

Clay geosphere

River water

Drinking water Irrigation water

Leachate

Groundwater flow

Soil Crops Cows

Atmosphere

(dust)

HUMAN

Root uptake

Irrigation

Adsorption

Foliar

Interception

Abstraction

Ingestion

Loss of

system

River flow

Suspension

External

irradiation

Ingestion (grain, root)

Ingestion

Ingestion

Fish

(pasture)

Inhalation

Water from well



Page 50 of 253

cutting the draining system above and below the cover. This water is more or less stagnant

on the concrete and diffuses (or percolate –Darcy law - if the permeability of the concrete

is not good) through the concrete. If water above the concrete is always in excess, the

amount of water which can leach the waste DM is limited by the diffusion (or percolation)

through 40 cm of concrete. The leakage time is assumed to be of one year, which is the

time necessary to detect the failure and to repair the cover.

The purpose of this scenario is to demonstrate the efficiency of the multi-barriers system.

Even in the case of a likely failure of the cover, during the institutional control period the

dose constraint will be observed.


This scenario can occur at any time. The worse moment is just before the closure.

All the (leaching) water extracted by dissolution charged with radio elements reaches

directly the non saturated area. The purpose of this scenario is to demonstrate that the

failure of roof of the cell and slab of the cell (parametric study) is not a catastrophic event

(if the cover has nominal performance).

Failure of the drainage system;

The calculations are the same as in the previous scenario in the different elements of the

disposal cell. The collecting system below the slab collects radioactive water only if the

water flow that reaches the bottom of the cell is more important than the amount which

can diffuse or percolate through the slab.

9.6.7.2. Passive institutional control during post-closure period



For the critical group – Consumption and use of the groundwater in a small farm



geosphere.

After the active institutional control period ends the damages of the cover system due to

the animal intrusion (bio-intrusion), wind erosion, human activities, etc, will be possible.

Consequently, the water infiltration rate through the cover system will increase as the

degradation progresses. During the passive control period the concrete and waste

degradation continue as in the previous period.

The conceptual model for the reference scenario for the critical group and for the

environmental impact is similar as for the active institutional control.



Failure of the roof closure system;

The calculation is the same as for the active control period. The scenario is a parametric

study which can be used to evaluate the performance of the repository during the passive

post closure period (just after the first 100 years). It can be worsened by assuming that the

concrete roof of the cells is also broken. If the radiological constraint of 0.3 mSv/year is

exceeded this means that the cover has to be repaired, and the active post closure period

might be prolonged.

Failure of the ground slab – the same as in active control period;



Page 51 of 253

Cell bath tubing effect;

Bath tub effect or “Bath tubing” scenario is a scenario which begins with infiltration of water

from precipitation or overflow entering the disposal unit. Dissolution of radionuclides occurs

and leachate accumulates in the disposal unit, as in a bath tub. This occurs due to the

repository design or the low permeability of the surrounding formations.

Bath tubing (scenario incurring the contamination by leachate accumulated in the

repository) is caused by failure of the drainage system and absence of mitigating actions by

the repository operator. Figure 9-5 – Conceptual model of Bath tubing scenario presents

the conceptual model for this scenario.

Figure 9-5 – Conceptual model of Bath tubing scenario

This conceptual model considers that the near-field structures (closure system, engineered

barriers and other near-field components) degrade until their hydraulic conductivity is more

than the surrounding soils and below layers. Consequently, there is a release from the near

field into the surrounding soil of excess contaminated infiltrating water, which cannot

percolate through the down layer. This release bypasses the geosphere. Prior to the

hydraulic conductivity of the near-field structures being greater than the surrounding soils

and underlying layers, the contaminated infiltrating water is assumed to flow into the

geosphere, and to be transported towards the water sources.

9.6.7.3. Post-closure period after 300 years



For the critical group – Consumption and use of the groundwater in a small farm on

the repository;


geosphere.

The intrusion could occur at any time after the end of the institutional control period. 300

years after the repository closure, its safety characteristics (multi-layer cover, waste modules,

cell walls, etc) cannot prevent the human intrusion. The site can be used by a family (the

Waste

Soil

Crops (root and green

vegetables)

Atmosphere

(dust)

HUMAN (site dwellers)

Precipitation

Overflow

leachate

Root uptake

Ingestion Inhalation

External

irradiation and

inadvertent

ingestion



Page 52 of 253

critical group) as a residence building. The excavated material is spread out on the

surrounding land surface, mixed with the soil and then used for agricultural purposes as

gardening and farming.

In order to model the scenarios in this period, the following assumptions are used:

Human intrusion in the repository can take place at any time after the end of the

institutional control (300 year after repository closure);

The total radionuclide inventory decreases in time only because of the radioactive

decay;

Scenarios have been developed in the context of the current habits in site

proximity. Since the human society evolution in time is unpredictable, the

recommended approximation is to consider the present technology and the

present behavior models or, in absence of site-specific information, to use

appropriate data for similar sites. The intrusion ways considered in these scenarios

should be similar to those determined by the current economical constraints, to the

present technology and methods used in resource exploitation;

The establishment of the amount of precipitation water entering the repository and the

amount of water contacting the waste is the main issue of this scenario. The waste forms,

and the waste containers will delay the contact of water with the waste, and the

engineered barriers to infiltration will prevent the entry of water into the repository for a

limited period. Degradation of waste forms, containers and engineered barriers will

eventually result in gradually increasing contact of waste with infiltrated water, and

dissolution of more and more radionuclides into the water, forming leachate. The

radionuclides in leachate will then migrate from the repository by advection, dispersion and

diffusion. Geochemistry of the repository will either enhance the migration from the

repository or substantially delay it.

Containers provide isolation of the waste for a limited time – 300 years. The cell and DM

concrete will be intact for around 100 years and after that it will degrade progressively.

Eventually they will degrade due to chemical and physical processes occurring within the

containers and within the disposal unit and water will contact the wastes. Materials for

containers lose their integrity because of the effects of chemical and physical processes

occurring within the containers and within the specific environment. Degradation of waste

forms, containers and engineered barriers will eventually result in gradual increase contact

of waste with infiltrated water, and dissolution of more and more radionuclides into the

water.

The scenario considers the construction of an individual house and the residence on site.

The human intrusion takes place only after the end of the institutional control period. During

the excavations of the house foundation, part of the repository cover is destroyed and the

radioactive material removed is mixed with the soil and spread out on the surrounding

surface. On this contaminated soil there will be performed agricultural activities as

cultivation of vegetable and roots and farming. The water used as drinking water for the

farmer’s family, for animals and irrigation comes from a well placed at disposal unit limit

(down the slope) drilled in the main aquifer of the zone (Berriasian aquifer).

All processes influencing the amount of water entering the repository (infiltration), the

amount of water passing through the disposal cells and the soil column below (drainage),

and the amount of water reaching the water level below (recharge) are considered in this

scenario.

The scenario assumes that the water from precipitations will percolate the long term cover

system of the repository, then the cells containing the DMs. In the modules, the water will be



Page 53 of 253

the transport media for the radionuclides released from the waste. After crossing (passing

through) the disposal structures, the water containing the dissolved radionuclides will

infiltrate in the geological layers beneath the repository. After the infiltration through these

layers, contaminated water will reach the aquifer and from here in the biosphere.

From/below the disposal cell the radionuclides carried by the infiltrated water can reach

the environment (biosphere) by means of two pathways:

A fraction could enter the internal cell drainage system partially degraded or

clogged up and from here it could move along the former internal draining system

and along the degraded/clogged up visiting galleries towards the hill slopes. It is

considered that the tank collection of the infiltration waters (operational over the

operational and institutional control periods) will be decommissioned at the end of

the institutional control period.

Other fraction could infiltrate through the geological layers beneath the repository,

until it reaches the aquifer beneath the repository. In this respect, see site model at

chapter 3 of the Safety Report. The Berriasian aquifer is connected to the Danube

and Danube-Black Sea Canal. Also, the Berriasian aquifer is the source of several

wells from Saligny village. It is considered that the hypothetic well of the farm in the

reference post-closure scenario is also supplied from the Berriasian aquifer (is also

drilled in the Berriasian aquifer). From these wells the contaminated water reaches

the biosphere.

The reference post-closure scenario also considers that some radionuclide are released in

the gas phase (H-3, C-14 issue) because of the corrosion of the metal drums and metallic

waste as well as because of the degradation reactions of the organic substances from the

waste. It is considered that the radionuclides reach the biosphere by water flow from the

Berriasian aquifer into a well drilled at the limit of the disposal unit whose water is used as

drinking water for people, animals and for culture irrigations in the farm on the site. It was

also considered that the Berriasian aquifer is connected to the Danube and the canal but

because of the dilution, these compartments are not of interest for the reference post-

closure scenario.

The critical group will consist in the farmers in the area. The representative person assumed

to be exposed to the maximum dose will be an adult farmer man and infant consuming

milk, grown plants (cereals and vegetables) and animals. The animals grown in the farm

(cows) will drink the water from the spring or will be fed with fodder produced inside the

farm and which could be contaminated.

The biosphere compartments are:

a well supplied by the Berriasian deposits;

the farm soil which could be contaminated by the irrigations water;

the atmosphere above the soil and sediments;

plants grown and the animals in the site area (from the farm considered in the

scenario).

Exposure occurs through the following pathways:

External irradiation by radionuclides located reaching the soil;

Ingestion of contaminated water and food and the inadvertent ingestion of

contaminated materials (e.g. soil and dust);

Inhalation of contaminated dust.



Page 54 of 253

The conceptual model of scenario “Building a residence on the site” is presented in Figure

9-6 Conceptual model of scenario “Building a residence on the degraded site – reference

scenario after 300 years”.

Figure 9-6 Conceptual model of scenario “Building a residence on the degraded site –

reference scenario after 300 years”

The main transfer processes of radionuclides in the biosphere compartment which will be

considered in the analyses are the following:

infiltration of irrigation water in the farm soil;

ingestion of contaminated water, fodders and soil by the animals;

up-take of water and contaminants from the soil by the flora cultivated on the farm

soil;

contaminated soil erosion;

evaporation of the contaminated water from irrigation;

formation of contaminated dust because of the soil erosion or by agricultural works,

transfer of the dust containing contaminants in the atmosphere and particle

deposition on the soil;

inhalation of contaminated air by farm’s animals;

ingestion of contaminated water by humans and of agricultural products produced

in the farm (contaminated vegetables and animal products);

inhalation of the contaminated air by humans;

direct irradiation from the contaminated soil.

Gas advection

Waste

Soil

HUMAN (site

dwellers)

Drinking water

Crops ( root and green vegetables)

Atmosphere (dust)

House

Root uptake

Suspension

inhalation

inhalation

Excavation

External irradiation inadvertent ingestion



Page 55 of 253


The alternative post closure scenarios are mainly determined by the future human activities

on the repository but also by occurrence of disruptive natural events. They could cover a

large diversity as: non-intrusive or intrusive investigations of the site, excavations for house or

road construction on the site, well drilling, developing of farms using the contaminated soil

by erosion of a part of the repository, erosion or disruptive dislocation of the land, or even

airplane crash on the disposal site.

The human behavior component is related to the human control of the site (social barrier).

Its main characteristic is the access without restriction if the site is released into the public

domain after the institutional control period.

Only inadvertent human intrusion is considered for the analysis of the safety assessment.

Human actions (including actions such as sabotage or any unplanned remediation or

retrieval) are considered to be out of the scope of the assessment due to the fact that the

current society cannot protect future societies from their own actions.


Farm on the totally degraded repository - repository disruption, failure of backfill,

fracture formation in concrete, failure of closure cover system;

This scenario considers the construction of a house and the residence on site in case of

totally degraded waste. The scenario considers totally degraded waste after the end of the

institutional control period.

The intruder contacts the waste during a specified period while building the basement for a

house. A specific amount of waste and cover and backfill material for the facility is

excavated during the operation.

Conservatively, the total degradation will take place after the end of the institutional

control period. The long term cover layers will maintain their integrity for around 100 years

after the repository closure, then they will degrade progressively so that after 500 years from

the repository closure they will be considered totally degraded. Subsequently, the entire

quantity of the water from precipitations will infiltrate inside the repository as in the natural

environment surrounding the repository.

Due to the water infiltrated in the disposal structures, the radionuclides from the waste will

migrate (by advection, diffusion, dispersion, surface rinse), through the conditioning matrix

and the modules’ walls/ceilings and then the water will transport them through the filling

material between the modules. It was considered that in this time the water draining

systems in the cells will be to some extent clogged up by the degraded material leached

by the water. The water containing dissolved radionuclides will pass through the foundation

slab (also considered degraded) and from here to the foundation improved layer below

the cells.

During the excavations of the house foundation, part of the repository cover is destroyed

and the radioactive material removed is mixed with the soil and spread out on the

surrounding area. On this contaminated soil there will be performed agricultural activities as

vegetable and roots cultivation and farming. The water for consumption comes from a

contaminated source. The direct exposure of the resident is considered in this scenario due

to the totally degraded waste.

The intruder contacts the waste during a specified period while building the basement for a

house. A specific amount of waste and cover and backfill material for the facility is

excavated during this operation.

Exposure occurs by the following means:



Page 56 of 253

o Direct exposure - irradiation by radionuclides located on dislocated soil,

in wastes;

o Ingestion by intakes of contaminated water and food and the

inadvertent ingestion of contaminated materials (e.g. soil and dust);

o Inhalation of contaminated dust.

The conceptual model of the scenario “Building a residence on a totally degraded site” is

presented in Figure 9-7 Conceptual model of scenario “Building a residence on totally

degraded site – alternative scenario after 300 years”

Figure 9-7 Conceptual model of scenario “Building a residence on totally degraded site –

alternative scenario after 300 years”

Geologist intrusion – investigation of samples collected from the site

This scenario has a certain probability and could occur if the investigation of the near

surface soil is envisaged. Individual exposure is due to the handling and examination of the

samples taken from the site.

The scenario assumes the intrusion on site of a working team (the potential critical group)

that investigates collected samples. The means considered significant for a potential

contamination are:

o external irradiation;

o contaminated dust inhalation;

o contaminated dust ingestion;

o entering of the contaminated dust in wounds.

The starting point of the calculation is the estimation of the radionuclide concentration of

these samples.

The conceptual model of “Geologist intrusion” scenario is presented in Figure 9-8

Conceptual model of “Geologist intrusion” scenario.

Gas advection

Waste

Soil

HUMAN (site

dwellers)

Drinking water

Crops ( root and green vegetables)

Atmosphere (dust)

House

Root uptake

Suspension

inhalation

inhalation

Excavation

External irradiation inadvertent ingestion



Page 57 of 253

Figure 9-8 Conceptual model of “Geologist intrusion” scenario

Archaeological investigation on site

The scenario assumes the intrusion on site of a working team (possible critical group)

investigating the collected archeological vestiges.

The contamination means considered in this case are external exposure, ingestion and

contaminated dust inhalation and eventually the contamination through wounds. Similar to

the sample investigation scenario, the relevant radionuclides concentrations correspond to

the intrusion moment. Approximation is also applied in this case, assuming that the activity

concentration for long life time radionuclides remains unchanged at the intrusion moment

(300 years as of repository closure). The external irradiation component for the β emitters is

also neglected. The dilution factor f for the excavated material is different compared to the

one from previous scenario.

The parameters used for calculations have been estimated according to the following

assumptions:

o The value of the dilution factor is based on the hypothesis of a lower

dilution of the contaminant in the uncontaminated material and

considers the fact that the archeologists could come in contact with the

contaminant especially through excavation activities performed by hand,

without using the automatic devices.

o The excavation time has a maximum value as concerns the probable

contact time with the contaminated samples.

o Air loading with dust has a larger value reflecting the proximity to the

contaminated surface (lap position – fold knees position of the

archeologists).

o The breathing rate corresponds to a medium physical effort (activities).

The conceptual model of “Archaeological investigation” scenario is presented in Figure 9-9

Conceptual model of “Archaeological investigation” scenario.

Waste

Samples

Atmosphere

(dust)

HUMAN

Extraction

Dust inhalation

Dust ingestion

External irradiation



Page 58 of 253

Figure 9-9 Conceptual model of “Archaeological investigation” scenario

Road construction (realistic profile without tunnel) - release of a contaminated dust

cloud for a period of 6 months. Critical group is the workers.

The conceptual model of “Road construction” scenario is presented in Figure 9-10

Conceptual model of “Road construction” scenario.

Figure 9-10 Conceptual model of “Road construction” scenario

Table 9-2 presents the contaminant release mechanisms and media, transport media and

mechanisms, and human exposure mechanisms in the post closure scenarios.

Waste

Archeological samples

Atmosphere (dust)

HUMAN

Extraction

Dust inhalation

Dust ingestion

External irradiation

Wastes

Atmosphere

(dust)

HUMAN

(Intruder)

External

Irradiation

Inadvertent

Ingestion

Suspension

Inhalation



Page 59 of 253

Table 9-2 Contaminant release mechanisms

Contaminant

release

mechanisms

Contaminant

release media

Contaminant

transport media

Contaminant

transport

mechanisms

Human exposure

mechanisms

Leaching (extraction by

dissolution) scenario -

small farm system using

water extracted from a

well or a surface water

body

Leaching Leachate Solute in

groundwater

Well, river–

irrigation, drinking

water

Soil

Crops

Animals – cows,

fish

Atmosphere - dust

Advection

Dispersion

Water abstraction

for irrigation and

drinking water

Foliar interception

Root uptake

Adsorption

Ingestion of water,

pasture and soil by

cows

Leaching

Erosion

River flow

Ingestion of water,

crops and animal

products

Inhalation of dust

External irradiation from

soil

Bath tubing effect

(Residence scenario

incurring the

contamination by

leachate accumulated

in the disposal facility)

Leaching Leachate Overflow leachate

Soil

Atmosphere – dust

Crops

Overflow of

leachate

Suspension

Root uptake

Adsorption

Ingestion of corps

Inadvertent ingestion

of soil

Inhalation of dust


soil

Residence building on

the disposal site

Excavation

Gas

generation

Excavated

wastes

Gas

House

Gas

Soil

Atmosphere – dust

Crops

Gas advection

Root uptake

Adsorption

Suspension

Ingestion of corps


of soil

Inhalation of dust and

gas


soil

Road construction Excavation Dust Atmosphere -dust Suspension

Adsorption


of contaminated



Page 60 of 253

Contaminant

release

mechanisms

Contaminant

release media

Contaminant

transport media

Contaminant

transport

mechanisms

Human exposure

mechanisms

material and wastes

Inhalation of dust


contaminated material

and wastes

Geologist intrusion -

Examination of samples

collected from the site

Excavation

Excavated

samples

Dust

Atmosphere – dust

Gas

Soil

Suspension

Adsorption

Inhalation of dust



and wastes

Archeological

investigation

Excavation Excavated

soil

Dust

Atmosphere –dust

Soil

Gas

Suspension Inadvertent ingestion

of contaminated

material and wastes

Inhalation of dust



and wastes

Residence scenario on

totally degraded

wastes

Leaching Leachate Overflow leachate

Soil

Crops

Animals – cows,

fish

Atmosphere – dust

Leaching

Gas advection

Root uptake

Adsorption

Suspension

Ingestion of corps


of soil

Inhalation of dust


soil



Page 61 of 253

9.7. DESCRIPTION OF THE APPLIED COMPUTER CODES

To cover all requirements of the Technical specification [1] a set of 5 computer codes is

selected. The purpose of the computer codes is defined and presented in Table 9-3.

Table 9-3 Computer codes

PURPOSE CODE

Source term definition DUST MS [22]

Transport of radionuclides through the unsaturated zone HYDRUS [29]

Transport of radionuclides through the saturated zone PORFLOW [32]

Transport of radionuclides through the biosphere RESRAD [33]

External exposure by sources MERCURAD 3D [16]

Note: The MERCURAD code is used for calculation of direct exposure of repository operators

and population, considering the Waste Inventory, defined as design condition.

Detailed information regarding the selected computer codes is presented in Chapter 8,

Appendix 8.2 “Description of Computer codes”. The following information about the

selected computer codes is presented:

1. Name and creator of the code;

2. Capabilities;

3. Verification and validation status;

4. Input data;

5. Assumptions;

6. Application of the code regarding Saligny site.

9.8. SAFETY ASSESSMENT FOR THE POST-CLOSURE PERIODS

The following types of models for safety evaluation in the post-closure period are developed

– both in general terms and in the terms of the applied software:

Engineered barriers – model of the specific design features, established in order to

prevent transport of radio-active materials outside the repository.

Human impact: operator actions and human intrusion.

Site conditions: characteristics of the site, behavior of natural barriers.

Environment: flora, fauna and food chains.

A summary of the most important features, related to the safety analysis calculations for the

post-closure period is presented in Table 9-4. The table presents the relations between the

selected scenarios for the post-closure period, boundary conditions, description of the

hypotheses and the computer codes applied for each scenario.



Page 62 of 253

Table 9-4 Description of the scenarios in the post-closure period

Scenario Description of initial and boundary conditions Type of calculation

Post-closure period – active institutional control (100 years)

Reference

scenario

1. For the operators - direct exposure to gamma radiation of staff performing

the control of the monitoring water tanks in the cell water drainage system

gallery

1. Dose for the operator performing

the control of the monitoring water

tanks in the collecting system

gallery – 1 hour per each gallery

2. For the critical group – Consumption and use of the groundwater in a small

farm outside of the facility considering the indirect irradiation to the

population

2. Doses for the population

3. For the environment – evaluation of the impact on the biosphere,

hydrosphere, geosphere

3. Evaluation of the impact on the

biosphere, hydrosphere, geosphere

Alternative

scenarios

1. Failure of the roof closure system - Fissure at the bottom of the cover. The

rain which falls on the cover runs down and infiltrates directly in the

concrete roof of a disposal cell. This water is more or less stagnant on the

concrete and diffuses (or percolates) through the concrete.

If water upon the concrete is always in excess, the amount of water which

can leach the waste disposal module is limited by the diffusion (or

percolation) through 40 cm of concrete. The leakage time is assumed to be

of one year, which is the time necessary to detect the failure and to repair

the cover.

a. Dose for the operator performing

the control in the gallery

b. Doses for the population

c. Evaluation of the impact on the


2. Failure of the ground slab - all the leaching water reaches directly the non

saturated zone. The purpose of this scenario is to demonstrate that the

failure of one or more slabs (parametric study) is not a catastrophic event (if

the cover has nominal performance). The result might be appreciate in

regard of 5mSv/year for one or a few failures and 100 mSv if there is a great

number of broken slabs (it is very improbable considering the design of the

repository).




c. Evaluation of the impact on the


3. Failure of the drainage system - direct accidental release of radioactive

water of the collecting system:

- into the storm basin and






Page 63 of 253


- into the ground c. Evaluation of the impact on the


Post-closure period – passive institutional control (200 years)

Reference

scenario


farm outside of the facility considering the indirect irradiation to the

population

Doses for the population from indirect

irradiation and consumption and use of

the groundwater


hydrosphere, geosphere

Evaluation of the impact on the


Alternative

scenarios

1. Failure of roof closure system a. Doses for the population

b. Evaluation of the impact on the

biosphere, hydrosphere, geosphere.

2. Failure of the ground slab a. Doses for the population



3. Cell bath tubing effect: Infiltration from precipitation or outflow entering the

disposal cell. Dissolution of radionuclides occurs and leachate accumulates

in the disposal cell, as in a bath tub.

Stage 1: a small part of the contaminated water penetrates the underlying

layers through the bottom slab, reaches the saturated zone and is

transported towards the water sources.

Stage 2: The cell walls degrade until their hydraulic conductivity becomes

higher than the surrounding soils.

Release through the cell walls into the surrounding soil of the excess

contaminated water, which cannot percolate through the slab and

underlying layers.

a. Doses for the population



Post-closure period – no control after 300 years (after failure of the engineered barriers)

Reference

scenario


farm onsite of the facility, considering the indirect irradiation of population;

Doses for the population



Page 64 of 253


During the excavations of house foundation, part of the repository cover

above the roof is destroyed and the material removed is mixed with the soil

and spread out on the surrounding surface.

The cover material could be contaminated by radio-nuclides diffusion and

gas release through the roof.

On this contaminated soil will be performed agricultural activities as

vegetable and roots cultivation and chicken farming.

The water used as drinking water for the farmer’s family, for animals and

irrigation comes from a well placed at disposal unit limit (down the slope)

drilled in the main aquifer.

Critical group will consist in the farmers in the area. The representative

person assumed to be exposed to the maximum dose will be a male adult

farmer and an infant consuming milk, growing plants (cereals and

vegetables) and animal products.

Exposure occurs through the following means:

- External exposure by the radionuclides, located under the concrete roof

- Ingestion by intakes of contaminated water and food and the


- Inhalation of contaminated dust;

- direct irradiation from the contaminated soil and from standing in the

cellar (one hour per day), just above the waste.


hydrosphere, geosphere. The animals grown on the farm (cows) will drink

contaminated water from the fountain or will be fed with fodder produced

inside the farm and which could be contaminated. The biosphere

compartments are:

a well supplied by the Berriasian aquifer;

the Danube – Black Sea canal;

the farm soil which could be contaminated by the water from irrigations;

the atmosphere above the soil and sediments;

Evaluation of the impact on the




Page 65 of 253


cultivated plants and the animals in the site area (from the farm

considered in the scenario).

The main transfer processes of the radionuclides in the biosphere

compartment are:

infiltration of irrigation water in the farm soil;

ingestion of contaminated water, fodders and soil by the animals;

consumption of water and contaminants from the soil by the cultivated

flora on the farm soil;

contaminated soil erosion;

evaporation of the contaminated water (water from irrigations);

formation of contaminated dust because of the soil erosion or by

agricultural works, the transfer of the dust containing contaminants in

the atmosphere and particle subsidence on the soil;

inhalation of contaminated air by farm animals;

ingestion of contaminated water by humans and of the agricultural

products produced in the farm (contaminated vegetables and animal

products);

Alternative

scenarios

1. Farm on the repository site - Residence scenario on totally degraded waste

repository (disposal facility disruption):

- failure of the closure cover;

- failure of the cell roof;

- failure of DMs;

- failure (cracking) of the cell bottom slab.

Construction of a house and residence on the site in case of totally

degraded waste repository. The intruder contacts the waste during a

specified period while building a basement for a house. A specific amount

of waste together with cover and backfill material for the facility is

excavated during the construction.

Exposure occurs through the following means:

- Direct exposure;






Page 66 of 253


- Ingestion by consumption of contaminated water and food and the


- Inhalation of contaminated dust.

2. Archaeological investigation of the site; Working team investigating the

collected archaeological vestiges. The contamination means are:

- external exposure,

- ingestion

- contaminated dust inhalation




3. Geologist intrusion – investigation of samples collected from the site;

Individual exposure is due to handling and examination of the samples

extracted from the site. Intrusion on the site of a working team (the potential

critical group) that investigates collected samples. The means are:

- external exposure;

- contaminated dust inhalation;

- contaminated dust ingestion

a. Doses for geologist

4. Road construction (realistic profile without tunnel) - creation of a

contaminated dust cloud. Critical group is the workers

a. Doses for the workers

- Inhalation of dust

- external body contamination





Page 67 of 253

9.8.1. Period of active institutional control after the closure

9.8.1.1. Doses for the operators

The doses for the operators during the active institutional control of post-closure

period are calculated using MERCURAD code.

The MERCURAD code is used for estimating the doses for the following scenarios:

Reference scenario for the active institutional control during post-closure period

1. Dose for the operator performing the control of the monitoring water tanks in

the collecting system gallery

Alternative scenario for the active institutional control during post-closure period:

1. Failure of a roof closure system for one year

1a) Dose for the operator performing the control in the gallery

2. Failure of the ground slab

2a) Dose for the operator performing the control in the gallery

3. Failure of the drainage system with influx of contaminated water into the

drainage pool (dose for the operator) or into the soil (environmental impact)

3a) Dose for the operator

9.8.1.1.1. Reference scenario – inspection of drainage galleries

The calculation is performed for the reference scenario “1) Dose for the operator

performing the control of the monitoring water tanks in the collecting system gallery”

for the active institutional control during post-closure period.

Configuration:

The cell is filled with disposal modules. The final closure of the cell was

performed.

At the beginning of the active institutional control period the operator shall

inspect 9 galleries. One operator inspects the drainage gallery for 1 hour

once every 2 weeks therefore the total working time is of 234h per year.

Dose calculation point:

Dose calculation point is 1m below the foundation slab.

Operation:

Inspection of drainage gallery during the active control

Model specifics:

Thickness of slab foundation is of 1m concrete.

Long side of the cell is presented vertically with first and second row of DMs.

These two rows represent a biological protection for the following rows

behind these ones. Their contribution is negligible and they are not

presented in our calculations.

The operator inspects the galleries once every two weeks. The total time per

year for inspection is of 234 h for 9 galleries.

In the scene used for calculations is presented the worst case when the gallery

is under the middle cell.



Page 68 of 253

Model scene:

Results:

Annual dose is calculated as follows:

Annual dose - (Dose rate µSv/h) x (Hours per operation = twice per month)

Operation

Number

of

operators

Distance

from cell

floor [m]

Time for 1

gallery

inspectio

n [h]

Dose rate

µSv/h

Annual dose

per operator

for 1 gallery

µSv/y

Drainage gallery

control 1 1 1 8.21E-04

2.13E-02

Conclusion:

During the active institutional control period the operator inspects 9 galleries. The

dose for one year when the operator will inspect all the 9 galleries is of 2.13 E-02

μSv/year x 9 = 1.92 E-01 μSv/year = 1.92 E-04 mSv/year which is much less than the

dose constraint for the operator - 5mSv/year. Consequently, one operator may

inspect the drainage gallery of all cells without any significant risk.


During the active institutional control period the access to the site is restricted and

operators perform routine monitoring of the air, soil and drainage galleries. The

alternative scenarios are related to failures of the engineered barriers:

Failure of the roof cover system – afflux of rain water on the concrete roof of

the cell;

Crack on the bottom (ground) of the concrete slab – afflux of contaminated

water into the soil;

Failure in the drainage system pipeline - afflux of contaminated water into the

drainage pool (dose for the operator) or directly into the soil (environmental

impact).

Operator

1m

Slab foundation



Page 69 of 253

For all three scenarios it is conservative to assume that the roof cover does not retain

the rain water. This allows for application of the same model which was applied for

the operational period when cell roof cover is not installed. Additional conservatism is

added by assuming simultaneous occurrence and development of cracks in the

roof, the DM and in the ground slab, allowing for the maximum possible wash-out

and transport of radionuclides into the soil beneath the repository.

9.8.1.1.2.1. Dose for the operator for scenarios 1a) Failure of a roof closure

and 2a) Failure of the ground slab

As a model for the source term evaluation for these scenarios is used DUST MS

diffusion model with time increasing water velocity, applied to the following barriers:

Cell concrete roof;

DMs;

Cell slab;

The DUST MS model assumes simultaneous occurrence and development of the

crack in the barriers. This feature is represented by time-increasing water velocity. The

reason for such conservative approach is the one-dimensional character of DUST MS

code.

The assumed simultaneous failure of the barriers provides for flow of the water from

the top to the bottom of the cell and consequently for a maximal transport of

radionuclides into the soil. Obviously the resulting values of source term and following

environmental impact are maximized. The same applies to the doses for the

operator.

Configuration:

The cell is full of disposal modules. The final closure of the cell is performed.

Failure of cell roof, penetration of water inside the disposal cell and DMs and

failure of the cell slab are considered.


Dose calculation point is 1m below the foundation slab.

Operation:

The operators work in the drainage gallery for accident consequences’

mitigation. The average time of presence inside the gallery for a single

operator is conservatively assumed at 8h (one shift).

Model specifics:

Thickness of slab foundation - 1m concrete.

Slab foundation is modeled as two layers with different activity. The activity of

these two layers is calculated with DUST MS diffusion model with time

increasing water velocity. The activity of 137Cs in the upper layer is 3.48E-01

Bq/cm3 and in the lower layer is 1.08E-02 Bq/cm3. These values are the

maximum ones, achieved with the DUST-MS calculation for the period from 0

to 400 years. This assumption provides a conservative basis for the evaluation

of the dose for the operators.



Page 70 of 253

The cell is presented with two layers of DMs. These two layers represent a

biological protection for the last layer of DMs, which is not presented in the

calculations.

In the scene used for calculations is presented the worst case when the gallery

is below the middle cell.

Model scene:

Results:

Total dose is calculated as follows:

Total dose - (Dose rate µSv/h) x (Hours per operation)

Operator Number of

operators

Distance

from cell

floor [m]

Dose rate

µSv/h

Hours of

exposure

Dose for

operator μSv

Operator

1

1

1,59E-03

8

1,27E-02

Conclusions:

1. Dose for the operator performing the accident mitigation activity for 8 h in the

gallery is below the dose constraint of 5mSv/y.

2. In the scene used for calculations is presented the worst case when the gallery is

below the middle cell.

9.8.1.1.2.2. Dose for the operator in scenario 3a) Failure of the drainage

system

Configuration:

Failure of the drainage system of the repository occurs. All contaminated

water from the drainage system is collected in one of the drainage pools.

The operator is situated in the middle of this pool – conservative assumption.

The source term is calculated with DUST MS diffusion model with time

increasing water velocity.

Upper layer

Lower layer

Operator

1m

Slab foundation



Page 71 of 253

Only the concentration of 137Cs is considered in the calculations. The

concentration of 60Co is not considered in the calculations due to fact that it

is negligible.

The value 3.48E-01 Bq/cm3 for 137Cs concentration is the maximum value (year

300) for the calculated period 0-400 years. This assumption is applied in order

to achieve bounding evaluation for the doses.


In the middle of the drainage pool – conservative assumption.

Operation:

The operators perform activities required for the accident mitigation.

Model specifics:

Number of the drainage pools - 3 with the total volume 10 000 m3;

Conservatively, it is assumed that all activity resulting from the failure of the

drainage system is collected in one of the draining pools.

The model considers one drainage pool as a source term for MERCURAD

calculations.

The average time of presence of a single operator is conservatively assumed

to 8h (one shift).

Model scene:

Results:

Total dose is calculated as follows:

Total dose = (Dose rate µSv/h) x (Hours per operation)

Operation

Number

of

operators

Distance

from

drainage

pool [m]

Dose rate

[µSv/h]

Hours for

accident

mitigation

Dose for the

operator [µSv]

Accident 1 0.05 6.53E-02 8 5.23E-01

Accident 1 1 6.18E-02 8 4.94E-01

Conclusion:

1. Dose for the operator is below the dose constraints of 5mSv/y.

2. In case of contaminated water dose rate measurements must be done for further

treatment.

Contact, 1m

Drainage pool



Page 72 of 253

9.8.1.2. Models of the Source term

The source term for the active institutional control is modeled and calculated using

DUST MS code.

The following models of DUST MS code are applied:

“DUST MS diffusion” model for the reference scenario “Control of the

monitoring water tanks in the collecting system gallery”;

“DUST MS diffusion” model with time increasing water velocity for the

alternative scenarios:

o 2) „Failure of the ground slab”

9.8.1.2.1. Calculations for the reference scenario

“DUST MS diffusion” model for the reference scenario “Control of the monitoring

water tanks in the collecting system gallery” is the same for the reference scenario in

the operational period. The description of the model, the assumptions made, the

input data used and results for 400 years are presented in Chapter 8.

The source term resulted from the calculations in this case consists in maximum

concentrations on the cell ground slab for each radionuclide considered, for the

active institutional control period.

The results are presented in Table 9-5.

Table 9-5 Concentrations for the active institutional control period for the reference

scenario

Active institutional control 65 - 165 years

Radionuclide Year Max. Concentration [Bq/cm3]

14C 165 1.19E-10

60Co 65 8.05E-17

3H 65 1.17E-04

90Sr 82 2.30E-17

36Cl 165 6.27E-14

137Cs 86 1.55E-06

241Pu 65 6.15E-30

9.8.1.2.2. Calculations for the alternative scenarios

“DUST MS diffusion” model for the alternative scenarios is the same as the model for

the alternative scenarios in the operational period. The description of the model,

assumptions made, input data used and results for 400 years are presented in

Chapter 8.

The source term resulted from the calculations in this case consists in maximum

concentrations on the cell ground slab for each radionuclide considered, for the

active institutional control period.

The results are presented in Table 9-6.



