NORM IV Conference May 2004, Szczyrk POLANDPAPERS1)STATUS OF THE
IMPLEMENTATION OF THEEUROPEAN DIRECTIVE 96/29/EURATOM IN IRELANDIN
RELATION WITH NORM - Catherine Organo ..........................
82)INVESTIGATION OF THE PEAT-FIRED POWERGENERATION IN IRELAND -
Catherine Organo, ElaineLee, Gerard Menezes, Eric Finch
.......................... 283)EXPOSURE FROM AN IGNEOUS PHOSPHATE
MINEOPERATION - A.J. vd Westhuizen, Foskor
.......................... 504)RAIL TRANSPORT OF IGNEOUS PHOSPHATE
ROCK -A.J. vd Westhuizen, G.P. de Beer ..........................
655)NORM IN BUILDING MATERIALS - Aliyev Chingiz
.......................... 856)RADIONUCLIDE CONTAMINATION OF THE
NATURALENVIRONMENT OF ABSHERON PENINSULA(AZERBAIJAN) - Sabina
Aliyeva .......................... 927)MITIGATION METHODS IN
SELECTION PLACES OFCONSTRUCTION SITES - Aliyev Chingiz,
TamaraZolotovitskaya, Sabina Aliyeva ..........................
1018)ENVIRONMENTAL RADIOLOGICAL IMPACT BY AFERTILIZER COMPLEX IN
THE EBRO RIVER (SPAIN) - E. Costa1), J.A. Sanchez-Cabeza, J.
Garcia, P. Masqu, J.O. Grimaltb ..........................
1099)EVALUATION OF OCCUPATIONAL RADIOLOGICALEXPOSURES ASSOCIATED
WITH FLY ASHES FROMFRENCH COAL POWER PLANTS - Jean-PierreDegrange,
Samuel Lepicard .......................... 126Page 1 of 894NORM IV
Conference May 2004, Szczyrk POLAND10)RECYCLING OF 232TH
CONTAMINATED TUNGSTENSCRAP - U. Quade, W. Mller
.......................... 14111)SOIL CONTAMINATION IN A RURAL SITE
USED FORRARE EARTH INDUSTRYBY-PRODUCT DISPOSAL - C. Briquet, D.
Lauria .......................... 15312)STATUS OF RADON DOSIMETRY
IN ZAMBIANUNDERGROUND MINES - P. Hayumbu1, S. Mulenga, M.Nomai, P.
Mulenga, R. Katebe, P. Shaba, T. Chunga, D.Inambao, F. Mangala, P.
Tembo, Y. Malama .......................... 16213)IMPORTANCE OF
SAMPLING IN RELATION OF THEGAMMA SPECTROSCOPIC ANALYSESOF NORM
MATERIAL - L.P.M. van Velzen, C.W.M.Timmermans
.......................... 17114)FACTORS CONTROLING MEASUREMENTS OF
MASSRADON EXHALATION COEFFICIENT - Nguyen DinhChau, Stefan J.
Kalita, Edward Chruciel, ukaszProklski ..........................
18815)CONCENTRATIONS OF 222Rn IN GROUNDWATERSFLOWING THROUGH
DIFFERENT CRYSTALLINEROCKS: AN EXAMPLE FROM LA MASSIF (Poland)-
Tadeusz A. Przylibski .......................... 20116)METHODS FOR
ASSESSMENT OF THEOCCUPATIONAL EXPOSURE AT WORKING PLACESOF
DIFFERENT TENORM INDUSTRIAL BRANCHES -Dietmar Wei, Harald Biesold,
Peter Jovanovic, LszlJuhsz, Ales Laciok, Karsten Leopold, Boguslaw
Michalik,Hana Moravansk, Andr Poffijn, Mihail Popescu,
CornelRadulescu, Pvel Szerbin, Jens Wiegand
.......................... 214Page 2 of 894NORM IV Conference May
2004, Szczyrk POLAND17)THE PROPOSAL OF THE SWEDISH COMMITTEE
ONMANAGEMENT OF NON-NUCLEAR RADIOACTIVEWASTE (IKA) AND THE
IMPLICATIONS FOR THEMANAGEMENT OF NORM AND STORAGE OF NORMWASTE -
Gustav kerblom, Nils Hagberg, Lars Mjnes,Ann-Louis Sderman
.......................... 22718)ASSESSMENT OF THE RADON
CONTRIBUTION FROMMINING SITES TOTHE GEOGENIC ENVIRONMENT - R. Rolle
.......................... 25219)NEW REGULATORY DEVELOPMENTS
ANDGUIDANCE IN THE EU WITH REGARD TO NORM - T.P.Ryan, A. Janssens,
E. Henrich, J.L. Daroussin ..........................
26120)INDUSTRIES GIVING RISE TO NORM DISCHARGES INTHE EU A REVIEW -
T.P. Ryan, A. Janssens, E.Henrich, J.L. Daroussin, Z.K. Hillis,
E.I.M. Meijne .......................... 27721)THE RAPID
IDENTIFICATION OF NORM DISCHARGESREQUIRING REGULATORY CONTROL A
POSSIBLESCREENING METHODOLOGY - E. Henrich, A.Janssens, T.P. Ryan,
J.L. Daroussin, K.R. Smith, M.Y.Gerchikov
.......................... 30722)POLISH NATIONAL INTERCOMPARISONS
OFMEASUREMENT METHODS OF 222RNCONCENTRATION IN WATERS - Tadeusz A.
Przylibski,Kalina Mamont-Ciela, Olga Stawarz, Barbara Kos,
JerzyDorda, SPI Team .......................... 32923)APPLICATION
OF INTERNATIONAL SAFETYSTANDARDS TO WORK INVOLVING EXPOSURE
TONATURAL RADIATION - Denis Wymer ..........................
35024)A SPECIFIC STUDY CONCERNING NORM INREFRACTORIES INDUSTRIES -
F. Trotti, C. Zampieri,G. Clauser, M. Facchinelli, D. Desideri, G.
Jia, P.Innocenzi, R. Ocone .......................... 372Page 3 of
894NORM IV Conference May 2004, Szczyrk POLAND25)GRAIN SIZE IN
RADIOMETRIC MEASUREMENTS OFGROUND - V. Gablin
.......................... 38326)TEST THRESHOLDS FOR ASSESSMENT
OFPOSSIBLE GROUNDWATER CONTAMINATION ATSITES CONTAMINATED WITH
RADIOACTIVEMATERIALS - Rainer Gellermann, Michael Hahn,
UlrikeHaberlau, Joachim Beetz ..........................
38927)NATURAL RADIOISOTOPE LEVEL DIFFERENTIATIONIN ARABLE AND
NONCULTIVATED SOILS AT CZNA-WODAWA LAKE DISTRICT A. Komosa,
St.Chibowski, J. Solecki, M. Reszka ..........................
40528)ATTEMPTS ON RADON EXHALATION RATEDETERMINATION FROM A
WASTE-DUMP AT THEBOGDANKA COAL MINE USING THE PICORADDETECTORS - A.
Komosa, St. Chibowski, St. Chaupnik ..........................
42329)APPLICATION OF LIQUID SCINTILLATION COUNTINGTECHNIQUE TO
GROSS ALPHA, GROSS BETA ANDRADON MEASUREMENTS IN PORTUGUESE WATERS
I. Lopes, M.J. Madruga, F.P. Carvalho ..........................
43730)EXAMINING THE NATURAL RADIOACTIVITY OFWATER SOURCES TO
EVALUATE THE IMPACT ONSURROUNDING COMMUNITIES - A. Faanhof,
P.Kempster .......................... 45731)PRESENCE OF NORM IN THE
CZECH REPUBLIC - H.Moravanska, A. Laciok ..........................
48232)INTERCOMPARISON OF INSTRUMENTS FORMEASURING RADON AND RADON
PROGENY HELD INTHE CLOR CALIBRATION CHAMBER - Kalina Mamont-Ciela,
Olga Stawarz (This work was partially supportedby Radon Center.)
.......................... 497Page 4 of 894NORM IV Conference May
2004, Szczyrk POLAND33)IDENTIFICATION OF ENHANCED CONCENTRATIONSOF
210PB AND 210PO IN DUST SAMPLES FROM STEEL-WORKS - J. Dring, J.
Gerler, M. Beyermann, U.K.Schkade, J. Freese
.......................... 51334)TEST OF THE MATERIAL FOR RADON
SEAL LAYERAT THE MINE WASTE DISPOSAL SITE JAZBEC - JozefRojc, Mine
Zirovski Vrh .......................... 51935)ESTIMATION OF RADON
DOSE IN SEVERALWORKPLACES USING DOSIMETRIC MODEL FORINHALATION OF
AIRBORNE RADIONUCLIDES - KalinaMamont-Ciela, Olga Stawarz
.......................... 53036)THE INVENTORY OF ITALIAN NORM
CONCERNEDWORK ACTIVITIES IN THE FRAME OF ENVIRONMENTPROTECTION - F.
Trotti, C. Zampieri, S. Bucci, G.Clauser, G. Colombo, D. Desideri,
M. Facchinelli, L.Gaidolfi, G. Torri ..........................
54037)URANIUM ISOTOPES IN PUBLIC DRINKING WATER INPOLAND - Zofia
Pietrzak-Flis, Iwona Kamiska, EdwardChrzanowski
.......................... 55538)CHARACTERISATION OF SCALE FROM A
FORMERPHOSPHORIC ACID PROCESSING PLANT - HelenBeddow, Stuart Black,
David Read .......................... 56839)IN SITU GAMMA-RAY
SPECTROMETRY IN COMMONROCK RAW MATERIALS MINED IN KRAKOWVICINITY,
POLAND - D. Malczewski, L. Teper, G.Lizurek
.......................... 59340)SOURCES OF TENORM INVENTORY
OFPHOSPHATE FERTILIZERS AND ALUMINUMINDUSTRIES - Dan Georgescu,
Florian Aurelian, MihaiPopescu, Cornel Rdulescu
.......................... 609Page 5 of 894NORM IV Conference May
2004, Szczyrk POLAND41)RADON MEASUREMENTS AS A
MONITORINGPOSSIBILITY FOR MINING SUBSIDENCEOCCURRENCES - A.Kies, A.
Storoni, Z. Tosheva .......................... 62542)NATURALLY
OCCURING RADIOACTIVE MATERIAL(NORM) ASSESSMENT OF OIL AND
GASPRODUCTION INSTALLATIONS IN NIGERIA - S.B.Elegba, I.I. Funtua
.......................... 63343)RADIUM LEACHING FROM MINE DEPOSITS
AS APOSSIBLE SOURCEOF GROUNDWATER CONTAMINATION - StanisawChaupnik
.......................... 63844)MEASUREMENT OF SHORT-LIVED
RADONDAUGHTERS IN POLISH MINES - Krystian Skubacz,Antoni Mielnikow
.......................... 65645)RADIUM REMOVAL FROM MINE WATERS
UNDERGROUND TREATMENT INSTALLATION -Magorzata Wysocka, Stanisaw
Chaupnik, ElbietaMolenda .......................... 66546)RADIUM
BALANCE IN DISCHARGE WATERS FROMCOAL MINESIN UPPER SILESIA REGION -
StanisawChaupnik, Magorzata Wysocka, Antoni Mielnikow,Bogusaw
Michalik, Jan Skowronek ..........................
68247)THEORETICAL STUDY OF RADIUM BEHAVIOUR INAQUIFERS Stanisaw
Chaupnik .......................... 69648)RADIUM BEHAVIOUR DURING
DESALINATIONPROCESSES OF MINE WATERS - Stanisaw Chaupnik,Krystian
Skubacz .......................... 71649)INVESTIGATIONS OF SURFACE
SETTLING POND -Magorzata Wysocka, Stanisaw Chaupnik
.......................... 73150)NORM LEGISLATION IN POLAND - Jan
Skowronek .......................... 745Page 6 of 894NORM IV
Conference May 2004, Szczyrk POLAND51)NORM IN MINING INDUSTRY IN
POLAND - JanSkowronek .......................... 77252)THE
ASSESSMENT OF EXPOSURE TO IONIZINGRADIATION AT SPOIL BANKS -
Bogusaw Michalik .......................... 78153)THE EFFECT OF
EARTHQUAKE-INDUCED RADONRELEASE ON THE POPULATION IN THE
SEISMICACTIVE REGIONS OF ARMENIA - E. Saghatelyan, A.Petrosyan, Yu.
Aghbalyan, M. Baburyan, A. Davtyan ..........................
80154)RADIUM IN GROUND WATER CLOSE TO BUENALAGOON IN COASTAL ZONE
OF RIO DE JANEIROSTATE, BRAZIL - Dejanira C. Lauria, Rodrigo M.
R.Almeida, and Ondra Sracek ..........................
81555)ENVIRONMENTAL ASSESSMENT OF THE MATERIALDEPOSITED ON THE
FORMER URANIUM MININGDISPOSAL DUMP IN RADONIW A.ak,
M.Biernacka,P.Lipiski, K.Isajenko ..........................
83956)IMPROVING CRITERIA FOR REMEDIATION OFMONAZITE BY-PRODUCTS
CONTAMINATED SITES INBRAZIL - Briquet, Claudia ; Silva, Katia, M.;
Cipriani, M. .......................... 85857)DISMANTLING OF A NORM
CONTAMINATEDPHOSPORIC ACID PLANT IN THE NETHERLAND -Rinus
Rentmeester Hydro Agri BV Vlaardingen NL (NorskHydro); Rene
Janssen, Radiation Protection Services. ..........................
86858)RADIOLOGICAL IMPACT ON THE UK POPULATION OFINDUSTRIES WHICH
USE OR PRODUCE MATERIALSCONTAINING ENHANCED LEVELS OF
NATURALLYOCCURRING RADIONUCLIDES: ZIRCON SANDSINDUSTRIES - W B
Oatway 1, J A Jones 2, P V Shaw 3and S F Mobbs 4
.......................... 879Page 7 of 894NORM IV Conference May
2004, Szczyrk POLANDSTATUS OF THE IMPLEMENTATION OF THEEUROPEAN
DIRECTIVE 96/29/EURATOM INIRELAND IN RELATION WITH NORMSEE ALSO:
ABSTRACTC. OrganoRadiological Protection Institute of Ireland, 3
Clonskeagh Square, ClonskeaghRoad, Dublin 14, Ireland.e-mail:
[email protected] the 13th May 2000, following the
implementation of the EU Basic SafetyStandards Directive
96/29/EURATOM, naturally occurring radioactive materials(NORM) in
Irish workplaces are subject to regulations if they are liable to
give riseto a radiation dose greater than 1 mSv in a year. The
Radiological ProtectionInstitute of Ireland (RPII) is the statutory
body in Ireland for matters pertaining toionising radiation. In
2001, the RPII undertook a review of industrial processeswhich, on
the basis of the literature were thought to lead to enhanced
exposure tonatural sources of radiation. This paper presents the
progress achieved inimplementing the legislation for the gas
extracting industry and for the peat- andcoal-firing power
generation.Page 8 of 894NORM IV Conference May 2004, Szczyrk
POLAND1. IntroductionIn 1996, the European Union Basic Safety
Standards Directive [1] included specialprovisions concerning
exposure to natural sources of ionising radiation,recognising the
specific problems that need addressing when the source ofexposure
has not been artificially generated but is of natural origin. In
Ireland, thenecessary laws and regulations to comply with this
Directive were brought intoforce in May 2000 [2]. Accordingly, work
activities where the presence of naturalradiation sources (commonly
referred to as NORM Naturally OccurringRadioactive Materials) is
liable to give rise to a radiation dose to workers ormembers of the
public greater than 1 mSv in a year are now controlled.2.
Identification of the relevant work activities2.1. European
Commission (EC) guidanceTo assist in the identification of the
relevant work activities, the EC produced aseries of documents
mostly limited to consideration of occupational exposures.Radiation
Protection 88 [3] recommends to target the work activities listed
in Table1.Table 1. Examples of work activities, industries and
products liable to lead to enhancedexposure to natural sources of
radiation [3]Industry / Work activity Product / MaterialsCoal-mine
de-watering plants Coal and fly ashProcessing of rare earths MgTh
alloysFertiliser/phosphoric acidproductionFoundry sands (zircon and
monazite)Sulphuric acid productionRefractories, abrasives, ceramics
(zirconiumminerals)Smelters (metal production) Thoriated welding
rods and gas mantelsOil and gas industry Porcelain teethTiO2
pigment industry Natural stoneOptical industry and glassware Fuel
peat ashPage 9 of 894NORM IV Conference May 2004, Szczyrk
POLANDThey mostly involve operations with and storage of materials
as well as productionof residues not usually regarded as
radioactive but which contain naturallyoccurring radionuclides
which could potentially cause a significant increase in theexposure
of workers and where appropriate, members of the public.