Page 73 of 253

Table 9-6 Concentrations for the active institutional control period for the alternative

scenario

Active institutional control 65 - 165 years


14C 165 5.20E-06

60Co 102 1.01E-07

3H 135 6.87E-04

90Sr 165 1.89E-07

36Cl 165 8.90E-06

137Cs 165 1.26E-02

241Pu 152 6.31E-11

9.8.1.3. Models of the processes in the unsaturated zone


The input data, assumptions, models and calculations for the processes in the

unsaturated zone are presented in Section 9.8.3.2 of this chapter. The calculations

are performed for the period from 0 to 400 years. The results for the period of active

institutional control clearly show the following:

The volumetric specific activity of all the radionuclides except H-3 in the

unsaturated-saturated zone boundary beneath the repository will be zero

during the operational period, the active control period and the passive

control period.

The volumetric specific activity in the lateral point in year 165 is 4.4E-07 Bq/m3.

The maximum volumetric specific activity in the lateral point (7.8E-7 Bq/m3)

appears approximately 200 years after the beginning of repository operation.

The maximum volumetric specific activity in the central point is at a later stage

because of the absence of infiltration water in the first 300 years. This is the

reason for the low H-3 volumetric activity in the central point.

The reference results are presented below:

H-3 volumetric specific activity in the lateral and the central part of the unsaturated –

saturated zone boundary beneath the repository is calculated using 2D HYDRUS

model.



Page 74 of 253

Figure 9-11 H-3 volumetric specific activity distribution in the unsaturated zone

-100 0 100 200 300 400

0.0000000

0.0000001

0.0000002

0.0000003

0.0000004

0.0000005

0.0000006

0.0000007

0.0000008

0.0000009

Vo

lum

etr

ic A

ctivity [B

q/m

3]

t [years]

Unsaturated - Saturated zone boundary

Lateral point

Figure 9-12 H-3 volumetric activity in the unsaturated – saturated zone boundary – side

area of the repository (linear scale)



Page 75 of 253

-100 0 100 200 300 400

1E-20

1E-19

1E-18

1E-17

1E-16

1E-15

1E-14

1E-13

1E-12

1E-11

1E-10

1E-9

1E-8

1E-7

1E-6

1E-5

Vo

lum

etr

ic A

ctivity [B

q/m

3]

t [years]


Lateral point


area of the repository (logarithmic scale)

-100 0 100 200 300 400

0.00E+000

1.00E-028

2.00E-028

3.00E-028

4.00E-028

5.00E-028

6.00E-028

t [years]


Central point

Volu

me

tric

Activity [B

q/m

3]

Figure 9-14 H-3 volumetric activity in the unsaturated – saturated zone boundary – the

region below the center of the repository


In order to present the radionuclide release during the alternative scenarios in the

operational period, the active control period and the passive control period

calculations for the first 400 years are performed by DUST-MS model considering time



Page 76 of 253

dependant failure of the barriers (time dependant infiltration through the cells and

foundation).

In order to calculate the radionuclide volumetric specific activity in the unsaturated –

saturated zone boundary beneath the repository, the results obtained by DUST-MS

are used as boundary volumetric activity for the HYDRUS computer code, which

calculates the radionuclide transport through the unsaturated zone.


unsaturated zone are presented in Chapter 8. The calculations are performed for the

period from 0 to 400 years. The results for the period of passive institutional control

clearly show the following:

The volumetric activity of all radionuclides except H-3 in the unsaturated-

saturated zone boundary beneath the repository will be zero during the

operational period, the active control period and the passive control period.

The maximum volumetric activity in the lateral point (3.8E-6 Bq/m3) appears

approximately 300 years after the beginning of repository operation. The

volumetric activity in the lateral point in year 165 is 4.7E-07 Bq/m3.

The maximum volumetric activity in the central point is at later stage because

of the low infiltration in the first 300 years. This is the reason for the low H-3

volumetric activity in the central point.

H-3 volumetric activity in the lateral and the central part of the unsaturated –


model.

Figure 9-15 H-3 volumetric activity distribution in the unsaturated zone



Page 77 of 253

-100 0 100 200 300 400

0.0000000

0.0000005

0.0000010

0.0000015

0.0000020

0.0000025

0.0000030

0.0000035

0.0000040

Vo

lum

etr

ic A

ctivity [B

q/m

3]

t [years]


Lateral point



-100 0 100 200 300 400

1E-18

1E-17

1E-16

1E-15

1E-14

1E-13

1E-12

1E-11

1E-10

1E-9

1E-8

1E-7

1E-6

1E-5

1E-4

Vo

lum

etr

ic A

ctivity [B

q/m

3]

t [years]


Lateral point





Page 78 of 253

-100 0 100 200 300 400

0.00E+000

2.00E-028

4.00E-028

6.00E-028

8.00E-028

1.00E-027

1.20E-027

1.40E-027

1.60E-027

t [years]

Vo

lum

etr

ic A

ctivity [B

q/m

3]


Central point



9.8.1.4. Models of the processes in the saturated zone


The PORFLOW model used for the calculation of the tritium distribution through the

saturated zone is the same as the model used for calculating the radionuclides

transport during the post-closure period after 300 years. The model is presented in

Figure 9-19 PORFLOW model of the saturated zone.

U



Page 79 of 253

Figure 9-19 PORFLOW model of the saturated zone

The dimensions of the models are X x Y x Z = 1600 x 500 x 35 meters;

The green region represents the Berriasian aquifer;

The blue region represents the pre-quaternary clay;

The violet region represent the contact area between unsaturated and

saturated zone and on this area the boundary conditions are set;

Direction of supposed Darcy u flow;

The boundary conditions are according to the HYDRUS results and they are

presented in next figure:

0 100 200 300 400

0.0

2.0x10-7

4.0x10-7

6.0x10-7

8.0x10-7

Tritium concentration

Co

nce

ntr

atio

n, B

q/m

3

Years

Figure 9-20 Results from HYDRUS – PORFLOW boundary condition

Four groups of six nodes are selected and located in depth of 1m, 5m, 10m, 15m,

20m, 25m. The nodes are located exactly one above another:

a. at 1400m distance from the “repository” projection on saturated zone

/nodes numbers 1-6/;

b. at 300 m distance from the “repository” projection on saturated zone


c. at 25 m distance from the “repository” projection on saturated zone /nodes

numbers 13-18/;

U



Page 80 of 253

d. beneath the repository /nodes numbers 19-24/;

The results for the four groups of nodes are presented in next figures:

0 100 200 300 400

1E-33

1E-32

1E-31

1E-30

1E-29

1E-28

Concentration in node 1






Co

nce

ntr

atio

n, B

q/m

3

Years

Figure 9-21 Tritium concentration for group a/ nodes

0 100 200 300 400

0.00E+000

1.00E-010

2.00E-010

3.00E-010

4.00E-010

5.00E-010







Co

nce

ntr

atio

n, B

q/m

3

Years

Figure 9-22 Tritium concentration for group b/ nodes



Page 81 of 253

0 100 200 300 400

0.00E+000

5.00E-008

1.00E-007

1.50E-007

2.00E-007

2.50E-007

3.00E-007







Co

nce

ntr

atio

n, B

q/m

3

Years

Figure 9-23 Tritium concentration for group c/ nodes

0 100 200 300 400

0.0

2.0x10-7

4.0x10-7

6.0x10-7

8.0x10-7







Co

nce

ntr

atio

n, B

q/m

3

Years

Figure 9-24 Tritium concentration for group d/ nodes



Page 82 of 253

The tritium concentration at 1400 meters from repository is very low in realty and it

can be accepted as being 0.

The concentration in nodes beneath the repository is very close to concentrations

used as boundary conditions.

The distribution of tritium at 25 meters /the fence perimeter/ leads to a decrease of

the concentration of about one order of magnitude in comparison to the values

given by HYDRUS.

The concentration of the tritium in the saturated zone during the active institutional

control period (65-165 years) for the reference scenarios is presented in Table 9-7.

Table 9-7 Tritium concentration for the reference scenario

Group nodes

Max Concentration

[Bq/m3]

Year of max

concentration

Period 65-165

a-1400m 0

b-300m 1.28E-13 170

c-25m 1.39E-07 170

d-below repository 4.91E-07 170

The main factor for tritium concentration’s decreasing remains the decay. Due to its

short half-time period /12.3 years/ the concentration of tritium is important for a

period of 1000 years.

The resulting concentrations of tritium are much lower than the limits for drinking

water, meaning of 7600 Bq/l which are set in Bulgarian Regulation on basic radiation

protection norms [35].


The PORFLOW model of the saturated zone for the alternative scenarios is the same

as the model used for the calculations of the radionuclides transport through the

saturated zone.

The scenario which represents a crack in the concrete slabs is modeled by a water

leakage through the repository, increasing in time.

The calculations with HYDRUS for this scenario show that for the 400 years period the

only isotope which reaches the saturated zone is Tritium. The assumption that the

whole repository is filled in first year of the 400 years is taken into consideration with

DUST-MS calculations.

The used boundary conditions for the current calculation are presented in the

following figure and in fact this is the concentration of the bottom layer of the

unsaturated zone according to HYDRUS results:



Page 83 of 253

50 100 150 200 250 300 350 400 450

-5.0x10-7

0.0

5.0x10-7

1.0x10-6

1.5x10-6

2.0x10-6

2.5x10-6

3.0x10-6

3.5x10-6

4.0x10-6


Co

nce

ntr

atio

n, B

q/m

3

Years

Figure 9-25 3H concentration on bottom layer

The results of the PORFLOW calculations are presented in following figures:

0 100 200 300 400

1E-35

1E-34

1E-33

1E-32

1E-31

1E-30

1E-29

1E-28







Co

nce

ntr

atio

n, B

q/m

3

Years

Figure 9-26 3H concentration in group a/nodes



Page 84 of 253

0 100 200 300 400

3.0x10-10

6.0x10-10

9.0x10-10

1.2x10-9

1.5x10-9

1.8x10-9

2.1x10-9







Co

nce

ntr

atio

n, B

q/m

3

Years

Figure 9-27 3H concentration in group b/nodes

0 100 200 300 400

0.0

2.0x10-7

4.0x10-7

6.0x10-7

8.0x10-7

1.0x10-6

1.2x10-6

1.4x10-6

1.6x10-6







Co

nce

ntr

atio

n, B

q/m

3

Years

Figure 9-28 3H concentration in group c/nodes



Page 85 of 253

0 100 200 300 400

0.0

1.0x10-6

2.0x10-6

3.0x10-6

4.0x10-6 Concentration in node 19






Co

nce

ntr

atio

n, B

q/m

3

Years

Figure 9-29 3H concentration in group d/nodes

The tritium concentrations set as boundary conditions are very close to the values

calculated in nodes d/group.

The resulting tritium concentrations for all four groups of nodes are one order of

magnitude higher in comparison than the tritium concentrations calculated for the

reference scenario.

The tritium concentration in the saturated zone for the period of active institutional

control 65-165 years for the alternative scenarios is presented in Table 9-8.

Table 9-8 Tritium concentration for the alternative scenarios

Group nodes

Max Concentration

[Bq/m3]

Year of max

concentration

Period 65-165

a 0

b 1.41E-13 170

c 1.52E-07 170

d 5.44E-07 170

The resulting tritium concentrations are much lower than the limits for drinking water

of 7600 Bq/l which is established in Bulgarian Regulation on basic radiation protection

norms [35].

9.8.1.5. Doses for the population

The results from the calculations with HYDRUS for the reference and alternative

scenarios prove that:



Page 86 of 253


saturated zone boundary beneath the repository is zero (HYDRUS

calculations for the operational period, presented in Chapter 8).

For the reference scenario the volumetric activity of H-3 in the lateral point in

year 165 is 4.4E-07 Bq/m3. The maximum volumetric activity of H-3 in the

lateral point (7.8E-7 Bq/m3) appears approximately 200 years after the

beginning of repository operation.

For alternative scenarios the maximum volumetric activity in the lateral point

(3.8E-6 Bq/m3) appears approximately 300 years after the beginning of

repository operation. The volumetric activity in the lateral point in year 165 is

4.7E-07 Bq/m3.

The maximum volumetric activity in the central point is at further stage


reason of the low H-3 volumetric activity in the central point.

The resulting concentrations of tritium calculated with PORFLOW (Table 9-7 and Table

9-8) are much lower than the limits for drinking water of 7600 Bq/l which are

established in the Bulgarian Regulation on basic radiation protection norms [35].

Due to the negligible concentration of H-3 and zero concentration of other

radionuclides in the unsaturated and saturated zones (results from HYDRUS and

PORFLOW simulations) the doses for the population for the active institutional control

are not calculated.

9.8.1.6. Evaluation of the impact on the environment

The main impact on the environment during the active institutional control is due to

the irrigation with contaminated water.

H-3 volumetric activity in the lateral direction in the unsaturated zone (Figures 9-11

and Figure 9-15) is very low (approximately 1 x E-10 Bq/m3).

The values of the radionuclides concentration in the saturated zone for the active

institutional control period are negligibly low.

Due to the negligible concentration of H-3 in the unsaturated and saturate zones

there will be no impact on the environment during the active institutional control

period.

9.8.2. Period of passive institutional control after the closure

9.8.2.1. Models of the source term

The source term for the passive institutional control period is modeled and calculated

using DUST MS code.

The following models of DUST MS code are applied:

“DUST MS diffusion” model for the reference scenario “Consumption and use

of the groundwater in a small farm outside the facility considering the

indirect irradiation of the population”;

“DUST MS diffusion” model with time increasing water velocity for the

alternative scenarios:

o 1) Failure of the roof closure system

o 2) Failure of the ground slab



Page 87 of 253


“DUST MS diffusion” model for the reference scenario “Consumption and use of the

groundwater in a small farm outside the facility considering the indirect irradiation of

the population” is the same as for the reference scenario in the operational period.

The description of the model, assumptions made, input data used and results for 400

years are presented in chapter 8. The source term includes the maximum

concentrations for each radionuclide for the passive institutional control period. The

results of the calculations are presented in Table 9-9.

Table 9-9 Concentrations for the passive institutional control period, reference scenario

Passive institutional control 165 - 365 years


14C 365 5.65E-10

60Co 165 2.21E-21

3H 165 3.15E-06

90Sr 165 1.30E-17

36Cl 365 3.06E-13

137Cs 165 9.42E-07

241Pu 165 3.91E-31


“DUST MS diffusion” model with time increasing water velocity used for the source

term of the alternative scenarios during the post-closure period is the same as the

model for the alternative scenarios in the operational period. The description of the

model, assumptions made, input data used and results for 400 years are presented in

Chapter 8.

The source term includes the maximum concentrations for each radionuclide for the

passive institutional control period. The results of the calculations are presented in

Table 9-10.

Table 9-10 Concentrations for the passive institutional control period, alternative

scenarios

Passive institutional control 165 - 365 years

Radionuclide Year Max. Concentration

[Bq/cm3]

14C 365 2.24E-03

60Co 165 3.15E-09

3H 165 4.84E-04

90Sr 334 8.09E-07

36Cl 365 2.30E-03

137Cs 301 2.19E-02



Page 88 of 253

241Pu 165 5.71E-11

9.8.2.2. Models of the processes in the unsaturated zone



unsaturated zone are presented in Section 9.8.3.2 of this chapter. The calculations

are performed for the period from 0 to 400 years.

The results for the period of passive institutional control clearly show the following:

The volumetric activity of all the radionuclides except H-3 in the unsaturated-




approximately 200 years after the beginning of repository operation.

The volumetric activity in the lateral point in year 365 is 3.3 E-08.



reason for the low H-3 volumetric activity in the central point.

The reference results are presented below:


saturated zone boundary beneath the repository is calculated by using 2D HYDRUS

model.




Page 89 of 253

-100 0 100 200 300 400

0.0000000

0.0000001

0.0000002

0.0000003

0.0000004

0.0000005

0.0000006

0.0000007

0.0000008

0.0000009

Vo

lum

etr

ic A

ctivity [B

q/m

3]

t [years]


Lateral point


region of the repository (linear scale)

-100 0 100 200 300 400

1E-20

1E-19

1E-18

1E-17

1E-16

1E-15

1E-14

1E-13

1E-12

1E-11

1E-10

1E-9

1E-8

1E-7

1E-6

1E-5

Volu

metr

ic A

ctivity [B

q/m

3]

t [years]


Lateral point


region of the repository (logarithmic scale)



Page 90 of 253

-100 0 100 200 300 400

0.00E+000

1.00E-028

2.00E-028

3.00E-028

4.00E-028

5.00E-028

6.00E-028

t [years]


Central point

Vo

lum

etr

ic A

ctivity [B

q/m

3]




In order to present the radionuclide release during the alternative scenarios in the

operational period, the active control period and the passive control period

calculations for the first 400 years are performed by DUST-MS model considering time

dependant failure of the barriers (time dependant infiltration through the cells and

foundation).

In order to calculate the radionuclide volumetric activity in the unsaturated –

saturated zone boundary beneath the repository, the results obtained by DUST-MS

are used as boundary volumetric activity for the HYDRUS computer code, which

calculates the radionuclide transport through the unsaturated zone.


unsaturated zone are presented in Chapter 8. The calculations are performed for the

period from 0 to 400 years. The results for the period of passive institutional control

clearly show the following:

The volumetric activity of all the radionuclides except H-3 in the unsaturated-




approximately 300 years after the beginning of repository operation.


because of the low infiltration in the first 300 years. This is the reason for the

low H-3 volumetric activity in the central point.



Page 91 of 253



model.


-100 0 100 200 300 400

0.0000000

0.0000005

0.0000010

0.0000015

0.0000020

0.0000025

0.0000030

0.0000035

0.0000040

Vo

lum

etr

ic A

ctivity [B

q/m

3]

t [years]


Lateral point





Page 92 of 253

-100 0 100 200 300 400

1E-18

1E-17

1E-16

1E-15

1E-14

1E-13

1E-12

1E-11

1E-10

1E-9

1E-8

1E-7

1E-6

1E-5

1E-4

Volu

me

tric

Activity [B

q/m

3]

t [years]


Lateral point



-100 0 100 200 300 400

0.00E+000

2.00E-028

4.00E-028

6.00E-028

8.00E-028

1.00E-027

1.20E-027

1.40E-027

1.60E-027

t [years]

Vo

lum

etr

ic A

ctivity [B

q/m

3]


Central point



9.8.2.3. Models of the processes in the saturated zone


The only radioactive isotope that reaches the saturated zone during active and

passive control periods in case of reference scenario is tritium.

The calculation performed with PORFLOW is only for tritium isotope.



Page 93 of 253

The boundary conditions are according to HYDRUS results and the latter are

presented in the following figure.

0 100 200 300 400

0.0

2.0x10-7

4.0x10-7

6.0x10-7

8.0x10-7

Tritium concentrationC

on

ce

ntr

atio

n, B

q/m

3

Years

Figure 9-38 Tritium concentration results from HYDRUS

9.8.2.3.1.1. PORFLOW input data

All parameters and dependent variables used in PORFLOW calculations for the

current model and task are in SI units.

Fluid properties:

the water is the only supposed fluid passing through layers beneath the

repository;

water density – 1000 kg/m3;

water viscosity – 0.001 sm

kg

..

Geological solid matrix properties :

density

1760 kg/m3 for clay ;

2700 kg/m3 for limestone aquifer ;

porosity

total porosity

0.33 for clay;

0.225 for aquifer;

effective porosity

0.17 for clay;



Page 94 of 253

0.0001 for aquifer;

hydraulic properties

matrix compressibility 1.0e-3

hydraulic conductivity in all directions [X, Y and Z]:

9.0e-8 m/s for clay ;

1.0e-5 m/s for aquifer;

transport properties -

distribution coefficients [m3/kg]:

Isotope Clay Aquifer

3H 0 3.0e-5

Molecular diffusivity – 1.0e-9 m2/s;

Longitudinal and transversal dispersivity according to [10] to be used

is

L = 1500 meters and L = 140 m and T = 28 m.

Source and sink specification

Because all isotopes are radioactive their half-lives in seconds are:

Isotope Half life [lives]

3H 3.88e+08

Output control – the user sets the nodes for which the results will be recorded

on file with extension .his.

Operational Control

time for calculations

Isotope Time [y] Time [s]

3H 400 1.262e+10

Time step for calculation is :

Isotope Max time step = Initial time step 3H 0.5 years



Page 95 of 253

9.8.2.3.1.2. Description of the model

The model is created in the following steps:

creation of an orthogonal grid with dimensions a x b x h = 1600 m x 500 m x 35 m.

The number of nodes includes 2 boundary nodes at the beginning and end of

“coordinates line”.

nodalization of grid a x b x h = 402 x 52 x 37. One node has the following

dimensions - 4m x 10m x 1m.

transport in horizontal direction /X axis/ caused by the hydraulic gradient is the

main process of interest in this issue.

o Three regions are inserted in the model:

region representing the pre-quaternary clay media;

region representing the Berriasian aquifer media;

very thin layer of pre-quaternary clay media at one end of the grid.

o The boundary conditions are the following:

o Zero initial concentration of radionuclides in both regions

representing the clay and aquifer media;

o The concentration will be input as boundary condition at Z- surface

of the thin layer.

The concentration values are from HYDRUS calculations and the area of the region is

equal to repository area. The thin region is imported with the purpose to represent the

contact area between saturated and unsaturated zones with surfaces equal to the

repository area.

9.8.2.3.1.3. Results

The results are presented for 24 nodes in 4 groups of 6 nodes. XY coordinates for each

group are the same and the 6 nodes are located in depth, 5 meters from each other.

Four groups of six nodes are selected and located in depth of 1m, 5m, 10m, 15m,

20m, 25m. The nodes are located exactly one above another:

a. at 1400m distance from the “repository” projection on saturated zone


b. at 300 m distance from the “repository” projection on saturated zone


c. at 25 m distance from the “repository” projection on saturated zone /nodes

numbers 13-18/;

d. beneath the repository /nodes numbers 19-24/;

The results are presented on the following figures:



Page 96 of 253

0 100 200 300 400

1E-33

1E-32

1E-31

1E-30

1E-29

1E-28







Co

nce

ntr

atio

n, B

q/m

3

Years

Figure 9-39 Tritium concentration in group a/nodes

0 100 200 300 400

0.00E+000

1.00E-010

2.00E-010

3.00E-010

4.00E-010

5.00E-010







Co

nce

ntr

atio

n, B

q/m

3

Years

Figure 9-40 Tritium concentration in group b/nodes



Page 97 of 253

0 100 200 300 400

0.00E+000

5.00E-008

1.00E-007

1.50E-007

2.00E-007

2.50E-007

3.00E-007







Co

nce

ntr

atio

n, B

q/m

3

Years

Figure 9-41 Tritium concentration in group c/nodes

0 100 200 300 400

0.0

2.0x10-7

4.0x10-7

6.0x10-7

8.0x10-7







Co

nce

ntr

atio

n, B

q/m

3

Years

Figure 9-42 Tritium concentration in group d/nodes

The resulted concentration is saved by PORFLOW in a file for each ten years. Due to

this the years of maximum concentration are given for years which are divisible by 10.



Page 98 of 253

9.8.2.3.1.4. Analysis of the results

The peak tritium concentration for the reference scenario in the passive institutional

control is presented in Table 9-11.

Table 9-11 Tritium concentration for the reference scenario

Group nodes

Max Concentration

[Bq/m3]

Year of max

concentration

Period 165-

365

a-1400m 6.74E-29 400

b-300m 4.94E-10 360

c-25m 3.20E-07 230

d-beneath the

repository 7.78E-07 210

The peak value of tritium concentration according to HYDRUS calculation occurs in

the years 208÷214.

Therefore, it is easy to describe the maximal value for the group of nodes beneath

the repository.

The difference between the years with peak concentration is due to the fact that the

transport through the saturated zone takes time.

The tritium peak concentration at 25 meters distance from repository is about 7 times

lower than the concentration beneath the repository.


water of 7600 Bq/l which are established by the Bulgarian Regulation on basic

radiation protection norms [35].


The PORFLOW model of the saturated zone for the alternative scenarios is the same

as the model used for calculating the radionuclides’ transport through the saturated

zone in case of the reference scenario.

The scenario which represents a crack in the concrete slabs is modeled by a water

flow through the repository increasing in time.

The calculations with HYDRUS for this scenario show that for the 400 years period the

only isotope which reaches the saturated zone is Tritium. The assumption that the

whole repository is filled in during the first year is taken into consideration at DUST-MS

calculations.

The boundary conditions used for the current calculation are presented in following

figure and, in fact, this is the concentration of the bottom layer of the unsaturated

zone according to HYDRUS results:



Page 99 of 253

50 100 150 200 250 300 350 400 450

-5.0x10-7

0.0

5.0x10-7

1.0x10-6

1.5x10-6

2.0x10-6

2.5x10-6

3.0x10-6

3.5x10-6

4.0x10-6


Co

nce

ntr

atio

n, B

q/m

3

Years

Figure 9-43 3H concentration on bottom layer

The results of the PORFLOW calculations are presented in the following figures:

0 100 200 300 400

1E-35

1E-34

1E-33

1E-32

1E-31

1E-30

1E-29

1E-28







Co

nce

ntr

atio

n, B

q/m

3

Years

Figure 9-44 3H concentration in group a/nodes



Page 100 of 253

0 100 200 300 400

3.0x10-10

6.0x10-10

9.0x10-10

1.2x10-9

1.5x10-9

1.8x10-9

2.1x10-9







Co

nce

ntr

atio

n, B

q/m

3

Years

Figure 9-45 3H concentration in group b/nodes

0 100 200 300 400

0.0

2.0x10-7

4.0x10-7

6.0x10-7

8.0x10-7

1.0x10-6

1.2x10-6

1.4x10-6

1.6x10-6







Co

nce

ntr

atio

n, B

q/m

3

Years

Figure 9-46 3H concentration in group c/nodes



Page 101 of 253

0 100 200 300 400

0.0

1.0x10-6

2.0x10-6

3.0x10-6

4.0x10-6 Concentration in node 19






Co

nce

ntr

atio

n, B

q/m

3

Years

Figure 9-47 3H concentration in group d/nodes

The tritium concentrations set as boundary conditions are very close to the values

calculated in nodes d/group.

The resulting tritium concentrations for all four groups of nodes are one order of

magnitude higher in comparison with the tritium concentrations calculated for the

reference scenario.

The concentration of the tritium in the saturated zone for the period of passive

institutional control 165-365 years for the alternative scenarios is presented in Table

9-12.

Table 9-12 Tritium concentration for alternative scenarios

Group nodes

Max Concentration

[Bq/m3]

Year of max

concentration

Period 165-365

a 7.45E-29 400

b 1.47E-09 370

c 1.60E-06 320

d 3.83E-06 300


water of 7600 Bq/l which are established by the Bulgarian Regulation on basic

radiation protection norms [35].



Page 102 of 253


9.8.2.4.1. Doses for the population during the reference scenario

The results from the calculations with HYDRUS for the reference and alternative

scenarios for the passive institutional control period prove that:


saturated zone boundary beneath the repository is zero (HYDRUS calculations

for the operational period, presented in Chapter 8).

For the reference scenario the maximum 3H volumetric activity in the lateral

point (7.8E-7 Bq/m3) appears approximately 200 years after the beginning of

repository operation. The volumetric activity in the lateral point in year 365 is of

3.3 E-08 Bq/m3.

For alternative scenarios the maximum volumetric activity in the lateral point

(3.8E-6 Bq/m3) appears approximately 300 years after the beginning of

repository operation.

The maximum volumetric activity in the central point is at further stage because

of the absence of infiltration water during the first 300 years. This is the reason for

the low H-3 volumetric activity in the central point.

The resulting concentrations of tritium calculated with PORFLOW (Table 9-11 and

Table 9-12) are much lower than the limits for drinking water of 7600 Bq/l which are

established by the Bulgarian Regulation on basic radiation protection norms [35].

Due to the negligible concentration of H-3 and zero concentration of other

radionuclides in the unsaturated and saturated zones (results from HYDRUS and

PORFLOW simulations) the doses for the population for the passive institutional control

are not calculated.

9.8.2.4.2. Doses for the population during the alternative scenarios

9.8.2.4.2.1. Dose for the population for alternative scenarios 1) Failure of

the roof closure system and 2) Failure of the ground slab

Scenario “3b) Crack of one element of the cell” for the operational scenario

(presented in Chapter 8) is the limit for scenarios “1) Failure of the roof closure system”

and “2) Failure of the ground slab” due to the fact that the simultaneous failure of

the cell roof and of the slab foundation is assumed, when the final roof cover layer of

the repository does not exist yet. This assumption allows for direct influx of water into

the radioactive waste matrix as well as for direct influx of contaminated water into

the unsaturated layer below the cell.

Figures 8-79, 8-80, 8-81 and 8-82 of Chapter 8 present the dose rate results for this

scenario.

During the operational, active control and passive control periods only H-3 (Figure 8-

79) has an impact on the dose for the human but it is negligible – the maximum value

is 6.7E-16mSv/year.

The maximum dose rate for the future generations is 3.5E-08mSv/y (in the year 2150

after the scenario initiation).

The dose of the current scenario is mainly of Cl-36 due to radionuclide transport to

the wells and air contamination of foods. The reason for this is the small distribution



Page 103 of 253

coefficients of Cl-36 in the unsaturated zone and subsequent contamination of the

well water used for irrigation and drinking.

All these values are much lower than the dose constraint of 0.3 mSv/y for a member

of the population.

In order to represent the effect of C-14 evasion into the atmosphere, a calculation in

which the contaminated layer is considered as open-air is performed (the cell cover

is assumed to be totally degraded). In this calculation the contaminated layer is

assumed to be represented by one cell with C-14 volumetric activity of 800 Bq/cm3.

Assumptions regarding the contaminated layer:

density of the cell (contaminated layer) is assumed to be 1.7 g/cm3

dimensions - 27.9 x 15.25 x 5.1 m

Conservatively, the thickness of evasion layer for C-14 in the soil is assumed to be 5.1

m, therefore the entire content of C-14 is available for evasion. The C-14 evasion flux

rate is assumed to be 3.7E-07 year-1 (the same value as for clay and loamy soils [41]).

The dwelling site and the agricultural areas are situated at 25 m, downwind from the

cracked cell.

The evasion of C-14 leads to higher dose (7.0E-03 mSv/y) (Figure 8-82) but it is still

below the dose constraint of 0.3mSv/year.

9.8.2.4.2.2. Dose for the population for alternative scenario 3) Bath tubing

effect

a) Source term modeling

When a "bath-tubing" effect scenario is considered, it is necessary to evaluate the

concentration of radionuclides in the overflowing leachate, Cdisp [Bq/m3]:

)()(

dbdcddispunit

mit

dispKdV

AetC

where

e-λt is the radioactive decay before the scenario [-];

Ami is the initial activity in the disposal unit [Bq];

Vdispunit is the volume of the disposal unit [m3];

ωcd is the moisture content of the disposal unit [-];

ρbd is the dry bulk density in the disposal unit [kg/m3];

Kdd is the distribution coefficient in the disposal unit [m3/kg];

b) Dose assessment

The dose due to the "bath-tubing" effect is expressed as (in [Sv/y]):

inginhext DoseDoseDoseDose

where

Doseext, Doseinh, and Doseing are the doses due to the external exposure, inhalation

and ingestion [Sv/y]:



Page 104 of 253

extoutindisp

soilsoil

ext DFttsfCTh

OFDose .

where

OF is the overflow water into the garden during one year [m];

ρsoil is the dry bulk density of the soil [kg/m3];

Thsoil is the soil thickness [m];

Cdisp is the concentration of radionuclides in overflowing leachate [Bq/m3];

sf is the shielding factor [-];

tin is the time spent indoor [h/y];

tout is the time spent outdoor [h/y];

DFext is the external exposure dose factor 11 BqhkgSv .

inhoutoutoutininindisp

soilsoil

inh DFtbrdusttbrdustCTh

OFDose .,,

where





dustin, dustout are the indoor and outdoor dust levels [kg/m3];

br,in, br,out are the indoor and outdoor breathing rates [m3/h];

DFinh is the dose factor for inhalation [Sv/Bq].

ingsoilvegetvegtdisp

soilsoil

ing DFQQTFCTh

OFDose

where





TFveget is the soil to plant concentration factor [ 1kgBq fresh weight / 1 kgBq dry soil];

Qveget is the annual vegetable consumption [kg/y];

Qsoil is the inadvertent soil ingestion rate [kg/y];

DFing is the dose factor for ingestion [Sv/Bq].

c) Values of several parameters according to [36]

The following values of several of the parameters are presented in [36]:



Page 105 of 253

OF = 0.1 m/y;

Sf = 0.1;

br,in, = 0.75 13 hm ;

br,out, = 1 13 hm ;

tin = 6575 1 yh ;

tout = 2191 1 yh ;

Qveget = 118 kg/y (root vegetables) + 31 kg/y (green vegetables) = 149 kg/y;

Qsoil = 0.03 kg/y;

Thsoil = 0.25 m;

3/1800 mkgsoil ;

dustin = 1.0e-08 kg/m3;

dustout = 2.0e-08 kg/m3.

According to [36] the main isotopes of interest for bath-tubing effect scenario are 3H, 90Sr, 137Cs, 129I.

d) Data regarding the DFDSMA repository

Moisture content 2.0%20 cd and dry bulk density 3/1700 mkgbd . These two

values are used in DUST-MS calculations.

Thickness of soil is considered to be of 3.2 meters, according to the value of final

repository cover layer thickness presented in [38].

The volume of the disposal unit is defined as:

3

3

5207.1

7.1*384*64mod*mod*

me

uleofvolumecellperulesofnumbercellsofnumberVdispunit

t = 165 years /the most conservative case is the beginning of the scenario when the

initial activity of nuclides is maximal/. 3/1540 mkgsoil .

In the following table are presented values of several parameters for each of the

isotopes as well as the results for C(t).

Isotope Inventory [Bq] Kd [m3/kg] λ C(t) [Bq/m3]

H-3 1.66E+14 2.00E-04 5.59E-02 2.51E+05

Sr-90 1.12E+13 5.00E-02 2.38E-02 2.15E+04

Cs-137 2.36E+13 2.00E-04 2.31E-02 8.01E+06

I-129 7.40E+08 1.50E-01 4.41E-08 2.40E+01

The initial inventory is according to [19]. The distribution coefficients are according to

[26].

Results for Doseext are presented in the following table:



Page 106 of 253

Isotope C(t) [Bq/m3] DFext (Sv.kg)/(h.Bq) Doseext [Sv/y]

H-3 2.51E+05 0 0.00E+00

Sr-90 2.15E+04 2.10E-12 2.60E-09

Cs-137 8.01E+06 1.20E-10 5.55E-05

I-129 2.40E+01 1.70E-13 2.36E-13

Dose factors DFext are taken from [36].

Results for Doseinh are presented in the following table:

Isotope C(t) [Bq/m3] DFinh [Sv/Bq] Doseinh [Sv/y]

H-3 2.51E+05 2.60E-10 1.24E-13

Sr-90 2.15E+04 1.60E-07 6.49E-12

Cs-137 8.01E+06 3.90E-08 5.90E-10

I-129 2.40E+01 3.60E-08 1.63E-15

Dose factors DFinh are taken from [36].

Results for Doseing are presented in the following table:

Isotope C(t) [Bq/m3] DFing [Sv/Bq] TFveget (root)

TFveget

(green) Doseing [Sv/y]

H-3 2.51E+05 2.60E-10 5.00E+00 5.00E+00 9.88E-07

Sr-90 2.15E+04 1.60E-07 9.00E-02 3.00E+00 7.22E-06

Cs-137 8.01E+06 3.90E-08 3.00E-02 3.00E-02 2.83E-05

I-129 2.40E+01 3.60E-08 1.00E-01 1.00E-01 2.61E-10

Dose factors DFing and soil to plant concentration factors (Bq.kg-1 fresh weight / Bq.kg-1

dry soil) are taken from [36].

The doses for the population for the considered isotopes are presented in the

following table:

Isotope Doseext [Sv/y] Doseinh [Sv/y] Doseing [Sv/y] Dose [Sv/y]

H-3 0.00E+00 1.23508E-13 9.88E-07 9.88E-07

Sr-90 2.60E-09 6.48854E-12 7.22E-06 7.22E-06

Cs-137 5.55E-05 5.90191E-10 2.83E-05 8.39E-05

I-129 2.36E-13 1.63446E-15 2.61E-10 2.62E-10

9.21E-05

The total dose for the four isotopes is of 9.21E-02 mSv/y and this value is below the

dose limits for the population.


9.8.2.5.1. Evaluation of the impact following the reference scenario

The main impact on the environment during the passive institutional control is due to

the irrigation with contaminated water.