RadiationProtection 95 [4] and Radiation Protection 107 [5]
investigate the pathways andthe exposure situations which should be
looked at when deciding if a work activitypotentially falls under
the scope of the regulations (Table 2).Table 2. Most significant
NORM industries within the EU, types of materials, pathways
andtypical exposure situations to be considered ([4];
[5])IndustriesTypes ofMaterialList of Pathways List of Exposure
situationsPhosphateindustry;Processing ofmetal ores;Zircon sandsand
refractorymaterials;Extraction ofrare earths;Manufactureand use of
Thcompounds;TiO2
pigmentindustry;Oil/gasextractionMineraloresBy-products,residuesProducts
ofthe processitselfExternalirradiation;Inhalation
ofcontaminateddust;Ingestion of dirtand dust;Inhalation ofradon
diffusingfrom thematerial;SkincontaminationProximity to large
amounts ofmaterial, little shielding;Dusty conditions, little
respiratoryprotection;Dirty, dusty areas, little
protectiveclothing;Enclosed room, large amounts ofmaterials, little
ventilation;Generic ES1: stockpiles of material exposure of
warehouse operativeGeneric ES2: residues and scales exposure of
worker removingresiduesGeneric ES3: process material invessels and
pipes exposure ofgeneral worker2.2. NORM industries of relevance in
IrelandIn 2001, the Radiological Protection Institute of Ireland
(RPII) commenced aprogramme to identify potential NORM industries
currently active in Ireland, basedon the above mentioned guidelines
(Table 3). Irish industries liable to produce oruse diffuse NORM
sources include the gas extracting and processing industry,
thefossil fuel power production (peat and coal), the bauxite
processing/aluminarefining industry and a range of other processes
producing/using bulk materialswith enhanced levels of natural
radioactivity (e.g. cement, fertilisers, ore extractingPage 10 of
894NORM IV Conference May 2004, Szczyrk POLANDindustries). Discrete
NORM sources identified as being important in an Irishcontext
include thoriated products and natural radioactivity in scrap,
which turnsup at metal dealers.Table 3. Irish NORM industries
potentially liable to involve NORMNORMCategoryIndustryDiffuse
sourcesNatural gas extraction and processingPower generation
peatcombustion/flyashPower generation coalcombustion/flyashBauxite
processing/alumina refiningCement productionHandling of
fertilisersDiscretesourcesUse of thoriated products (TIGwelding,
etc)Metal recyclingAt the end of 2001, the RPII started a detailed
investigation of the gasextracting/processing industry and of the
fossil fuel power production. The resultsobtained so far are
presented in the following sections. For work activitiesinvolving
NORM, the existence of a radiation risk is usually incidental to
theprocess and the undertaking might not be aware of it. Therefore,
it is alwaysnecessary to meet the staff management of a particular
industry, to discuss thepotential occurrence of radiological
hazards and to review what a complete orpartial radiological
assessment will involve.3. The gas extracting industry in
IrelandThe Kinsale Head gas field is located about 50 km off the
coastline of CountyCork (S Ireland) and was discovered in 1971. It
entered into production in 1978.An adjacent gas field (Ballycotton)
was discovered in 1989 about 15 km north ofKinsale Head. Between
the two of them, they supply approximately 16% ofIrelands energy
requirements. An additional subsea gas well (Greensand) cameon
stream in 2003 to enhance the productivity of the Kinsale Head gas
producingPage 11 of 894NORM IV Conference May 2004, Szczyrk
POLANDGreensand reservoir, thereby extending the exhaustion point
of the Kinsale Headgas to year 2015. Since December 2003, the
Kinsale Heads operator providesfirm capacity to process and
transport gas extracted from another gas field (SevenHeads) located
a further 35 km to the SW of the Kinsale Head field. The
KinsaleHead facilities consist of two offshore production
platforms, Alpha and Bravo.They both produce and process natural
gas for transportation to an onshoremetering station. The Bravo
platform and the metering station are NormallyUnmanned
Installations (NUI) [6].The Corrib gas field is the second large
scale exploration project in Ireland. It issituated some 70 km west
of the County Mayo coastline (NW Ireland). Theoperator is currently
going through a planning application process in relation to
thedevelopment of an onshore terminal facility. If the project goes
ahead, up to 60%of the Irish domestic gas demand could be met from
the Corrib field which has aprojected life of 20 years. Unlike the
Kinsale Head field, there will be no mannedfacilities located
offshore. All the Corribs subsea facilities will be controlled
andmonitored from the onshore terminal via an electro-hydraulic
remote controlsystem.3.1. Recognised issues of radiological
significance in the gas industryRadon (222Rn) is released from the
gas reservoir and is transported with theextracted natural gas to
the processing plant. In routine operations, as the gasflows
continuously through the system and 222Rn decays, its short-lived
decay-products (218Po, 214Pb, 214Bi and 218Po) tend to plate out on
surfaces that come intocontact with the gas to form thin dark
grey/black films on the internal side of theequipment ([7]; [8];
[9]; [10]; [11]). The penetrative high energy gamma radiationthey
emit may result in significant occupational external gamma
radiation doserates in the vicinity of contaminated equipment.
During shut downs (repair ormaintenance operations), the gas flow
stops and within several hours, 222Rn andits short-lived
decay-products have decayed. Gamma radiations are no longeremitted
but the long-lived decay-products of radon (210Pb, 210Bi and 210Po)
remainin the film deposits. These radionuclides emit weak gamma
radiation but thePage 12 of 894NORM IV Conference May 2004, Szczyrk
POLANDenergetic alpha emissions of 210Po and 210Pb represent a
potential hazard if theybecome airborne and are ingested or
inhaled.Filter assemblies in gas lines remove radon decay-products
from the gas withother particulate matter (heavy-metal
decay-products preferentially attach to dustparticles and
aerosols). Therefore, they could also become radioactive
byaccumulating residues with enhanced radionuclide concentrations.
Sludgeaccumulating in separator vessels, storage tanks, gas lines
and other filterassemblies contain 226Ra, 228Ra, 210Pb, 210Bi and
210Po. Generally, scales do notoccur at gas producing facilities as
long as formation water is not produced inlarge quantities. This
only happens towards the end of a fields life [12]. Scaleinhibitors
are injected in the system when formation water starts to be
produced.This can raise the issue, in the future, of possible 226Ra
and 228Ra discharges tothe environment and contamination of water
treatment equipment.Extracted natural gas is not used directly as
it comes from the well. It needs toundergo some processing to
remove liquids and/or impurities. Depending on itscomposition, it
might be thermally fractionated to recover Natural Gas
Liquids(ethane, propane, butane, and pentane) [10]. As radon has a
boiling pointbetween that of ethane and propane, the highest radon
levels are generally foundin equipment associated with
ethane/propane processing [7]. If the natural gasstream does not
need to be fractionated (pure methane), 222Rn concentrations inthe
production stream will remain relatively constant and will only be
changed bymixing streams with different concentrations.For workers
involved in the gas producing industry, the greatest risks of
exposureoccur during shut downs when the production equipment is
opened orcomponents are replaced ([10]; [12]). In routine
operations, significant exposure toNORM is unlikely to arise as
these latter are mostly contained within pipes andvessels and are
therefore shielded by the walls of these vessels. However, it
ispossible that high-energy gamma radiation can pass through the
walls of suchcomponents and personnel working in close proximity of
such equipment could beat risk of receiving a radiation dose.Page
13 of 894NORM IV Conference May 2004, Szczyrk POLAND3.2. Progress
of the investigation to dateRadon gas concentrations were measured
in all the Irish gas streams at theproduction point. The results
are shown in Table 4.Table 4. Radon gas concentrations in Irish
extracted gasGas FieldRadon concentration(Bqm-3)Measurement
locationKinsale Head (priorto tie-back withSeven Heads
gas)493529775817865average:696Alpha platform (inlet
separator)Terminal (export line)Terminal (Calorimeter)Seven Heads
(priorto tie-back withKinsale Head gas)number of
measurements:11;average: 147; range: 39 252Development
wellsCombined KinsaleHead/Seven Headsstreams680 Terminal
(Calorimeter)411Terminal (Calorimeter) 3-month measurement
(CR-39)CorribNumber of measurements: 4;average: 99; range: 25 -
190Development wellsSamples were collected using a grab sampling
technique into previouslyevacuated Lucas cells. In one case, radon
was continuously monitored over a 3-month period (105 days) by
means of passive solid state nuclear track detectors(CR-39).
Combining all the measurements (excluding Corrib as this field is
notproducing) gives an average 222Rn concentration in the
distributed Irish gas of 590Bqm-3. Dixon [13] demonstrated that for
typical rates of gas usage and anaverage radon level of about 200
Bqm-3 at point of use, the estimated dose fordomestic users from
the use of natural gas was only 4 Sv and for a critical
grouprepresenting commercial users (commercial kitchens) a few tens
of microsievert.Based on these results and on the radon gas
concentrations measured in Ireland,it can be concluded that the
exposure of the Irish public and employees working incommercial
kitchens from the combustion of gas in homes and workplaces
isunlikely to give rise to a dose greater than 1 mSv.It is
recognised that a great part of the radioactivity in the gas
extracting industry isdeposited in sludge in wellhead separators
and in water/condensate separationPage 14 of 894NORM IV Conference
May 2004, Szczyrk POLANDsystem [14]. Both the Kinsale Head/Seven
Heads and the Corrib gases are dryand as such are mostly composed
of pure methane (98.8% and 93.7% methanefor Kinsale/Seven Heads and
Corrib, respectively). Therefore, the mainprocessing needed before
they can commercially be distributed is dehydration.The Kinsale
Head gas does not contain condensate (heavier liquid
hydrocarbonsextracted from the gas) although there is a possibility
that some amount could beproduced from the Seven Heads gas.
However, at the time of writing, this was notconfirmed. It is not
possible to predict in advance if condensate will be produced inthe
Corrib field, but any condensate produced will be re-used as fuel
within theTerminal. On the Alpha platform, the separators are
inspected every four years onaverage. It requires shutting down the
facilities. After shut down, the productionequipment is ventilated
and the inside of the vessels is cleaned. Workers are onlyinvolved
at the end of the cleaning procedure to remove any residues
(sludge)deposited at the bottom of the tanks. Sludges are then sent
ashore for disposaland the wash down water after the sludge is
removed is discharged at sea. In2003, the amount of sludge sent
ashore was approximately 60 kg. The RPIIvisited the Alpha platform
during a shut down to observe the working proceduresinvolved in the
cleaning of inlet separators used in the dehydration process.