H-3 volumetric activity in lateral direction of the unsaturated zone (Figures 9-30 and 9-

34) is very low (approximately 1 x E-10).



Page 107 of 253

The values of the radionuclides concentration in the saturated zone for the passive

institutional control period are negligible.

Due to the negligible H-3 concentration in the unsaturated and saturate zones there

will be no impact on the environment in the passive institutional control period.

9.8.2.5.2. Evaluation of the impact following the alternative scenarios

Scenario “3b) Crack of one cell element” for the operational scenario (presented in

Chapter 8) is the limit for scenarios “1) Failure of the roof closure system” and “2)

Failure of the ground slab” due to the fact that simultaneous failure of the cell roof

and foundation slab is assumed.

The impact on the environment is presented in Chapter 8.

9.8.3. Post-closure period after 300 years

9.8.3.1. Models of the source term

DUST MS code is used for the modeling and calculation of the source term during the

post-closure period after the control period.

The “DUST MS DM break“ model presents CBF-K depositing module break at year 300

which is the bounding conditions for the post-closure period. This model is developed

for the following scenarios:

Reference scenario “Consumption and use of the groundwater in a small farm

onside the facility”;

Alternative scenarios:

o 1) Farm on the repository - Residence scenario on totally degraded waste;

o 3) Geologist intrusion;

9.8.3.1.1. Description of the model

The DUST MS model is presented in Figure 9-48 DUST MS model.

Figure 9-48 DUST MS model

For the calculations of source term the repository is modeled in the following way:



Page 108 of 253

The code is one dimensional;

The main direction of interest is “downwards” (from repository to unsaturated

layer). If the flow values are negative numbers this means that the flow

direction is “upwards”;

25 nodes – each 50 cm thick;

For short life isotopes the calculation time will be between 1000 and 2500

years.

For long life isotopes calculation time will be 3.0e+4 years or 1.0e+5 years. This

time is long enough for the processes of water transport through the

repository.

The expected number of cells within repository will be of 64 [38].

The characteristics of the disposal cell, based on data presented in [38], are:

Thickness of the slab: 1m;

Thickness of wall and roof: 40 cm and 40 cm, respectively.

DP type: Disposal cell

Dimensions 15.75 x 27.90 x 5.10 m

Number of Disposal

modules

384 – 3 levels x 128 modules

All DUST MS calculations are performed for 64 cells.

9.8.3.1.2. Input data

The data used for calculations corresponds to the 64 cells of the repository.

The data in the input file is structured in 10 groups. The input for the respective groups

is presented as follows.

1. Title :

a. name of the project;

b. isotopes imported in the problem;

c. atomic mass and half time of the isotope;

Isotope Half-life /years/

C-14 5.73E+03

Cl-36 3.01E+05

Co-60 5.27E+00

Cs-134 2.06E+00

Cs-137 3.02E+01

H-3 1.23E+01

I-129 1.59E+07

Nb-93m 1.36E+01

Ni-59 8.00E+04

Ni-63 1.00E+02

Pu-241 1.47E+01

Sr-90 2.90E+01



Page 109 of 253

d. solubility limit - the solubility limit value is needed for a model of a

process which is not included in the current problem and due to this

value of 1 g/cm3 for all isotopes is used.

2. Time – time period in years for the model simulation :

Isotope Time for simulation /years/

C-14 1.00E+05

Cl-36 3.00E+04

Co-60 1.00E+03

Cs-137 1.00E+03

H-3 1.00E+03

I-129 1.00E+05

Nb-93m 1.00E+03

Ni-59 1.00E+05

Ni-63 2.50E+03

Pu-241 1.00E+03

Sr-90 1.00E+03

3. Material parameters :

a. Density of waste – 1.7 g/cm3 [19];

b. Density of concrete – 2.3 g/cm3 [19];

c. Dispersion coefficient – 200 cm (the value is justified by the analysis);

d. Distribution coefficients [10] :

Isotope Distribution coefficient cm3/g

C-14 2.00E+02

Cl-36 1.00E+00

Co-60 1.00E+00

Cs-134 2.00E-01

Cs-137 2.00E-01

H-3 2.00E-01

I-129 1.50E+02

Nb-93m 1.00E+04

Ni-59 5.00E+01

Ni-63 5.00E+01

Pu-241 6.00E+03

Sr-90 5.00E+01 e. Diffusion coefficient – 1.0E-6 cm2/s ((the value is justified by the analysis)

In this model the diffusion coefficient is the parameter characterizing the

properties of the material which will be used for filling the spaces

between containers.

4. Output – the user establishes which nodes’ results will be recorded in “.dat” file

5. Facility dimensions:

a. Repository area 2.367e+08 cm2 [38];



Page 110 of 253

b. Thickness of nodes representing waste containers and slab foundation –

50 cm;

6. Initial and boundary conditions:

a. Boundary conditions

i. Zero flow on top of repository

ii. Zero concentration on bottom of repository

b. Initial conditions - initial concentration in all nodes = 0 Bq/cm3.

7. Water flow – the following values are justified by the sensitivity analysis:

a. Initial volumetric moisture content – 20 %;

b. Water velocity equal to 7.0e-08 cm/s;

8. Containers :

a. Number of containers – 10

b. Failure time of containers – 300 years [19]

c. Type of failure – general

9. Waste form :

a. Waste geometry – rectangular [19]

b. Rectangular geometry :

i. base dimensions - 145 cm x 145 cm [19]

ii. volume – 3.05e+06 cm3 [19];

iii. 100% diffusion fraction;

iv. Diffusion coefficients [26]:

Isotope diffusion coefficient cm2/s

C-14 5.80E-10

Cl-36 1.00E-11

Co-60 1.00E-13

Cs-134 1.00E-09

Cs-137 1.00E-09

H-3 1.00E-08

I-129 1.00E-11

Nb-93m 1.00E-17

Ni-59 1.00E-15

Ni-63 1.00E-15

Pu-241 1.00E-17

Sr-90 1.00E-12 v. Initial inventory per container [19]



Page 111 of 253

Isotope Bq

C-14 9.67E+12

Cl-36 4.80E+08

Co-60 1.61E+14

Cs-134 1.42E+07

Cs-137 2.36E+12

H-3 1.66E+14

I-129 7.40E+07

Nb-93m 5.58E+10

Ni-59 1.26E+07

Ni-63 2.39E+12

Pu-241 2.07E+14

Sr-90 1.12E+12

The data for the expected facility inventory is presented in Table 9-13.

Table 9-13 Expected inventory within repository in the year 2080 [19]

Nuclide Operation (Bq) Dismantling (Bq) Total (Bq) (*) 14C 3.49E+13 2.96E+13 9.67E+13 36Cl 1.65E+07 3.18E+09 4.80E+09

244Cm 9.76E+09 2.05E+10 4.54E+10 60Co 1.12E+11 1.07E+15 1.61E+15 134Cs 4.61E+07 4.88E+07 1.42E+08 137Cs 1.57E+13 5.10E+10 2.36E+13 152Eu 1.21E+11 1.68E+09 1.84E+11 154Eu 6.11E+09 6.79E+09 1.93E+10 155Eu 1.72E+07 2.23E+09 3.36E+09 55Fe 2.46E+09 5.45E+14 8.18E+14

3H 1.06E+14 5.08E+12 1.66E+14 129I 4.94E+08 5.41E+04 7.40E+08

93mNb 5.94E+06 3.72E+11 5.58E+11 59Ni 2.27E+06 8.14E+07 1.26E+08 63Ni 2.68E+10 1.59E+13 2.39E+13

241Pu 1.45E+12 1.38E+15 2.07E+15 106Ru 2.65E+11 5.89E+11 1.28E+12 125Sb 6.92E+02 8.00E+03 1.30E+04

90Sr 7.46E+12 4.09E+10 1.12E+13

Alpha LL 3.72E+12 4.50E+11 6.25E+12

Beta LL 1.12E+11 1.41E+12 2.28E+12

* According to a conservative assumption from [19] the inventory is multiplied by 1.5

(included in table values) for all nuclides.

9.8.3.1.3. Assumptions and boundary conditions

The isotopes for which calculations are preformed are the following: 14C, 36Cl, 60Co, 134Cs, 137Cs, 3H, 129I, 93mNb, 59Ni, 63Ni, 241Pu and 90Sr.

The water velocity parameter represents the quantity of water passing through a

certain section during the time unit [s,h,y]. The measurement unit of water velocity

parameter is [cm/s] but this is not speed. The coincidence is due to the formula



Page 112 of 253

s

cm

s

surfacecm

watervolumecm

velocityWater ][

]_[

_2

3

The selected value 7.0e-08 cm/s for whole period (from 1500 to 100 000 years) was

selected after a sensitivity analysis performed for several different isotopes. This

analysis is presented in 9.9.5.1.

Waste forms and release mechanisms

According to [22], when the containers fail, the contaminants can be released over

time by one of three release mechanisms: surface wash, diffusion or dissolution. The

type of release mechanism and the release rates depend on the characteristics of

the waste form. These release mechanisms are described as follows:

Surface Wash: radionuclides on the wastes are partitioned and carried

downward into the unsaturated zone by infiltration water. This model is usually

applied to the general laboratory trash waste forms.

Diffusion: radionuclides and chemicals that are encased in a waste form may

diffuse to the surface of the waste form where surface-wash mechanisms

predominate. This model is usually applied to sludge and grouted or concrete-

encased waste forms.

Dissolution: this release mechanism covers the dissolution of materials containing

radionuclides, the radionuclides being part of the material matrix. This model is

usually applied for activated metals.

According to [10], the release of radionuclides from waste forms can be modeled

with the following three mechanisms for release of radionuclides from waste forms:

Rinse or wash-off release occurs when water removes or washes radionuclides

from the surface of the waste form. This release mechanism is appropriate for

surface contaminated waste consisting of laboratory trash, clothing, plastics, etc.

Diffusion release occurs when the release is limited by diffusion through a porous

waste form such as cement-stabilized waste form.

Dissolution release occurs when the release is controlled by the corrosion rate of

a metal waste form, such as activated metals.

Source discretization

The whole repository will be considered as one area of 2.367E+04 m2. The

radionuclide precipitation will be considered equivalent over the entire area.

Release parameters

The main process which occurs in cemented waste is diffusion. Repository will be

modeled only as process diffusion which will cause contaminants’ leaching out of the

repository.

9.8.3.1.4. Results from the calculations of “DUST MS DM BREAK” model

The main purpose of the calculations is to obtain the maximum value of radioactivity

released by the wastes. If a range of values for diffusion coefficients for cement is

presented – the highest value will be used. This conservative choice leads to

maximum radioactivity release from the repository.



Page 113 of 253

The diffusion coefficients for “water zone” are established at 1.0E-06 cm2/s.

The distribution coefficient for 14C is according to [10].

The diffusion coefficient for Carbon is not presented in [26]. The value of 5.8E-10 cm2/s

is used.

The calculation results are given on the figures below in alphabetical order of

elements. The results are presented in Bq/cm3 concentration as time function /years/.

Due to the fact that in [26] two Kd values are presented, in the calculation for 129I was

used the higher value for Kd. The presented values are:

Kd = 0.8±0.1 x 10-3 m3/kg which corresponds to iodine concentration of 0.2 mol/l;

Kd = 150 ± 16 x 10-3 m3/kg which corresponds to iodine concentration of 2.8x10-7

mol/l.

The calculations used the second Kd value (the highest) because the second

concentration is very close to iodine concentration in the repository.

Iodine inventory in moles is 7.4E+8 Bq x 1.19E-9 mol/Bq = 0.8806 moles of 129I in the

entire repository. The conversion coefficient 1.19e-9 mol/Bq is taken from [21]. The

expected volume of the repository is 2.367E+08 cm2 * 500 cm = 1.183e+11 cm3 =

1.183E+08 liters and the average iodine concentration is 0.8806 mol/1.183e+08 liters =

7.444E-9 mol/l. This value is closer to the second concentration and this is another

reason for using the higher Kd.

0 20000 40000 60000 80000 100000

1E-6

1E-5

1E-4

1E-3

0.01

0.1

Co

nce

ntr

atio

n, B

q/c

m3

Years

C-14

Figure 9-49 Concentration of 14C



Page 114 of 253

0 5000 10000 15000 20000 25000 30000

-0.00001

0.00000

0.00001

0.00002

0.00003

0.00004

0.00005

C

on

ce

ntr

atio

n, B

q/c

m3

Years

Cl-36

Figure 9-50 Concentration of 36Cl

250 300 350 400

1E-23

1E-22

1E-21

1E-20

1E-19

C

on

ce

ntr

atio

n, B

q/c

m3

Years

Co-60

Figure 9-51 Concentration of 60Co



Page 115 of 253

300 400 500 600 700

1E-7

1E-6

1E-5

1E-4

1E-3

C

on

ce

ntr

atio

n, B

q/c

m3

Years

Cs-137

Figure 9-52 Concentration of 137Cs

250 300 350 400 450 500

1E-10

1E-9

1E-8

1E-7

1E-6

Co

nce

ntr

atio

n, B

q/c

m3

Years

H-3

Figure 9-53 Concentration of 3H /tritium/



Page 116 of 253

0 20000 40000 60000 80000 100000

0.0

2.0x10-7

4.0x10-7

6.0x10-7

8.0x10-7

Co

nce

ntr

atio

n, B

q/c

m3

Years

I-129

Figure 9-54 Concentration of 129I

320 400 480 560 640

1E-28

1E-27

1E-26

1E-25

1E-24

Co

nce

ntr

atio

n, B

q/c

m3

Years

Nb-93m

Figure 9-55 Concentration of 93mNb



Page 117 of 253

0 20000 40000 60000 80000 100000

0.00E+000

2.00E-010

4.00E-010

6.00E-010

8.00E-010

1.00E-009

Co

nce

ntr

atio

n, B

q/c

m3

Years

Ni-59

Figure 9-56 Concentration of 59Ni

0 500 1000 1500 2000 2500

1E-12

1E-11

1E-10

1E-9

1E-8

1E-7

Co

nce

ntr

atio

n, B

q/c

m3

Years

Ni-63

Figure 9-57 Concentration of 63Ni



Page 118 of 253

300 400 500 600 700

1E-24

1E-23

1E-22

1E-21

1E-20

1E-19

Co

nce

ntr

atio

n, B

q/c

m3

Years

Pu-241

Figure 9-58 Concentration of 241Pu

0 200 400 600 800 1000

0.00E+000

1.00E-010

2.00E-010

3.00E-010

4.00E-010

5.00E-010

6.00E-010

Co

nce

ntr

atio

n, B

q/c

m3

Years

Sr-90

Figure 9-59 Concentration of 90Sr



Page 119 of 253

9.8.3.1.5. Analysis of the results for the reference scenario

Table 9-14 presents the maximal resulting concentration beneath the repository and

the limits according to [35].

Table 9-14 Maximum concentrations according to DUST calculations and limits

according to [35]

Isotope Max. conc.

in year:

Maximum

concentration,

Bq/cm3

Limit concentration

according to [35],

Bq/L

Limit concentration

according to [35],

Bq/cm3 3H 318 6.59E-07 7600 7.6

14C 8750 5.78E-02 230 0.23 36Cl 723 4.88E-05 61 0.061

60Co 312 9.24E-20 14 0.014 59Ni 15290 9.36E-10 1100 1.1 63Ni 569 8.01E-08 460 0.46 90Sr 393 5.36E-10 1.9 0.0019

93mNb 348 6.02E-25 420 0.42 129I 44590 7.11E-07 0.96 0.00096

137Cs 322 6.79E-04 11 0.011 241Pu 353 3.95E-20 29 0.029

The resulting concentration for all isotopes is below the limits in [35]. The ratio

between limit concentration in [35] and the resulting concentration is at least 10 for

all isotopes except 14C.

14C is the most problematic isotope among all the isotopes within repository inventory.

The reasons for 14C retardation difficultly are:

high initial inventory of 14C in repository;

long T1/2;

possible chemical reaction with oxygen resulting in CO2, which is gas and its

distribution is very quick;

The three isotopes with highest concentration beneath the repository are:

14C with maximal concentration 5.78E-02 Bq/cm3;

137Cs with maximal concentration 6.79E-04 Bq/cm3;

36Cl with maximal concentration 4.88E-05 Bq/cm3;

9.8.3.2. Models of the processes in Unsaturated zone

The estimation of the transport of radionuclides released from the repository via the

unsaturated zone to the saturated zone is performed using HYDRUS computer code,

which deals with water flow and leachate (solute) transport.

Three HYDRUS models were developed for modeling the unsaturated zone of Saligny

repository:

3D model of Saligny site unsaturated zone according to site characteristic data

in 2009 [28].

2D model of Saligny site unsaturated zone for modeling the lateral transport of

radionuclides according to site characteristic data in 2009 [28].



Page 120 of 253

2D model of Saligny site unsaturated zone for evaluation of the influence of the

data obtained from the two additional boreholes PH01 and PH03 according to

site characteristics in 2010 [7].

9.8.3.2.1. 3D model of Saligny site unsaturated zone

The 3D HYDRUS model is used for the following scenarios:

Reference scenario “Consumption and use of the groundwater in a small farm

onside of the facility”;

Alternative scenario – “Farm on the repository - Residence scenario on totally

degraded waste”;

9.8.3.2.1.1. Input data

As radionuclide concentrations input for the 3D HYDRUS calculations are used the

results obtained by the computer code DUST-MS for the reference scenario.

9.8.3.2.1.2. Assumptions

Assumptions related to the repository cell:

The disposal cells are reinforced concrete vaults, comprising the foundation slab and

external walls. The external walls are 40cm thick and the foundation slab (concrete) is

1 m thick. Below the foundation is considered to exist a 2m compacted loess layer

[38].

Conservatively, the properties of compacted loess are assumed to be equal to those

for silty loess.

Another calculation (in which the properties of compacted loess are assumed to be

the same with the red clay – non-conservative assumption) is performed in order to

demonstrate the influence of the compacted loess properties on the radionuclide

transport.

Assumptions related to the site geology:

The details on the each layer: thickness, physical and chemical characteristics, etc.

considered are reflected in the specific calculations of 3D model and comply with

the data presented in [28].

The layers representing the unsaturated zone are defined as follows:

o Ia – representing the silty loess;

o Ib – representing the clayey loess;

o Ic– representing the red clay, red sandy clay and the red clayey

sand;

o Id – representing the pre-quaternary complex, consisting of

different types of clays, lenses of sand, gravel, limestone and

sandstone.

The loess horizon contains thin fossilized distinct layers, having a larger content of clay

and higher moisture content. The Ib layer is divided in sub-layers (The upper lb layer,

The fossilized loess levels Iab1 and Iab2, The lower lb clayey loess), with different

parameters.



Page 121 of 253

The existence of fossilized levels is only presumed based on some observations in an

outcrop situated near the site. There is no description of such things in borehole logs

in [28] therefore their exact thickness cannot be evaluated.

Due to this reason in the 3D model only four layers are considered as natural barriers

(Ia, Ib, Ic and Id), and for layer Ib the soil with the most conservative properties is

considered. In the 2D model the data for the fossilized levels are consistent with [21].

Assumptions related to the calculation period:

The following assumption is used as basis for the definition of the calculation period:

“We suppose that for the period of time for which the effective dose can be

considered as a valid indicator of the repository safety (10 000 years), the site

geology maintains the present configuration”.

The other factor influencing the calculation period is the decay half-time and

sorption coefficients of the radionuclides studied (Ni 59 – T1/2 = 7.54 E+04 years).

The large decay half-times of several radionuclides imposed the necessity to assume

geological stability of the site for periods longer than 10 000 years, but not more than

100 000 years.

9.8.3.2.1.3. Geometrical model

The site relief is modeled considering the boreholes elevation. Beneath the repository,

the elevation of the foundation slab will be of 58 m. The elevation of compacted

loess will be of 57m, and the elevation of the first layer (Ia) will be of 55m [38].

In the model of unsaturated zone, the compacted loess layer with thickness of 2

meters represents the distance between elevations 55 and 57 beneath the

repository.

The elevation of the unsaturated zone is assumed to be equal to that of the Aptian

Deposits. Due to the limited information on the Aptian Deposits Hydrostatic levels,

interpolation between boreholes is used.

Conservatively, in this assessment the drainage system is not modeled.

The thickness of the ld layer of the unsaturated zone in different boreholes is defined

as follows:

ldi=Zi–lai-lbi-lci-ZAq,i

Where:

lai,lbi,lci – the thickness of different layers, in different boreholes, considering

the decreased elevation of la beneath the repository (elevation 55 m)

Zi –the elevation of the borehole – considering the decreased elevation

beneath the repository

ZAq,i – the elevation of the Aptian Aquifer, in different boreholes.



Page 122 of 253

Figure 9-60 3D model of Saligny site unsaturated zone for HYDRUS

Figure 9-61 Saligny site repository area



Page 123 of 253

Figure 9-62 Cross section of Saligny site unsaturated zone

The first layer - compacted loess (dark blue on Figures 9-60, 9-61 and 9-62) is available

only on the repository area. The 1E-05m thickness (the minimal thickness allowed in

HYDRUS) of this layer outside the repository is introduced. Due to this reason,

compacted loess is available outside the repository in the model (Figures 9-60, 9-61

and 9-62) but it is with minimal thickness.

9.8.3.2.1.4. 2D model representing the transport of the radionuclides in

lateral directions

In order to present the lateral transport of radionuclides, 2D model corresponding to

the geological formation of borehole FS1 is drafted. It includes 103 m representing

the repository and 30m on both sides of the repository, representing the natural soil.

The model geometry is 2D-Vertical Plan XZ.

Using this model, calculations for the radionuclides with the small sorption coefficients

and long half-life decay (C-14, I-129) are performed.

Figure 9-63 2D model, presenting the repository and lateral area

a. Soil hydraulic properties



Page 124 of 253

Table 9-15 Hydraulic parameters of the unsaturated geological formations of Saligny site

[28] and [50]

b. Specific assumptions

The layers Iab, Ib superior, I-ab2 and Ib inferior are assumed to be a single layer, Ib

with the most conservative values for the concentration in the lowest layer (Ib

superior, with the highest saturated hydraulic conductivity Ks).

In order to demonstrate the conservatism of this assumption the second natural layer

is modeled as fossilized silty loess. It should be noted that all the parameters are

changing in the same way for the other soils (except the parameter for lower

clayey loess). The results presenting the comparison of C-14 concentration in the

lowest layer in these two cases (Fossilized silty loess and Upper clayey loess,

representing the second natural layer) are shown graphically (section 9.8.3.2.2.1). In

this study the properties of compacted loess layer are considered equal to those for

the red clay.

The infiltration rate through the compacted loess is assumed to be equal to those for

natural soil in Saligny site.

c. Water flow modeling

It is assumed that the water flow in each geological layer can be represented by the

Van Genuchten formula. The parameters of the Van Genuchten relation for each

layer are summarized in Table 9-15. The rain water (natural precipitations) constantly

infiltrates through the repository cover and reaches the disposal cells.

The infiltration rate through the compacted loess is assumed to be equal to that of

the natural soil in Saligny site.

Geological layer

Density

(g/cm3) r s

Ks

(cm/s)/

m/year

(1/m) n

Silty loess 1.540.06 0.067 0.37 1.E-04

31.557

0.634 1.64

Fossilized silty loess 1.780.10 0.049 0.47

7.5E-06

2.3668 0.935 1.297

Upper clayey loess 1.570.07 0.076 0.38 2.E-05

6.3116

0.590 1.59

Fossilized clayey

loess

1.720.07 0.022 0.42

9.5E-06

2.998 1.393 1.195

Lower clayey loess 1.690.11 0.059 0.44

1.8E-05

5.6804 0.53 1.46

Red clay 1.760.17 0.001 0.43 5.E-06

1.5779

0.209 1.131

Aptian clay 1.760.15 0.001 0.41

9.E-06

2.8402 0.176 1.15



Page 125 of 253

The infiltration scenario beneath the repository used in these calculations is the same

as in [21]:

Infiltration 0 to 300 years: 0 mm/year

Infiltration 300 to 500 years: 2 mm/year

Infiltration after 500 years: 20 mm/year

For the calculation period the rain water infiltration rate outside the repository is

constantly equal to 20 mm/year.

The decision to use the constant infiltration rate was taken as result of the previous

transient water flow simulations, which showed that seasonal variations of the

infiltration rate do not propagate deeper than 4m.

The contaminants are leached from the repository with a rate proportional to the

water quantity that contacts the waste and with the adsorption coefficient of the

radionuclides.

d. Radionuclide transport

The radionuclides released from the disposal modules contact the cement of the

cells. The cement represents the first barrier against the transport of many

radionuclides, large part of the long-life contaminants being strongly adsorbed in

cement.

The radionuclide transport from disposal modules, through foundation to compacted

loess is calculated using DUST-MS computer code. The results are used as boundary

conditions for HYDRUS calculations.

The sorption coefficients of Cs-137, Sr-90, Co-60 and C-14 in the geological formations

of Saligny site have been experimentally determined [43]. For the other radionuclides

the sorption coefficients are considered according to the information in [50].

In contaminant transport modeling the representative values (best estimates) of

parameters have been used [43].



Page 126 of 253

Table 9-16 Distribution coefficients of radionuclides in the geological formations of Saligny site kd (m3/kg)

Element Aquifer Improved

foundation

ground

Surface

soil (Upper

soil)

Non-

degraded

concrete

Degraded

concrete

Water

from

well

Silty

loess

Clayey

loess

Red

clay

Aptian clay Permeable

inter-layers

H 3 E-5 0 3E-5 0 0 0 0 0 0 0 0

Co 200 0.031 0.06 0.1 0.01 5 0.033 0.03 0.031 0.03 0

C 0.1 0.006 0.1 2 0.2 0.005 0.005 0.005 0.006 0.006 0.005

Cs 10 3.8 1 0.02 0.02 1 0.995 0.995 3.8 1.1 0

Nb 10 1 0.03 0.5 0.5 10 1 1 1 1 0.55

I 0.001 0.001 0.0008 0.064 0.001 0.001 0.001 0.001 0.001 0.001 0

Ni 10 0.6 0.1 0.1 0.01 10 0.6 0.6 0.6 0.6 0.4

Sr 0.5 0.012 0.03 0.001 0.001 1 0.006 0.006 0.012 0.012 0

Tc 0.01 0.001 0.00003 0.5 0 0.01 0.001 0.001 0.001 0.001 0.0001

U 0.05 0.0014 0.05 2 0.1 0.05 0.0014 0.0014 0.0014 0.0014 0.001

Pu 100 7.6 2 5 1 100 7.6 7.6 7.6 7.6 0.5

Am 1000 21.5 0.8 1 0.2 5 13.4 13.4 21.5 27.4 0

Th 5000 6 60 5 1 10 6 6 6 6 0.9

Ra 0.5 9 9 0.05 0.05 0.5 9 9 9 9 3

Rn 0 0 0 0 0 0 0 0 0 0 0

Pb 10 0.5 0.1 0.5 0.05 10 0.5 0.5 0.5 0.5 0.02

Po 10 3 0.4 0.5 0 10 3 3 3 3 0.15

Pa 5 7.6 2 5 0.1 5 7.6 7.6 7.6 7.6 0.34

Ac 10 7.6 0.8 1 0.2 10 7.6 7.6 7.6 7.6 0.34

Np 0.5 7.6 0.01 5 0.1 0.01 7.6 7.6 7.6 7.6 0.005



Page 127 of 253

Table 9-17 Half Life(years)/ Decay constant (y-1) of the considered radionuclides

Radionuclide Half-life period

(yrs)

Decay constant

(y-1)

H-3 12.4 0.0559

C-14 5730 1.21E-4

Ni-59 7.54 E+4 9.19E-6

Ni-63 100.1 6.92E-3

Co-60 5.27 0.132

Sr-90 29.1 0.024

Nb-94 2.03 E+4 3.41E-5

Tc-99 2.13 E+5 3.25E-6

I-129 1.57 E+7 4.41E-8

Cs-134 2.06 0.336

Cs-137 30 0.023

U-234 2.45 E+5 2.83E-6

U-235 7.04 E+8 9.85E-10

U-238 4.47 E+9 1.55E-10

Pu-238 87.7 7.90E-3

Pu-239 2.41 E+4 2.88E-5

Pu-240 6540 1.06E-4

Pu-241 14.4 0.048

Am-241 432 1.60E-3

The radionuclide decay is represented by:

λ= - decay constant

It should be noted that kd distribution coefficients have sometimes different values depending

on different sources.

In these assessments are used the values from [43].

e. Dispersion and dispersivity

According to [10], a general approximation that is frequently used is that the longitudinal (in

the direction of groundwater flow) dispersivity (αL) is set to one-tenth of the scale of the

problem.

For the repository area, the thickness of the unsaturated zone is approximately 40m which

leads to:

longitudinal dispersivity : 4m

transversal dispersivity: 0.8 m (1/5 the longitudinal dispersivity)

A more refined approach that takes into account the scale of the problem has also been

suggested:

L < 100 m: αL = 0.0017 L 1.5

L > 100 m: αL = 0.32 L 0.83

where

L is the traveled distance (m), approximately 40m for the current calculation;



Page 128 of 253

αL is the longitudinal dispersivity (m).

αL: αT ≈1:0.2

αT – transversal dispersivity (m)

Using these formulas the following values are obtained:

longitudinal dispersivity : 0.43m

transversal dispersivity: 0.09 m (1/5 the longitudinal dispersivity)

The calculations with these parameters lead to negative concentrations of the radionuclides

in some points. These results are non-physical.

Numerical solutions of the transport equation often exhibit oscillatory behavior and/or

excessive numerical dispersion near relatively sharp graphical concentration fronts. These

problems can be especially serious for convection-dominated transport characterized by

small dispersivities. One way to partially avoid numerical oscillations is to use upstream

weighing [29] (its use does not solve the problem in the calculations for some radionuclides).

Undesired oscillations can often be prevented also by selecting an appropriate combination

of space and time discretization. Two dimensionless numbers may be used to characterize the

space and time discretization. One of these is the grid Peclet number, Peei, which defines the

predominant type of the solute transport (notably the ratio between the convective and

dispersive transport terms) in relation to size of the finite element grid:

iiii

e

i DxqPe /

where Δx is the characteristic length of a final element.

The Peclet number increases when the convective part of the transport equation dominates

the dispersive part, i.e. when a relatively steep concentration front is presented. In order to

achieve acceptable numerical results, the spatial discretization must be kept relatively fine to

maintain a low Peclet number. Numerical oscillation can be virtually eliminated when the local

Peclet numbers do not exceed 5. However, acceptably small oscillations may be obtained

with local Peclet numbers as high as 10 (Huyakorn and Pinder, 1983, [29]). Undesired oscillation

for higher Peclet numbers can be effectively eliminated by using upstream weighing (Section

6.4.2 of [29]).

A second dimensionless number which characterizes the relative extent of numerical

oscillations is the Courant number, Crei. The Courant number is associated with time

discretization as follows:

ii

e

i xRtqCr /

Three stabilizing options are used in HYDRUS in order to avoid oscillations in the numerical

solution of the solute transport equation [29].

One option is upstream weighing which effectively eliminates undesired oscillations at

relatively high Peclet numbers.

A second option for diminishing or eliminating numerical oscillations uses the criterion

developed by Perrochet and Berod [1993] quoted in [29]:

Pe .Cr ≤ωs = 2

where ωs is the performance index [-]. This criterion indicates that convection-dominated

transport problems having large Pe numbers can be safely simulated provided that Cr is

reduced according to the previous inequality [29]. When small solution oscillations are

tolerated, ωs can be increased to about 5 or 10.



Page 129 of 253

A third stabilization option implemented in HYDRUS also uses the previous criterion. However,

instead of decreasing Cr to satisfy the equation this option introduces an artificial dispersion in

order to decrease Peclet number. The additional amount of longitudinal dispersion, DL [L], is

given by [29]

The use of the values of 0.43 and 0.09m for the longitudinal and transversal dispersivity leads to

such oscillations (negative concentrations of the radionuclides).

In order to prevent these negative concentrations, the Peclet number should be decreased.

Decreasing of model area allows decreasing of characteristic length of a final element. Due

to such reasoning, the calculations include only the area beneath the repository.

Sufficiently decrease of the characteristic length of final elements in this manner is not

acceptable because of the large area of the repository, which leads to a great number of

elements (long calculation time). Therefore the highest values - 4m for the longitudinal and

0.8m for the transversal dispersivity are used.

f. Diffusion

According to [30], the typical diffusion coefficients are of the order 10-5 m2/sec in air and 10-9

m2/sec in water. These values are used in the calculations, converted in m2/year:

Molecular diffusion in water ~0.032 m2/year;

Molecular diffusion in air ~320 m2/year.

g. Initial and boundary conditions

The initial water content is considered as follow:

loess layers – 0.25;

clay layers– 0.35.

The limiting conditions as concerns the water flow at upper boundary are as discussed in

Water flow modeling. For this purpose we use time-dependent boundary conditions for the

repository boundary. On the lower boundary, constant water content of 99% of the layer

saturation content is considered (≈0.40). The vertical boundaries are considered as ‘no flux

boundary’.

For the radionuclide concentrations at the upper boundary (radionuclide boundary condition)

are used the results obtained by DUST-MS. For the HYDRUS calculation, these values (in

Bq/cm3), are converted in Bq/m3 (multiplying by 106). These values are introduced as time

variable boundary conditions (volumetric activity [Bq/m3] time dependant).

9.8.3.2.1.4.1. Model validation

a. Validation of 3d model

In order to validate the 3D model of the unsaturated zone beneath the repository, the C14

results obtained with the 2D model are compared to the results obtained with the 3D model. In

these calculations the properties of compacted loess layer are assumed to be equal to those

for red clay. The values of boundary volumetric activity are not representative for Saligny Site

repository – these values are used only for the purpose of validation. C14 time-dependant

volumetric activity for the last layer (the unsaturated and saturated zone boundary) in the

region of FS1 is presented in figure 9-64.



Page 130 of 253

Figure 9-64 Validation of 3D model of the repository unsaturated zone

These graphics show a good compliance between 2D and 3D models.

b. Justified selection of the soil model (the choice of Upper clayey loess as a second

layer of the unsaturated zone)

As it was mentioned the loess horizon contains thin fossilized distinct layers, having a larger

content of clay and higher moisture content. In order to prove the conservatism of the choice

of Upper clayey loess as a second layer of the unsaturated zone, two calculations for C14 are

performed, with different properties of the second natural layer (Fossilized Loess and Upper

clayey loess) of unsaturated zone by using the 2D model. The values of boundary volumetric

activity used in this study are not representative for Saligny Site repository.

Figure 9-65 C14 volumetric activity in the unsaturated-saturated zone boundary, considering

different properties of the second natural layer

The results show that the use of upper clayey loess leads to higher value for the volumetric

activity in the lowest layer (the boundary between unsaturated and saturated area). Due to

10000 12000 14000 16000 18000 20000 22000

27000

28000

29000

30000

31000

32000

33000

34000

35000

Vo

lum

etr

ic a

ctivity [B

q/m

3]

Time [years]

Fossilized Loess

Upper clayey loess

0 10000 20000 30000 40000 50000 60000 70000

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

22000

24000

26000

28000

30000

32000

34000

36000

Volu

me

tric

activity [B

q/m

3]

Time [years]

Fossilized Loess

Upper clayey loess



Page 131 of 253

this reason, the Upper clayey loess is used for all calculations as a second natural layer of the

unsaturated zone model.

9.8.3.2.1.4.2. Results and analysis

a. Sr-90 volumetric activity

The Sr-90 depth-dependant volumetric activity distribution is presented in Figure 9-66. These

values are in the region of FS1 borehole. The properties of compacted loess layer are assumed

to be equal to those for silty loess.

0 500 1000 1500 2000 2500

1E-14

1E-12

1E-10

1E-8

1E-6

1E-4

0.4m

0.8m

2m

4.3m

6.3m

10.2m

Volu

me

tric

Activity [B

q/m

3]

t [years]

Figure 9-66 Sr90 volumetric activity (the properties of compacted loess layer are assumed to be

equal to those for silty loess)

Figure 9-67 Sr-90 volumetric activity in the unsaturated-saturated zone boundary

The concentration of Sr in the lower layers is approximately zero.

b. Co-60 volumetric activity

0 500 1000 1500 2000 2500 3000 3500

0.00E+000

2.00E-022

4.00E-022

6.00E-022

8.00E-022

1.00E-021

Volu

me

tric

Activity [B

q/m

3]

t [years]


32.25m



Page 132 of 253

The properties and the boundary concentration of Co60 in comparison to Sr-90 are as follow:

higher distribution coefficient

shorter half-life

lower initial concentration

This means that the concentration of Co in the lower layers will be lower than the Sr

concentration (which is approximately zero).

Due to this reason Co calculation is not performed.

c. C-14 Volumetric activity

The C-14 depth-dependant volumetric activity distribution is presented in Figure 9-68. These

values are in the area of FS1 borehole. The properties of the compacted loess layer are

assumed to be equal to those for silty loess.

0 20000 40000 60000 80000 100000

1

10

100

1000

10000

100000 0.4m

6.3m

10m

19.9m

30m

32.25m - Unsat. - Sat.

zone boundary

t [years]

Vo

lum

etr

ic A

ctivity [B

q/m

3]

Figure 9-68 C-14 volumetric activity (the properties of compacted loess layer are assumed to be


The C-14 volumetric activity in the last layer (the boundary between unsaturated and

saturated area of Saligny site) is presented in three points (in the FS1, FS16 and FS2 areas).

These values are presented in Figure 9-69. As it can be seen the maximum volumetric activity is

in the area of FS1 and FS16 boreholes and it is almost equal.



Page 133 of 253

0 20000 40000 60000 80000 100000

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

11000

12000V

olu

me

tric

Activity [B

q/m

3]

t [years]

FS1

FS2

FS16


saturated area of Saligny site) in different regions

1000 1200 1400 1600 1800 2000 2200 2400

0.0000

0.0002

0.0004

0.0006

0.0008

0.0010

FS1

FS2

FS16

Volu

me

tric

Activity [B

q/m

3]

t [years]


saturated area of Saligny site) in different regions, for the first 2500 years

From this graphic is clear that the C-14 reaches the unsaturated – saturated zone boundary

more than 1500 years after the beginning of the facility operation.

The volumetric activity in the lateral regions is calculated by using the 2D model. The results are

shown in Figure 9-71.



Page 134 of 253

Figure 9-71 C-14 Volumetric activity distribution in lateral and transversal direction (2D model)

The results prove that up to 30 m sideward of the repository the volumetric activity is less than

0.010 Bq/m3.

In Figure 9-72 is presented the volumetric activity in two points - one beneath the repository

(central part) and another – in the lateral part of the repository.

0 20000 40000 60000 80000 100000

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

11000

12000

t [years]

Vo

lum

etr

ic A

ctivity [B

q/m

3]

Central point

Lateral point

Figure 9-72 C-14 volumetric activity in the central and lateral points of the unsaturated – saturated

zone boundary beneath the repository

From this graphic is clear that the maximum C-14 volumetric activity in the unsaturated –

saturated zone boundary is in the area beneath the repository.

d. H-3 Volumetric activity

The H3 depth-dependant volumetric activity distribution is presented in Figure 9-73. These

values are in the area of FS1 borehole.

In order to demonstrate the influence of the compacted loess layer over the radionuclide

volumetric activity distribution, two calculations are performed. The properties of compacted

loess layer are assumed to be equal to those for red clay in the first one, and to those for silty

loess in the second.



Page 135 of 253

Figure 9-73 H-3 volumetric activity (the properties of compacted loess layer are assumed to be

equal to those for red clay on the left graphic and to those for silty loess on the right graphic)

These graphics show that changing the properties of the compacted loess does not lead to

significant difference in H-3 volumetric activity in the lower layers of the unsaturated zone. For

instance at 10 m depth the maximum volumetric activity is 3.9*10-5Bq/m3 in case of silty loess

and 1.8*10-5Bq/m3 in case of red clay. The reason for this is the H-3 distribution coefficient,

which is equal to zero for both these layers.

The H-3 volumetric activity in the last layer - the boundary between unsaturated and saturated

area of Saligny site in the FS1 area is presented in Figure 9-74. The compacted loess is modeled

as silty loess (conservative assumption).

0 200 400 600 800 1000

0.00E+000

2.00E-010

4.00E-010

6.00E-010

8.00E-010

1.00E-009

1.20E-009

1.40E-009

1.60E-009

1.80E-009

Vo

lum

etr

ic A

ctivity [B

q/m

3]

t [years]

Last layer, 32.25m

Figure 9-74 H-3 volumetric activity in the last layer – the FS1 area (the boundary between

unsaturated and saturated area of Saligny site)

200 400 600 800

1E-10

1E-9

1E-8

1E-7

1E-6

1E-5

1E-4

1E-3

0.01

0.1

1

Volu

me

tric

Activity[B

q/m

3]

t[years]

0.29m

0.86m

2m

3.9m

6.05m

8m

10.1m

200 400 600 800 1000

1E-10

1E-9

1E-8

1E-7

1E-6

1E-5

1E-4

1E-3

0.01

0.1

1

0.4m

0.8m

2m

4.3m

6.7m

8.6m

10.2m

20m

Vo

lum

etr

ic A

ctivity [B

q/m

3]

t [years]



Page 136 of 253

In order to present the effect of the water infiltrating outside the repository on the volumetric

activity in the unsaturated-saturated zone boundary, a 2D calculation is performed and the

results are presented for two points – one just beneath the repository and one – in the lateral

part of the repository.

200 400 600 800 1000

1E-11

1E-10

1E-9

1E-8

Central point

Lateral poin

Volu

me

tric

Activity [B

q/m

3]

t [years]


saturated area of Saligny site), performed with the 2D model

The results are presented for one point just beneath the repository and one in the lateral part.


saturated area of Saligny site), performed with the 2D model

The maximum H-3 volumetric activity in the lateral point (4.8*10-9) is higher than the one in the

central point (3.9*10-10 Bq/m3) of the repository unsaturated-saturated boundary. The reason

for this is the higher infiltration rate in the lateral region and the zero distribution coefficient of

H-3.

The H-3 volumetric activity in the central point of repository in the unsaturated - saturated

boundary obtained by the 3D model (1.62*10-9 Bq/m3) is higher than the one obtained with

the 2D model (3.9*10-10 Bq/m3) by a 4.2 factor. Due to this reason, the multiplication by 4.2

(conservatively) of the volumetric activity in the lateral point of repository in the unsaturated -

saturated boundary obtained by the 2D model. Thus, the maximum H-3 volumetric activity in

the unsaturated-saturated zone boundary is 4.8*10-9*4.2=2.02*10-8Bq/m3.



Page 137 of 253

e. Cs-137 Volumetric activity

The Cs-137 depth-dependant volumetric activity distribution is presented in Figure 9-77. These

values are in the FS1 borehole area. In order to demonstrate the influence of the compacted

loess layer over the radionuclide volumetric activity distribution, two calculations are

performed. The properties of compacted loess layer are assumed to be equal to those for red

clay in the first one, and to those for silty loess in the second.

Figure 9-77 Cs-137 volumetric activity (the properties of compacted loess layer are assumed to be

equal to those for red clay on the left graphic and to those for silty loess on the right)

The Cs-137 volumetric activity in lower levels increases strongly in case of compacted loess

represented by silty loess in comparison to those represented by red clay. The reason for this is

the smaller distribution coefficient for the silty loess.

0 500 1000 1500 2000 2500

-1,00E-023

-8,00E-024

-6,00E-024

-4,00E-024

-2,00E-024

0,00E+000

2,00E-024

4,00E-024

6,00E-024

8,00E-024

1,00E-023

Vo

lum

etr

ic A

cti

vit

y [

Bq

/m3

]

t [years]

Unaturated - Saturated zone boundary

32.25m

Figure 9-78 Cs-137 volumetric activity in the last layer – FS1 area (the boundary between


The Cs-137 volumetric activity strongly decreases in depth. No matter the compacted loess

material (even if its properties are equal to those for the silty loess – with the most conservative

properties) the Cs-137 volumetric activity is negligible at depths higher than 2.5m.

0 500 1000 1500 2000 2500

1E-26

1E-22

1E-18

1E-14

1E-10

1E-6

0.01

0.23m

0.6m

1m

1.2m

2m

Vo

lum

etr

ic A

ctivity [B

q/m

3]

t[years]0 500 1000 1500 2000 2500

1E-17

1E-15

1E-13

1E-11

1E-9

1E-7

1E-5

1E-3

0.1

0.23m

0.6m

1m

1.2m

2m

2.5m

Volu

me

tric

Activity [B

q/m

3]

t [years]



Page 138 of 253

The Cs-137 volumetric activity in the saturated – unsaturated zone boundary is zero.

f. I-129 Volumetric activity

I-129 depth-dependant volumetric activity distribution is presented in Figure 9-79. These values

are in FS1 borehole area. The properties of compacted loess layer are assumed to be equal to

those for the silty loess.

0 20000 40000 60000 80000 100000

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

Vo

lum

etr

ic A

ctivity [B

q/m

3]

t [years]

0.5m

2m

10m

19.9m

29.7m

32.25m - Unsat - Sat.

zone boundary (FS1)

Figure 9-79 I-129 volumetric activity (the properties of compacted loess layer are assumed to be


In order to present the time at which I-129 reach the unsaturated – saturated zone boundary,

the volumetric activity in this layer is presented for the first 1000 years.

400 600 800 1000

0.00E+000

1.00E-008

2.00E-008

3.00E-008

4.00E-008

5.00E-008

6.00E-008

Vo

lum

etr

ic A

ctivity [B

q/m

3]

t [years]

Unsaturated-Saturated zone boundary

32.25m

Figure 9-80 I-129 volumetric activity in the unsaturated – saturated zone boundary in the first 1000

years (the properties of compacted loess layer are assumed to be equal to those for the silty loess)



Page 139 of 253

I-129 volumetric activity does not decrease in depth because of the low distribution

coefficients and the long half-life.

The volumetric activity in the lateral regions is calculated by using 2D model. In this calculation

the properties of compacted loess layer are assumed to be equal to those for silty loess. The

results are shown graphically in Figure 9-81.

Figure 9-81 I-129 Volumetric activity distribution in lateral and transversal direction at different

times (2D model)

The main radionuclide transport direction is downward. The volumetric activity of I-129 in the

lateral regions (30 meters from the repository) is a few orders of magnitude smaller than this in

the lower layers of unsaturated zone.

In Figure 9-82 is presented the volumetric activity in two points - one just beneath the repository

and one – in the lateral part of the repository.



Page 140 of 253

0 20000 40000 60000 80000 100000

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

Lateral point

Central point

Vo

lum

etr

ic A

ctivity [B

q/m

3]

t [years]

Figure 9-82 I-129 volumetric activity in the central and lateral point of the unsaturated – saturated

zone boundary beneath the repository

The maximum I-129 volumetric activity in the unsaturated – saturated zone boundary is in

the area beneath the repository.

g. Ni-63 Volumetric activity

The Ni-63 depth-dependant volumetric activity distribution is presented in Figure 9-83. These

values are in FS1 borehole area. The properties of compacted loess layer are assumed to be

equal to those for the silty loess.

0 1000 2000 3000 4000 5000

1E-13

1E-11

1E-9

1E-7

1E-5

1E-3

0.1

Vo

lum

etr

ic A

ctivity [B

q/m

3]

t [years]

0.12m

0.3m

0.5m

1m

2m

2.5m

3.55m



At 2.5m the Ni-63 volumetric activity decreases by more than 7 orders of magnitude.



Page 141 of 253

0 1000 2000 3000 4000 5000

-1,00E-020

-8,00E-021

-6,00E-021

-4,00E-021

-2,00E-021

0,00E+000

2,00E-021

4,00E-021

6,00E-021

8,00E-021

1,00E-020

Vo

lum

etr

ic A

ctivity

[Bq

/m3

]

t [years]


32.25m

Figure 9-84 Ni63 volumetric activity in the last layer – the FS1 area (the boundary between


Due to high distribution coefficient and relatively short half-life of Ni-63 its volumetric activity in

unsaturated – saturated zone boundary is zero.

h. Ni-59 Volumetric activity

The Ni-59 depth-dependant volumetric activity distribution is presented in Figure 9-85. These


equal to those for the silty loess.

0 20000 40000 60000 80000 100000 120000 140000 160000

1E-15

1E-13

1E-11

1E-9

1E-7

1E-5

1E-3

Vo

lum

etr

ic A

ctivity

[Bq

/m3

]

t [years]

0.5m

1m

2m

3m

6m

10m

20m

32.25m Unsat. -

Sat. zone boundary





Page 142 of 253

80000 100000 120000 140000 160000

1E-16

1E-15

1E-14

1E-13

1E-12

1E-11

Vo

lum

etr

ic A

ctivity [B

q/m

3]

t [years]

32.25m Unsat. -

Sat. zone boundary

Figure 9-86 Ni-59 volumetric activity in the last layer – the FS1 area (the boundary between


According to the assumptions related to the calculation period, the final calculation time is

assumed to be the year 100 000. Because of the relatively high distribution coefficient and

long half-life of Ni-59, the maximum volumetric activity in the unsaturated-saturated zone

boundary appears at a later stage.

i. Cl-36 Volumetric activity

The Cl-36 depth-dependant volumetric activity distribution is presented in Figure 9-87. These


equal to those for the silty loess. The distribution coefficients are assumed to be equal to those

for I-129.

0 5000 10000 15000 20000 25000 30000

0

10

20

30

40

50

Vo

lum

etr

ic A

ctivity [B

q/m

3]

t [years]

0.5m

2m

10m

19.9m

29.7m

32.25m Unsat. - Sat.

zone boundary

Figure 9-87 Cl-36 volumetric activity in the last layer – the FS1 area (the boundary between

unsaturated and saturated area of Saligny site



Page 143 of 253

j. Pu-241/Am-241Volumetric activity

Am-241 is a product of Pu-241 radioactive decay. The half-life of Pu-241 is of 14.4years, and the

half-life of Am-241 is of 432.7years.

The maximum Pu-241 volumetric activity released from the repository is 3.9 *10-17 Bq/l [10].

We assumed that this is the volumetric activity of this radionuclide in the drinking water. This is

not a physical assumption because of its high distribution coefficient in the soil layers. But if this

concentration in water does not lead to a significant dose due to ingestion the calculation of

Pu-241 transport to the wells will not be necessary.

The assumed drinking rate is 3l per day by person, 365 days per year.

The Pu-241 Dose Conversion Factor (for ingestion) is 4.7 x 10-9Sv/Bq [23].

The dose received by drinking contaminated water is defined as:

D=C*DCF*DR*t

Where

D – effective dose [Sv]

C - volumetric activity [Bq/l]

DCF – Dose Conversion Factor [Sv/Bq]

DR – Drinking Rate [l/day]

t – time [days]

Pu-241 dose:

D=3.9 *10-17*4.7 *10-9*3*365=2 *10-23Sv

The Pu-241 Dose Conversion Factor (for ingestion by infant) is 5.6 10-8Sv/Bq [23].

D=3.9 *10-17*5.6 10-8*3*365=2.4* 10-21Sv (for infants) even if the drinking rate is 3l per day.

The received dose due to drinking of water contaminated with Pu-241 with such a volumetric

activity does not lead to significant dose accumulation.

Due to this reason the transport of these radionuclides to the saturated zone and to the well is

not assumed.

The used data for DCF are from [23] - ICRP 72 (Adult).

Due to the higher half-life of Am-241 in comparison with Pu-241, its volumetric activity increases

in time.

The Am-241 time-dependant volumetric activity, at different depths beneath the repository is

presented in Figure 9-88.



Page 144 of 253

0 5000 10000 15000 20000 25000

1E-19

1E-17

1E-15

1E-13

1E-11

1E-9

1E-7

1E-5

1E-3

0.1 0.1m

0.2m

0.4m

0.6m

1m

1.2m

1.4m

2m

2.52m

Vo

lum

etr

ic A

ctivity [B

q/m

3]

t [years]

Figure 9-88 Am-241 volumetric activity (the properties of compacted loess layer are assumed to

be equal to those for silty loess)

The Am volumetric activity decreases strongly in depth due to the high distribution coefficient.

In the first layer (compacted loess layer which properties are assumed to be equal to those of

the silty loess) the volumetric activity [Bq/m3] of Am decreases approximately 12 orders of

magnitude.

0 5000 10000 15000 20000 25000

-1,00E-020

-8,00E-021

-6,00E-021

-4,00E-021

-2,00E-021

0,00E+000

2,00E-021

4,00E-021

6,00E-021

8,00E-021

1,00E-020

Vo

lum

etr

ic A

ctivity [B

q/m

3]

t [years]

Unsaturated - saturated zone boundary

32.25

Figure 9-89 Am-241 volumetric activity in the last layer – FS1 area (the boundary between


The volumetric activity of Am in the unsaturated-saturated zone boundary is zero.



Page 145 of 253

9.8.3.2.1.4.3. Conclusions

A reference scenario for the downward and lateral radionuclide transport in the unsaturated

area of Saligny site is considered. The results show that the radionuclides that reach the

unsaturated – saturated zone boundary are:

Sr-90;

C-14;

H-3;

I-129;

Ni-59

Cl-36

The H-3 maximum volumetric activity in the lateral point is higher than the one in the central

point of the repository’s unsaturated-saturated boundary. The reason for this is the higher

infiltration rate in the lateral region and the zero distribution coefficient of H-3. For the

radionuclides with non-zero distribution coefficients the volumetric activity in the lateral point is

lower than in the central point of the repository’s unsaturated-saturated boundary.

9.8.3.2.2. Calculation of radionuclides’ transport considering the soil's hydraulic

data from [7]

After the completion of Site Characterization in 2010, hydro-geological data for Saligny site

unsaturated area are available from 2 additional drilled boreholes (PH01 and PH03). The data

from the investigations of these boreholes are presented in detail in Chapter 3, [7] and [51].

In order to evaluate the influence of the hydro-geological data from the additional boreholes

on the radionuclide transport in Saligny Site unsaturated area, a 2D model of the unsaturated

area is developed (considering the latest geological and hydro-geological investigations,

presented in [7], [51] and in Chapter 3).

a) Characteristics of the Unsaturated zone in boreholes PH01 and PH03

The soil parameters of the unsaturated zone for the additional boreholes – PH01 and PH03 are

presented in details in Chapter 3, [7] and [51].

Figure 9-90 and Figure 9-91present the soil composition in the additional boreholes depending

on the depth.

The depth (from/to) of the layers, clay, dust and sand contents, bulk density and the saturation

ratio are presented in Table 9-18 (for PH01) and Table 9-19 (for PH03).

PH01 soil parameters



Page 146 of 253

0

10

20

30

40

50

60

70

80

90

0 5 10 15 20 25 30 35 40 45 50

Depth [m]

Co

nte

nt

%

Argila, < 0.005 mmClay, %

Praf, 0.005-0.05 mmSilt, %

Nisip, 0.05-2 mmSand, %

Figure 9-90 PH01 soil composition

Table 9-18 PH01 unsaturated zone parameters

Layer

Depth

[m] Clay % Silt % Sand %

Bulk

density

[g/cm3]

Saturatio

n ratio

1 0-5 13 58 29 1.52 0.145

2 5-7.5 20.7 49.7 29.6 1.57 0.19

3 7.5-10 13.5 51.5 35 1.6 -

4 10-17.5 28.2 51.6 20.2 1.73 0.41

5 17.5-22.7 20 58 22 1.86 -

6 22.7-24.2 33 57 10 1.89 -

7 24.2-28.5 28 57 15 1.91 0.48

8 28.5-30.5 28 53 19 2.05 0.98

9 30.5-36.5 3 14 83 2 -

10 36.5-40.8 30 15 55 1.94 -

11 40.8-50 27 29 44 2.03 0.95



Page 147 of 253

PH03 soil parameters

0

10

20

30

40

50

60

70

80

1 3 5.2 7.8 11.8 17.2 23 26.6 33.6 35 38.6 40.8 43.6 49.4

Depth [m]

Co

nte

nt

%

Nisip, 0.05-2 mm

Sand, %

Praf, 0.005-0.05 mm

Silt, %

Nisip, 0.05-2 mm

Sand, %

Figure 9-91 PH03 soil composition

Table 9-19 PH03 unsaturated zone parameters

Layer

Depth

[m] Clay % Silt % Sand %

Bulk

density

[g/cm3]

1 8 19 54 27 1.34

2 9.5 27 49 24 1.81

3 17.5 17 53 30 1.64

4 24 21 52 27 1.8

5 26 43 49 8 1.81

6 34 27 58 15 1.96

7 42 45 46 9 1.16

8 45 32 22 46 2.13

9 50 65.5 30 4.5 2.07

b) Evaluation of Van Genuchten parameters of the unsaturated zone

The van Genuchten parameters of the unsaturated zone are obtained by HYDRUS calculation

by using the unsaturated zone parameters presented in Table 9-18 and Table 9-19.

The calculated van Genuchten parameters of the unsaturated zone are presented in Table

9-20 (for PH01) and Table 9-21 (for PH03).

Table 9-20 PH01 Van Genuchten parameters of the unsaturated zone

Layer

Depth

[m] θr θs α n

Ks

[m/year] I

1 0-5 0.0494 0.3586 0.69 1.5869 54.604 0.5

2 5-7.5 0.06 0.366 0.82 1.5176 23.068 0.5

3 7.5-10 0.0453 0.3398 1 1.4885 37.303 0.5

4 10-17.5 0.0655 0.3496 1.02 1.3862 7.4825 0.5



Page 148 of 253

5

17.5-

22.7 0.0476 0.3048 1.28 1.3333 7.6285 0.5

6

22.7-

24.2 0.0645 0.3272 1.23 1.2924 3.066 0.5

7

24.2-

28.5 0.0566 0.3109 1.28 1.2922 3.6135 0.5

8

28.5-

30.5 0.0494 0.278 1.87 1.2106 2.1535 0.5

9

30.5-

36.5 0.0379 0.2571 4.62 1.5203 123.99 0.5

10

36.5-

40.8 0.053 0.2971 3.6 1.1433 6.0955 0.5

11 40.8-50 0.0462 0.2748 3.7 1.1431 3.285 0.5

Table 9-21 PH03 Van Genuchten parameters of the unsaturated zone

Layer Depth θr θs α n

Ks

[m/year] I

1 8 0.0649 0.4133 0.56 1.6454 76.9785 0.5

2 9.5 0.0582 0.3248 1.29 1.3147 5.6575 0.5

3 17.5 0.0511 0.3418 0.91 1.4843 23.4695 0.5

4 24 0.0502 0.315 1.27 1.3437 8.9425 0.5

5 26 0.0774 0.3579 1.36 1.27 3.431 0.5

6 34 0.0532 0.2989 1.38 1.2702 3.1755 0.5

7 42 0.1025 0.5436 1.44 1.3748 120.851 0.5

8 45 0.051 0.2634 3.84 1.1264 2.2995 0.5

9 50 0.0782 0.3048 1.98 1.1641 1.9345 0.5

c) 2D HYDRUS model of PH01 zone

The 2D model of unsaturated zone is developed considering the soil layers presented in Table

9-18 and Table 9-20. This model represents the cross-section of the repository with 103 m width

plus 30m both sides, representing the natural soil in the lateral directions.

Beneath the repository, the elevation of the foundation slab will be of 58m. The elevation of

compacted loess will be of 57m, and the elevation of the first layer (layer 1) will be of 55m [38].

In the model of the unsaturated zone, compacted loess layer with thickness of 2 meters

represents the distance between elevation 55m and 57m beneath the repository.

The model geometry is 2D-Vertical Plan XZ and is presented in Figure 9-92.



Page 149 of 253

Figure 9-92 2D model of Saligny site unsaturated zone according to [7]– region PH01 – (different

colors represent different soil layers)

The description of water flow modeling, radionuclide transport, dispersion and dispersivity and

diffusion are presented in detail in Section 9.8.3.2.1.

The initial water content is assumed based on θs values and saturation ratio according to

Table 9-18 and Table 9-20:

- Layers 1, 2 and 3 – 0.1;

- Layers 4, 5, 6, 7 – 0.15;

- Layer 8 – 0.26;

- Layer 9 – 0.15 – due to the high Ks of the layer, and due to the fact that layer 8 has a

lower Ks than layer 10;

- Layers 10 and 11 – 0.25.

The water flow boundary conditions of the upper boundary are presented in Water flow

modeling (Section 9.8.3.2.1). Time-dependent boundary conditions for the repository

boundaries are used in order to represent the water afflux.

On the lower boundary, constant water content of 0.26 is assumed.

The vertical boundaries are considered as ‘no flux boundary’.

For the radionuclide concentrations at the upper boundary (radionuclide boundary condition)

are used the results obtained by DUST-MS. For the HYDRUS calculation, these values (in

Bq/cm3), are converted in Bq/m3 (multiplied by 106).

These values are introduced as time variable boundary conditions (volumetric activity [Bq/m3]

depending on time).

d) Calculations

Considering:

the soil-hydraulic properties of the regions PH01 and PH03 (presented in Table 9-20 and

Table 9-21)

the composition of the soil in these regions (presented in Table 9-18 and Table 9-19);

the information regarding the elevation of the unsaturated zone layers (presented in

Table 9-18 and Table 9-19);



Page 150 of 253

the removal of the upper level of the site relief (to level 55m)

The following observations are made:

the region PH01 has higher Ks than the region PH03;

the region PH01 has a lower clay content than the region PH03;

the unsaturated zone beneath the repository in region PH01 is thicker than in PH03.

As concerns the radionuclide transport through the unsaturated zone the region PH01 has

more conservative characteristics than the region PH03.

Due to this reason, the calculations are performed considering the parameters of borehole

PH01 in the unsaturated zone.

As reference for the calculation C-14 is considered. According to Table 9-16, the distribution

coefficient Kd of C-14 in the clay layers is of 0.006 m3/kg and in the layers with lower clay

content – 0.005 m3/kg.

For the current calculation, the values of Kd are assumed as follow:

Clay content of the layer <25% - assumed Kd 0.005 m3/kg (layers 1, 2, 3, 5, 9);

Clay content of the layer >25% - assumed Kd 0.006 m3/kg (layers 4, 6, 7, 8, 10, 11).

e) Results

The results for C-14 (in the region PH01) obtained considering the site characterization data

according to [7] and [51] are compared with the results obtained from the data from [28],

which are presented in Section 9.8.3.2.1.

Below is presented the comparison of these results.

0 20000 40000 60000 80000 100000

0

2000

4000

6000

8000

10000

12000

C 1

4 C

on

ce

ntr

atio

n [B

q/m

3]

t [years]

% (C14 concentration - calculated according [7])


% (C14 concentration – calculated according [28])


Figure 9-93-Comparison of the results for C-14 concentration in the unsaturated – saturated zone

boundary



Page 151 of 253

f) Conclusions

The results presenting the radionuclide concentration in the unsaturated – saturated zone

boundary confirm that the hydro-geological data from [28] are more conservative than the

hydro-geological data from [7] and [51].

Due to this reason, conservatively, the results calculated by using the model including the

hydro-geological data from [28] are assumed to be representative for the radionuclide

concentration in the unsaturated-saturated zone boundary.

9.8.3.3. Models of the processes in the Saturated zone

The mass transport of radionuclides from unsaturated to saturated zone is modeled and

calculated by using PORFLOW program.

The PORFLOW model is developed for the following scenarios:

Reference scenario “Consumption and use of the groundwater in a small farm onside of

the facility”;

Alternative scenario – “Farm on the repository - Residence scenario on totally degraded

waste”;

9.8.3.3.1. Input data

All parameters and dependent variables used in PORFLOW calculations for the current model

and task are in SI units.

a. Fluid properties:

the water is the only supposed fluid passing through layers beneath the repository;

water density – 1000 kg/m3;

water viscosity – 0.001 kg

m . s .

b. Solid matrix properties :

density

- 1760 kg/m3 for clay ;

- 2700 kg/m3 for limestone aquifer ;

porosity

- total porosity

0.33 for clay;

0.225 for aquifer;

- effective porosity

0.17 for clay;

0.0001 for aquifer;

hydraulic properties

- matrix compressibility 1.0e-3

- hydraulic conductivity in all directions [X, Y and Z]:



Page 152 of 253

1.0e-5 m/s for aquifer;

transport properties

- distribution coefficients [m3/kg]:

Isotope Clay Aquifer

14C 0.005 0.1

3H 0 3.0e-5

129I 0.001 0.001

90Sr 0.012 0.5

- Molecular diffusivity – 1.0e-9 m2/s;

- Longitudinal and transversal dispersivity used according to [10].

L = 1500 meters and L = 140 m and T = 28 m.

c. Source and sink specification

All isotopes are radioactive and their half-lives in seconds are:

Isotope Half live [s]

14C 1.81e+11

3H 3.88e+08

129I 4.95e+14

90Sr 9.15e+08

Output control – the user sets the nodes for which the results will be recorded on file

with extension “.his”.

Operational Control -

- time for calculations

Isotope Time [y] Time [s]

14C 100 000 3.154e+12

3H 5 000 1.577e+11

129I 100 000 3.154e+12

90Sr 6 000 1.8924e+11

- Time step for calculation is :



Page 153 of 253

Isotope Max time step = Initial time step 14C 10 years 129I 10 years 90Sr 2 years 3H 5 years

9.8.3.3.2. Assumptions

The model assumptions are the following:

Darcy flow is considered to be from repository towards Danube river (the most

favorable case);

Darcy flow is PKu s .

9.8.3.3.3. Description of the model

The model is created in the following steps:

o creation of an orthogonal grid with dimensions

a x b x h = 1600 m x 500 m x 35 m.

The number of nodes includes 2 boundary nodes at the beginning and end of “the line of

coordinates”.

o nodalization of grid a x b x h = 402 x 52 x 37. One node will have the

following dimensions - 4m x 10m x 1m.

o horizontal transport /X axis/ caused by the hydraulic gradient is the main

process of interest in this problem.

- Three regions are inserted in the model:

◦ region representing the Aptian clay media;

◦ region representing the Berriasian aquifer media;

◦ a very thin layer of Aptian clay media at one end of the grid.

o The boundary conditions will be the following:

- Zero initial concentration of radionuclides in both regions representing the clay

and aquifer media;

- The concentration will be input as boundary condition at Z- surface of the thin

layer.

The concentration values are from HYDRUS calculations and the area of the region is equal to

repository area. The thin region is imported with the purpose to represent the contact area

between saturated and unsaturated zones with area equal to repository area.

9.8.3.3.4. Boundary conditions

The boundary conditions for concentration at the Z- surface of the region representing the

projection of the repository on the contact plan between saturated and unsaturated zones.

The HYDRUS results at boundary between unsaturated and saturated zones. These results are

used as boundary condition for PORFLOW calculations.



Page 154 of 253

0 20000 40000 60000 80000 100000

0

2000

4000

6000

8000

10000

12000

Co

nce

ntr

atio

n B

q/m

3

Years

C-14

Figure 9-94- Carbon concentration – HYDRUS results

0 20000 40000 60000 80000 100000

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Co

ncen

tra

tio

n B

q/m

3

Years

I-129

Figure 9-95 Iodine concentration – HYDRUS results



Page 155 of 253

0 500 1000 1500 2000 2500 3000 3500

0.00E+000

2.00E-022

4.00E-022

6.00E-022

8.00E-022

1.00E-021

Co

nce

ntr

atio

n, B

q/m

3

Years

Sr-90

Figure 9-96 Strontium concentration – HYDRUS results

0 200 400 600 800 1000

0.00E+000

5.00E-009

1.00E-008

1.50E-008

2.00E-008

Co

nce

ntr

atio

n B

q/m

3

Years

H-3

Figure 9-97 Tritium concentration – HYDRUS results



Page 156 of 253

60000 80000 100000 120000 140000

1E-19

1E-18

1E-17

1E-16

1E-15

1E-14

1E-13

1E-12

Co

nce

ntr

atio

n B

q/m

3

Years

Ni-59

Figure 9-98 Nickel concentration – HYDRUS results

0 5000 10000 15000 20000 25000 30000

0

5

10

15

20

25

Co

nce

ntr

atio

n B

q/m

3

Years

Cl-36

Figure 9-99 Chlorine concentration – HYDRUS results



Page 157 of 253

9.8.3.3.5. Results

PORFLOW allows setting the nodes for which the resulting values for any of the dependent

variables can be recorded on file.

In current calculation the variable of interest is concentration /C/ and its values for some

chosen nodes will be recorded on file.

Four groups of six nodes are selected and located at depths of 1m, 5m, 10m, 15m, 20m, 25m.

The nodes are located exactly one above another:

at 1400m distance from the “repository” projection on saturated zone /nodes numbers 1-6/;

at 300 m distance from the “repository” projection on saturated zone /nodes numbers 7-12/;

at 25 m distance from the “repository” projection on saturated zone /nodes numbers 13-18/;

beneath the repository /nodes numbers 19-24/;

The results for Iodine-129 are presented in the following figures:

0 20000 40000 60000 80000 100000

0.00E+000

2.00E-013

4.00E-013

6.00E-013

8.00E-013

1.00E-012

1.20E-012







Co

nce

ntr

atio

n, B

q/m

3

Years

Figure 9-100 Iodine concentration for group a/ nodes



Page 158 of 253

0 20000 40000 60000 80000 100000

0.0000

0.0005

0.0010

0.0015

0.0020

0.0025







Co

ncen

tra

tio

n, B

q/m

3

Years

Figure 9-101 Iodine concentration for group b/ nodes

0 20000 40000 60000 80000 100000

-0.05

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35







Co

ncen

tra

tio

n, B

q/m

3

Years

Figure 9-102 Iodine concentration for group c/ nodes



Page 159 of 253

0 20000 40000 60000 80000 100000

-0.1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7







Co

nce

ntr

atio

n, B

q/m

3

Years

Figure 9-103 Iodine concentration for group d/ nodes

The results for Carbon-14 are presented in the following figures:

0 20000 40000 60000 80000 100000

1E-22

1E-21

1E-20

1E-19

1E-18

1E-17

1E-16

1E-15

1E-14







Co

nce

ntr

atio

n, B

q/m

3

Years

Figure 9-104 Carbon concentration for group a/ nodes



Page 160 of 253

0 20000 40000 60000 80000 100000

-2

0

2

4

6

8

10

12

14

16

18







Co

nce

ntr

atio

n, B

q/m

3

Years

Figure 9-105 Carbon concentration for group b/ nodes

0 20000 40000 60000 80000 100000

0

1000

2000

3000

4000

5000

6000







Co

nce

ntr

atio

n, B

q/m

3

Years

Figure 9-106 Carbon concentration for group c/ nodes



Page 161 of 253

0 20000 40000 60000 80000 100000

0

2000

4000

6000

8000

10000

12000







Co

nce

ntr

atio

n, B

q/m

3

Years

Figure 9-107 Carbon concentration for group d/ nodes

The results for Sr-90 are presented in the following two figures:

For nodes 1-6 the concentrations are 0 Bq/m3.

For nodes 7-12 the concentrations are close to 1.0e-40 Bq/m3 which is an extremely low value.

0 1000 2000 3000 4000 5000

1E-27

1E-26

1E-25

1E-24

1E-23

1E-22 Concentration in node 13






Co

nce

ntr

atio

n, B

q/m

3

Year

Figure 9-108 Strontium concentration for group c/ nodes



Page 162 of 253

0 1000 2000 3000 4000 5000

1E-27

1E-26

1E-25

1E-24

1E-23

1E-22







Co

nce

ntr

atio

n, B

q/m

3

Year

Figure 9-109 Strontium concentration for group d/ nodes

The results for tritium are presented in the following figures:

0 500 1000 1500 2000 2500 3000

1E-33

1E-32

1E-31

1E-30

1E-29

1E-28







Co

nce

ntr

atio

n, B

q/m

3

Years

Figure 9-110 Tritium concentration for group a/ nodes



Page 163 of 253

0 500 1000 1500 2000 2500 3000

0.00E+000

2.00E-012

4.00E-012

6.00E-012

8.00E-012

1.00E-011







Co

nce

ntr

atio

n, B

q/m

3

Years

Figure 9-111 Tritium concentration for group b/ nodes

0 500 1000 1500 2000 2500 3000

0.00E+000

2.00E-009

4.00E-009

6.00E-009

8.00E-009







Co

nce

ntr

atio

n, B

q/m

3

Years

Figure 9-112 Tritium concentration for group c/ nodes



Page 164 of 253

0 500 1000 1500 2000 2500 3000

0.00E+000

5.00E-009

1.00E-008

1.50E-008

2.00E-008







Co

nce

ntr

atio

n, B

q/m

3

Years

Figure 9-113 Tritium concentration for group d/ nodes

The calculations for Ni-59 are performed for 140 000 years and the results are presented in the

following figures:

For nodes 1-6 the concentrations are 0 Bq/m3.