Asurvey of the equipment (external and internal sides) was
originally planned usinga range of radiation monitors to determine
areas of potential NORM exposure andcontamination but this could
not be performed for safety reasons and had to bepostponed until
2005. Two sludge samples were collected from the bottom of
twoseparators and analysed by high resolution gamma spectrometry
(Table 5).Compared with results published in the literature, the
Kinsale sludges contain verylow levels of natural radionuclides.
Van Weers et al. [12] for example report thatthe maximum activity
concentrations measured in sludges collected on Dutchplatforms were
as follow: 800 Bqg-1 226Ra, 500 Bqg-1 228Ra, 60 Bqg-1 228Th.
Irishsoils on average contain 60 Bqkg-1 of 226Ra [15].Page 15 of
894NORM IV Conference May 2004, Szczyrk POLANDTable 5. Radionuclide
composition of sludge samples collected on the Alpha
platform.Results are in Bqkg-1 and are quoted on a dry weigh
basisRadionuclideSludge 1Sludge2234Th 17.7 3.6 < 6226Ra 5.5 1.8
< 10214Pb 7.6 0.8 1.3 0.6214Bi 7.4 0.8 1.5 0.7228Ac (228Ra) 15.4
1.2 5.0 1.2228Th 9.9 8.7 < 17224Ra 12.6 4.7 < 8212Bi 13.5 2.7
5.7 4.6212Pb 11.3 1.3 5.4 0.9208Tl 3.5 0.4 1.4 0.4According to the
operator, replacement of equipment (pipes, valves, pumps,
etc)occurs only when the general layout of the installation needs
to be modified, as itwas the case when the Seven Heads gas was tied
back to the Kinsale Headfacilities. Disused equipment is usually
stored onshore in a warehouse. A visit ofthe storage site will be
organised in 2005 to carry out a radiation survey and checkthat
surface contaminations (210Pb/210Po), scales/deposits and sludges
are not anissue to be considered in the future.From 2004 onward,
discharges of radioactive substances into the OSPAR regionfrom all
non-nuclear sectors will have to be reported to the OSPAR
Commission[16]. Information requested will include the nature of
all discharges (origin,physical and chemical properties including
their radionuclide composition) and forthe oil and gas industry
they will also include the total discharges of
radioactivesubstances from offshore installations (produced water,
descaling anddecommissioning operations and tracer experiments).
For the Kinsale Head gasfield, the total volume of produced water
discharged at sea in 2003 was 1,830 m3.Page 16 of 894NORM IV
Conference May 2004, Szczyrk POLAND4. The fossil fuel power
generation in Ireland4.1. The peat-fired power productionAnnually,
approximately 15% of Irelands electricity requirement is
providedthrough the combustion of 3 106 tonnes of peat. While
literature on the coal-firedpower generation is quite abundant,
studies on the peat-fired power generationindustry from a
radiological point of view are scarce. A study of the largest
Irishpeat-fired power plant, Shannonbridge (located in the Irish
Midlands) was carriedout in collaboration with Trinity College
Dublin to review the potential occupationalradiation exposures
arising from the occurrence of NORM at different stages ofthe
industrial process. Ambient gamma dose rate measurements,
radonmeasurements, quantification of the occupational exposure from
inhalation ofairborne particles and gamma spectrometry analysis of
peat, peat ash and effluentsamples from the ash ponds were
undertaken. Details of the industrial processand results are
presented elsewhere [17]. The total annual effective dose likely
tobe received by a worker involved in the processing of peat and
handling of peatash in Shannonbridge was found to be about 0.3 mSv
(312 Sv). Most of theexposure situations where workers are involved
on a regular basis wereinvestigated with the exception of
maintenance duties like the cleaning of hoppersand freeing of
blockages in the grit arrestors. These duties are the only
oneswhere workers are directly in contact with the peat fly ash.
However, one wouldnot expect the associated annual effective dose
to be significant as this type ofwork is always carried out with
personal protection equipment (PPE), isundertaken in wet conditions
to minimise the dust generation, occurs infrequently(3 times in a
year) and is usually completed within a week. Another
exposuresituation is the inhalation of peat ash dust on the
landfill sites (generation ofwindborne ash on the ash pond). This
is not included in this study as the top layerof the pond, when
dried out, usually forms a crust underneath which the ash
istrapped. It is therefore unlikely to be wind blown.4.2. The
coal-fired power productionPage 17 of 894NORM IV Conference May
2004, Szczyrk POLAND4.2.1. Description of the industrial
processMoneypoint is the only coal-fired power generating station
in Ireland. It is locatedin the West of the country, along the
Shannon estuary. It consumes 2 106tonnes of world trade coal per
annum and produces 40% (total capacity of 915MW) of the total Irish
demand in electricity. On its arrival at the plant, the coal
isstored outdoor in a stockyard protected with a wind barrier. Two
conveyor beltsystems carry the coal from the stockyard to the
boiler bunkers. From there, theprinciples of combustion and
production of ash are similar to those described forthe peat-firing
power generation [17]. Coarse ash (bottom ash) is collected
underthe furnace and pulverised fly ash (PFA) is collected by
electrostatic precipitators(ESPs). About 180-200 103 tonnes of ash
are produced annually at Moneypoint,of which 85% is PFA and the
remaining 15% bottom ash. Approximately 100 103tonnes of PFA are
sold annually to the cement industry. It enters in thecomposition
of the cement for 5 to 10%, as a shale substitute. The remaining
PFAis conditioned on site with water (to prevent dust generation)
and transferred bytruck to the disposal area (total capacity of 3
106 m3, approximately 10 m deep)in dry condition. The bottom ash is
hydraulically transferred from the plant in aslurry form, dewatered
in silos, loaded into trucks and transferred to the landfillarea
where it is kept separate from the PFA. Truck drivers and workers
on thelandfill wear dust masks. The disposal area is regularly
checked for groundwatertesting by the Irish Environmental
Protection Agency.4.2.2. Radiological protection issuesClearly, the
radiation doses received by individual workers at coal-fired
powerstations vary substantially depending on their duties, with
the majority receivingtrivial doses. This is illustrated by the
results of the study carried out by the NRPB[18], which considered
parameters such as routine operation, atmosphericreleases,
discharges to landfill and sales of ash. This study found that
theradiological impact on the UK population of the coal-fired
industry was low, withtwo exceptions: the use of coal ash in
building materials and the possibility of highPage 18 of 894NORM IV
Conference May 2004, Szczyrk POLANDlevels of naturally occurring
radionuclides in scales on boiler tubes. Theseconclusions provided
the basis of an investigation initiated by the RPII in 2003
todetermine if the work activities carried out at Moneypoint were
giving rise to dosesliable to exceed 1 mSv to any individual in a
12 month-period.Over the last 15-20 years, a number of studies and
measurements of coal andcoal ash samples have been carried out
through collaborations betweenMoneypoint (Electricity Supply
Board), the RPII, Trinity College Dublin andUniversity College
Dublin (Table 6).Table 6. Radionuclide composition (in Bqkg-1) of
coal processed in Moneypoint andcomparison with coal processed in
other countriesCountry of origin of
coal238U226Ra210Pb232Th40KMoneypointPoland 45 39-86 20-32 11-12
80Australia 25-40 2-13 20-50USA 5-32 6-60 10-16 5-12 30-75Columbia
25-30 3-9 80-100UK 14 24 27 8 75[18] UK average 20 15-20 20
7.5[19]Poland 38 30 290Australia 30-48 30 40USA 18 21 52UK 15 13
150[20] Hungary 300-500[21] Brazil 24-35 27-48 351-447The
238U-series is generally in equilibrium in the coal, apart from a
reduction inconcentration of the later daughter nuclides due to a
loss of radon during thecombustion process. For each radionuclide,
significant variations of activityconcentrations can be observed.