60000 80000 100000 120000 140000

1E-30

1E-29

1E-28

1E-27

1E-26

1E-25

1E-24

1E-23







Co

nce

ntr

atio

n, B

q/m

3

Years

Figure 9-114 Ni-59 concentration for group b/ nodes



Page 165 of 253

60000 80000 100000 120000 140000

1E-20

1E-19

1E-18

1E-17

1E-16

1E-15

1E-14







Co

nce

ntr

atio

n, B

q/m

3

Years

Figure 9-115 Ni-59 concentration for group c/ nodes

60000 80000 100000 120000 140000

1E-20

1E-19

1E-18

1E-17

1E-16

1E-15

1E-14

1E-13

1E-12

Co

nce

ntr

atio

n, B

q/m

3

Years







Figure 9-116 Ni-59 concentration for group d/ nodes

The calculation for chlorine is performed for 30 000 years and the results are presented in the

following figures:



Page 166 of 253

5000 10000 15000 20000 25000 30000

0.00E+000

5.00E-012

1.00E-011

1.50E-011

2.00E-011

2.50E-011







Co

ncen

tra

tio

n, B

q/m

3

Years

Figure 9-117 Cl-36 concentration for group a/ nodes

0 5000 10000 15000 20000 25000 30000

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07 Concentration in node 7






Co

nce

ntr

atio

n, B

q/m

3

Years

Figure 9-118 Cl-36 concentration for group b/ nodes



Page 167 of 253

0 5000 10000 15000 20000 25000 30000

0

2

4

6

8

10

12







Co

nce

ntr

atio

n, B

q/m

3

Years

Figure 9-119 Cl-36 concentration for group c/ nodes

0 5000 10000 15000 20000 25000 30000

0

5

10

15

20

25







Co

nce

ntr

atio

n, B

q/m

3

Years

Figure 9-120 Cl-36 concentration for group d/ nodes



Page 168 of 253

9.8.3.3.6. Analysis and conclusions

The results lead to the following observations:

a/ the concentrations for all isotopes are decreasing in more distant nodes from the contact

area between saturated and unsaturated zones beneath the repository;

b/ the strontium concentration at 1400 meters and 300 meters distances are zero for the entire

5000 years simulation period;

c/ for 129I and 14C the peak concentration at supposed Danube side are close to 1.0E-12 and

respectively 3.0E-15 Bq/m3 . This is the concentration in Berriasian aquifer;

d/ the effect of time dependence of carbon peak concentrations for distant nodes’ groups is

clearly seen on the Figures. It is due to the high value of Aptian clay Kd for carbon;

e/ the effect of time dependence of iodine peak concentrations for distant nodes’ groups is

presented on the Figures and it is not so strong as the same effect seen for carbon-14. The

weaker effect is due to the low value of Aptian clay and Berriasian aquifer Kd-s for iodine;

f/ the tritium distributes at large distances through the aquifer /1400m and 300m/ due to its

extremely low distribution coefficient for Aptian clay and for Berriasian aquifer;

g/ tritium’s short half-life leads to a fast decrease of tritium concentrations;

h/ the Ni-59 concentration in all nodes is increasing during the period of 140 000 years. The

appearance of nickel in the saturated zone is after 80 000 year and this is the isotope which

appears very late in the saturated zone in comparison with all other isotopes.

i/ the Cl-36 concentrations at 1400 m distance is very low – 2.5E-11 Bq/m3. The concentration

at 25 m distance is one order of magnitude lower than the concentration beneath the

repository. The Cl-36 coefficients are close to the Iodine parameters as well as the

distribution of chlorine through the saturated zone.


9.8.3.4.1. Dose for the population during the reference scenario

The model for the reference scenarios is developed by RESRAD OFFSITE code.

For the reference scenario for the post-closure period after 300 years is supposed that a family:

Builds a house on the repository site;

Digs of a well located in the saturated zone beneath the repository;

Begins farming and planting on repository site, while water from well is used for animal

consumption and plant irrigation;

Uses the water from the well for drinking.

The RESRAD OFFSITE model for the reference scenario is presented in Figure 9-121.



Page 169 of 253

Figure 9-121 RESRAD OFFSITE model for the reference scenario

9.8.3.4.1.1. Input data

Configuration:

The disposal cells are reinforced concrete vaults, comprising the foundation slab and external

walls. The external walls are 40cm thick and the foundation slab (concrete) is 1 m thick.

Beneath the foundation is considered a 2m layer of compacted loess. Conservatively, the

properties of compacted loess are assumed to be equal to those of silty loess.

Water flow:

According to [50], the precipitation and evapotranspiration rate on Saligny site are:

evapotranspiration rate – 0.42m/year

precipitation rate – 0.456m/year

Evaporation and transpiration occur simultaneously and there is no easy way to distinguish

them. When the crop is small, water is predominantly lost by soil evaporation, but once the

crop is well developed and completely covers the soil, transpiration becomes the main

process. Evapotranspiration is the combination of evaporation from the soil surface and

transpiration from vegetation. The evapotranspiration rate is normally expressed in length per

unit time (meaning mm/d and m/yr).

Unsaturated zone:

The layers representing the unsaturated zone are defined as follows:

Ia – representing the sedimentary loess;

Ib – representing the clayey loess;

Ic– representing the red clay, red sandy clay and the red clayey sand ;



Page 170 of 253

Id – representing the pre-quaternary complex, consisting of different types of clays,

lenses of sand, gravel, limestone and sandstone.

The model of unsaturated zone is presented in detail in section 9.8.3.2 of this report.

The soil hydraulic properties of the unsaturated zone (according to [50]) are presented in Table

9-22

Table 9-22 Soil hydraulic properties of the unsaturated zone

The values for the b-parameter (an empirical and dimensionless parameter used to evaluate

the saturation ratio (or the volumetric water saturation), Rs, of the soil, according to a soil

characteristic function called the conductivity function (meaning the relationship between

the unsaturated hydraulic conductivity, K, and the saturation ratio, Rs), are according to [52].

For the loess layers, the value of 5.3 is assumed (default value for Silty loess). For the clay layers,

the value of 11.4 is assumed (default value for clay).

The compacted loess layer is assumed to have the same properties as the silty loess.

DISPERSIVITY: According to [10], a general approximation frequently used is that the

longitudinal (in the direction of groundwater flow) dispersivity (αL) is set to 1/10 of the scale of

the problem. This approximation is used in the current calculations.

Saturated zone:

The saturated zone beneath the repository is presented by a part of Aptian clay and by the

Berriasian aquifer.

RESRAD-OFFSITE allows introducing only one layer for the saturated zone. The properties of the

saturated layer are assumed to be equal to the ones of the Berriasian aquifer.

Total porosity: 22.5%

Effective porosity: 0.03%

Hydraulic conductivity: 10-3 cm/s – approximately 315m/year

The assumed value for the hydraulic gradient in the saturated zone is 7.7*10-3 – the maximum

measured value, according to [50]. This value is used for the hydraulic gradient to the well and

to the surface water body.

Geological layer

Density

(g/cm3)

Total

porosity

(%)

Ks

(cm/s)

Ks

(m/yr)

b

(-) r Effective porosity

(%)

Silty loess 1.540.06 423 1.0E-04 31.5578 5.3 0.067 325

Fossilized silty

loess

1.780.10 364 7.5E-06

2.3668 5.3 0.049

284

Upper clayey

loess

1.570.07 422 2.0E-05

6.3116 5.3 0.076 323

Fossilized clayey

loess

1.720.07 354 9.5E-06

2.9980 5.3 0.022

267

Lower clayey

loess

1.690.11 366 1.8E-05

5.6804 5.3 0.059

279

Red clay 1.760.17 33 10 5.0E-06 1.5779 11.4 0.001 216

Aptian clay 1.760.15 33 7 9.0E-06 2.8402 11.4 0.001 183



Page 171 of 253

The depth of aquifer contributing to the well and to the surface water body is assumed as

follows:

To the well: 10m

To the surface water body: 30m

The longitudinal dispersivity in saturated zone is assumed to be one tenth of modeled water

flow distance.

Dispersion in an aquifer is in fact a three dimensional phenomenon and must be represented

by a tensor with three main components, i.e. the longitudinal (αL), horizontal (αT) and vertical

dispersion (αV). Based on a recent literature review it has been concluded that the best

estimate of the ratio of αL: αT: αV is 1:0.2:0.0087

Source:

The radionuclide concentration in RESRAD is introduced as weight activity of the soil [Bq/g].

The primary contamination area is assumed to be 24000m2 – this is the area covered by

modules.

Radionuclide transport:

The distribution coefficients for radionuclides are presented in Table 9-16 of this report. The

distribution coefficients of the repository (waste) are assumed to be equal to those of the

concrete. For the radionuclides not presented in this table the default RESRAD-OFFSITE values

are used.

The distribution coefficients for Sediment in surface water body for all radionuclides are

assumed to be the default values given by RESRAD-OFFSITE.

The deposition velocity for all radionuclides is assumed to be the default value given by

RESRAD-OFFSITE.

All transfer factors for all radionuclides are assumed to be the default values given by

RESRAD-OFFSITE.

The dose conversion factors for all radionuclides is assumed to be the ones recommended by

ICRP-72 (adult) given by RESRAD-OFFSITE parameter library.

All storage times for water and food are assumed to be the default values given by RESRAD-

OFFSITE.

Atmospheric transport:

Conservatively, the wind direction is assumed to be from the repository area to the dwelling

site.

The wind speed is assumed to have a constant value of 4m/s, and the atmospheric stability

class is assumed (conservatively) to be F.

The other parameters assumed in the ATMOSPHERIC TRANSPORT MODEL are:

Ambient temperature – 290K (16.8oC)

Release height – 0.1m – minimum allowed value

Release heat flow – 0 cal/s

AM (antemeridian) atmospheric mixing height – 400m (default RESRAD-OFFSITE value)

PM (postmeridian) atmospheric mixing height – 1600m (default RESRAD-OFFSITE value)

For the dispersion model, Pasquill-Gifford coefficients are used.

Human diet:



Page 172 of 253

The values for human and livestock ingestion rates are assumed to be the default RESRAD-

OFFSITE values.

Inhalation and external gamma:

The assumed value for the breathing rate is 13140 m3/year [39].

Mass loading: Mass Loading for Inhalation is the average mass of breathable particles in an air

unit volume when humans are present on site (includes the effects of human activity). It is used

in calculating the inhalation pathway.

Mean Onsite Mass Loading: This is the average mass loading of airborne contaminated soil

particles above the primary contamination. It is used to estimate the contaminant release rate

into the atmosphere.

According to [52]:

As average, ambient concentrations of transportable particles range from 3.3 × 10-5 to 2.54 ×

10-4 g/m3 in urban locations and from 9 × 10-6 to 7.9 × 10-5 g/m3 in non-urban locations.

Anspaugh (1974) and Healy and Rodgers (1979) used 1 × 10-4 g/m3 for predictive purposes and

ascertained that the predicted results and the real cases are comparable. The EPA (EPA 1977)

has used the same value to verify the calculations.

The mass loading value will fluctuate above its ambient level depending on human activities

such as plowing and cultivating dry soil or driving on an unpaved roads. The estimated mass

loading for inhalation from construction activities is about 6.0 × 10-4 g/m3; in case of exposure

to construction traffic on unpaved roads it is 4.0 × 10-4 g/m3; and for agriculture-generated

dust, it is about 3.0 × 10-4 g/m3 . The maximum breathable dust loading inside the cab of heavy

construction equipment during a surface coal mining operation was found to be 1.8 × 10-3

g/m3 . Estimates of mass loadings have been as high as 1.3 g/m3 for instantaneous mass

loadings during tilling.

Gilbert (1983) suggests a mass loading factor of 2.0 × 10-4 g/m3 for transportable particles at an

on-site loading, in order to take into account short periods of high mass loading and long

periods of normal farmyard activities for which the dust level may be somewhat higher than

the ambient.

According to [50], the average values for these parameters are:

mass loading for inhalation: 1.4*10-5 g/m3

Mean Onsite Mass Loading : 4*10-5

The use of a high, short-term loading will result in an overestimate of the annual dose. A time

average mass loading factor should be used in RESRAD (onsite) and RESRAD-OFFSITE for a

more realistic dose estimate. Similarly, the use of short-term loadings for the average onsite

mass loading in RESRAD-OFFSITE is discouraged.

9.8.3.4.1.2. Construction of a farm on the repository

ASSUMPTIONS

The repository is assumed to be totally degraded after 300 years from the beginning of the

repository operation. The engineered barriers no longer perform their functions and the waste

inventory is distributed as soil layer.

It is assumed that at 300 years after the beginning of repository operation a farm will be built

on the repository. In order to build the house, it is assumed that the final cover of the repository

will be dug and the constructor will be subject to direct exposure from the upper row of



Page 173 of 253

disposal modules. The final cover of the repository around the house will be planted with fruits,

leafy and non-leafy vegetables, pastures and grain fields – it is considered agricultural area.

EXTERNAL EXPOSURE

In order to calculate the external exposure during the house construction, it is assumed that

the final cover layer of the repository does not exist. The primary contaminated layer is

contaminated with the inventory of non-compactable waste – the third row of disposal

modules and the constructor works over it.

PRIMARY CONTAMINATION – RADONUCLIDES MASS ACTIVITY

The radionuclide mass activity in the primary contamination is obtained by dividing the

volumetric activity of non-compactable waste depending on waste’s density (2.58 g/cm3).

Because the modules are considered broken the total activity is distributed in a volume equal

to the total volume of the modules, not the inner ones. In order to define the activity per mass

activity in the 300th year, the radioactive decay of the nuclides is considered.

Table 9-23 Radionuclide mass activity for non-compactable waste

Isotope Volumetric

Activity

[Bq/m3]

Total

Activity

[Bq]

Volumetric

Activity after

repository

degradation

[Bq/m3]

Decay

Constant

Year-1

Volumetric

Activity at

t=300

[Bq/m3]

Mass

Activity

[Bq/g]

3.375

3H 2.80E+08 6.71E+12 1.92E+08 5.59E-02 1.00E+01 3.88E-06 14C 1.20E+05 2.88E+09 8.24E+04 1.21E-04 7.95E+04 3.08E-02 59Ni 1.99E+02 4.77E+06 1.37E+02 9.19E-06 1.36E+02 5.28E-05 60Co 8.50E+07 2.04E+12 5.84E+07 1.32E-01 3.70E-10 1.43E-16 63Ni 7.30E+06 1.75E+11 5.01E+06 7.22E-03 5.75E+05 2.23E-01 90Sr 5.05E+05 1.21E+10 3.47E+05 2.38E-02 2.75E+02 1.07E-04 94Nb 4.62E+02 1.11E+07 3.17E+02 3.41E-05 3.14E+02 1.22E-04 129I 1.01E+01 2.42E+05 6.94E+00 4.41E-08 6.94E+00 2.69E-06 134Cs 4.20E+05 1.01E+10 2.89E+05 3.36E-01 4.82E-39 1.87E-45 137Cs 1.60E+06 3.84E+10 1.10E+06 2.31E-02 1.07E+03 4.17E-04

The total activity is obtained by multiplying the volumetric activity by the total inner volume of

the modules with non-compactable waste (128 modules per cell, 64 cells, inner dimension =

1.5m). The volumetric activity after the repository degradation is obtained by dividing the total

activity by the total outer volume of the modules with non-compactable waste (128 modules

per cell, 64 cells, outer dimension = 1.7m).

SPECIFIC ASSUMPTIONS

The primary contamination layer is assumed to have the following properties:

o hydraulic properties of silty loess

o density of non-compactable waste – 2.58g/cm3

o thickness – 1.7m – outer dimension of the module

It is assumed that the constructor spends 6 hours per day on the contaminated zone – the

building area.

The Cl distribution coefficients are assumed to be equal to those of Iodine.

The assumed mass loading factor for inhalation is 6.0 × 10-4 g/m3 – for building activities.



Page 174 of 253

RESULTS

Figure 9-122 Dose per person, all nuclides summed, all pathways summed

Figure 9-123 Dose per person, all nuclides summed, component pathways



Page 175 of 253

The maximum effective dose is 1.7E-4 mSv/year, which is below the dose constraint of

0.3 mSv/y.

9.8.3.4.1.3. Farm on the repository

It is assumed that a farm is built on the final cover layer of the repository. Over the primary

contaminated area are situated:

o Fruits, leafy and non-leafy vegetables, pastures and grain fields used for food

consumptions

o The dwelling site

o The well

The primary contaminated layer is contaminated with the total waste inventory.

PRIMARY CONTAMINATION – RADONUCLIDES MASS ACTIVITY

The radionuclide mass activity is obtained by dividing the volumetric activity of the total waste

inventory by the waste density. Due to the fact that the modules are considered broken, the

total activity is distributed in volume equal to the total volume of the modules, not the inner

volume.

In order to define the mass activity in the 300th year, the radioactive decay of the nuclides is

considered. The values of the total activity are according to [19].

Table 9-24 Radionuclide mass activity

Radionuclide Total

Activity

[Bq]

Volumetric

Activity

[Bq/cm3]

Mass Activity

[Bq/g]

(Waste density =

1.97g/cm3)

Decay

Constant

[1/year]

Mass Activity

[Bq/g] At

t=300

C-14 9.67E+13 7.99E+02 4.06E+02 0.000121 3.91E+02

Cl-36 4.80E+09 3.97E-02 2.01E-02 2.30E-06 2.01E-02

Cm-244 4.54E+10 3.75E-01 1.90E-01 0.0383 1.95E-06

Co-60 1.61E+15 1.33E+04 6.75E+03 1.32E-01 4.28E-14

Cs-134 1.42E+08 1.17E-03 5.96E-04 3.36E-01 9.96E-48

Cs-137 2.36E+13 1.95E+02 9.90E+01 2.31E-02 9.68E-02

Eu-152 1.84E+11 1.52E+00 7.72E-01 5.21E-02 1.26E-07

Eu-154 1.93E+10 1.60E-01 8.10E-02 7.88E-02 4.38E-12

Eu-155 3.36E+09 2.78E-02 1.41E-02 1.46E-01 1.34E-21

Fe-55 8.18E+14 6.76E+03 3.43E+03 2.57E-01 1.13E-30

H-3 1.66E+14 1.37E+03 6.96E+02 5.59E-02 3.63E-05

I-129 7.40E+08 6.12E-03 3.10E-03 4.41E-08 3.10E-03

Nb-93m 5.58E+11 4.61E+00 2.34E+00 5.10E-02 5.30E-07

Ni-59 1.26E+08 1.04E-03 5.29E-04 9.19E-06 5.27E-04

Ni-63 2.39E+13 1.98E+02 1.00E+02 7.22E-03 1.15E+01

Pu-241 2.07E+15 1.71E+04 8.68E+03 4.81E-02 4.70E-03

Ru-106 1.28E+12 1.06E+01 5.37E+00 7.08E-01 3.06E-92

Sb-125 1.30E+04 1.07E-07 5.45E-08 2.50E-01 1.46E-40

Sr-90 1.12E+13 9.26E+01 4.70E+01 2.38E-02 3.72E-02

SPECIFIC ASSUMPTIONS

The primary contamination layer is assumed as having the following properties:

o hydraulic properties of silty loess

o density – 1.97 g/cm3 – considering the density and presence of the different types

of wastes



Page 176 of 253

o thickness – 5.1 m (3 rows x 1.7m)

o distribution coefficients of radionuclides – equal to those for degraded concrete

o the hydraulic properties of the foundation are assumed equal to those of the silty

loess

o irrigation rate above primary contamination – 0.23m/year (the primary

contamination area/agricultural fields area = 0.25/0.23, and the irrigation rate on

agricultural areas is 0.25m/year)

All distribution coefficients for Eu, Fe, Cd are assumed to be the default values given by

RESRAD-OFFSITE.

The Cl-36 distribution coefficients are assumed to be equal to these of I-129.

Assumptions regarding the final cover:

o Thickness – 3.8m – 3.2m for the final cover and 0.7m for the filling material in the

cell

o Density – 2.7 m/cm3 – as for granite

o Soil erosion factor – 0.17 tons/ha (1ha=2.471acres) → 0.069 t/acres

(http://www.ifen.fr/index.php?id=1450)

All agricultural fields are situated over the primary contamination, so there is no food

produced in the clean area.

It is assumed that all water used for drinking and irrigation is from the well.

The assumed mass loading factor for inhalation is 2.0 × 10-4 g/m3.

The longitudinal dispersivity in the saturated zone is assumed to be 1/10 of modeled water flow

distance (approximately 1500m to the Danube – the surface water body, and 2m for the well).

o longitudinal dispersivity of saturated zone to the surface water body – 150m

o longitudinal dispersivity of saturated zone to the well – 0.2m

The dispersivities values are:

o αT to the surface water body - 0.2*150=30m

o αT to the well – 0.2*0.2=0.04m

o αV to the surface water body - 0.0087*150=1.31m

o αV to the well - 0.0087* 0.2=1.74*10-3m

C-14 TRANSPORT MODEL

According to [41], the transport of C-14 is assumed to be the same with that of carbon stable

in the environment. The carbon-14 Evasion Rate Factors for different soils are as follow:

o Clay: 12 years-1

o Loamy soils: 12 years-1

o Sandy soils: 22 years-1

o Organic soils: 22 years-1

o Soils with stable carbon in carbonates: 0.0032 years-1

o Water: 0.91 years-1



Page 177 of 253

In this calculation the evasion rate of C14 is assumed to be equal to 12 years-1

The thickness of evasion layer for C-14 in soil is assumed to be 0.3m – the default RESRAD value.

This is the maximum soil layer thickness through which C-14 can escape into the air by

conversion to CO2. C-14 below this depth is assumed trapped in the soil.

Fraction of carbon absorbed by vegetation from soil: 0.02

Fraction of carbon absorbed by vegetation from air: 0.98

For the mass fraction of C-12 default RESRAD-OFFSITE values are used:

o C-12 mass fraction in contaminated soil: 0.03

o C-12 mass fraction in local water: 2x10-5

o C-12 mass fraction in fruits, grains, non leafy vegetables: 0.4

o C-12 mass fraction in leafy vegetables: 0.09

o C-12 mass fraction in pasture and silage: 0.09

o C-12 mass fraction in grain: 0.4

o C-12 mass fraction in meat: 0.24

o C-12 mass fraction in milk: 0.07

RESULTS

Calculations for this scenario, considering the erosion of the final cover layer and the primary

contamination area are presented below:

0 10000 20000 30000 40000 50000 60000 70000 80000

0.00

0.02

0.04

0.06

0.08

0.10

0.12

Do

se

Ra

te [m

Sv/y

ea

r]

t [years]

Figure 9-124 Dose for the human – all radionuclides summed, all pathways summed



Page 178 of 253

0 500 1000 1500 2000 2500 3000

0.000

0.001

0.002

0.003

0.004

0.005

0.006D

ose

Ra

te [m

Sv/y

ea

r]

t[years]

Figure 9-125 Dose for the human – I-129, all pathways summed

0 500 1000 1500 2000 2500 3000

0.0000

0.0005

0.0010

0.0015

0.0020

0.0025

0.0030

0.0035

0.0040

Do

se

Ra

te [m

Sv/y

ea

r]

t [years]

Figure 9-126 Dose for the human –Cl-36, all pathways summed



Page 179 of 253

0 10000 20000 30000 40000 50000 60000 70000

0.00

0.02

0.04

0.06

0.08

0.10

0.12

Do

se

Ra

te [m

Sv/y

ea

r]

t [years]

Figure 9-127 Dose for the human – C-14, all pathways summed

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0 10000 20000 30000 40000 50000 60000 70000 80000

Years

Direct radiation from soil (waterborne)

Ingestion of Fish

Radon (waterborne)

Plant (waterborne)

Meat (waterborne)

Milk (waterborne)

Soil ingestion (waterborne)

Water

Direct radiation from soil (direct & airborne)

Inhalation

Radon (direct & airborne)

Plant (direct & airborne)

Meat (direct & airborne)

Milk (direct & airborne)

Soil ingestion (direct & airborne)

SALIGNI-INTEGRAL-farm.ROF 01/22/2010 16:42 GRAPHICS.ASC

DOSE: All Nuclides Summed, Component Pathways

Figure 9-128 Dose for the human – all radionuclides summed, component pathways



Page 180 of 253

CONCLUSSIONS:

From the results one can conclude that the received dose due to the building activities (the

maximum effective dose is about 1.7E-04 mSv/year mainly by external exposure) does not

exceed the dose constraint 0.3mSv/year.

After building the house and planting the final cover of the repository (300 years after the

beginning of repository operation) the dose is mainly due to C-14. The dose for the human of

approximately 0.12mSv/year (approximately 15 500 years after the beginning of the repository

operation) does not exceed the dose limits.

9.8.3.4.2. Doses for the population during the alternative scenarios

9.8.3.4.2.1. Alternative scenario 1) Farm on the repository - Residence scenario on

totally degraded waste

For this alternative scenario for the post-closure period after 300 years is supposed that a

family:

Builds a house on the repository site with totally degraded waste;

Digs a well located in the saturated zone beneath the repository;

Begins farming and planting over repository site while water from well is used for animal

consumption and plant irrigation;

Uses water from the well for drinking.

The contamination with radionuclides of upper layers of soil is only due to the watering of

plants with contaminated water.

Dose calculations:

According to the HURDUS and PORFLOW calculations the radionuclides which reach the

saturated zone are 3H, 14C, 90Sr, 159I, 59Ni.

The calculations are performed for the liquid scenario according to [36] /p.83/ and for

leachate scenario [36] /p.100/.

Two assumptions are made for this calculation:

Cwater values are according to PORFLOW results. In the calculation the maximum

concentration values are used, which represents the worst case – totally degraded

waste;

Cwater is decreasing by an exponential curve depending on λ for each radionuclide. This

assumption complies with PORFLOW results for the concentrations in the saturated

area.

The dose by ingestion of radionuclides is:

ingextinh DoseDoseDoseDose ,

and the three summed doses are calculated as follows:

inhoccupnormoccupactrsoilinh DFdustdustbAD %1%.8766..

extsoilext DFAD .8766.

animalingcropingfishingwateringing DDDDD ____ .

One of the parameters in these formulas is the concentration in the soil Asoil and the calculation

equation is as follows:



Page 181 of 253

soileffwater

soilsoil

soil ACTh

Irrig

dt

dA

. (1)

where

Irrig is the irrigation rate [m/y]. Value of 0.3 m/y for temperate climate is used according

to [36];

soil is the dry soil bulk density [kg/m3]. The value of 1540 kg/m3 is used according to

existing SAR [50];

Thsoil is the soil thickness [m]. The value of 0.25 m is used as a boundary condition in time

0 and the value of 3.2 m is used for the calculation of Asoil according to [36];

λeff is an effective decay [1/y];

soilsoil

plantplant

ssoilsoilsoil

eff

erosioneffTh

YeildTF

KdTh

P

.

.

).(

(2)

where

λ is the radionuclide decay constant [1/y];

λerosion is the soil erosion rate [1/y]. The value of 2.0e-04 y-1 is used for temperate climate

according to [36];

Peff is the water infiltration rate through the soil [m/y]. The value of 0.6 m/y is used for

temperate climate according to [36];

soil is the soil kinematical porosity [-]. The value of 0.3 is used according to [36];

Kds is radionuclide distribution coefficient in the soil [m3/kg]. The values for silty loess

according to [50] are used;

TFplant is the soil to plant concentration factor for the plant [Bq.kg-1 fresh weight / Bq.kg-1

dry soil]. Values according to [36] are used.

Yeildplant is the annual crop yield [kg.m-2.y-1]. Values according to [36] are used.

The following table presents the calculation for λeff for five isotopes:

Isotope C water kd 3rd add λ TF plant 4th add λeff

H-3 1.99E-08 0 6.25E-01 5.59E-02 5 3.55E-03 6.85E-01

C-14 1.13E+04 0.005 2.34E-02 1.21E-04 0.1 7.10E-05 2.38E-02

Ni-59 6.77E-13 0.6 2.03E-04 9.19E-06 0.03 2.13E-05 4.33E-04

Sr-90 9.62E-22 0.006 1.97E-02 2.38E-02 0.09 6.39E-05 4.37E-02

I-129 7.00E-01 0.001 1.02E-01 4.41E-08 0.1 7.10E-05 1.02E-01

Note – the measure units of the parameters in the table are presented above. The names “3rd

add” and “4th add” means that in this column are presented the values for the 3rd and 4th

terms of the sum (2).

The conclusion of equation (1) is as follows:

tt

effsoilsoil

effeBeC

Th

IrrigtA

....

)( 0

.



Page 182 of 253

BC

Th

IrrigC

Th

IrrigA

effsoilsoilsoilsoil

0

2

0

1

..

..

)0(

,

In t=0 the exponents are equal to 1 and in Thsoil1 = 0.25 m [36] and Thsoil2 = 3.2 m [39].

In the following table are presented the calculated values for B constants which appear from

integration of (1):

C water A0 λ λeff B

H-3 1.99E-08 1.55E-11 5.59E-02 6.85E-01 1.36E-11

C-14 1.13E+04 8.81E+00 1.21E-04 2.38E-02 -2.02E+01

Ni-59 6.77E-13 5.28E-16 9.19E-06 4.33E-04 -9.66E-14

Sr-90 9.62E-22 7.50E-25 2.38E-02 4.58E-02 -1.91E-24

I-129 7.00E-01 5.45E-04 4.41E-08 1.02E-01 1.28E-04

The resulting equations are:

For 3H : A(t) = ).685.0(.0559.0 .1136.1.1155.1 tt eEeE ;

For 14C : A(t) = ).0238.0().0421.1( .2.20.81.8 ttE ee ;

For 59Ni : A(t) = ).0433.4().0619.9( .1466.9.1628.5 tEtE eEeE ;

For 90Sr: A(t) = ).0458.0().0238.0( .2491.1.2550.7 tt eEeE ;

For 129I: A(t) = ).102.0().0841.4( .0428.1.0445.5 ttE eEeE .

The concentration (as a function of time) of isotopes 3H, 59Ni and 90Sr is not possible to reach

values higher than 1.0E-10 Bq/kg because:

The coefficients multiplying the exponents are lower than 1.0e-10 and

The exponential function with negative exponent is always less than 1.

The calculations will be performed only for 14C and 129I.

Results for the soil concentration depending on time are presented in the following table. The

beginning of the time intervals is considered the time when the maximum concentration value

in the saturated zone is reached - 18800 years for 14C and 52800 for 129I.



Page 183 of 253

t [years] A(t) C14 [Bq/kg] A(t) I129 [Bq/kg]

1 0.00E+00 6.61E-04

2 0.00E+00 6.49E-04

3 0.00E+00 6.39E-04

4 0.00E+00 6.30E-04

5 0.00E+00 6.22E-04

10 0.00E+00 5.91E-04

25 0.00E+00 5.55E-04

50 2.61E+00 5.46E-04

75 5.34E+00 5.45E-04

100 6.83E+00 5.45E-04

200 8.43E+00 5.45E-04

300 8.48E+00 5.45E-04

500 8.29E+00 5.45E-04

1000 7.81E+00 5.45E-04

2000 6.92E+00 5.45E-04

5000 4.81E+00 5.45E-04

10000 2.63E+00 5.45E-04

20000 7.83E-01 5.45E-04

50000 2.08E-02 5.44E-04

75000 1.01E-03 5.43E-04

The maximum values for Asoil [Bq/kg] according to the table above are:

Isotope Max value Year of peak

C-14 8.48 19100

I-129 6.61E-04 52801

The calculation of the doses with maximum soil concentrations is provided below:

1. The dose due to inhalation is expressed as:

inhoccupnormoccupactrsoilinh DFdustdustbAD %1%.8766..

where

o br is the breathing rate [m3/h]. The value of 1 m3/h is used according to [36];

o 8766 are the hours of one year [h/y];

o dustact and dustnorm are the dust concentrations during ploughing and non-

ploughing activities [kg/m3]. The values for dustact = 1.0e-06 kg/m3 and

dustnorm=2.0e-08 kg/m3 according to [36] are used;

o %ocup is the occupancy factor for ploughing activities [-]. The value of 0.034

according to [36] is used;

o DFinh is the dose factor for inhalation [Sv/Bq]. The values used are according

to [36] and they are presented in the following table:

Isotope C-14 I-129

Dose factor for inhalation [Sv/Bq] 5.80E-09 3.60E-08

830.2098.5*966.0*080.2034.0*060.1*8766*1*48.8/14/ EeEECDinh mSv/y



Page 184 of 253

1111.1086.3*966.0*080.2034.0*060.1*8766*1*0461.6/129/ EeEEEIDinh mSv/

y.

2. The dose due to external exposure is expressed as:

extsoilext DFAD .8766.

o DFinh is the external exposure dose factor 11... BqhkgSv . The values used are

according to [36] and they are presented in the following table:

Isotope C-14 I-129

External exposure factor 0.00E+00 1.70E-13

1084.9137.1*8766*0461.6/129/ EEEIDext mSv/y

3. The dose due to ingestion is expressed as :

animalingcropingfishingwateringing DDDDD ____

o Ding_water is the dose due to filtered water ingestion [Sv/y]

ing

w

waterwaterwatering DFpartKd

CQD ..1

1.._

where

- Qwater is the annual consumption of water [m3/y]. The value of 0.73 m3/y


- Cwater is the concentration of radionuclides in water [Bq/m3]. The values

according to PORFLOW calculations are used;

- Kdw is the distribution coefficient water/particles [m3/kg];

- Part is the suspended particle concentration in river [kg/m3];

Due to fact that determination of parameters Kdw and Part is not presented, the value of 1 for

the component within the brackets is used.

DFing is the dose factor for ingestion [Sv/Bq]. The values according to [36] are used and they

are presented in the following table:

Isotope C14 I129

Dose factor for ingestion [Sv/Bq] 5.80E-10 1.10E-07

380.4108.5*1*11300*73.0/14/_ EECD watering mSv/y

562.5071.1*1*7.0*73.0/129/_ EEID watering mSv/y

o Ding_fish is the dose due to fish consumption [Sv/y]

ingfishwaterfishfishing DFTFCQD ..._

Cwater has to be considered as a concentration in the water in which the fish swim /in the river/.

The Cwater used in this calculation is in accordance with PORFLOW calculations for the

saturated zone. The scenario considers the water consumption from well, not from river.

PORFLOW calculations show that the resulting concentrations of 14C and 129I in the saturated

zone at 1400 meters from repository /the location of Danube/ are close to 1.0E-15 and 1.0E-12



Page 185 of 253

Bq/m3 which is extremely low. Due to this fact, the dose from the fish consumption is

considered 0 mSv/y.

o Ding_crop is the dose due to crop consumption [Sv/y]

graingreenroot

ingcropsoilwatercropcroping DFTFAYeild

IntIrrigCQD

,,

_

.

where

- Irrig is the irrigation rate [m/y]. The value of 0.3 m/y for temperate climate is

used according to [36];

- Int is the interception factor [-]. The value of 0.33 according to [36] is used;

- Yeildplant is the annual crop yield [kg.m-2.y-1]. Values according to [36] are used;

- TFcrop is the soil to plant concentration factor for the plant [Bq.kg-1 fresh weight /

Bq.kg-1 dry soil]. Values according to [36] are used;

- Qcrop is the annual crop consumption rate [kg/y]. Values according [36] are

used.

The parameters used in the calculation are considered according to the following table:

consumption [kg/y] yeild kg/(m^2.y)

root 235 3.5

green 62 3.0

grain 148 0.5

The results from the dose calculation are presented in the following table:

isotope DFing Cwater TF Dingroot Dinggreen Dinggrain Dtotal

C-14 5.80E-10 1.130E+04 1.00E-01 4.368E-05 1.344E-05 1.921E-04 2.493E-04

I-129 1.10E-07 7.000E-01 1.00E-01 5.135E-07 1.580E-07 2.822E-06 3.493E-06

Note: All doses in the table are presented in Sv/y.

The results for the total dose from consumption of plants for both isotopes are as follows:

Doseing_crop /C 14/ = 0.249 mSv/y

Doseing_crop /I 129/ = 3.49e-03 mSv/y.

o Ding_animal is the dose due to consumption of animal products [Sv/y]

milkbeef

inganimalpasturesoilpasturesoilsoilwaterwateranimalanimaling DFTFTFAqAqCqQD,

_ ..