This is more than likely due to the differentcountry of origin of
the coal supplies. Despite this variability, activityPage 19 of
894NORM IV Conference May 2004, Szczyrk POLANDconcentrations
averaged over one year of power production are
generallyconstant.Radionuclide concentrations in PFA are
consistently higher, by a factor of ten orso, compared to those in
coal (Table 7). This is because at furnace temperatures,some
elements originally contained in the coal are partly or
completelyevaporated. Between the furnace and the ESPs, the gas and
fly ash stream iscooled down to remove the heat from the gas prior
to its emission to theatmosphere. As the flue gases cool down, the
volatilised elements condense ontothe fly ash particles, giving
rise to an enrichment of their concentrations in the flyash trapped
by the ESPs. Table 7. Radionuclide composition (in Bqkg-1) of coal
ash produced in Moneypoint andcomparison with ash produced in other
countriesCoal origin and/or
[References]238U226Ra210Pb232Th40KMoneypoint1986-1990 (average)
[22] 120 134 89 53 6501993 (average) [23] 116 118 69 545USA (2002)
[24] 73 137 83 72 536Columbia (2002) [24] 46 71 37 34 235Australia
(2002) [24] 52 113 69 64 155Indonesia (2002) [24] 72 118 105 90
229[18]UK Measurements range 43-110 44-74 98-188 19-40Used for dose
calculations 100 100 100-200 50 900[25] EU arithmetic mean 230 100
570[20] Hungary 1000-1500 Approx. 1400[26] Poland 116-156 86-104
112-183 66-84 608-720[27] Greece Up to 1443 273-1377 Up to398641-65
143-661[28] Australia 96 170 203The activity concentrations of the
coal processed and the ash produced inMoneypoint do not differ
significantly from the ones used in [18]. Therefore,Page 20 of
894NORM IV Conference May 2004, Szczyrk POLANDassuming similar
industrial processes in Ireland and the UK, the conclusionsreached
in [18] should also apply to the Irish coal-fired electricity
generation.Only a small fraction of the fuel gases that contain
radionuclides in gaseous formpasses through the ESPs and is then
discharged through the stack to theatmosphere. On average 12% of
the total ash (and non-volatile elements) isremoved in the furnace
(bottom ash) and about 87% is removed in the ESPs(PFA). This gives
a total removal in excess of 99%. Specific emissions ofparticulate
matter are on average below 80 mgm-3, which corresponds to
anemission rate of about 20 g of ash per second from each unit at
305 MW output([29], Table 8).Table 8. Fly ash annual emission into
the air (downstream of the ESPs) for 5 different typesof coal,
assuming 7,500 full load hours [29]Indonesia South Africa Australia
Columbia East USA386 ty-1 perboiler585 ty-1 perboiler229 ty-1 per
boiler 71 ty-1 per boiler225 ty-1 perboilerIt is this fraction of
the fly ash as well as the gaseous fraction that
preferentiallydeposits in the pulmonary and bronchial regions of
the respiratory tract and thiscould be an issue of concern for
members of the public because of thepreferential enrichment in
210Po and 210Pb onto the finer fly ash particles. The off-site
radiological effects of the Moneypoints operation were investigated
between1986 and 1990 using a gaseous dispersion model of
radiologically active traceelements in the Moneypoint plume [30].
They were found negligible.According to Smith et al. [18],
comparing the doses arising from building materialscontaining 30%
ash (with activity concentrations quoted in Table 7) with the
dosesarising from materials not containing ash leads to a predicted
excess externaldose to that received outdoors of 600 Svy-1 after
subtraction of externalbackground. This is within the range of 0.3
to 1 mSvy-1 for which the EC guidanceindicates that controls on the
use of such building materials should be instituted([25]; [31]).
Trinity College Dublin is currently investigating the significance
and thePage 21 of 894NORM IV Conference May 2004, Szczyrk
POLANDextent of external doses arising from building materials
containing coal ashcommonly used in Ireland.In 2001, Huijbregts et
al. [32] reported the occurrence of scale deposits on theoutside of
pipes within boilers of coal-fired power stations, which contained
210Pbat levels exceeding the Dutch regulatory limit of 100 Bqg-1.
Both the rate ofaccumulation and the composition of the scale were
found to be very dependentupon the chemical environment and the
temperature inside the boilers. Smith etal. [18] conservatively
estimated that a scale with a 210Pb concentration of 100Bqg-1 could
give rise to doses in the region of 100 Svy-1 for workers involved
inboiler maintenance. On average, the coal processed in Moneypoint
has a lowerchlorine content (< 2%) than the coal processed in
the Dutch study. High chlorinecontents favour the establishment of
reducing conditions in the boilers which inturn lower the
temperature of condensation for Pb (660C instead of 880C
inoxidising conditions). The Moneypoint boilers also operate at
higher stoechiometrythan the ones used in the Netherlands because
they are fitted with first generationof low NOx burners which
operate in oxidising conditions. Finally, the boilerscurrently in
use in Moneypoint are smaller in size than in the Netherlands,
whichmeans that higher combustion temperatures are prevailing in
Moneypoint. Thisincreases the chance to exceed the condensation
temperature of 880C for Pb,thereby decreasing the chance of Pb
condensation on the waterwall tubes insidethe boilers. For all
these reasons, the build-up of scales and therefore thepotential
existence of increased levels in 210Pb in the Moneypoint boilers
wereruled out [33]. In order to reach the future European standard
for low NOxemissions, the current generation of boilers will have
to be replaced by the 1stJanuary 2008 by a second generation of
large-size boilers operating in forcedreducing conditions. This
means that from 2008 onward, the occurrence of scaleswill have to
be controlled and monitored on a regular basis.Radon concentrations
in air at different locations throughout Moneypoint weremeasured in
1988. All the readings were found to be well below the
Irishregulatory limit of 400 Bqm-3. The RPII requested to have a
more complete radonsurvey being carried out to assess the radon
concentrations on the totality of thepremises, including offices,
workshops, etc. Sixty passive solid state nuclear trackPage 22 of
894NORM IV Conference May 2004, Szczyrk POLANDdetectors (CR-39)
were dispatched on site for a period of 3 months and returnedfor
analysis. They are currently being processed.5. Future
investigationsThe largest bauxite processing plant in Western
Europe is located in the West ofIreland. It produces annually
approximately 1 106 tonnes of alumina from 2 106tonnes of bauxite.
A radiological assessment of the industrial process,
feedingmaterial, waste streams and work practices will be carried
out. In 1992, OGrady[34] surveyed fertiliser handling practices in
Ireland and estimated the radiationdoses to workers involved in
manufacture, transport and storage, to farm-workersand to members
of the public. This study concluded that, since the cessation
ofphosphoric acid production in Ireland in 1981, the dose to the
most exposedindividual was unlikely to exceed 100 Sv per year and,
on average, was wellbelow this. Thorium is used as an additive in a
number of industrial processes toimprove heat stability of metal
alloys. In the welding industry thorium is added toelectrodes used
in tungsten inert gas (TIG) welding to facilitate arc starting and
toincrease arc stability. TIG welding has particular advantages in
stainlessfabrication work and is widely used in Ireland for this
purpose. Ludgwig et al. [35]showed that in some cases the exposure
to operators involved in welding andgrinding could exceed 1 mSvy-1.
Following an incident involving the scrapping of aradiocaesium
source in the early 90s, portal monitoring was installed at the
onlysteel plant operating in Ireland at that time [36]. Up until
the closure of the plant inMay 2001, the RPII was notified of alarm
activations approximately once a monthand radioactive sources in
scrap metal were regularly identified, the majority ofwhich were
found to be NORM materials. Dismantling/decommissioning
activitiesof major industries such as the Irish Fertiliser Industry
(IFI) and the replacement ofdisused equipment in still active
industries (cement industry) need to be monitoredand controlled for
the presence of NORM contamination. Finally, disused minesand
industries/companies involved in the use and transport of zircon
sands andtitanium dioxide will also have to be identified and
reviewed.Page 23 of 894NORM IV Conference May 2004, Szczyrk
POLAND6. ConclusionsSince May 2000 and the incorporation into Irish
law by Ministerial Order of theEuropean Basic Safety Standards
Directive, industries liable to involve workactivities resulting in
significant exposure to natural radiation sources are subjectto
regulation if they are liable to give rise to a radiation dose
greater than 1 mSv ina year. The gas extracting industry, the peat
and coal-fired power generation werethe first industries to be
investigated by the RPII. To date and based on the resultsof field
and laboratory measurements, none was found to be of
radiologicalconcern, although work is still on-going for some of
the issues raised. Investigationof the bauxite processing/alumina
refining industry is due to commence before theend of the current
year while the TIG welding industry, disused mining activitiesand
dismantling/decommissioning operations will be dealt with a later
stage.AcknowledgementsThe author wishes to express her thanks to
Mrs E.M. Lee (Physics Department,Trinity College Dublin), Mr D.
Toomey (Marathon International Petroleum IrelandLtd.), Dr J. Lyons
(Environment and Chemicals, ESB Shannonbridge) and Mr F.McCarthy
(Station Chemist, ESB Moneypoint) for their contribution to the
workreported in this paper. The gamma spectrometry analyses of
sludge wereperformed at the Environmental Laboratory of the
RPII.References1. Council of the European Union, Basic Safety
Standards for the HealthProtection of the General Public and
Workers Against the Dangers of IonisingRadiation, Council Directive
96/29/EURATOM, Luxembourg (1996).2. Stationery Office, Radiological
Protection Act, 1991 (Ionising Radiation)Order. Statutory
Instrument 125 of 2000, Department of Public Enterprise,Government
Publications Office, Dublin (2000).Page 24 of 894NORM IV Conference
May 2004, Szczyrk POLAND3. European Commission, Recommendations for
the implementation of TitleVII of the BSS concerning significant
increase in exposure due to natural radiationsources. Radiation
Protection 88. EC Directorate-General Environment,Luxembourg
(1997).4. European Commission, Reference levels for workplaces
processingmaterials with enhanced levels of naturally occurring
radionuclides: a guide toassist implementation of Title VII of the
European BSS Directive concerningNatural Radiation Sources.
Radiation Protection 95. EC Directorate-GeneralEnvironment,
Luxembourg (1999).5. Penfold, J.S.S., Mobbs, S.F., Degrange, J.P.,
Schneider, T., Establishmentof reference levels for regulatory
control of workplaces where materials areprocessed which contain
enhanced levels of naturally-occurring radionuclides.Radiation
Protection 107. EC Directorate-General Environment,
Luxembourg(1999).6. Carroll, K., Gas storage - More energy in
store. Institution of Engineers ofIreland (IEI), The Engineers
Journal, Issue Nov. 2002 (2002).7. Summerlin, J.Jr., Prichard, H.,
Radiological health implications of Lead-210and Polonium-210
accumulations in LPG refineries. Am. Ind. Hyg. Assoc. J., 46(4):
202-205 (1985).8. Gray, P.R., NORM contamination in the petroleum
industry. J. of PetroleumIndustry, 45(1): 12-16 (1993).9. American
Petroleum Institute, Bulletin on Management of NORM in oil andgas
production, API Bulletin E2, First Ed. (1992).10. Gesell, T.F.,
Occupational radiation exposure due to 222Rn in natural gasand
natural gas products. Health Physics, 29:681-687 (1975).11.
Bjrnstad, T., Ramsy, T., The invisible radioactive scale,
Proceedings ofthe 10th International Oil Field Chemicals Symposium,
Norwegian Society ofChartered Engineers, Oslo, 195-211 (1999).
[available online at www.ife.no] 12. van Weers, A.W., Pace, I.,
Strand, T., Lysebo, I., Watkins, S., Sterker, T.,Meijne, E.I.M.,
Butter, K.R., Current practice of dealing with natural
radioactivityfrom oil and gas production in EU Member States,
Report EUR 17621 EN,Nuclear Safety and the Environment, European
Commission, Luxembourg (1997).Page 25 of 894NORM IV Conference May
2004, Szczyrk POLAND13. Dixon, D.W., Radon exposures from the use
of natural gas in buildings.Rad. Prot. Dos., 97(3): 259-264
(2001).14. Scholten, L.C. Approaches for regulating management of
large volume ofwaste containing natural radionuclides in enhanced
concentrations, Report EUR16956 EN, Nuclear Safety and the
Environment, European Commission,Luxembourg (1996).15. Marsh, D.,
Radiation mapping and soil radioactivity in the Republic ofIreland,
MSc. Thesis, Trinity College, National University of Ireland,
Dublin (1991).16. RSC 2004, Summary Records [available online at
www.ospar.org, Zip File].17. Organo, C., Lee, E.M., Menezes, G.,
Finch, E.C., Investigation of the peat-fired power generation in
Ireland, NORM IV Conference, 16-21 May 2004,Szczyrk, Poland.18.
Smith, K.R., Crockett, G.M., Oatway, W.B., Harvey, M.P., Penfold,
J.S.S.,Mobbs, S.F., Radiological impact on the UK populations of
industries which use orproduce materials containing enhanced levels
of naturally occurring radionuclides:Part I: Coal-fired Electricity
Generation, Report NRPB-R327, National RadiologicalProtection
Board, Chilton, Didcot (2001).19. United Nations Scientific
Committee on the Effects of Atomic Radiation,Sources and Effects of
Ionizing Radiation. Report to the General Assembly, withScientific
Annexes. United Nations, New York (2000).20. Papp, Z., Dezso, Z.,
Daroczy, S., Significant radioactive contamination ofsoil around a
coal-fired thermal power plant. J. Environmental Radioact., 59:
191-205 (2002).21. Flues, M., Moraes, V., Mazzilli, B.P., The
influence of a coal-fired powerplant operation on radionuclide
concentrations in soil. J. of EnvironmentalRadioactivity, 63:
285-294 (2002).22. McAulay, I.R., Department of Physics, Trinity
College Dublin. Unpublisheddata (1986-1990).23. Electricity Supply
Board (ESB), Moneypoint, Personal Communication(2003).24. Lee,
E.M., Department of Physics, Trinity College Dublin,
PersonalCommunication (2002).Page 26 of 894NORM IV Conference May
2004, Szczyrk POLAND25. European Commission, Enhanced radioactivity
of building materials.Radiation Protection 96. Directorate-General
Environment, Luxembourg (1999).26. Bem, H., Wieczorkowski, P.,
Budzanowski, M. Evaluation of technologicallyenhanced natural
radiation near the coal-fired power plants in the Lodz region
ofPoland. J. of Environmental Radioactivity, 61: 191-201 (2002).27.
Petropoulos, N.P., Anagnostakis, M.J., Simopoulos, E.E.,
Photonattenuation, natural radioactivity content and radon
exhalation rate of buildingmaterials. J. of Environmental
Radioactivity, 61: 257-269 (2002).28. Beretka, J., Mathew, P.J.,
Natural radioactivity of Australian buildingmaterials, industrial
washes and by-products. Health Physics, 48(1): 87-95 (1985).29.
Meij, R., Emission testing including mass balances of
representative coalsat Moneypoint power stations, KEMA Report (TSA
Power Generation andSustainables), Arnhem (2003).30. Electricity
Supply Board (ESB), Nuclear Energy Board (NEB), Unpublisheddata
(1986-1990).31. European Commission, Practical use of the concepts
of clearance andexemption Part II Application of the concepts of
exemption and clearance tonatural radiation sources. Radiation
Protection 122. Directorate-GeneralEnvironment, Luxembourg
(2001).32. Huijbregts, W.M.M., de Jong, M.P., Timmermans, C.W.M.,
Hazardousaccumulation of radioactive lead on the water wall tubes
of coal-fired boilers. Anti-corrosion Methods and Materials, 7(5):
274-279 (2000).33. McCarthy, F., Electricity Supply Board (ESB),
Moneypoint, PersonalCommunication (2003).34. OGrady, J.,
Radioactivity and fertilisers. Technology Ireland,
24:41-45(1992).35. Ludgwig, T., Schwa, D., Seitz, G., Seikmann, H.,
Intakes of thorium whileusing thoriated tungsten electrodes for TIG
welding. Health Physics, 77(4): 462-469 (1999).36. OGrady, J.,
Hone, C., Turvey, F.J., Radiocaesium contamination at a steelplant
in Ireland. Health Physics, 70(4): 568 (1996).Page 27 of 894NORM IV
Conference May 2004, Szczyrk POLANDINVESTIGATION OF THE
PEAT-FIREDPOWER GENERATION IN IRELANDSEE ALSO: ABSTRACTC. Organo1,
E. M. Lee2, G. Menezes2 and E. C. Finch2e-mail: [email protected]
Radiological Protection Institute of Ireland, 3 Clonskeagh Square,
ClonskeaghRoad, Dublin 14, Ireland.2 Department of Physics, Trinity
College, Dublin 2, Ireland.AbstractAnnually, approximately 15% of
Irelands electricity requirement is providedthrough the combustion
of 3 106 tonnes of peat. While literature on the coal-firedpower
generation is quite abundant, studies on the peat-fired power
generationindustry from the radiological point of view are scarce.
A study of the largest Irishpeat-fired power plant was initiated to
review the potential occupational radiationexposures arising from
the occurrence of Naturally Occurring RadioactiveMaterials (NORM)
at different stages of the industrial process. Ambient gammadose
rate measurements, radon measurements, quantification of the
occupationalexposure from inhalation of airborne particles and
gamma spectrometry analysisof peat, peat ash and effluent samples
from the ash ponds were undertaken. Theresults indicate that the
plant workers are unlikely to receive a radiation doseabove 300 Sv
per annum over the typical working hours.Page 28 of 894NORM IV
Conference May 2004, Szczyrk POLAND1. IntroductionAround 90% of
human radiation exposure arises from natural sources such ascosmic
radiation, exposure to radon gas and terrestrial radiation.
However, someindustries processing natural resources may
concentrate radionuclides to adegree that they may pose risk to
both humans and the environment if they arenot controlled. In May
2000, legal controls were introduced in Ireland coveringwork
activities where the presence of natural radioactivity could lead
to the risk ofa significant increase in exposure to workers or
members of the public. Thesecontrols are set out in the
Radiological Protection Act, 1991 (Ionising Radiation)Order.