- Qanimal is the annual product consumption rate [kg/y]. Values of 330 kg/y for milk

consumption and 95 kg/y for meat consumption according to [36] are used;

- qwater is the daily water consumption [m3/day]. The value of 0.06 m3/day


- qsoil is the daily soil intake [kg/day]. The value of 0.6 kg/day according to [36] is

used;

- qpasture is the daily pasture consumption [kg/day]. The value of 55 kg/day


- TFpasture is the soil to plant concentration factor for pasture [Bq.kg-1 fresh weight /

Bq. kg-1 dry soil];



Page 186 of 253

- TFanimal is the transfer coefficient to animal products [day/kg].

TFpasture and TFanimal for 14C and 129I are considered according to [36] and they are presented in

the following table:

Isotope TFmeat TFmilk TFpasture

C-14 0.12 0.01 0.1

I-129 0.04 0.01 0.1

The results are presented in the following table:

Isotope DFing Cwater DFingmeat DFingmilk Dtotal

C-14 5.80E-10 1.13E+04 4.98E-06 1.44E-06 6.43E-06

I-129 1.10E-07 7.00E-01 1.82E-08 1.58E-08 3.39E-08

Note: All doses for total dose from consumption of animal products for both isotopes are

presented in Sv/y.

The results for the total dose from consumption of animal products for both isotopes are as

follows:

Doseing_animal /C 14/ = 6.43E-03 mSv/y

Doseing_animal /I 129/ = 3.39e-05 mSv/y.

The total dose for all pathways /external, inhalation and ingestion/ is presented in the following

table:

isotope Dinh Dext Dwater Dcrop Danimal Dtotal

C-14 2.30E-08 0 4.80E-03 0.249 6.43E-03 2.60E-01

I-129 1.11E-11 9.84E-10 5.62E-05 3.49E-03 3.39E-05 3.58E-03

The total dose from all pathways /external, inhalation and ingestion/ is:

Dose from C-14 0.260 mSv/y.

Dose from I-129 3.58E-03 mSv/y.

The doses for C-14 and I-129 from all pathways /external, inhalation and ingestion/ are below

the dose constraints for the population – 0.3 mSv/y.

9.8.3.4.2.2. Alternative scenario 2) Archaeological investigation of the site

a) Calculations based on TECDOC 1380 [36]

The scenario assumes the intrusion on site of a working team investigating the collected

archeological vestiges.

The contamination pathways considered in this scenario are:

external exposure;

ingestion;

contaminated dust inhalation.

The relevant radionuclides concentrations correspond to the intrusion moment. In this case is

also applied the approximation assuming that the activity concentration for long life

radionuclides remains unchanged at intrusion (300 years from the repository closure).

The parameters used in the calculations have been estimated according to the following

assumptions:

The value of the dilution factor is based on the hypothesis of lower dilution of the

contaminant in the uncontaminated material and takes into account the fact that the



Page 187 of 253

archeologists could come in contact with contaminants especially through the excavation

activities made manually and not by using the automatic devices.

The excavation time has a maximum value for the probable contact time with the

contaminated samples.

Air loading with dust has a larger value reflecting the proximity towards the contaminated

surface (lap position – fold knees position of archeologists).

The breathing rate corresponds to a medium physical effort (this activity in framed within

this category of physical effort).

Configuration:

Archaeologist investigation on the repository.

Input data

Volume of repository cover – 1.5E+05 m3

Soil density ρ = 1540 kg/m3

Dust [36] – 1.00E-06 kg/m3

Dilution factor– 0.7

Breathing rate [39] – BR = 1.5 m3/h

Time of exposure – 2190 [h/y]

Source term calculations [36]:

Assumption

It is assumed that 70% of waste activity is diluted in the repository cover layer.[36].

Calculated activities:

The total activity is considered according to [19]. The initial activity is calculated as follows:

Ainitial = (Total activity with decay) / Volume of repository cover layer

The total activity with decay for 300 years and the source term for the calculations are

presented in Table 9-25.

Table 9-25 Total activity with decay for 300 years

Nuclides

Total activity

without decay [Bq]

[19]

Total activity with

decay for 300y [Bq]

Initial activity

[Bq/kg]

14C 9.67E+13 6.53E+13 2.83E+05

36Cl 4.80E+09 3.36E+09 1.45E+01

244Cm 4.54E+10 3.45E+05 1.49E-03

60Co 1.61E+15 9.85E-03 4.26E-11

134Cs 1.42E+08 3.70E-36 1.60E-44

137Cs 2.36E+13 1.70E+10 7.37E+01

152Eu 1.84E+11 2.82E+04 1.22E-04

154Eu 1.93E+10 4.63E-01 2.00E-09

155Eu 3.36E+09 1.76E-09 7.64E-18

55Fe 8.18E+14 1.63E-19 7.08E-28



Page 188 of 253

Nuclides

Total activity

without decay [Bq]

[19]

Total activity with

decay for 300y [Bq]

Initial activity

[Bq/kg]

3H 1.66E+14 5.71E+06 2.47E-02

129I 7.40E+08 5.18E+08 2.24E+00

93mNb 5.58E+11 3.91E+11 1.69E+03

59Ni 1.26E+08 8.80E+07 3.81E-01

63Ni 2.39E+13 2.15E+12 9.33E+03

241Pu 2.07E+15 7.49E+08 3.24E+00

106Ru 1.28E+12 0.00E+00 0.00E+00

125Sb 1.30E+04 3.20E-29 1.38E-37

90Sr 1.12E+13 5.93E+09 2.57E+01

Table 9-26 Dose conversion factors according to [36]:

Nuclides DFingestion [Sv/Bq] DFinhhalation [Sv/Bq] DFexternal [Sv*kg

/Bq*h]

14C 5.80E-10 5.80E-09 0

36Cl 9.30E-10 5.10E-09 0

244Cm 1.20E-07 1.70E-05 0

60Co 3.50E-09 3.10E-08 5.50E-10

134Cs 1.90E-08 2.00E-08 3.30E-10

137Cs 1.30E-08 3.90E-08 1.20E-10

152Eu 1.40E-09 4.20E-08 3.00E-10

154Eu 2.00E-09 5.30E-08 2.60E-10

155Eu 3.20E-10 4.70E-09 2.60E-10

55Fe 3.30E-10 7.70E-10 1.60E-20

3H 1.80E-11 2.60E-10 0

129I 1.10E-07 3.60E-08 1.70E-13

93mNb 1.20E-10 1.80E-09 5.80E-15

59Ni 6.30E-11 4.40E-10 1.10E-19

63Ni 1.50E-10 1.30E-09 0.00E+00

241Pu 4.80E-09 2.30E-06 3.00E-16

106Ru 7.00E-09 6.60E-08 4.80E-11

125Sb 1.10E-09 1.20E+08 8.30E-11

90Sr 3.10E-08 1.60E-07 2.10E-12

Results:

Mass of repository cover layer – mcover = Vcover * ρ = 2.31E+08 kg

Dose calculation – Dose = Ainitial * [(soil ingestion rate)*DFingestion +DFexternal +

BR*dust*DFinhalation]*(exposure time) [Sv/y]

The doses for the archaeologists per radionuclide are presented in Table 9-27.



Page 189 of 253

Table 9-27 Doses for the archaeologists

Nuclides Dose for the archaeologists [Sv/y] per

nuclide

14C 1.76E-05

36Cl 1.25E-09

244Cm 9.68E-11

60Co 5.14E-17

134Cs 1.16E-50

137Cs 1.95E-05

152Eu 8.03E-11

154Eu 1.14E-15

155Eu 4.35E-24

55Fe 1.92E-38

3H 5.42E-14

129I 1.95E-08

93mNb 4.66E-08

59Ni 2.34E-12

63Ni 1.44E-07

241Pu 2.57E-08

106Ru 0.00E+00

125Sb 5.45E-32

90Sr 1.91E-07

TOTAL DOSE FOR THE WORKER 3.75E-05 Sv/y

Conclusions:

1) The dose for the archaeologists is of 3.75E-02 mSv/y and is below the dose constraint for

the population 0.3 mSv/y.

b) Calculation with RESRAD OFFSITE

h. ASSUMPTIONS

300 years after the closure of the repository operation, the engineering structures are assumed

as totally degraded. The engineered barriers no longer fulfill their functions and the waste

inventory is distributed as soil layer.

Archaeological investigations are assumed to be performed on the repository area in the year

300 after the closure of the repository operation. The final cover layer is removed and the

contaminated layer is dug so the upper soil layer becomes contaminated soil. The

radionuclides inventory is assumed to be distributed uniformly in a soil layer with thickness of

5.1m.

The primary contamination (radionuclides mass activity and the hydraulic properties of the

layer) is assumed to be the same as in the reference scenario but this area is not irrigated. The

final cover is not considered due to the archeological activities.



Page 190 of 253

The agricultural areas and the dwelling site are situated on the exclusion area boundary,

outside of the repository area.

The purpose of this calculation is to determine the dose for the archaeologist due to

archaeological investigation as well as the impact of such investigation on the environment

(the concentration of radionuclides in the agricultural area and in the air - mainly due to rise

up of the primary contamination and the subsequent atmospheric transport). Therefore, this

calculation is performed for 10 years – for this period the infiltrating water and the

radionuclides do not reach the saturated zone and respectively the well water used for

irrigations and drinking.

The assumed mass loading factor for inhalation and average onsite mass loading are of 1E-6

kg/m3. It is assumed that the archaeologist spends 6 hours per day on the contaminated zone

– the investigation area.

In this calculation the evasion rate of C14 is assumed to be equal to 12 years-1.

In order to demonstrate the effect of C-14 evasion due to the contaminated zone’s digging,

the thickness of evasion layer for C-14 in soil is assumed to be 5.1m (the thickness of the

contaminated layer). This conservative assumption means that the entire C-14 inventory is

available to evasion at the initial time, not being considered the duration of the digging

activities.

i. RESULTS

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

Do

se

Ra

te [m

Sv/y

ea

r]

t [years]

Total Dose Rate

Dose Rate - C-14

Dose Rate - Cs-137

Figure 9-129 Dose for the human – all pathways summed



Page 191 of 253

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

0.000

0.005

0.010

0.015

0.020

0.025

0.030

0.035

0.040

0.045

0.050

0.055

Do

se

Ra

te [m

Sv/y

ea

r]

Dose from inhalation

Dose - direct radiation

from soil

t [years]

Figure 9-130 Dose for the human – component pathways

If it is assumed that the archaeologist spends 6 hours per day outside at the primary

contamination and the rest of the day – inside in the dwelling site, situated on the restricted

area boundary, the results are as follows:

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.10

0.11

0.12

Do

se

Ra

te [m

Sv/y

ea

r]

t [years]

Total Dose Rate

Dose Rate - C-14

Dose Rate - Cs-137

Figure 9-131 Dose for the human – all pathways summed



Page 192 of 253

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

Do

se

Ra

te [m

Sv/y

ea

r]

t [years]

Dose from inhalation

Dose - radiation

from soil (direct and airborne)

Figure 9-132 Dose for the human – component pathways

j. CONCLUSIONS

The maximum dose rate calculated for this scenario is approximately 0.11mSv/year in case the

archaeologist lives on the restricted area.

The dose for the human is mainly from C-14 inhalation (C-14 evasion due to digging of the

repository contaminated layer) and Cs-137 radiation from soil (direct and air borne). Although

the conservative assumptions used in this calculation (the entire C-14 inventory is available for

evasion at time zero which means that the contaminated layer is dug instantaneously) the

dose rate does not exceed the dose rate limit of 0.3mSv/year established for the repository.

The real case is as follows: during the digging period only the C-14 composition distributed in a

soil layer with a thickness of 0.3m (the default RESRAD-OFFSITE thickness value for C-14 evasion)

is available for evasion.

The results for the dose from external exposure obtained in a) and b) are compared in Table

9-28.

Table 9-28 Comparison between the calculations in cases a) and b)

Case Dose from external

exposure [mSv/y]

Total dose [mSv/y]

Case a)-TECDOC 1380 [36] 2.51E-02 3.75E-02

Case b) RESRAD OFFSITE 2.1E-02 0.12

The results from the calculations of cases a) and b) show that the dose from external exposure

is nearly equal. The difference in the total dose between the cases a) and b) is due to the C-14

evasion considered in RESRAD OFFSITE calculations.



Page 193 of 253

9.8.3.4.2.3. Alternative scenario 3) Geologist intrusion

This scenario could occur if the investigation of the repository site is envisaged. Individual

exposure is due to the handling and examination of the sample extracted from the site.

The scenario assumes the intrusion on site of a working team (the potential critical group) that

investigates collected samples. The pathways considered significant for a potential

contamination are:

external exposure;

contaminated dust inhalation;

contaminated dust ingestion;

The starting point of the calculation is the estimation of the radionuclide concentration on the

sample.

The critical group for this scenario is the geologist which examines the sample collected from

the site.

Dose from external exposure:

Configuration:

The repository is closed. The periods of active and passive institutional control are over.

The access on the repository is free.

It was conservatively considered that the drill samples are taken from the repository site

as soon as possible early after the institutional control is over.

Dose calculation points (position of the geologist):

Contact dose - 0.05m;

0.5m from the body - source in the hand of the geologist;

Height 20cm in the middle of the source

Operations:

The geologist drills the repository site using the geological probe.

Model specifics:

Source – radius 5cm, height 40cm

Source activity calculated with DUST MS – 2.56E-03 Bq/cm3 for 137Cs

Radionuclide 60Co is not considered due to the small half-life period. At this period this

radionuclide will not be presented.



Page 194 of 253

Model scene

Results:

Operation Geologist Distance from the source [m] Dose rate µSv/h

Drilling 1 0.05 3.81E-05

Drilling 1 0.5 2.16E-06

Conclusion:

1. The dose for the geologist from external exposure calculated for 1 year (2190h) is

4.72E-06 mSv/y.

2. The presented dose rates of the geologist from external exposure are lower than the

natural gamma radiation.

Dose from inhalation and ingestion of contaminated dust

Configuration

Geologist drills a sample from repository (conservatively).

Input data

Volume of repository – 2.95E+05 m3


Dust [36] – 1.00E-06 kg/m3

Dilution factor [36] – 1




Assumption:

It is assumed that geologist takes sample from the repository (conservatively)[36].



Ainitial = (Total activity with decay) / Volume of repository cover layer

The total activity with decay for 300years and the source term for the calculations are


Geological sonde

0.05m,

0.5m

Operator



Page 195 of 253

Table 9-29 Total activity with decay for 300years

Nuclides Total activity without

decay [Bq] [19]

Total activity with

decay for 300y

[Bq]

Initial activity

[Bq/kg]

14C 9.67E+13 9.33E+13 1.60E+05

36Cl 4.80E+09 4.80E+09 8.25E+00

244Cm 4.54E+10 4.93E+05 8.49E-04

60Co 1.61E+15 1.41E-02 2.42E-11

134Cs 1.42E+08 5.28E-36 9.09E-45

137Cs 2.36E+13 2.43E+10 4.19E+01

152Eu 1.84E+11 4.03E+04 6.94E-05

154Eu 1.93E+10 6.61E-01 1.14E-09

155Eu 3.36E+09 2.52E-09 4.34E-18

55Fe 8.18E+14 2.34E-19 4.02E-28

3H 1.66E+14 8.15E+06 1.40E-02

129I 7.40E+08 7.40E+08 1.27E+00

93mNb 5.58E+11 5.58E+11 9.60E+02

59Ni 1.26E+08 1.26E+08 2.16E-01

63Ni 2.39E+13 3.08E+12 5.30E+03

241Pu 2.07E+15 1.07E+09 1.84E+00

106Ru 1.28E+12 0.00E+00 0.00E+00

125Sb 1.30E+04 4.57E-29 7.86E-38

90Sr 1.12E+13 8.47E+09 1.46E+01


Nuclides DFingestion [Sv/Bq] DFinhhalation [Sv/Bq]

14C 5.80E-10 5.80E-09

36Cl 9.30E-10 5.10E-09

244Cm 1.20E-07 1.70E-05

60Co 3.50E-09 3.10E-08

134Cs 1.90E-08 2.00E-08

137Cs 1.30E-08 3.90E-08

152Eu 1.40E-09 4.20E-08

154Eu 2.00E-09 5.30E-08

155Eu 3.20E-10 4.70E-09

55Fe 3.30E-10 7.70E-10

3H 1.80E-11 2.60E-10

129I 1.10E-07 3.60E-08



Page 196 of 253

Nuclides DFingestion [Sv/Bq] DFinhhalation [Sv/Bq]

93mNb 1.20E-10 1.80E-09

59Ni 6.30E-11 4.40E-10

63Ni 1.50E-10 1.30E-09

241Pu 4.80E-09 2.30E-06

106Ru 7.00E-09 6.60E-08

125Sb 1.10E-09 1.20E+08

90Sr 3.10E-08 1.60E-07

Results:

Mass of repository – mrep = Vrep * ρ = 5.81E+08 kg

Dose calculation – Dose = Ainitial * [(soil ingestion rate)*DFingestion + BR*dust*DFinhalation]*(exposure

time) [Sv/y]

Table 9-31 presents the doses for the geologists per radionuclide.

Table 9-31 Doses for the geologists

Nuclides Dose for the geologists [Sv/y] per

nuclide

14C 9.99E-06

36Cl 7.10E-10

244Cm 5.50E-11

60Co 8.77E-21

134Cs 1.35E-53

137Cs 4.59E-08

152Eu 1.68E-14

154Eu 3.67E-19

155Eu 1.70E-28

55Fe 1.09E-38

3H 3.08E-14

129I 1.06E-08

93mNb 1.43E-08

59Ni 1.33E-12

63Ni 8.18E-08

241Pu 1.46E-08

106Ru 0.00E+00

125Sb 3.10E-32

90Sr 4.13E-08

TOTAL DOSE FOR THE GEOLOGIST 1.02E-05 [Sv/y]

Total dose calculation

Total dose = (dose from external exposure)+(dose of ingestion)+(dose of inhalation)



Page 197 of 253

The total dose for the geologist is 1.02E-02 mSv/y (resulting mainly from inhalation and

ingestion) and is below the dose constraint for the population.

9.8.3.4.2.4. Alternative scenario 4) Road construction

The scenario assumes the on site intrusion of a working team that builds a road on the

repository site. The pathways considered as significant for a potential contamination of the

workers are:

external exposure;

contaminated dust inhalation;

contaminated dust ingestion;

The activity to which the intruder is exposed, Aint [Bq/kg of waste], is given by:

Ainitial= A m.e-t1. Dil, [36]

where

Am is the initial concentration of disposed radionuclides [Bq/kg of waste];

is the radioactive decay constant [y-1] (if required, other mechanisms contributing to

diminishing the radioactivity could also be incorporated in an effective decay term

(λeff));

t1 is the time before intrusion [y];

dil is the dilution factor [-].

The dose due the road construction scenario is expressed in [Sv/y] as:

Dose = Ainitial * [(soil ingestion rate)*DFingestion +DFexternal + BR*dust*DFinhalation ]*t2 [Sv/y], [36]

where

Ainitial is the activity to which the intruder is exposed [Bq/kg of waste];

Qsoil is the inadvertent soil ingestion rate of the intruder [kg/h];

DFing is the dose factor for ingestion [Sv/Bq]

DFext is the external exposure dose factor [Sv.h-1.Bq-1.kg]

BR is the breathing rate of the intruder [m3/h]

dust is the dust level to which the intruder is exposed [kg./m3]

DFinh is the dose factor for inhalation [Sv/Bq]

t2 is the exposure duration [h]

Configuration

Road construction on the covered repository after 300 years.

Input data

Volume of repository cover considered in the calculations - 1.5E+05 m3


Dust [36] – 1.00E-06 kg/m3

Dilution factor [36] – 0.3





Page 198 of 253


Assumption

It is assumed that 30% of the waste activity is diluted in the repository cover layer [36].



Ainitial = (Total activity with decay) / Volume of repository cover

The total activity with decay for 300 years and the source term for the calculations are


Table 9-32 Total activity with decay for 300 years

Nuclides

Total activity

without decay [Bq]

[19]

Total activity with

decay for 300y [Bq]

Initial activity

[Bq/kg]

14C 9.67E+13 2.80E+13 1.21E+05

36Cl 4.80E+09 1.44E+09 6.23E+00

244Cm 4.54E+10 1.48E+05 6.40E-04

60Co 1.61E+15 4.22E-03 1.83E-11

134Cs 1.42E+08 1.58E-36 6.86E-45

137Cs 2.36E+13 7.30E+09 3.16E+01

152Eu 1.84E+11 1.21E+04 5.24E-05

154Eu 1.93E+10 1.98E-01 8.58E-10

155Eu 3.36E+09 7.56E-10 3.27E-18

55Fe 8.18E+14 7.01E-20 3.03E-28

3H 1.66E+14 2.45E+06 1.06E-02

129I 7.40E+08 2.22E+08 9.61E-01

93mNb 5.58E+11 1.67E+11 7.25E+02

59Ni 1.26E+08 3.77E+07 1.63E-01

63Ni 2.39E+13 9.23E+11 4.00E+03

241Pu 2.07E+15 3.21E+08 1.39E+00

106Ru 1.28E+12 0.00E+00 0.00E+00

125Sb 1.30E+04 1.37E-29 5.93E-38

90Sr 1.12E+13 2.54E+09 1.10E+01


Nuclides DFingestion [Sv/Bq] DFinhhalation [Sv/Bq] DFexternal [Sv*kg /Bq*h]

14C 5.80E-10 5.80E-09 0

36Cl 9.30E-10 5.10E-09 0

244Cm 1.20E-07 1.70E-05 0

60Co 3.50E-09 3.10E-08 5.50E-10

134Cs 1.90E-08 2.00E-08 3.30E-10



Page 199 of 253

Nuclides DFingestion [Sv/Bq] DFinhhalation [Sv/Bq] DFexternal [Sv*kg /Bq*h]

137Cs 1.30E-08 3.90E-08 1.20E-10

152Eu 1.40E-09 4.20E-08 3.00E-10

154Eu 2.00E-09 5.30E-08 2.60E-10

155Eu 3.20E-10 4.70E-09 2.60E-10

55Fe 3.30E-10 7.70E-10 1.60E-20

3H 1.80E-11 2.60E-10 0

129I 1.10E-07 3.60E-08 1.70E-13

93mNb 1.20E-10 1.80E-09 5.80E-15

59Ni 6.30E-11 4.40E-10 1.10E-19

63Ni 1.50E-10 1.30E-09 0.00E+00

241Pu 4.80E-09 2.30E-06 3.00E-16

106Ru 7.00E-09 6.60E-08 4.80E-11

125Sb 1.10E-09 1.20E+08 8.30E-11

90Sr 3.10E-08 1.60E-07 2.10E-12

Results:

Mass of repository cover– mcover = Vcover * ρ = 2.31E+08 kg

Dose calculation – Dose = Ainitial * [(soil ingestion rate)*DFingestion +DFexternal +

BR*dust*DFinhalation]*(exposure time) [Sv/y]

The doses for the workers constructing the road are presented in Table 9-34.

Table 9-34 Doses for the workers constructing the road

Radionuclides Dose for the workers [Sv/y] per nuclide

14C 7.54E-06

36Cl 5.36E-10

244Cm 4.15E-11

60Co 2.20E-17

134Cs 4.97E-51

137Cs 8.34E-06

152Eu 3.44E-11

154Eu 4.89E-16

155Eu 1.86E-24

55Fe 8.22E-39

3H 2.32E-14

129I 8.34E-09

93mNb 2.00E-08

59Ni 1.00E-12

63Ni 6.17E-08



Page 200 of 253

Radionuclides Dose for the workers [Sv/y] per nuclide

241Pu 1.10E-08

106Ru 0.00E+00

125Sb 2.34E-32

90Sr 8.17E-08

TOTAL DOSE FOR THE WORKER 1.61E-05

Conclusions:

1) The dose for the workers constructing the road of 1.61E-02 mSv/y is below the dose

constraint for the population 0.3 mSv/y.


9.8.3.5.1. Evaluation of the impact according to the reference scenario

The model and scenario description is presented in p. 9.8.3.4.1 of this chapter (Dose for the

population during the reference scenario).

IMPACT

C-14 concentration

0 10000 20000 30000 40000 50000 60000 70000

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

2.2

2.4

Co

nce

ntr

atio

n [B

q/l]

t [years]

C-14 well water concentration

Figure 9-133 C-14 concentration in well water



Page 201 of 253

0 10000 20000 30000 40000 50000 60000 70000

0

200

400

600

800

1000

t [years]

C-1

4 c

on

ce

ntr

atio

n [B

q/k

g]

Fruits, non-leafy vegetables

Leafy vegetables

Pasture, silage

Grain

Figure 9-134 C-14 concentration in plants

The C-14 concentration in fruits and non-leafy vegetables is equal to the C-14 concentration in

grains.

The C-14 concentration in leafy vegetables is equal to the C-14 concentration in pastures and

silages.

0 10000 20000 30000 40000 50000 60000 70000

0

100

200

300

400

500

600

Co

nce

ntr

atio

n [B

q/k

g]

t [years]

C-14 Meat concentration

Figure 9-135 C-14 concentration in meat



Page 202 of 253

0 10000 20000 30000 40000 50000 60000 70000

0

20

40

60

80

100

120

140

160

180

Co

nce

ntr

atio

n [B

q/l]

t [years]

C-14 Milk concentration

Figure 9-136 C-14 concentration in milk

I-129 concentration is presented in the following figures

0 500 1000 1500 2000 2500 3000

0.000

0.002

0.004

0.006

0.008

0.010

0.012

Co

nce

ntr

atio

n [B

q/l]

t [years]

I-129 well water concentration

Figure 9-137 I-129 concentration in well water



Page 203 of 253

0 500 1000 1500 2000 2500 3000

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

0.55

0.60

0.65

0.70

0.75 Fruits, non-leafy vegetables

Leafy vegetables

Pasture, silage

Grain

Co

nce

ntr

atio

n [B

q/k

g]

t [years]

Figure 9-138 I-129 concentration in plants

0 500 1000 1500 2000 2500 3000

0.00

0.02

0.04

0.06

0.08

Co

nce

ntr

atio

n [B

q/k

g]

t [years]

I-129 meat concentration

Figure 9-139 I-129 concentration in meat



Page 204 of 253

0 500 1000 1500 2000 2500 3000

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35C

on

ce

ntr

atio

n [B

q/l]

t [years]

I-129 milk concentration

Figure 9-140 I-129 concentration in milk

Cl-36 concentration is presented in the following figures

0 500 1000 1500 2000 2500 3000

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

Co

nce

ntr

atio

n [B

q/l]

t [years]

Cl-36 well water concentration

Figure 9-141 Cl-36 concentration in well water



Page 205 of 253

0 500 1000 1500 2000 2500 3000

0

1

2

3

4

5

6

7

8

9

10

11


Leafy vegetables

Pasture, silage

Grain

Co

nce

ntr

atio

n [B

q/k

g]

t [years]

Figure 9-142 Cl-36 concentration in plants

0 500 1000 1500 2000 2500 3000

0

5

10

15

20

25

30

35

Co

nce

ntr

atio

n [B

q/k

g]

t [years]

Cl-36 meat concentration

Figure 9-143 Cl-36 concentration in meat



Page 206 of 253

0 500 1000 1500 2000 2500 3000

0

2

4

6

8

10

12

Co

nce

ntr

atio

n [B

q/l]

t [years]

Cl-36 milk concentration

Figure 9-144 Cl-36 concentration in milk

Table 9-35 Comparison between maximum limits of the contaminants in drinking water and the

maximum concentration in well water

Isotope

Maximum

concentration,

Bq/l

Max. conc. in year:

Limit concentration

according to [35],

Bq/l 3H 3.1e-7 120 7600

14C 2.2 15000 230 36Cl 0.07 1300 61 129I 0.011 1300 0.96

All concentrations of radionuclides in the well water are below the limits in [35].

CONCLUSIONS

The radionuclide concentration in the drinking water is below the limits.

9.8.3.5.2. Evaluation of the impact according to the alternative scenarios

9.8.3.5.2.1.1. Archaeological investigation of the site

The model and scenario description is presented in p. 9.8.3.4.2.2 of this chapter

(Archaeological investigation of the site). The results for the radionuclides that produce the

main dose are graphically presented below.

RESULTS

C-14 concentration



Page 207 of 253

0 1 2 3 4 5

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

Co

nce

ntr

atio

n [B

q/m

3]

t [years]

C-14 air concentration -

above the primary contamination

Figure 9-145 C-14 concentration in the air above the primary contamination

0 1 2 3 4 5

0.0000

0.0002

0.0004

0.0006

0.0008

0.0010

0.0012

0.0014

0.0016

0.0018

t [years]

Co

nce

ntr

atio

n [B

q/m

3]

C-14 air concentration -

above the offsite dwelling

Figure 9-146 C-14 concentration in the air above the offsite dwelling



Page 208 of 253

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

0.000000

0.000002

0.000004

0.000006

0.000008

0.000010

0.000012

0.000014

0.000016

0.000018

0.000020

C-1

4 c

on

ce

ntr

atio

n [B

q/g

]

t [years]

C-14 concentration -

offsite dwellin surface soil

Figure 9-147 C-14 concentration in the offsite dwelling surface soil

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

0

2

4

6

8

10

12

14

16

C-1

4 c

on

ce

ntr

atio

n [B

q/k

g]

t [years]


Leafy vegetables

Pasture, silage

Grain

Figure 9-148 C-14 concentration in plants



Page 209 of 253

0 1 2 3 4 5

0

1

2

3

4

Co

nce

ntr

atio

n [B

q/k

g]

t [years]

C-14 meat concentration

Figure 9-149 C-14 concentration in meat

0 1 2 3 4 5

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Co

nce

ntr

atio

n [B

q/l]

t [years]

C-14 milk concentration

Figure 9-150 C-14 concentration in milk

Cs-137 concentration is presented in the following figures:



Page 210 of 253

0 1 2 3 4 5

0.070

0.075

0.080

0.085

0.090

0.095

0.100

0.105

Co

nce

ntr

atio

n [B

q/g

]

X Axis Title

Cs-137 concentration in the

primary contaminated soil

Figure 9-151 Cs-137 contamination in the contaminated soil (time variation)

0 5 10 15 20 25 30 35 40

0.0000000

0.0000001

0.0000002

0.0000003

0.0000004

0.0000005

0.0000006

0.0000007

0.0000008

0.0000009

0.0000010

Cs-1

37

co

nce

ntr

atio

n [B

q/g

]

t [years]

Cs-137 concentration -

offsite dwellin surface soil

Figure 9-152 Cs-137 concentration in the offsite dwelling surface soil

9.8.3.5.2.1.2. Road construction

The model and scenario description is presented in point 9.8.3.4.2.4 of this chapter (Road

construction).

The radionuclide concentration in air is obtained by [39]:



Page 211 of 253

Cair,i = Csoil,i . ρ

Cair,i – radionuclide i concentration in the air

Csoil,i - radionuclide i concentration in the soil

ρ – dust rate = 1*10-6 kg/m3 [39].

The concentration in soil is presented in p. 9.8.3.4.2.4 of this chapter.

Table 9-36 Radionuclide concentration in the air above the road construction zone

Nuclides Initial activity

[Bq/kg]

Air concentration

[Bq/m3]

14C 1.21E+05 1.21E-01

36Cl 6.23E+00 6.23E-06

244Cm 6.40E-04 6.40E-10

60Co 1.83E-11 1.83E-17

134Cs 6.86E-45 6.86E-51

137Cs 3.16E+01 3.16E-05

152Eu 5.24E-05 5.24E-11

154Eu 8.58E-10 8.58E-16

155Eu 3.27E-18 3.27E-24

55Fe 3.03E-28 3.03E-34

3H 1.06E-02 1.06E-08

129I 9.61E-01 9.61E-07

93mNb 7.25E+02 7.25E-04

59Ni 1.63E-01 1.63E-07

63Ni 4.00E+03 4.00E-03

241Pu 1.39E+00 1.39E-06

106Ru 0.00E+00 0.00E+00

125Sb 5.93E-38 5.93E-44

90Sr 1.10E+01 1.10E-05

International Commission for Radiological Protection establishes in Publication 30 [15] the

maximum concentration of tritium in the air at 540 µCi/m3 (2.0E+07 Bq/m3). In this case the

calculated 3H air concentration is 1.06E-08 Bq/m3.



Page 212 of 253

9.9. UNCERTAINTY AND SENSITIVITY ANALYSIS

9.9.1. PURPOSE

The main purpose of this chapter is to present the uncertainty and sensitivity analysis of the

results from the calculations performed in the field of safety assessment for the post-closure

period. The process includes:

Review of the relevant requirements of the Romanian regulation [3];

Review of the international recommendations, guides and practices related to

uncertainty and sensitivity analysis techniques in the field of radioactive waste disposal

facilities.

Review of all calculations performed in the field of the safety assessment for the post-

closure period.

Elaboration and implementation of a specific strategy for sensitivity evaluation and

uncertainty analysis of the results from the calculations performed in the field of safety

assessment for the post-closure period.

Performance of studies and elaboration of justified conclusions.

9.9.2. REGULATORY REQUIREMENTS AND RECOMMENDATIONS

9.9.2.1. Romanian requirements and recommendations

According to the Romanian regulation [3] Art. 34, the robustness can be achieved by

implementing the technical and management systems that tend to eliminate the effects of

uncertainties.

According to Art. 4 of Annex 2 of [3], uncertainties shall be tolerated for the safety assessment:

“The results of an evaluation of the repository include the identification of the uncertainties.

These must be compared with the objective of the repository model and the regulation criteria,

taking into account the contributions to the acceptability of the repository.”

Additional recommendations related to the uncertainties are presented in [3]:

1) the validity of the output data of mathematical simulations shall be considered through the

uncertainties from the input data for models, hypothesis from different parts of the models,

hypothesis regarding the interface between the individual parts of the model and the

uncertainties concerning the long term evolution of the disposal system (art. 9 of Ann. 2);

2) the need for the safety assessment data to be specified with different uncertainty detailing

degrees that depends on the objectives of the safety assessment (art. 14 of Ann. 2);

3) at least two sources of uncertainties shall be considered: degree in which the model

represents the real system (input data, site characteristics, engineering characteristics of

the repository and their interaction with the environment as well as the simulation itself);

non-estimation of the future human actions and of the facility evolution and the

environment per large periods of time (art. 40 of Ann. 2);

4) the main importance of the sensitive and uncertainties’ analysis for the regulation decisions

is using them as means for evaluation of the compliance with the safety requirements

towards the uncertainties. If the compliance with the safety standards can be proved by

other means, for example by using a conservative model, then the analysis of uncertainties

is no longer necessary (art. 41 of Ann. 2);



Page 213 of 253

5) if safety assessment results are sensitive to specific input data (initial and/or boundary

conditions), the uncertainty of the concerned input data shall be minimized by further data

acquisition (art. 46 of Ann. 2);

9.9.2.2. IAEA requirements and recommendations

The Romanian legislation is well synchronized with the IAEA requirements and

recommendations. The IAEA requirements related to the uncertainty analysis presented in [11]

are considered in [3] as well. The recommendations concerning the uncertainty methodology

presented in [12] are considered in Annex 2 of [3].

Additional IAEA guides and recommendations are presented in IAEA Safety Assessment

Methodologies for Near Surface Disposal Facilities [10] and in IAEA-TECDOC-1380 [36].

However, according to the IAEA Experts Mission Report [6], both documents ([10] and [36])

were created with illustrative purposes and should not be regarded as appropriate for site-

specific assessments.

9.9.3. REVIEW OF THE PERFORMED CALCULATIONS

The repository safety assessment is based on calculations performed with the following

computer codes:

Table 9-37 Computer codes used for the safety assessment

№ Code Name Short Description

1 DUST-MS Evaluation of source term, 1D transport code

2 HYDRUS Contaminants’ transport in the unsaturated layer, 3D transport

code

3 PORFLOW 3D, Contaminants’ transport in the saturated layer

4 RESRAD-OFFSITE Environmental impact and dose assessment

5 MERCURAD Dose assessment of gamma exposure, 3D Monte-Carlo transport

code

Input data for most calculations are ensured by the data basis drafted during the site

characterization phase in 2009 [28] and the Conceptual design of the repository [38]. Input

data uncertainties are applied in conservative direction by engineering judgment considering

the recommendations of the developers of the concerned computer codes.

In all cases the input models for calculations are based on the most conservative assumptions.

The values applied in all models are conservatively selected considering the criteria for

acceptance of results, namely:

Acceptable concentration of radionuclides in the drinking water [35];

Acceptable doses for the population (Romanian legislation and Design constraints).

In order to cover all possible deviations in non-conservative direction, the following initial

assumption is imposed to all calculations:

The initial activity of RAW, which will be stored in Saligny repository is increased by a factor of

1.5 according to the waste inventory in [19].