Statutory Instrument 125 of 2000 [1] and hereafter referred to as
S.I. 125 of2000, which implements the European Union Basic Safety
Standards Directive96/29/EURATOM [2]. Article 3 of S.I. 125 of 2000
in particular provides for theregulation of naturally occurring
radioactive materials in the workplace, mostly ofterrestrial origin
and hereafter referred to as NORM, if they are liable to give rise
toa radiation dose greater than 1 mSv in a year. In 2001, the
Radiological ProtectionInstitute of Ireland (RPII) initiated a
programme to identify industries currentlyactive in Ireland which,
on the basis of the literature, were considered liable toinvolve
work activities resulting in exposure to diffuse NORM sources. To
date,they include the gas extracting industry, the fossil fuel
(peat and coal) powerproduction and a range of industrial processes
using bulk materials with enhancedlevels of natural radioactivity
(e.g. bauxite refining). A joint study was designed incollaboration
with the Physics Department of Trinity College Dublin to
determinethe radioactivity levels in Irish peat and peat ash,
compare the results with similarstudies in other countries and with
national and international legislation andinvestigate the extent of
any radiation exposure of workers arising from thehandling, burning
and storage of peat ash. Environmental exposure to elevatedlevels
of radionuclides resulting from the gaseous emissions from the
stack wasnot investigated.Page 29 of 894NORM IV Conference May
2004, Szczyrk POLAND2. The Irish peat-fired power generationUntil
recently, up to nine peat-fired power plants were in operation in
Ireland. Bythe end of 2004, this generation of power stations built
between 1950 and theearly 80s will be replaced by two newly-built
power plants processing just over 2 106 tonnes of peat per annum
between the two of them. This study wasundertaken at the largest
existing peat-fired power station in the country,Shannonbridge. It
is located in the Midlands region (Figure 1) and has beenoperating
since 1965. The current plant consumes approximately 1.1-1.2
106tonnes of peat per annum and produces 125 MW of electricity. On
average, 20 to25 103 tonnes of peat ash are produced every year
(1/3 of the total ashproduced by all the Irish peat-fired plants).
Five million tonnes of ash are currentlylandfilled on site at the
plant. The Irish Peat Board (Bord na Mna) supplies themilled peat
to Shannonbridge from a local bog where it is mechanically
harvestedby scraping the top of the bog to a depth of up to 30 cm,
milled (72 mesh), solardried and transported to the power station
by light rail. Each convoy of 15 wagonscarries 75 tonnes of peat.
On arrival at the plant a tippler unloads each wagonsequentially
into a hopper from where the peat is transferred by conveyor
beltsinto the plant. At this stage, the peat is milled further into
a fine dust and blowninto the furnaces for combustion in suspension
at about 1,000-1,100C.Approximately 5-10% of the total ash produced
falls below the furnace as 'bottomash'. The remaining 90-95% passes
into the flue gas stream as 'fly ash'.Page 30 of 894NORM IV
Conference May 2004, Szczyrk POLANDFigure 1. Schematic sketch of
the Shannonbridge peat-fired power plant with locations of the
measurements undertaken and samples analyzedduring this study (the
scale of the objects are not respected) GDR = gamma dose rate
measurement, Rn = radon measurement. A map ofIreland is inserted to
show the location of Shannonbridge1. Wet ash pond: 1 GDR2. Effluent
from ash pond: 2 samples3. Bunker: 2 peat samples, 2 Rn and 2 GDR4.
Boilers: 2 GDR and 2 Rn5. Offices and workshop: 2 Rn6. Dry ash
pile: 2 GDR and 4 bottom ash samples7. Fly ash: 2 samples8.
Tippler: 1 peat samples, 1 Rn and 1 GDR9. Incoming peat from bog: 2
samples10. Control site (Shannonbridge church)outside the plant
perimeter: 1 GDR11. ChimneyPeat and peat ash fluxes through the
processPage 31 of 894River Shann153264789101NORM IV Conference May
2004, Szczyrk POLANDThis gaseous-particulate mixture leaves the
furnace and is drawn through a seriesof grit arrestors designed to
retain about 90% of the fly ash and any unburnedcarbon. At furnace
temperatures, some elements originally contained in the peatare
partly or completely evaporated. Between the furnace and the grit
arrestors,the gas and fly ash stream passes over banks of tubes
containing water or air togive a more efficient removal of the heat
from the gas prior to its emission toatmosphere. As the flue gases
cool down from 1,000 to 200C, the volatilizedelements condense onto
the fly ash particles, giving rise to an enrichment of
theirconcentrations in the fly ash trapped by the grit arrestors.
Only a small fraction ofthe fuel gases containing small quantities
of radionuclides in gaseous form passesthrough the grit arrestors
and is discharged through the stack to the atmosphere.Sampling of
fly ash is possible only when the boilers are not in operation.
Thenumber of samples that could be obtained was therefore limited.
InShannonbridge, the bottom ash is disposed of in 'wet' or 'dry'
conditions. Drybottom ash is produced by two of the three furnaces
in operation. It is transportedin a trailer attached to a tractor
to a dry ash pile. Wet bottom ash from the thirdfurnace is
hydraulically piped out by flexible tubing to two nearby wet ash
pondstogether with the totality of the fly ash trapped in the grit
arrestors. In the ponds,the ash resides in a 50% minimum aqueous
environment to minimize theproduction of airborne particles.3.
Materials and methodsGamma spectrometry analysis of peat, peat ash
and effluent samples collected atthe plant, airborne peat dust
analysis, aerial radon gas measurements andambient gamma dose rate
measurements were carried out. Samples for gammaspectrometry
analysis were counted in Marinelli geometry and analyzed using alow
background n-type HPGe GMX gamma-ray detector (relative efficiency
of34%, resolution of 2 keV (FWHM) at 1.33 MeV). Each sample was
counted for a24-hour period. Activity concentrations of 238U-series
radionuclides, 232Th, 40K andPage 32 of 894NORM IV Conference May
2004, Szczyrk POLAND137Cs were determined. Ra-226 activities were
ascertained using the two gamma-ray lines at 93 keV and 186 keV,
corrected for the interference of 235U at 186 keV.Th-232 was
determined from the gamma-ray emissions at 911, 969, 338, 965,795,
and 463 keV from 228Ac. K-40 and 137Cs activities were determined
from theirrespective lines at 1461 keV and 662 keV. Airborne peat
dust concentration wasmeasured in the plant to assess the potential
radiation dose through inhalation ofairborne particles. A
filtration sampling method (AEA Technology filter holder,Casella
London Ltd.) was used, where a known volume of air is drawn through
apre-weighed glass fibre filter paper (25 mm diameter, pore size 80
m) by meansof an air pump. On site, the filter holder was placed in
a static position atapproximately 1.60 m high (breathing zone
height). The flow rate of the pump wasset at 2 litres per minute
and the pump was allowed to run from 9.30 am until 5.15pm (standard
work shift). Passive long-term radon measurements were carried
outto determine if the concentrations exceeded the national
Reference Level forworkplaces, 400 Bqm-3 averaged over a minimum
period of 3-months. Passivealpha track detectors consisting of a
two-part polypropylene holder and a CR-39(poly allyl diglycol
carbonate) detection plastic were used. Upon completion of
themeasurements the tracks recorded on the plastics are analysed
and countedusing a Leitz Ergolux AMC microscope coupled to a Leica
Quantimet Q520 imageanalysis system. A track density is determined
for each plastic and converted intoradon concentration C (Bqm-3)
after subtraction of a fixed background value andtaking into
account a pre-determined calibration factor as well as the
exposureduration. A seasonal correction is applied to C when the
detectors are exposed forless than twelve months [3]. Gamma dose
rate measurements were carried outusing a NE Technology portable
gamma dose rate meter (type PDR1) and a MiniInstruments integrating
Geiger Mller-Background Monitor-Type 6-80 (GM6-80).Instantaneous
gamma dose rate readings were taken with the PDR1 meter andan
average value was calculated from the lowest and highest readings.
The GM6-80 meter was fixed to a tripod at each location for 1000
seconds. The readingswere converted to an ambient gamma dose rate
(Svhr-1) using a calibrationconversion table relevant to the
instrument.Page 33 of 894NORM IV Conference May 2004, Szczyrk
POLAND4. Results4.1. Peat, peat ash and effluent from the wet ash
pondIf the activity concentrations of radionuclides present in the
ash are significantthere could be a potential for increased
radiation exposure to workers handlingand working with the ash.