Consequently, the main purpose of the uncertainty study is to verify whether the cumulative

uncertainty of all calculations could override the envelope, established by this initial

assumption, considering the estimation of human and environmental impact.



Page 214 of 253

Detailed presentations of calculations performed for the operational period scenarios are

presented in detail at the previous points of this report.

9.9.4. STRATEGY FOR UNCERTAINTY EVALUATION

Based on the review of regulation requirements (“If the compliance with the safety standards

can be proved by other means, for example by using a conservative model, then the analysis

of uncertainties is no longer necessary.”, Art. 41, Ann. 2 of [3]) and the critical comments of the

IAEA experts missions (“…uncertainties in modeling studies can arise from several causes and

need to be approached by means of sensitivity analyses or probabilistic methods or both.”[5];

“Uncertainty and sensitivity analysis: This chapter needs a more systematic and profound

treatment of uncertainties; currently the emphasis is on parameter uncertainty, with little

attention on the scenario and conceptual model uncertainty.”[6]) parameters’ uncertainty

analysis is not needed as all the models used for the concerned computer codes are

conservative.

Conceptual and scenario uncertainties shall be accounted by:

1) Scenario uncertainties – conservative alternative scenarios are considered for the post-

closure period;

2) Conceptual uncertainties – sensitivity analysis will be performed for the assumptions related

to the conservative models, applied by the concerned computer codes for the reference

scenario.

The alternative scenario calculations for the post-closure period are presented in detail in the

previous chapters of this report.

The matrix of calculations, which are performed within the sensitivity studies, is presented at p.

9.9.6 below.

9.9.5. REVIEW OF RESULTS FROM CALCULATIONS OF ALTERNATIVE SCENARIOS

9.9.5.1. DUST-MS

The safety assessment for the post-closure period is divided in three sub-periods:

Active institution control for 100 years;

Passive institution control for 200 years;

Post-closure period after 300 years.

For the first two post-operational periods – the reference source term calculations are

performed with the same reference model used in the operational period (“DUST MS diffusion”

– intact engineered barriers are assumed). The reference source term calculations for the post-

closure period are performed with the assumption of container break after 300 years.

Alternative scenarios for the institution control periods are based on the assumption of a cell

element failure. The model used is the same as for the operational period – “DUST-MS diffusion

with time increasing Water velocity”.

For the post-closure period after 300 years the alternative source term scenario is the same as

the reference scenario source term due to the conservative assumptions applied to the

reference scenario for the post-closure period after 300. As the calculations’ results for both

scenarios are the same – this period is not included in the scenario uncertainty.

Input data, assumptions, models and calculations are presented in detail in p. 9.8



Page 215 of 253

A summary of calculations’ results and scenarios’ uncertainties for the post-closure period

scenarios are presented in Table 9-38.

Table 9-38 DUST-MS Scenario uncertainties for the post-closure period

Note: Logarithms of concerned maximum values are used due to value differences by orders

of magnitude.

9.9.5.2. HYDRUS

For all scenarios, in all operational periods the evaluation of contaminants’ concentration at

the unsaturated – saturated zone boundary are performed with the HYDRUS 2D and 3D

models for the post-closure period after 300 years. This is due to the fact that for all the periods

the site geological characteristics are assumed to be the same. Changes in calculations are in

initial and boundary conditions – most changes of infiltration rate outside and beneath the

repository, and contaminants’ concentration.

For the first two post-closure periods (periods of institution control), contaminants’

concentration in the unsaturated-saturated zone boundary reference scenario is evaluated

with the same 2D model and under the initial/boundary conditions as in the operational

period.

For the alternative scenarios of the institution control periods the same model and

initial/boundary conditions as the operational period alternative scenario are used.

Calculations are performed for 3H only, based on contaminants’ concentration calculations’

results for the unsaturated-saturated zone boundary during the post-closure period after 300

years.

For the post-closure period after 300 years, the reference scenario model and initial/boundary

conditions are the same for the alternative scenario. No HYDRUS scenario uncertainty is

evaluated for this period. A summary of the calculations results and scenarios’ uncertainties for

the post-closure period scenarios are presented in Table 9-39.

Isoto

pe

65 – 165 y 165 – 365 y

Ref.

scenario

Alt.

scenario

Rel. Log.

Unc.

Ref.

scenario

Alt.

scenario

Rel. Log.

Unc.

Max.

Conc.

[Bq/cm3]

Max.

Conc.

[Bq/cm3]

- Max.

Conc.

[Bq/cm3]

Max.

Conc.

[Bq/cm3]

-

14C 1.19E-10 5.20E-06 4.68E-01 5.65E-10 2.24E-03 7.13E-01 60Co 8.05E-17 1.01E-07 5.65E-01 2.21E-21 3.15E-09 5.88E-01 3H 1.17E-04 6.87E-04 1.96E-01 3.15E-06 4.84E-04 3.97E-01 90Sr 2.30E-17 1.89E-07 5.96E-01 1.30E-17 8.09E-07 6.39E-01 36Cl 6.27E-14 8.90E-06 6.17E-01 3.06E-13 2.30E-03 7.89E-01 137Cs 1.55E-06 1.26E-02 6.73E-01 9.42E-07 2.19E-02 7.25E-01 241Pu 6.15E-30 6.31E-11 6.51E-01 3.91E-31 5.71E-11 6.63E-01



Page 216 of 253

Table 9-39 HYDRUS Scenario uncertainties for the post-closure period

Sc. Ref.

Sc. Alt.Sc. Ref.

Conc. M ax.

Conc. M ax. - Conc. M ax. Unc. Rel.

9.9.5.3. PORFLOW

Due to the assumption of constant geological parameters of the saturated zone at Saligny

repository area, the PORFLOW model is the same for all interest periods. Again, as in case of

HYDRUS calculations, the differences in the calculations’ results are due to changes in the

initial and boundary conditions.

Evaluation of contaminant concentration is made for four points of the saturated zone:

1) at 1400m distance from the “repository” projection on saturated zone;

2) at 300 m distance from the “repository” projection on saturated zone;

3) at 25 m distance from the “repository” projection on saturated zone;

4) beneath the repository.

For each of the points, six nodes are taken into account. The nodes are located one above

the other at the following depths in the saturated layer: 1m, 5m, 10m, 15m, 20m, 25m. Only the

node with maximum contaminant concentration is object of the scenario uncertainty study.

Both reference and alternative scenarios for the post-closure period after 300 years are

performed by using the same model and initial/boundary conditions. No PORFLOW scenario

uncertainty is evaluated for this period.

The same model is used for the two institutional control post-closure periods and the same

initial and boundary conditions as for the concerned reference and alternative scenarios – the

differences between them is the contaminant concentration on the upper saturated layer.

A summary of calculations’ results and scenarios’ uncertainties for the post-closure period

scenarios are presented in Table 9-40.

Table 9-40 PORFLOW Scenario uncertainties for the post-closure period

Isoto

pe

65 – 165 y 165 – 365 y

Ref. scenario Alt. scenario Rel.

Uncertain

ty

Ref.

scenario

Alt. scenario Rel.

Uncertain

ty

Lat. point

max. conc.

[Bq/cm3]

Lat. point

max. conc.

[Bq/cm3]

- Lat. point

max. conc.

[Bq/cm3]

Lat. point

max. conc.

[Bq/cm3]

-

3H 4.40E-07 4.70E-07 6.82E-02 7.80E-07 3.80E-06 3.87E+00

Group

nodes

65 – 165 y 165 – 365 y

Ref.

scenario

Alt.

scenario

Rel.

Uncertaint

y

Ref.

scenario

Alt.

scenario

Rel.

Uncertain

ty

Max Conc.

[Bq/m3]

Max Conc.

[Bq/m3]

- Max Conc.

[Bq/m3]

Max Conc.

[Bq/m3] -

a-1400m 0 0 0 6.74E-29 7.45E-29 1.05E-01

b-300m 1.28E-13 1.41E-13 1.02E-01 4.94E-10 1.47E-09 1.98E+00

c-25m 1.39E-07 1.52E-07 9.35E-02 3.20E-07 1.60E-06 4.00E+00



Page 217 of 253

Sc. Ref.

Sc. Alt.Sc. Ref.

Conc. M ax.

Conc. M ax. - Conc. M ax. Unc. Rel.

9.9.5.4. RESRAD

RESRAD computer code is used in the Safety Assessment for evaluation of the contaminant

transport into the biosphere. Results are dose for population and environmental impact.

For the first post-closure period (active institution control) – no RESRAD calculations, neither for

population dose load nor for the environmental impact evaluation are performed.

For the second post-closure period (passive institution control) – no reference scenario

calculations are performed. Respectively – no model uncertainties for this period could be

evaluated as they are based on reference scenario calculation’s results.

For the final post-closure period considered in the safety assessment (post-closure period after

300 years) the reference scenario considers farm building and population representatives living

in the concerned farm.

The comparison of the reference and alternative scenarios results is presented in Table 9-41.

Table 9-41 RESRAD Scenario uncertainties for the post-closure period

Ref. Sc. Alt. Sc. 1 –

residence on totally

degraded wastes

Alt. Sc. 2 - Arch.

Investigation

Alt. Sc. 3 - Geol.

Intrusion

Alt. Sc. 4 - Road

Construction

Dose

rate,

mSv/y

Dose

rate,

mSv/y

Rel.

Unc.

Dose

rate,

mSv/y

Rel.

Unc.

Dose

rate,

mSv/y

Rel.

Unc.

Dose

rate,

mSv/y

Rel.

Unc.

1.20E-01 2.64E-01 1.20E+00 1.20E-01 0.00E+00 1.02E-02 9.15E-01 1.16E-02 9.03E-01

9.9.5.5. MERCURAD

In case of MERCURAD scenario uncertainties for operational period, the comparison of the

MERCURAD related reference and alternative scenarios for the first post-closure period is

considered as not reasonable. For the other two post-closure periods – it is not possible, as only

one scenario is calculated with MERCURAD.

9.9.5.6. Conclusions for scenario uncertainties

A comparative approach of scenario uncertainties is not completely applicable to the

scenarios modeled with one of the computer codes – MERCURAD. The approach is limited

due to lack of reference scenarios evaluated with this code (final periods) or inapplicable

scenario comparison.

For the rest of the computer codes used the results from scenario uncertainties show that:

1) For DUST-MS – the relative logarithmic uncertainties of the scenario are within the margin

defined by the 1.5 times conservative increase of the inventory;

2) For HYDRUS – the margin defined by the 1.5 times increase of the inventory is maintained in

the first post-closure period. In the other period – the period of the passive institution control,

the relative uncertainty is higher than the margin, but the tritium concentration is below the

drinking water limits;

d-beneath

repository 4.91E-07 5.44E-07 1.08E-01 7.78E-07 3.83E-06 3.92E+00



Page 218 of 253

3) For PORFLOW – in the first post-closure period, the conservative margin is maintained. In the

second post-closure period the relative uncertainty is higher in almost all control points.

Even if the conservative margin is not maintained, tritium concentration in all control points

is lower than the drinking water limits;

4) For RESRAD – the conservative margin defined by the conservative repository inventory

increase is maintained in all considered cases.

9.9.6. MATRIX OF SENSITIVITY CALCULATIONS

The matrix of sensitivity calculations presents in detail the process of evaluation of results’

sensitivity to the changes in the input data and assumptions.

If a computer code model essentially differs for the two considered periods (Operational and

Post-closure) two additional sensitivity studies (for the concerned periods) are performed.

The sensitivity study is performed only for the reference scenario models.

9.9.6.1. Review of input data range

In this chapter are presented the variations of the input data that are considered important for

the final calculations’ results. The selection of important Input data is based on the following:

International accepted practice;

Recommendations of experts from the concerned computer code elaboration / support

teams;

Engineering judgment (opinion).

Appropriate alternatives of assumptions (if any) which are considered important for the model

are also described and taken into account.

9.9.6.1.1. DUST-MS

The process which mostly contributes to contaminant release is diffusion. This assumption is

based on statements from [10] and [12]. No proper alternatives are considered, due to the

specifics of the waste conditioning process before delivery into the repository (cementation).

The variations of parameters considered important are presented in Table 9-42.

Table 9-42 Range of sensitivity parameters for DUST-MS

Parameter Unit Range [ref./min./max.] Selection criteria

Moisture content % 20 / 5 / 40 Engineering judgment

Density of the wastes g/cm3 1.7 / 1.5 / 1.9 Engineering judgment

Density of the

concrete slab g/cm3 2.3 / 2.1 / 2.5 Engineering judgment

Darcy flow cm/s 7.0 E-8 / 7.0 E-10 / 7.0 E-6 Engineering judgment

Waste matrix diffusion

coefficient cm2/s 1.0 E-6 / 1.0 E-7 / 1.0 E-5 Engineering judgment

No calculations are performed for the waste inventory as the initially expected inventory was

conservatively increased by 50% (see [19]). All calculations are performed with this

conservative inventory.



Page 219 of 253

9.9.6.1.2. HYDRUS

9.9.6.1.2.1. Change of layer types

The HYDRUS model for all periods is the same, as no assumptions for changes in the

unsaturated layer in the repository area are considered. Due to this, the sensitivity analysis is

performed for the model for the post-closure period after 300 years.

Sensitivity study is performed for the first two layers of the model.

For the first layer (compacted loess layer) – the reference model assumes that it is silty loess. As

concerns the sensitivity case – it is changed to red clay.

For the second natural layer – the reference model assumes that it is upper clayed loess, as

concerns the sensitivity case – it is changed to fossilized loess. Parameters of the concerned soil

types are presented in Table 9-43.

Table 9-43 Range of sensitivity parameters for HYDRUS

Parameter Unit Silty loess Upper clayed

loess

Fossilized

loess

Red clay

Density g/cm3 1.54 1.57 1.78 1.76

Residual porosity, r - 0.067 0.076 0.049 0.001

Saturated water

content, s

- 0.37 0.38 0.47 0.43

Saturated hydraulic

conductivity, Ks

cm/s

m/year

1.10-4

31.5578

2.10-5

6.3116

7.510-6

2.3668

5.10-6

1.5779

9.9.6.1.2.2. Existence of sand layer

A sensitivity study considering a sand layer above the red clay in Saligny site unsaturated zone

is performed in order to evaluate the sensitivity of HYDRUS results of Saligny site model to the

existence of the sand level. The sand layer may influence the radionuclide transport through

the unsaturated zone of Saligny. No data regarding the sand level in the borehole logs is

available. Due to the missing data the exact thickness of the sand level cannot be evaluated.

In order to represent the effect of the possible existence of a sand layer in the unsaturated

zone of Saligny site a calculation considering the existence of a sand layer of one meter

thickness is performed. The calculation is performed for C-14 – the radionuclide with the

highest radiological impact in the post-closure period from point of view of the radionuclide

transport to the well.

Another reason to perform this calculation only for C-14 is the distribution coefficients of the

radionuclides that reach the unsaturated – saturated zone boundary (Sr-90, C-14, H-3, I-129, Ni-

59, Cl-36). As it is shown at p. 9.8.3.2, the concentration of all radionuclides except C-14, H-3, I-

129, Ni-59 and Cl-36 decreases strongly in depth, no matter of the soil layer type. Among these

radionuclides, however, only C-14 has different distribution coefficients in silty loess and in red

clay (table 9-24). For the rest of the radionuclides the distribution coefficients in all geological

layers of Saligny site unsaturated zone are equal.

At p. 9.8.3.2, the distribution coefficients for Cl are assumed to be equal to these for Iodine.

o Unsaturated zone model

A detail model of Saligny site unsaturated zone and the applied assumptions for the HYDRUS

calculations are presented at point 9.8.2.2. The 2D model of unsaturated zone is applied for

this sensitivity analysis.



Page 220 of 253

o Specific assumptions

A sand layer of one meter thickness is assumed to be available in the unsaturated zone. This

layer is situated over the red clay layer and it replaces the red clay.

The 2D model representing the unsaturated zone corresponds to the geological formation of

FS1 borehole where the existence of the sand layer is assumed.

The properties of the sand are considered to be equal to those of the silty loess (Table 9-22).

Figure 9-153 presents the 2D model of Saligny unsaturated zone.

Figure 9-153 2D model, presenting the repository and lateral area

The layers presented are as follow:

- The blue layer (bigger) represents the Silty loess

- The green layer represents the Upper clayey loess

- The blue layer (smaller) represent the sand layer;

- The red layer represents the Red clay;

- The pink layer represents the Aptian clay.

Parameters of the respective soil types are presented in Table 9-44.

Table 9-44 Parameters of the geological layers considered in the HYDRUS sensitivity scenario

Parameter Unit Sand

(assumed as

silty loess)

Red clay

Density g/cm3 1.54 1.76

Residual porosity, r - 0.067 0.001

Saturated water

content, s

- 0.37 0.43

Saturated hydraulic

conductivity, Ks

cm/s

m/year

1x10-4

31.5578

5x10-6

1.5779



Page 221 of 253

9.9.6.1.3. PORFLOW

Similar to HYDRUS calculations – the model for PORFLOW calculations is the same for all periods

of repository existence, due to assumed constant geological and hydro-geological properties

of Saligny site.

The variations of parameters considered important are presented in Table 9-45.

Table 9-45 Range of sensitivity parameters for PORFLOW

Parameter Units Range [ref./min./max.] Selection criteria

Clay effective porosity - 0.17 / 0.10 / 0.30 Engineering judgment

Darcy flow m/s 1E-08 / 1E-09 / 1E-07 Engineering judgment

9.9.6.1.4. RESRAD

Sensitivity study is performed for the reference model for the last post-closure period – post-

closure after 300 years.

Two parameters are varied – the quantity of the consumed “Fruits, grains and non-leafy

vegetables” (FGNLV) and the quantity of the consumed water.

Parameters range is presented in Table 9-46.

Table 9-46 Range of sensitivity parameters for RESRAD


Fruits, grains and non-

leafy vegetables

(FGNLV)

kg/y 160 / 100 / 200 Engineering judgment

Water Ingestion l/y 510 / 400 / 730 Engineering judgment

9.9.6.1.5. MERCURAD

Sensitivity study is performed for the model used in the only reference scenario calculations

with MERCURAD for the post-closure periods – the model for scenario “1) Dose for the operator

performing the control of the monitoring water tanks in the collecting system gallery”.

Changes of two parameters from the reference model are studied – density of concrete for

foundation slab and density of spent filters.

Parameters changes are presented in Table 9-47.

Table 9-47 Range of sensitivity parameters for MERCURAD


Density of spent filters

g/cm3

1.40/1.00/2.00

Engineering judgment

Density of concrete

slab

g/cm3

2.3/1.5/3.0

Engineering judgment

9.9.6.2. Calculations

In this chapter are presented the reflections of model modifications (related to input data and

assumptions change) in calculations’ results.

Calculations are performed for each of parameters considered important with all other input

data and assumptions remaining the same as in the base model.



Page 222 of 253

Performed calculations are represented by Figures and/or Tables.

9.9.6.2.1. DUST-MS

Analysis is performed for several isotopes. These isotopes are selected so that at least one is

short life /T1/2 < 137Cs T1/2 years/ and at least one is long-life /T1/2 > 137Cs T1/2 years/.

In all figures time is given in years and concentration is given in Bq per cubic centimeter.

9.9.6.2.1.1. Moisture content

The value used in calculation is 20% and the other values used for verification are 5% and 40%.

The comparison of the results is performed for three isotopes – 14C, 60Co and 137Cs.

0 20000 40000 60000 80000 100000

0,00

0,01

0,02

0,03

0,04

0,05

0,06

Co

nce

ntr

atio

n, B

q/c

m3

Time, years

Moisture 5%

Moisture 20%

Moisture 40%

250 300 350

0,00E+000

2,00E-020

4,00E-020

6,00E-020

8,00E-020

1,00E-019

1,20E-019

Co

nce

ntr

atio

n, B

q/c

m3

Time, years

Moisture 5%

Moisture 20%

Moisture 40%

Figure 9–154 14C concentration Figure 9–155 60Co concentration

200 300 400 500 600

0,0000

0,0002

0,0004

0,0006

0,0008

0,0010

Moisture 5%

Moisture 20%

Moisture 40%

Co

nce

ntr

atio

n, B

q/c

m3

Time, years

Figure 9–156 137Cs concentration

9.9.6.2.1.2. Waste density

The waste density in the base model is 1.7 g/cm3.

Values selected for analysis are waste density 1.5 g/cm3 and 1.9 g/cm3.



Page 223 of 253

Calculations are performed for 90Sr and 36Cl.

0 200 400 600 800 1000

0,00E+000

1,00E-010

2,00E-010

3,00E-010

4,00E-010

5,00E-010

6,00E-010

7,00E-010

Density = 1,5 g/cm3

Density = 1,7 g/cm

Density = 1,9 g/cm

Co

nce

ntr

atio

n, B

q/c

m3

Time, years

0 2000 4000 6000 8000 10000

0,0

1,0x10-5

2,0x10-5

3,0x10-5

4,0x10-5

5,0x10-5

Density = 1,5 g/cm3

Density = 1,7 g/cm

Density = 1,9 g/cm

Co

nce

ntr

atio

n, B

q/c

m3

Time, years

Figure 9–157 90Sr concentration Figure 9–158 36Cl concentration

9.9.6.2.1.3. Density of concrete

The density of concrete in the base model is 2.3 g/cm3.

Values selected for analysis are 2.1 g/cm3 and 2.5 g/cm3.

Calculations are performed for 14C and 137Cs.

0 20000 40000 60000 80000 100000

0,00

0,02

0,04

0,06

Density = 2,1 g/cm3

Density = 2,3 g/cm3

Density = 2,5 g/cm3

Co

nce

ntr

atio

n, B

q/c

m3

Time, years300 400 500 600

0,0000

0,0001

0,0002

0,0003

0,0004

0,0005

0,0006

0,0007

Density = 2,1 g/cm3

Density = 2,3 g/cm3

Density = 2,5 g/cm3

Co

cn

en

tra

tio

n B

q/c

m3

Time, years

Figure 9–159 14C concentration Figure 9–160 137Cs concentration

9.9.6.2.1.4. Darcy Flow

The value used in the base model is 7.0E-8 cm/s. This value was considered appropriate for

DFDSMA safety assessment.

Values selected for analysis are in the range from 7.0E-10 to 7.0E-6 cm/s.

Calculations are performed for 129I, 14C, 59Ni, 137Cs and 36Cl.



Page 224 of 253

0 10000 20000 30000 40000 50000

0,00

0,02

0,04

0,06

0,08

0,10

Vd=7.0e-10 cm/s

Vd=7.0e-9 cm/s

Vd=7.0e-8 cm/s

Vd=7.0e-7 cm/s

Vd=7.0e-6 cm/s

Co

nce

ntr

atio

n, B

q/c

m3

Time, years

0 5000 10000 15000 20000 25000 30000

0,0

5,0x10-5

1,0x10-4

1,5x10-4

2,0x10-4

2,5x10-4

3,0x10-4

Vd=7.0e-10 cm/s

Vd=7.0e-9 cm/s

Vd=7.0e-8 cm/s

Vd=7.0e-7 cm/s

Vd=7.0e-6 cm/s

Co

nce

ntr

atio

n, B

q/c

m3

Time, years

Figure 9–161 14C concentration Figure 9–162 36Cl concentration

300 350 400 450 500 550 600

0,0

1,0x10-4

2,0x10-4

3,0x10-4

4,0x10-4

5,0x10-4

6,0x10-4

7,0x10-4

Vd=7.0e-10 cm/s

Vd=7.0e-9 cm/s

Vd=7.0e-8 cm/s

Vd=7.0e-7 cm/s

Vd=7.0e-6 cm/s

Co

nce

ntr

atio

n B

q/c

m3

Time, years

0 20000 40000 60000 80000 100000

0,0

2,0x10-7

4,0x10-7

6,0x10-7

8,0x10-7

1,0x10-6

Vd=7.0e-10 cm/s

Vd=7.0e-9 cm/s

Vd=7.0e-8 cm/s

Vd=7.0e-7 cm/s

Vd=7.0e-6 cm/s

Co

nce

ntr

atio

n, B

q/c

m3

Time, years

Figure 9–163 137Cs concentration Figure 9–164 129I concentration



Page 225 of 253

0 20000 40000 60000 80000 100000

0,00E+000

5,00E-010

1,00E-009

1,50E-009

2,00E-009

Co

nce

ntr

atio

n, B

q/c

m3

Time, years

Vd=7.0e-10 cm/s

Vd=7.0e-9 cm/s

Vd=7.0e-8 cm/s

Vd=7.0e-7 cm/s

Vd=7.0e-6 cm/s

Figure 9–165 59Ni concentration

9.9.6.2.1.5. Material diffusion coefficient

No reference values for the coefficients are available.

The referent coefficient used in the base model is 1.0E-6 cm/s.

Values selected for analysis are 1.0E-7 m/s and 1.0E-5 m/s.

Calculations are performed for 59Ni, 36Cl and 129I.

0 20000 40000 60000 80000 100000

0,0

1,0x10-7

2,0x10-7

3,0x10-7

4,0x10-7

5,0x10-7

6,0x10-7

7,0x10-7

8,0x10-7

Diffusion 1.0e-7 cm2/s



Co

cn

en

tra

tio

n, B

q/c

m3

Time, years

0 3000 6000 9000 12000 15000

0,0

1,0x10-5

2,0x10-5

3,0x10-5

4,0x10-5

5,0x10-5




Co

cn

en

tra

tio

n, B

q/c

m3

Time, years

Figure 9–166 129I concentration Figure 9–167 36Cl concentration



Page 226 of 253

0 20000 40000 60000 80000 100000

0,00E+000

2,00E-010

4,00E-010

6,00E-010

8,00E-010

1,00E-009

Co

cn

en

tra

tio

n B

q/c

m3

Time, years




Figure 9–168 59Ni concentration

9.9.6.2.2. HYDRUS


Red clay

For the red clay layer comparative sensitivity calculations are performed for 3H.

Results for the differences in the concerned presented depths contaminant concentrations

are presented in the figures below.

0 200 400 600 800 1000

0,00

0,05

0,10

0,15

0,20

0,25

0,30

Co

nce

ntr

atio

n, B

q/m

3

Time, years

2 m - Red clay

2 m - Silty loess

0 200 400 600 800 1000

-5,0x10-6

0,0

5,0x10-6

1,0x10-5

1,5x10-5

2,0x10-5

2,5x10-5

3,0x10-5

3,5x10-5

4,0x10-5

Co

nce

ntr

atio

n, B

q/m

3

Time, years

10 m - Red clay

10 m - Silty loess

Figure 9–169 3H concentration – 2 m Figure 9–170 3H concentration – 10 m

Fossilized loess

For the fossilized loess layer comparative sensitivity calculations are performed only for one of

the long life isotopes – 14C.

Results for the differences in the unsaturated-saturated boundary zone contaminant

concentrations are presented in the figures below.



Page 227 of 253

0 10000 20000 30000 40000 50000 60000 70000

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

22000

24000

26000

28000

30000

32000

34000

36000

Co

nce

ntr

atio

n [B

q/m

3]

Time [years]

Fossilized Loess

Upper clayey loess

10000 12000 14000 16000 18000 20000 22000

27000

28000

29000

30000

31000

32000

33000

34000

35000

Co

nce

ntr

atio

n [B

q/m

3]

Time [years]

Fossilized Loess

Upper clayey loess

Figure 9–171 - 14C concentration Figure 9–172 - 14C concentration – peak zoom in


The C-14 concentration in the unsaturated-saturated zone boundary in case of one meter

sand above the red clay layer is compared with the C-14 concentration in the unsaturated-

saturated zone boundary obtained at p. 9.8.3.2.1.

0 20000 40000 60000 80000 100000

0

2000

4000

6000

8000

10000

12000

Co

nce

ntr

atio

n [B

q/m

3]

t [years]

Sand

No sand

Figure 9-173 Comparison of C-14 concentration

The comparison of the results shows a negligible effect of the existence of sand on the C-14

concentration in the unsaturated – saturated zone boundary – 11300 Bq/m3 in the case

without sand and 11400 Bq/m3 in the case with sand.

12000 14000 16000 18000 20000 22000 24000

10000

10200

10400

10600

10800

11000

11200

11400

11600

Co

nce

ntr

atio

n [B

q/m

3]

t [years]

Sand

No sand



Page 228 of 253

Figure 9-174 C-14 Volumetric activity distribution in lateral and transversal direction, considering

one meter of sand (2D model)

In Figure 9-174 is shown that the C-14 concentration in lateral direction decreases strongly and

the concentration is negligible at 30m from the repository (this is the modeled lateral distance

from the repository). The concentration at this distance is not higher than 5Bq/m3 and the limit

concentration in the drinking water for C-14 according to [35] is 230 Bq/L (2.3E+05Bq/ m3).

9.9.6.2.3. PORFLOW

Calculations are performed for tritium contamination only.

Calculation time is 900 years.

The figures below present the 3H concentrations for the nodes with maximum contaminant

concentration, in this case – the nodes located at a distance of 25 m from the repository, at

1m depth in the saturated zone.

0 200 400 600 800 1000

0,00E+000

2,00E-009

4,00E-009

6,00E-009

8,00E-009

Co

nce

ntr

atio

n, B

q/m

3

Time, years

Clay eff. porosity = 0.10



Figure 9–175 3H concentration dependence on clay effective porosity



Page 229 of 253

0 200 400 600 800 1000

0,00E+000

1,00E-009

2,00E-009

3,00E-009

4,00E-009

5,00E-009

6,00E-009

7,00E-009

8,00E-009

9,00E-009

Co

nce

ntr

atio

n, B

q/m

3

Time, years

Darcy flow = 1E-9 m/s



Figure 9–176 3H concentration dependence on Darcy flow

9.9.6.2.4. RESRAD

The figures present the sensitivity of the dose rate (all nuclides, all pathways summed) towards

the concerned selected parameters.

0 20000 40000 60000 80000 100000

0,00

0,02

0,04

0,06

0,08

0,10

0,12

0,14

Do

se

ra

te (

mS

v/y

)

Time (Years)

FGNLV-100 kg/y

FGNLV-160 kg/y

FGNLV-200 kg/y

Figure 9–177 Dose rate dependence on “Fruits, grains and non leafy vegetables” consumption



Page 230 of 253

0 20000 40000 60000 80000 100000

0,00

0,02

0,04

0,06

0,08

0,10

0,12

0,14

Do

se

ra

te (

mS

v/y

)

Time (Years)

WIng = 400 l/y

WIng = 510 l/y

WIng = 730 l/y

Figure 9–178 Dose rate dependence on “Water Ingestion”

9.9.6.2.5. MERCURAD

The scene of the model is presented below.

The scene represents the visual inspection of the galleries bellow the repository cells.

Conservatively is assumed (in the reference scenario) that the cells are completely filled with

spent filters.

Figure 9–179 MERCURAD scene for calculations

9.9.6.3. Calculations summary

In this chapter the results from the sensitivity study are summarized.

Operator

1m

Foundation slab



Page 231 of 253

9.9.6.3.1. DUST-MS

The summary of the sensitivity of DUST-MS post-closure model to changes in the input data is


Analysis of the Results:

1) The sensitivity of most results of input parameters’ deviations is small;

2) Significant sensitivity is observed only in two cases (1.2 for 137Cs dependence on water flow

and 1.1 for 90Sr dependence on waste density);

3) Strong sensitivity (5.9) is observed for 14C in “minimum” case only. However, the sensitivity is

negative and leads to decrease of 14C concentration;

4) All cases (except for 14C dependence on minimum deviation of water flow) are covered

by sufficient margin by the initial assumption for 1.5 times increase of the actual waste

activity;

Table 9-48 - DUST-MS sensitivity study summary for the post-closure period

Input parameter /

Nuclides

Min Max Ref dMin=|

Min-

Ref|/Ref

dMax=|M

ax-

Ref|/Ref

Sensitivity

(Min)

Sensitivit

y (Max)

Moisture content, % 5 40 20 7.50E-01 1.00E+00 dMinRez/

dMinInp

dMaxRe

z/dMaxI

np

14-C 5.77E-02 5.80E-02 5.78E-02 1.70E-03 3.50E-03 2.30E-03 3.50E-03

60-Co 1.06E-19 3.43E-20 9.24E-20 1.50E-01 6.30E-01 2.00E-01 6.30E-01

137-Cs 9.18E-04 4.95E-05 6.79E-04 3.50E-01 9.30E-01 4.70E-01 9.30E-01

Density of waste,

g/cm3

1.5 1.9 1.7 1.20E-01 1.20E-01 dMinRez/

dMinInp

dMaxRe

z/dMaxI

np

90-Sr: 2.67E-10 2.13E-10 2.37E-10 1.30E-01 1.00E-01 1.10E+00 8.60E-01

36-Cl: 5.05E-05 4.72E-05 4.88E-05 3.50E-02 3.30E-02 3.00E-01 2.80E-01

Density of concrete

slab, g/cm3

2.10E+00 2.50E+00 2.30E+00 8.70E-02 8.70E-02 dMinRez/

dMinInp

dMaxRe

z/dMaxI

np

14-C: 6.17E-02 5.44E-02 5.78E-02 6.70E-02 5.90E-02 7.80E-01 6.80E-01

137-Cs: 6.88E-04 6.70E-04 6.79E-04 1.30E-02 1.30E-02 1.50E-01 1.50E-01

Water debit, cm/s

(logarithmic):

dMin=abs[(logMin-

logRef)/logRef]

dMax=abs[(logMax-

logRef)/logRef]

7.00E-10 7.00E-06 7.00E-08 2.80E-01 2.80E-01 dMinRez/

dMinInp

dMaxRe

z/dMaxI

np

14-C: 5.31E-04 5.56E-02 5.78E-02 1.60E+00 1.40E-02 5.90E+00 4.90E-02

36-Cl: 2.90E-04 4.37E-06 4.88E-05 1.80E-01 2.40E-01 6.40E-01 8.70E-01

137-Cs: 6.21E-05 1.12E-04 6.79E-04 3.30E-01 2.50E-01 1.20E+00 8.80E-01

129-I: 2.92E-07 7.27E-08 7.11E-07 6.30E-02 1.60E-01 2.20E-01 5.80E-01

59-Ni: 9.06E-10 1.11E-10 9.36E-10 1.60E-03 1.00E-01 5.60E-03 3.70E-01

Material diffusion

coefficient, cm2/s

(logarithmic sensitivity)

1.00E-07 1.00E-05 1.00E-06 1.70E-01 1.70E-01 dMinRez/

dMinInp

dMaxRe

z/dMaxI

np

129-I: 7.14E-07 6.78E-07 7.11E-07 3.00E-04 3.40E-03 1.80E-03 2.00E-02

36-Cl: 4.91E-05 4.61E-05 4.88E-05 6.20E-04 5.70E-03 3.70E-03 3.40E-02

59-Ni: 9.42E-10 8.80E-10 9.36E-10 3.10E-04 3.00E-03 1.80E-03 1.80E-02



Page 232 of 253

dMin(Max)Inp – Difference between the “minimum” (“maximum”) and the reference cases

input data;

dMin(Max)Rez – Difference between the calculation results in “minimum” (“maximum”) and

“reference” cases;

Qualitative sensitivity is: small (ΔResult /ΔInput < 0.5), significant (0.5 < ΔResult /ΔInput < 1.5) or

strong (ΔResult /ΔInput > 1.5).

The following sensitivity evaluation method is applied to the minimum and maximum input

values:

ref.

sensref

Result

ResultResult=ΔResult

,

ref

sensref

Input

InputInput=ΔInput

.

The logarithms of Input/Result values are used when input is changed by orders of magnitude.

9.9.6.3.2. HYDRUS

HYDRUS model sensitivity study is summarized below, depending on changed soil types.

As the change of the soil type is related to changes of more than one parameter, the

parameter with maximum deviation and expectedly high influence on the contaminants’

concentration results is selected for the sensitivity evaluation.


Red Clay

In Table 9-49 is presented the comparison of the results from the calculations with the HYDRUS

reference model and the first “sensitivity” model, in which the first model layer is changed to

red clay.

In this case – the sensitivity parameter selected is the residual porosity. Its relative deviation is

98.5 % and the contaminant concentration depends on it proportionally – see the formula in p.

Error! Reference source not found. – residual porosity is presented indirectly as a part of the

“volumetric water content – θ”.

Table 9-49 – Summary of HYDRUS sensitivity study – Silty loess replacement

Unit Soil Type Parameter

rel. deviation

Qualitative

Sensitivity Red clay Silty loess

Density g/cm3 1.760E+00 1.540E+00 1.429E-01 -

Residual porosity, θr - 1.000E-03 6.700E-02 9.851E-01 -

Saturated water content, θs - 4.300E-01 3.700E-01 1.622E-01 -

Saturated hydraulic

conductivity, Ks

cm/s 5.000E-06 1.000E-04 9.500E-01 -

m/year 1.578E+00 3.156E+01 9.500E-01 -

Max. 3H concentration – 2 m Bq/m3 6.398E-02 2.937E-01 7.822E-01 7.941E-01

Max. 3H concentration – 10 m Bq/m3 1.835E-05 3.848E-05 5.231E-01 5.310E-01



..Re

...Re..Re.

Scf

ScSensScf

a

aaDevlPar



Page 233 of 253

DevParInpMax

DevConcetrHMax

...

...y Sensitivit

3

Fossilized loess

In Table 9-50 is presented the evaluation of HYDRUS model sensitivity to changes in the second

natural layer.

The reference layer of Upper Clayed loess is replaced by Fossilized loess.

In this case – the sensitivity parameter selected is the saturated hydraulic conductivity. Its

relative deviation is 62.5 % and, again, as in the previous case, the contaminants’

concentration depends on it proportionally.

Table 9-50– Summary of HYDRUS sensitivity study – Upper clayed loess replacement


rel. deviation

Qualitative

Sensitivity Fossilized

loess

Upper

Clayed

loess

Density g/cm3 1.780E+00 1.570E+00 1.338E-01 -



Saturated hydraulic

conductivity, Ks

cm/s 7.510E-06 2.000E-05 6.245E-01 -

m/year 2.367E+00 6.312E+00 6.250E-01 -

Max. 14C concentration at

the unsaturated-saturated

zone boundary

Bq/m3 3.27E+4 3.39E+4 3.540E-02 5.664E-02



..Re

...Re..Re.

Scf

ScSensScf

a

aaDevlPar

DevParInpMax

DevConcetrHMax

...

...y Sensitivit

3


In Table 9-51 is presented the evaluation of HYDRUS model sensitivity considering a sand level

above the red clay of Saligny site unsaturated zone.

In this case – the sensitivity parameter selected is the residual porosity. Its relative deviation is

98.5 % and the contaminants’ concentration depends on it proportionally – see the formula at

p. 9.8.3.2.3.1 – residual porosity is presented indirectly as a part of the “volumetric water

content – θ”.



Page 234 of 253

Table 9-51 – Summary of HYDRUS sensitivity study – Silty loess replacement


rel. deviation

Qualitative

Sensitivity Red clay Sand

(assumed

as Silty

loess)

Density g/cm3 1.760E+00 1.540E+00 1.429E-01 -



Saturated hydraulic

conductivity, Ks

cm/s 5.000E-06 1.000E-04 9.500E-01 -

m/year 1.578E+00 3.156E+01 9.500E-01 -

Max. 14C concentration –

unsat.-sat. zone boundary

Bq/m3 11300 11400 8.85E-03 8.98E-03



..Re

...Re..Re.

Scf

ScSensScf

a

aaDevlPar

DevParInpMax

DevConcetrHMax

...

...y Sensitivit

3

9.9.6.3.2.3. Summary of the results from HYDRUS sensitivity study

The results summarized in Table 9-49, Table 9-50 and Table 9-51 show that:

1) HYDRUS model has significant sensitivity (between 0.5 and 1.5) to changes in the first

layer of the model and small sensitivity (<0.5) to changes in the second layer of the

model , as well as in the model when one meter of the red clay layer is replaced with

sand;

2) The selected layer configuration in the first two models is conservative – the results

achieved give higher concentration values than the sensitivity ones. The existence of

the sand layer instead of red clay increases the radionuclides’ concentration in the

unsaturated – saturated zone boundary.

3) The sensitivity of the model does not exceed the 1.5 boundary defined by the

conservative repository inventory.

9.9.6.3.3. PORFLOW

In Table 9-52 is presented the summary of the sensitivity study performed for PORFLOW code

for the reference post-closure scenario model.

Analysis of the results:

1) The model sensitivity to the selected parameters is small, except for one of the sensitivity

cases – maximum clay effective porosity, where the sensitivity is significant;

2) If the sensitivity is significant – the result deviation is negative, the contaminants’

concentration decreasing;



Page 235 of 253

3) All sensitivity study results are covered by the 1.5 margin defined by the conservative

increase of the repository radionuclide inventory;

Table 9-52 – Summary of PORFLOW sensitivity study results

Input parameter /

Nuclides

Min Max Ref dMin=|Min

-Ref|/Ref

dMax=|

Max-

Ref|/Ref

Sensitiv

ity

(Min)

Sensitivit

y (Max)

Clay eff. Porosity, % 0.10 0.30 0.17 4.1E-01 7.6E-01 dMinR

ez/dMi

nInp

dMaxRe

z/dMaxI

np 3H Concentration,

Bq/m3

7.64E-9 6.68E-9 7.26E-9 5.2E-02 8.0E-02 1.3E-01 1.5E+00

Darcy flow, m/s 1.0E-9 1.0E-7 1.0E-8 9.0E-01 9.0E+00 dMinR

ez/dMi

nInp

dMaxRe

z/dMaxI

np 3H Concentration,

Bq/m3,

3.54E-9 8.14E-9 7.26E-9 5.1E-01 1.2E-01 5.7E-01 1.3E-02

dMin(Max)Inp – Difference between the “minimum” (“maximum”) and the reference cases

input data;

dMin(Max)Rez – Difference between the calculation results in “minimum” (“maximum”) and

“reference” cases;



The following sensitivity evaluation method is applied to the minimum and maximum input

values:

ref.

sensref

Result

ResultResult=ΔResult

,

ref

sensref

Input

InputInput=ΔInput

.

9.9.6.3.4. RESRAD

In Table 9-53 are presented the results from RESRAD model sensitivity study evaluation.

Presented dose rates are for all nuclides, for all pathways summed.

Analysis of the results:

1) In only one of the studied cases the qualitative sensitivity of the model is significant

(between 0.5 and 1.5) – in case of the minimum FGNLV consumption;

2) In all other cases the model sensitivity is small, for dependence on water ingestion

model – even negligible;

3) In case of the highest sensitivity – it is observed when the FGNLV consumption is

decreased, as well as the scenario resultant dose rate;

4) The model sensitivity is covered by the conservative increase of the repository inventory

by 1.5 times.



Page 236 of 253

Table 9-53 – Sensitivity study results for the post-closure reference scenario RESRAD model

Input parameter / Dose

rate

Min Max Ref dMin=|Min

-Ref|/Ref

dMax=|

Max-

Ref|/Ref

Sensitiv

ity

(Min)

Sensitivit

y (Max)

Fruits, grains and non

leafy vegetables

(FGNLV), kg/y

100 200 160 3.8E-01 2.5E-01 dMinR

ez/dMi

nInp

dMaxRe

z/dMaxI

np

Dose rate, mSv/y 8.47E-

02

1.38E-

01

1.17E-

01

2.7E-01 1.8E-01 7.3E-01 4.9E-01

Water Ingestion, l/y 400 730 510 2.2E-01 4.3E-01 dMinR

ez/dMi

nInp

dMaxRe

z/dMaxI

np

Dose rate, mSv/y 1.17E-

01

1.17E-

01

1.17E-

01

1.2E-03 2.4E-03 5.6E-03 5.6E-03

Qualitative sensitivity is: small (ΔResult /ΔInput < 0.5), significant (ΔResult /ΔInput < 1.5) or


9.9.6.3.5. MERCURAD

The summary of MERCURAD model sensitivity to changes in the input data for the first post-

closure period is presented in Table 9-54.

Analysis of the Results:

1) MERCURAD model for the reference scenario has significant sensitivity to changes in the

density of wastes;

2) The sensitivity changes are in reverse direction – when density is decreased, the dose is

increased. This effect is due to the self-absorption in the waste – when the density is

decreased, self-absorption also decreases and respectively – the dose increases.

Table 9-54 MERCURAD sensitivity study summary for the operational period

Parameter Min Max Ref dMin=|Mi

n-

Ref|/Ref

dMax=|M

ax-

Ref|/Ref

Sensitivit

y (Min)

Sensitivi

ty

(Max)

Density of spent

filters, g/cm3

1.00 2.00 1.40 2.9E-01 4.3E-01 dMinRez

/dMinIn

p

dMinRe

z/dMinI

np

Dose, µSv/h 1.11E-03 5.87E-04 8.21E-04 3.5E-01 2.9E-01 1.2E+00 6.7E-01

Density of

concrete slab,

g/cm3

1.50 3.00 2.30 3.5E-01 3.0E-01 dMinRez

/dMinIn

p

dMinRe

z/dMinI

np

Dose, µSv/h 9.768E-

04

8.216E-

04

8.21E-04 1.9E-01 7.3E-04 5.5E-01 2.4E-03



9.9.6.4. SENSITIVITY STUDY – REVIEW AND CONCLUSIONS

Based on the performed calculations, the sensitivity of the models, used in the computer

codes for the safety assessment, is the following:



Page 237 of 253

9.9.6.4.1. DUST-MS

DUST-MS model for the post-closure period has significant sensitivity to changes in the following

parameters:

1) Moisture Content – in two of the considered cases (maximum deviation for 60Co and 137Cs) the sensitivity is higher than 0.5. However, the sensitivity is not proportional – the

parameter increase leads to contaminants’ concentration decrease.

2) Waste density – for the calculation of 90Sr contamination the qualitative sensitivity in

both cases is higher than 0.5. This is partially valid for the long life isotope, represented

in the calculations by 36Cl, but in a lower degree due to its lower transport

coefficients.

3) Density of concrete slab – for 14C the sensitivity is significant mostly due to its

interaction with concrete elements, represented by the carbon transport parameters

for concrete.

4) Water (Darcy) flow – for 36Cl concentration evaluation, the water flow base model

causes higher contamination compared to the base model calculation results. For

the rest of the long life isotopes included in the study the effect has variable intensity

depending on their transport coefficients.

5) Material diffusion coefficient – the DUST-MS model is not sensitive to changes in this

parameter.

Except for one case, the significant model sensitivities are covered by the initial conservative

assumption for the increase of inventory by 1.5 times.

If it is not covered by this margin the sensitivity result is lower than the reference model result.

9.9.6.4.2. HYDRUS

The performed sensitivity study shows that HYDRUS model is not sensitive to soil changes in the

second natural layer and to the replacement of one meter of the red clay layer with sand

(sand assumed to have the same properties as silty loess).

Changes in the first layer of the model causes significant changes in the final result for

contaminant concentration, but the study proved that the current model reference involves

conservative configuration.

All considered model uncertainties are covered by the conservative margin defined by the

repository inventory increase by 1.5 times.

9.9.6.4.3. PORFLOW

The post-closure period reference PORFLOW model is significantly sensitive to changes in the

clay effective porosity.

The significant sensitivity to clay effective porosity changes is observed only if the parameter

increases. In the other case – the sensitivity is small.

Even if the model is sensitive to this parameter – its increase leads to contaminant

concentration decrease.

PORFLOW model has small sensitivity to changes in Darcy flow.

PORFLOW model sensitivity is covered by the defined conservative margin.



Page 238 of 253

9.9.6.4.4. RESRAD

RESRAD reference model has very low, practically no sensitivity to the quantity of water

consumed by the population.

The model has significant sensitivity to the quantity of fruits, grains and non leafy vegetables

(FGNLV) consumed in the minimum parameter deviation case only.

The dependence of the final result for the calculated dose rate in this case is direct – when the

FGNLV consumption decreases – the dose rate also decreases.

The model sensitivity is again covered by the 1.5 margin defined by the conservative inventory

increase.

9.9.6.4.5. MERCURAD

As expected, MERCURAD model has significant sensitivity to radioactive waste density, in this

case – conservatively represented by spent filters.

The sensitivity is especially observed when the waste density is decreased – this leads to the

decrease of gamma-radiation self-absorption in the source and respectively to high source

activity.

The model has small sensitivity to changes in the density of concrete slab, as its thickness is of 1

m and not even a change in density of more than 30 % density modification percent has any

strong influence on the dose rate at detector’s position.

The model sensitivity is covered by the defined conservative margin.

9.10. CONCLUSIONS

Chapter 9 presents the safety assessment for the post-closure period. The following main steps

of the methodology for the safety assessment are presented in detail in this chapter:

Elaboration of the list of features, events and processes (FEPs) for the post-closure period;

Development and justification of the reference and alternative scenarios;

Development of physical models for the reference and alternative scenarios;

Development of the models for the source term, unsaturated zone, saturated zones and

environment;

Calculations of the doses for the workers and public for the reference and alternative

scenarios;

Sensitivity and Uncertainty analysis;

Comparison of the results to the safety criteria.

The methodology of post-closure safety assessment is based on the Safety Assessment

Methodologies for Near Surface Disposal Facilities [10] and on the Romanian norm NDR-05 [3],

considering the recommendations from IAEA missions [5] and [5], IAEA documents [8] –[13] as

well as the French experience [39].

According to the requirements of the Technical specification [1] and considering the

international practice, separate models for the source term, unsaturated zone, saturated zone

and environment are developed.

For more detailed modeling of the processes the post-closure period is sub-divided in three

periods:



Page 239 of 253

Active institutional control period;

Passive institutional control period;

Post-closure period after 300 years.

The source term for the post-closure period is modeled and calculated by using DUST MS

code.

The models of the source term for the active and passive institutional control periods are the

same as for the operational period:

“DUST MS diffusion” model for the reference scenario:

o Active control - Control of the collecting system gallery;

o Passive control - Consumption and use of groundwater in a small farm

outside of the facility considering the indirect irradiation of the population.

“DUST MS diffusion” model with time increasing Water velocity for alternative scenarios:

o Active control -2) „Failure of the foundation slab”

o Passive control - 1) Failure of the roof closure system

2) Failure of the foundation slab

The following source term model is developed for the post-closure period after 300 years:

“DUST MS CBF-K break“ model - presents CBF-K container break in year 300, which is the

limiting conditions for the post-closure period.

This model is developed for the following scenarios:

o Reference scenario “Consumption and use of groundwater in a small farm

onside of the facility”;

o Alternative scenarios:

- 1) Farm on the repository - Residence scenario on totally degraded waste;

- 3) Geologist intrusion;

The concentrations in the foundation slabs of the repository for the post-closure period are

presented as a peak concentration for each considered radionuclide. These concentrations

are below the limits of the contaminants in the drinking water according to [35].

The unsaturated zone models are developed by using HYDRUS code. The models of

unsaturated zone present the radionuclide transport through the unsaturated zone.

The results obtained by DUST-MS are used as boundary volumetric activity in HYDRUS models.

The following models of the unsaturated zone for the post-closure period are applied:

• 2D model:

considers the repository area +lateral area of 30m

applied for modeling the lateral radionuclide transport

• 3D model:

considers the repository area

applied for modeling of the vertical radionuclide transport

The volumetric activity of all the radionuclides except for H-3 in the unsaturated-saturated

zone boundary beneath the repository will be zero during the active control period and the



Page 240 of 253

passive control period. The maximum volumetric activity in the lateral point of the repository

appears approximately 200 year (reference scenario) and respectively 300 years (alternative

scenarios) after the beginning of repository operation. The maximum volumetric activity in the

central point is at further stage because of the low infiltration in the first 300 years.

The results from HYDRUS calculations for the post-closure period after 300 years show that the

radionuclides reaching the unsaturated – saturated zone boundary are as follows:

Sr-90;

C-14;

H-3;

I-129;

Ni-59

Cl-36

For this period the maximum H-3 volumetric activity in the lateral point is higher than in the

central point of the repository unsaturated-saturated boundary. The reason for this is the higher

infiltration rate in the lateral region and the zero distribution coefficient of H-3. For the

radionuclides with non-zero distribution coefficients the volumetric activity in the lateral point is

lower than in the central point of the repository unsaturated-saturated boundary.

The concentrations of radionuclides in the unsaturated-saturated boundary are below the

limits of the contaminants in the drinking water according to [35].

The saturated zone model is developed and calculated by using PORFLOW code. The

boundary conditions are according to HYDRUS results.

The resulting concentrations of tritium for the active and passive institutional control periods

are much lower than the limits for drinking water of 7600 Bq/l which are established by the

Bulgarian Regulation on basic radiation protection norms [35].

For the post-closure period after 300 years the following observations are made:

the concentrations for all isotopes are decreasing in more distant nodes from contact

area between saturated and unsaturated zones.

Sr-90 concentration on distances of 1400 meters and 300 meters is zero for the entire

simulation period of 5000 years;

for 129I and 14C the peak concentrations at supposed Danube side are close to 1.0E-12

Bq/m3 and 3.0E-15 Bq/m3 respectively. This is the concentration in the Berriasian aquifer;

the effect of time dependence of carbon peak concentrations for distant nodes’ groups

is due to the high value of the distribution coefficient Kd for 14C for pre-quaternary clay;

the effect of time dependence of iodine peak concentration for distant nodes’ groups is

not so strong as the same effect observed for 14C. The smaller effect is due to the low

value of the distribution coefficient Kd for iodine for Aptian clay and Berriasian lime;

the tritium distributes at large distances through the aquifer /1400m and 300m/ due to its

extremely low distribution coefficient for Aptian clay and for Berriasian aquifer;

short tritium half-life leads to a fast decreasing of the tritium concentrations.

Ni-59 concentration in all nodes is increasing during the period of 140 000 years.

The Cl-36 concentration at 1400 m distance is very low – 2.5E-11 Bq/m3. The concentration

at 25 m distance is one order of magnitude lower than the concentration beneath the



Page 241 of 253

repository. The Cl-36 coefficients are close to the Iodine parameters as well as the

distribution of Cl-36 within the saturated zone.

The resulting concentrations of radionuclides for the post-closure period are lower than the

limits for drinking water established in the Bulgarian Regulation on basic radiation protection

norms [35].

The doses for the personnel and the populations for the active institutional control are

calculated by using MERCURAD code.

RESRAD code is used for calculating the dose for the population and for analyzing the

environment impact in the alternative scenarios of the post-closure period. The calculated

doses for the population for the reference and alternative scenarios are lower than the dose

constraint of 0.3 mSv/year. The results from the environment impact analysis are presented as

concentration of radionuclides in milk, meat, water, plants. The concentration of radionuclides

in the well water is below the limits established by the Bulgarian Regulation on basic radiation

protection norms [35].

The calculations with DUST MS, HYDRUS, PORFLOW, RESRAD are made with conservative

models according to the international practice with the purpose to cover the uncertainties in

the input data.

Input data uncertainties are applied in conservative direction by engineering judgment with

consideration of recommendations by the concerned computer code developers.

The safety assessment calculations for the post-closure period are performed at the end of

2009. The data from the site characterization at this stage were preliminary and incomplete.

The calculations with HYDRUS, PORFLOW and RESRAD model are performed by applying the

data from the site characterization available until the end of 2009 [21], [28].

The site characterization process was completed in 2010 after the completion of the safety

assessment. The new data regarding the site parameters are presented in [7].

The verification of the parameters regarding the soil hydraulic properties in the unsaturated

and saturated zones against those obtained during the final stage of site characterization

(2010) was performed in order to evaluate the differences in parameters’ values.

The unsaturated zone 3D HYDRUS model was created as a seven layers model according to

the site characterization data of 2009 phase [28]. Due to fact that the site characterization

data in 2010 phase supposed the unification of several layers, a 2D HYDRUS model has been

created considering the complete data from the site characterization in 2010 phase [7] and

[51].

The differences between the values used for HYDRUS calculations are really small and

according to performed sensitivity study presented in Section 9.9 there are no significant

differences in resulting concentrations of radionuclides which may reach the unsaturated-

saturated zone boundary of the site, being evaluated by means of the two sets of input data.

The results presenting the radionuclides’ concentration in the unsaturated – saturated zone

boundary confirm that the hydro-geological data from [28] are more conservative than the

hydro-geological data from [7] and [51].

Due to this reason, conservatively, the results calculated by using the model including the

hydro-geological data from [28] are assumed to be representative for the radionuclides’

concentration in the unsaturated-saturated zone boundary.

The calculations with PORFLOW are made by implementing the available updated data

according to [7] towards the data existing in 2009 (document [28]). The changes identified



Page 242 of 253

during the comparison of the parameters by characterizing the saturated zone (from [7] and

[28]) are as follows:

• Two layers representing saturation zone – Aptian clay and Berriasian aquifer are united in

one layer called Aptian deposits;

• Document [7] includes updated values for the following parameters:

o Density;

o Hydraulic conductivity;

o Total porosity;

o Effective porosity.

During preparation of the safety assessment a sensitivity analysis with PORFLOW has been

performed for the parameters listed above plus one additional parameter - Darcy flow. The

results from the sensitivity study clearly show that there are no differences in the results for all

parameters that have varied considering the changed values of the following parameters:

• Density;

• Total porosity;

• Hydraulic conductivity.

The results are different if the changed values of the following parameters are considered:

• Effective porosity;

• Darcy flow.

The results from sensitivity study are presented at point 9.9.6.3.3.

The following table presents the results related to different input values of both parameters –

effective porosity and Darcy flow:

Input parameter /

Nuclides

Min Max Ref dMin=|Mi

n-

Ref|/Ref

dMax=|

Max-

Ref|/Re

f

Sensitivit

y (Min)

Sensitivity

(Max)

Clay eff. Porosity, % 0.10 0.30 0.17 4.1E-01 7.6E-01 dMinRez

/dMinIn

p

dMaxRez/

dMaxInp

3H Concentration,

Bq/m3

7.64E-9 6.68E-

9

7.26E-9 5.2E-02 8.0E-02 1.3E-01 1.5E+00

Darcy flow, m/s 1.0E-9 1.0E-7 1.0E-8 9.0E-01 9.0E+00 dMinRez

/dMinIn

p

dMaxRez/

dMaxInp

3H Concentration,

Bq/m3,

3.54E-9 8.14E-

9

7.26E-9 5.1E-01 1.2E-01 5.7E-01 1.3E-02

The resulting concentrations have the same order of magnitude even if in case of Darcy flow

there is a difference of 2 orders of magnitude.

Therefore, the most important parameters leading to changing of the final results remain Kd

and half-time. These two parameters are not changed in the new set of data [7].

Considering the performed sensitivity analysis new calculations with HYDRUS and PORFLOW

model are not necessary.



Page 243 of 253

Table 9-55 presents the summary of the calculated doses for the workers (operators) and for

the members of the population for the active institutional control period.

Table 9-55 Calculated doses for the active institutional period

Scenarios Doses for the operators

performing the control

Doses for the

population

Reference scenario

1. For the operators - direct exposure to

gamma radiation of staff performing the

control of the monitoring water tanks in

the collecting system gallery

1m – 1.92 E-04 mSv/y

(234h – 9galleries)

N.A.

2. For the critical group – Consumption and

use of groundwater in a small farm

outside of the facility considering the

indirect irradiation of the population

N.A. Negligible doses

Alternative scenarios

1. Failure of the roof closure system.


1m – 1.27E-05 mSv/ 8h Negligible doses

3. Failure of the drainage 0.05m – 5.23E-04

mSv/8h

1m – 4.94E-04 mSv/8h

Negligible doses

Table 9-56 presents the summary of the calculated doses for one member of the population

for the passive institutional control period.

Table 9-56 Calculated doses for the passive institutional period

Scenarios Doses for the population

Reference scenario

1. For the critical group –

Consumption and use of

groundwater in a small farm

outside of the facility considering

the indirect irradiation of the

population

Negligible doses


1. Failure of roof closure system


H-3 – max 6.7E-16mSv/y

future generation max. dose in year 2159 – 3.5E-08

mSv/y

C-14 – 7.0E-03 mSv/y

3. Cell bath tubing effect 9.21E-02 mSv/y

Table 9-57 presents the summary of the calculated doses for one member of the population

for the post-closure period after 300 years.

Table 9-57 Calculated doses for the post-closure period after 300 year




Page 244 of 253


Reference scenario

1. For the critical group – Consumption

and use of groundwater in a small

farm onsite of the facility

1.7E-04 mSv/y –construction of the farm

0.12 mSv/y – residence, consumption of

water and food in the farm [RESRAD]


1. Farm on repository site - Residence

scenario on totally degraded waste

repository (disposal facility disruption)

C-14 – 0.26 mSv/y [36]

I-129 – 3.58-03 mSv/y [36]

2. Archaeological investigation of the

site

a) 3.75 E-02 mSv/y [36]

b) 0.12 mSv/y [RESRAD]

3. Geologist intrusion 1.02E-02 mSv/y [36]{MERCURAD}

4. Road construction 1.61E-02 mSv/y [36]

The chapter also includes the comparison of the doses calculated with the acceptance

criteria (safety indicators) presented at p. 9. 2 of this chapter.

The comparison resulted into the fact that the calculated doses for the reference scenario

and alternative scenarios for the workers and population for the post-closure period are below

the established dose constraints.

A total of 13 scenarios have been exhaustively studied by implementation of different

computer codes and analytical models.

Significant margins of conservatism are introduced in all modeling assumptions in order to

cover the uncertainty of input data and calculations.

All studies are performed in compliance with the Romanian legislation, considering French

experience and IAEA recommendations.

The repository design assures the safety of operators, population and environment with

sufficient margin, which covers possible uncertainties of input data and calculations.



Page 245 of 253

9.11. REFERENCES

[1] Technical specification for Support to ANDRAD to get the siting license for Saligny LILW

near surface repository PHARE RO 2006/018-147.05.01

[2] License for the development of nuclear activities no. DFDSMA_ANDRAD_01/2008 by

which CNCAN partially authorizes ANDRAD to place DFDSMA in Saligny, Constanta

county

[3] Norms regarding the near-surface disposal of the radioactive wastes (NDR-05) approved

by the CNCAN President’s Decree No. 400/13.12.2005 and published in the Official

Gazette of Romania, Part I No. 345/17.04.2006

[4] Fundamental Norms of Radiological Safety (NSR-01) approved by CNCAN Decree No.

14/24.01.2000 and published in the Official Gazette of Romania No. 404 bis/29.08.2000

[5] Report of Mission WATRP/2006 for verification the Technical and Safety Documentation

necessary for the authorization of the Saligny site for DFDSMA

[6] Report of the Mission of Experts IAEA no. IAEA-TCR-03852 “Assistance and assessment of

the application of siting the radioactive waste disposal facility proposed for the Saligny

site”, January 2008, requested by CNCAN within the IAEA TC Project ROM/9/028

“Technical assistance for the Romanian Regulatory Authority for the Enhancement of the

Regulating Capacity”

[7] Final Assessment report of the Saligny site performance, Reference 1373-02-00018-NT-09-

903

[8] INTERNATIONAL ATOMIC ENERGY AGENCY, Disposal of Radioactive Waste, IAEA, Safety

Standards Series, IAEA, Vienna (draft-DS 354)

[9] IAEA, Safety Standard Series, The safety case and safety assessment for radioactive

waste disposal (draft DS 355), IAEA, Vienna, 2008

[10] Improvement of Safety Assessment Methodologies for Near Surface Disposal Facilities.

Volume I: Review and Enhancement of Safety Assessment Approaches and tools. IAEA-

ISAM-1, Vienna, 2004

[11] Near Surface Disposal of Radioactive Waste, IAEA Safety standards Series No.WS-R-1,

Vienna 1999

[12] Safety Assessment for Near Surface Disposal of Radioactive Waste, IAEA Safety Guide

No. WS-G-1.1, Vienna, 1999

[13] INTERNATIONAL ATOMIC ENERGY AGENCY, Safety Assessment for Facilities and Activities,

IAEA General safety requirements, Part 4, IAEA, Vienna, 2009

[14] Council Directive 96/29/Euratom of 13 May 1996 laying down basic safety standards for

the protection of the health of workers and the general population against the dangers

arising from ionizing radiation

[15] ICRP PUBLICATION 30: LIMITS FOR INTAKES OF RADIONUCLIDES BY WORKERS, PART 3, 30

[16] MERCURAD Dose rate calculation software, User manual, L. Berger, CEA 2003

[17] Porous Materials - The University of Edinburgh, Division of Engineering, Session 2001-2002,

Materials Science and Engineering

[18] IAEA TECDOC 1256, Technical considerations in the design of near surface disposal

facilities for radioactive waste, November 2001



Page 246 of 253

[19] Waste inventory DFDSMA Saligny, 1373 JMM 0200018NT 09348-4, OTGP August 2009

[20] IAEA TECDOC 1255, Performance of engineered barrier materials in near surface disposal

facilities for radioactive waste, November 2001

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of Long-lived Solid Radioactive Waste, 2000

[28] Saligny Data base 08.04.2009

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of Water, Heat, and Multiple Solutes in Variably-Saturated Media, Technical Manual

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Corsi, University of Texas, Austin, Department of Civil Engineering

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Page 247 of 253

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National Laboratory, Argonne, Illinois, April 1993



Page 248 of 253

APPENDIX 9.1 – INTERACTION MATRIXES FOR POST-CLOSURE PERIOD

Interaction matrix for the active control post-closure period (100 years)

Radionuclide transport and human exposure mechanisms

R1 R2 R3 R4 R5 R6 R7 R8 R9 G1 G2 G3 G4 B1 B2 B3 B4 B5 B6 B7 E1

1 Roof

2

Advectio

n,

Diffusion

Waste form

Advectio

n,

Diffusion

3 Containme

nt Drum

Colloid

generatio

n

4

Concrete

Module

Advectio

n,

Diffusion

Advectio

n,

Diffusion

5 Backfillin

g

6 Cell

Advectio

n,

Diffusion

7

Vault

internal

Drainage

Advectio

n,

Diffusion

8

Advectio

n,

Diffusion

9 Supporting Supportin

g

Supportin

g

Supportin

g

Supportin

g

Supportin

g

Supportin

g

Foundatio

n ground

Advection,

Dispersion,

Diffusion,

Mineralizatio

n, Particles

1

0 Diffusion

Silty loess-

L1a

Advection,

Dispersion,

Diffusion,

Mineralizatio

n

Particles

Advection,

Dispersion,

Diffusion,

Mineralizatio

n

Particles

1

1 Diffusion

Clayey

Loess-L1b

Advection,

Dispersion,

Diffusion,

Mineralizatio

n

Particles

1

2 Diffusion Red clay

1

3

Aptian

Deposit

s

Advection,

Dispersion,

Diffusion,

Mineralizatio

n

Particles

Under-

ground

Water flow

Advectio

n,

Diffusion,

Dispersion



Page 249 of 253


1

4

Well

supplied

from Aptian

Deposits

Under-

ground

Water flow

Irrigation Irrigation Drinking

Water

Evaporatio

n

Drinking

Water

1

5

Danube –

Black Sea

Canal

Irrigation Evaporatio

n

External

irradiatio

n, fishing

Advectio

n,

Diffusion,

Dispersion

1

6

Under-

ground

Water flow

Under-

ground

Water flow

Soil Roots

Uptake

Ingestion

,

External

irradiatio

n

Dust raise

Gas

release

Ingestion,

External

irradiatio

n

1

7 Flora Ingestion Ingestion

1

8

Animals

from

farm

Ingestion

1

9

Transpor

t with

rain or

snow

Depositio

n

Inhalatio

n

Atmospher

e

Inhalatio

n

Advectio

n

2

0

Building,

Maintenanc

e

Maintenanc

e

Irrigation

,

Manurin

g

Irrigation,

Soil

manuring

,

Feeding,

Watering HUMAN

2

1 EXTERNAL

During this period the access to the repository area is restricted. No farm will exist on repository. The considered plants and animals will not grow /live/ on the repository but on the area near the repository.

Water infiltration through the modules in excluded because during this period the modules are considered still intact.



Page 250 of 253

Interaction matrix for the passive control post-closure period (200 years)



1 Roof

2

Advec

tion,

Diffusio

n

Waste

form

Advectio

n,

Diffusion

3 Containm

ent Drum

Colloid

generatio

n

4

Concrete

Module

Advectio

n,

Diffusion

Advectio

n,

Diffusion

5 Backfillin

g

6 Cell

Advectio

n,

Diffusion

7

Vault

internal

Drainage

Advecti

on,

Diffusion

8

Depth

drainag

e

Advecti

on,

Diffusion

9 Supportin

g

Supporti

ng

Supportin

g

Supportin

g

Supportin

g

Supportin

g

Supporti

ng

Foundati

on

ground

Advectio

n,

Dispersion

,

Diffusion,

Mineraliza

tion,

Particles

10 Diffusion Silty loess

– L1a

Advectio

n,

Dispersion

,

Diffusion,

Mineraliza

tion

Particles

Advectio

n,

Dispersion

,

Diffusion,

Mineraliza

tion

Particles

11 Diffusion

Clayey

Loess –

L1b

Advectio

n,

Dispersion

,

Diffusion,

Mineraliza

tion

Particles


13 Aptian

Deposits

Advection,

Dispersion,

Under-

ground

Advection,

Diffusion,



Page 251 of 253


Diffusion,

Mineralizati

on

Particles

Water

flow

Dispersion

14

Well

supplied

from

Aptian

Deposits

Under-

ground

Water

flow

Irrigati

on

Irrigati

on

Drinking

Water

Evapora

tion

Drinking

Water

15

Danube –

Black

Sea

Canal

Irrigati

on

Evapora

tion

External

irradiatio

n, fishing

Advection,

Diffusion,

Dispersion

16

Under-

ground

Water flow

Under-

ground

Water

flow

Soil Roots

uptake

Ingestion,

External

irradiation

Dust

raise

Gas

release

Ingestion

,

External

irradiatio

n


18 Animals

from farm Ingestion

19

Transp

ort

with

rain or

snow

Deposi

tion Inhalation

Atmosp

here

Inhalatio

n Advection

20

Building,

Maintenan

ce

Mainten

ance

Irrigati

on,

Manuri

ng

Irrigati

on,

Soil

manuri

ng,

Feeding,

Watering HUMAN

21 EXTERNAL

During this period the access to repository area is restricted. No farm will exist on repository. The considered plants and animals will not grow /live/ over repository but on area near the repository.

Water infiltration through the modules in excluded because during this period the modules are considered still intact. Dispersion is a macro process, that’s why in order for this process to occur a crack in

module accepted.



Page 252 of 253

Interaction matrix for the post-closure period after 300 years


R1 R2 G1 G2 G3 G4 B1 B2 B3 B4 B5 B6 B7 E1

1 Radionuclides from

the waste

Advection,

Dispersion,

Diffusion,

Mineralization

Particles

2 Improved

Foundation ground

Advection,

Dispersion,

Diffusion

Mineralization

Particles

3 Diffusion Silty loess – L1a

Advection,

Dispersion,

Diffusion,

Mineralizati

on

Particles

Advectio

n,

Dispersion

,

Diffusion

Mineraliza

tion,

Particles

4 Diffusion Clayey

Loess – L1b

Advectio

n,

Dispersion

,

Diffusion,

Mineraliza

tion

Particles


6 Aptian deposits

Advection,

Dispersion,

Diffusion,

Particles

Under-ground

Water flow

Advect

ion,

Diffusio

n,

Dispersi

on

7 Well supplied from

Aptian deposits

Under-ground

Water flow Irrigation Irrigation,

Drinking

Water

Evapora

tion Drinking Water

8 Danube – Black

Sea Canal Irrigation

Evapora

tion

External

irradiation,

fishing

Advect

ion,

Diffusio

n,

Dispersi

on

9 Under-ground

Water flow

Under-ground

Water flow Soil

Roots

uptake

Ingestion,

External

irradiation

Dust

raise

Gas

release

Ingestion,

External

irradiation




Page 253 of 253

R1 R2 G1 G2 G3 G4 B1 B2 B3 B4 B5 B6 B7 E1

11 Animals

from farm Ingestion

12 Transport with

rain or snow Deposition Inhalation

Atmosp

here Inhalation

Advect

ion

13 Building, Maintenance Maintenance Irrigation,

Manuring

Irrigation,

Soil

manuring,

Feeding,

Watering HUMAN

14 EXTERN

AL

After 300 year it is considered that all engineered barriers will be destroyed and no longer fulfill their safety functions. The degraded barriers are as follows: drum, disposal module, cell and drainage system. All

physical barriers such as: fences, markers are considered destroyed by natural processes. The repository area is not controlled and it is accessible for all human to live, to breed animals, to cultivate plants, to

build house and so on. In this period all types of human exposure to radiation are possible.

The roof cover system is considered intact but it can be damaged by human intrusion in the repository area. In this case the barrier will no longer fulfill its purpose established by the project.