Radionuclide analysis of peat, bottom ash and fly ashfrom
Shannonbridge indicate a great variability of activity
concentrations (Table 1).In general, fly ash presents significantly
higher concentrations than the bottom ashin the U-series, while the
bottom ash contains more 40K than the fly ash. Table 2shows that
there is a wide range of activities between the fly ash produced
atdifferent peat-fired power stations in Ireland [8]. Compared with
other types ofNORM or with the average Irish soils, it is clear
that the peat and the peat ashproduced in Shannonbridge contain
lower levels of naturally occurringradionuclides.Page 34 of 894NORM
IV Conference May 2004, Szczyrk POLANDTable 1. Specific activities
of U-series radionuclides, 232Th, 40K and 137Cs (in Bqkg-1, dry
weight) measured in the peat, peat ash and effluent from theash
pond. Errors quoted are the counting uncertainties at one standard
deviation from the mean count. BDL = Below Detection Limit of 0.19
Bqkg-1Sample Type238U234Th226Ra214Pb210Pb232Th40K137CsPEATentering
plant 2.80.4 4.30.6 2.60.4 4.41.0 18.81.5 BDL 6.15.7 4.20.1entering
plant 4.00.3 2.00.2 1.80.1 0.50.1 5.00.6 0.40.0 BDL 2.20.1in
tippler 10.95.3 14.11.0 6.33.1 3.80.6 27.31.6 BDL 6.52.9 12.30.3in
bunker 7.43.9 10.81.0 5.42.8 2.20.4 37.82.6 BDL BDL 11.50.3dust in
bunker BDL 3.80.4 4.30.2 1.60.1 23.81.6 BDL BDL BDLMAX VAL 15 15 10
5 50 1 10 20FLY ASH301.213.9 306.35.8 28.91.4 59.20.9 225.910.4
7.270.4 66.52.0 67.51.052.11.4 115.17.6 32.20.9 41.76.3 297.014.9
BDL BDL BDLMAX VAL 300 300 50 70 350 10 50 50Page 35 of 894NORM IV
Conference May 2004, Szczyrk POLANDBOTTOMASH77.113.8 33.00.9
14.91.4 3.80.1 13.90.8 BDL 7.60.8 4.80.167.92.9 19.61.1 7.20.3
13.50.4 211.19.1 4.21.3 185.019104.01.632.13.2 29.32.9 19.32.0
9.80.2 167. 36.0 2.80.8 121.030 92.31.49.10.6 7.10.8 6.30.4 0.30.1
8.21.0 0.590.1 BDL BDLMAX VAL 100 50 20 20 250 5 200
150EFFLUENT0.310.1 2.90.5 BDL 0.50.1 3.00.3 BDL BDL 0.60.0BDL
1.10.1 0.70.1 BDL 0.270.2 BDL BDL BDLPage 36 of 894NORM IV
Conference May 2004, Szczyrk POLANDTable 2. Comparison of the
results from this study and other references in the
literature(activity concentrations in Bqkg-1)Sample
Type238U234Th226Ra210Pb232Th40K137Cs ReferencesRAWMATERIAL Irish
peat 15 15 10 50 1 10 20 This studyFinnish peat 16 11 30 5.3 28 27
[4]Coal Moneypoint19 (5-45)30 (6-67)14 (4-27)8 (2-13)61
(20-100)[5]Coal UK 15 15 15 15 7.5 144 [6]Coal worldaverage24 22
100[7]FLY ASHThis study 300 300 50 350 10 50 50 This
studyPeatShannonbridge133 71 7 32 130[8]Peat Ferbane 290 121 11 112
20 [8]PeatLanesborough74 68 14 263 79[8]Peat Rhode 121 127 8 57 127
[8]Peat Bellacorick 38 31 10 153 47 [8]Peat Finland 120 46 390
[9]Coal Moneypoint 110 156 79 68 445 [5]Coal UK 100 100 100 100-200
50 900 [5]BOTTOM ASHThis study 100 50 20 250 5 200 150 This
studyCoal Moneypoint 73 84 23 43 307 [5]Coal worldaverage85 61
510[6]OTHER NORMPage 37 of 894NORM IV Conference May 2004, Szczyrk
POLANDBauxite Bok 78 110 [10]Bauxite 400-600400-600[11]Red mud
260-540340-500[12]Red mud 250 300 [13]Phosphogypsum 1000
[14]Phosphate ore 30-500020-2000 3-200[11]Zircon
sands3000-400010000[11]Average Irishsoils46 25 418[15]With regard
to the radioactivity enhancement in the fly ash and the bottom
asharising from the combustion process, some radionuclide
concentrations could beenhanced by a factor 20 to 25 compared with
concentrations in the original peatas indicated in [16]. Pb-210
shows the largest enrichment onto small fly ashparticles (< 1.3
m) according to Mustonen and Jantunen [4], indicating a
volatilebehaviour at the furnace temperature. Enrichment factors
(EF) for differentradionuclides can be calculated using the
formula:peatpeat rashash rRacRacEF] [] [] [] [226 226=(1)where [cr]
and [226Ra] are the activity concentrations of a potentially
enriched (ordepleted) radionuclide r and 226Ra, respectively.
Ra-226 is used as a referencenuclide because of its non-volatile
nature at furnace temperature [4]. To simplifythe calculations, a
single activity concentration for each radionuclide in the peat,
inthe fly ash and in the bottom ash was assumed by rounding up to
the maximumconcentration measured (conservative end of the range of
concentrationsmeasured). The values are displayed in italics in
Table 1 where they are quotedas MAX VAL. EF values in the fly ash
were calculated to be 1.4, 4, 2, 1 and 0.5 forPage 38 of 894NORM IV
Conference May 2004, Szczyrk POLAND210Pb, 238U, 232Th, 40K and
137Cs, respectively. For the same radionuclides, EFvalues in the
bottom ash are 2.5, 3.3, 2.5, 10 and 3.75.4.2. Airborne dust
concentrationThe dustiest location of the plant was found to be the
bunker, an indoor-type ofwarehouse where a 4-hour supply of milled
peat is temporarily stored at any timebefore it is fed into the
mills. In this area, employees are carrying out dry sweepingduties
of spilled peat dust, regularly generating large amounts of fine
airbornedust. A single air sampling experiment over an 8-hour
working shift was carriedout during which the dust concentration
was measured at 25.6 mgm-3. This is verysignificant in terms of
occupational dust exposure (the Irish OccupationalExposure Limit
(OEL) for nuisance dust is set at 10 mgm-3 [17]). Employeesworking
in this area are required to wear personal protection equipment
(PPE)including protective clothing and a face dust mask. They also
only work in thislocation for very short periods of time.4.3. Radon
gasIn industries dealing with diffuse NORM an important radiation
exposure pathwaycan be radon and radon daughters inhalation from
storage of large volume ofmaterials. This is because these
materials are often crushed or powdered beforethey are processed
(allowing for radon to escape more easily from the matrix) andmay
be stored in poorly ventilated spaces (allowing radon
concentrations to buildup). The associated radiation dose may
substantially vary as it is stronglydependent on a wide range of
parameters such as the emanating fraction, thedose equilibrium
factor, the dose conversion factor, the ventilation rate, the
roomsize, the surface to volume ratio and the diffusion
coefficients [13]. Two radonsurveys were carried out in
Shannonbridge over the last 8 years and the resultsare displayed in
Table 3. Not only are all the measurements below 400 Bqm-3, butPage
39 of 894NORM IV Conference May 2004, Szczyrk POLANDthey are all
similar to outdoor radon concentrations commonly measured
inIreland. As such, they are of no radiological significance from
the point of view ofradon occupational exposure.Table 3. Results of
passive long-term radon measurements carried out in
theShannonbridge peat-fired power plant and associated effective
dose (Svy-1); (1) Based onthe characteristics of each work practice
on site; (2) Employees in the maintenance roomspend the whole
working year at this location; (3) ICRP 65 [18] dose coefficients
and F factorof 0.4 used for the calculations; (4) Calculated
assuming a maximum radon concentration of15 Bqm-3 in the boiler
roomLocationMeasurementperiodRadonconcentration
(Bqm-3)Assumedexposureduration (hy-1)(1)Effective
dosefromradoninhalation(Svy-1) (3)Maintenance room02/1995 to05/1996
17 2000 (2) 110Conference room02/1995 to05/1996 33 20 2Tippler
area12/2002 to03/2003 11 100 3Bunker12/2002 to03/2003 12 100
4Control room inbunker12/2002 to03/2003 10 0 (unoccupied) 0Boiler 1
12/2002 to 03/2003 10Boiler 2 12/2002 to 03/2003 15680 32 (4)4.4.
Ambient gamma dose rate measurementsThe locations of the
measurements carried out are displayed on Figure 1 and theresults
are shown in Table 4. Page 40 of 894NORM IV Conference May 2004,
Szczyrk POLANDTable 4. Ambient gamma dose rate measurements at the
Shannonbridge peat-fired powerplant and associated effective dose
(Svy-1); (1) [15]; (2) Based on the characteristics ofeach work
practice on siteLocationsDose rate recorded(Svh-1)PDR1
GM6-80Assumedexposureduration (hy-1)(2)Effectivedose(Svy-1)Tippler
area 0.06 0.06 100 6Bunker area 0.08 0.06 100 8Boiler 1 Bottom ash
area 0.12 0.07 340 41Boiler 2 Bottom ash area 0.18 0.07 340
61Bottom ash pile (inactive disposalarea) 0.08 0.07 50 4Bottom ash
pile (active disposalarea) 0.08 0.07 500 40Wet ash pond 0.13 0.06
400 52Control measurement (outsideplant)0.13 0.07 2000 260Irish
average (1) 0.03 (absorbed doserate in air 33 nGyh-1)2000 66The
values given by the two dose rate meters are in good agreement and
rangefrom 0.06 to 0.18 Svh-1. They are not significantly different
from the ambientgamma dose rate recorded outside the perimeter of
the plant and used as acontrol measurement of the natural
background (0.07 0.13 Svh-1). More thanlikely, the readings given
by the GM6-80 (0.07 Svh-1 on average) give a betteridea of the real
situation as these are integrated counts over 20 minutes instead
ofPage 41 of 894NORM IV Conference May 2004, Szczyrk
POLANDinstantaneous values given by the PDR1 (0.10 Svh-1 on
average). In Ireland, theaverage absorbed dose rate in air is 33
nGyh-1, with a range of 2 to 110 nGyh-1[15]. Using a conversion
factor of 1 SvGy-1 [7], it leads to an average effectivedose for
adults of 0.03 Svh-1 (range of 2 103 to 0.11 Svh-1). Therefore,
thedose rates measured in Shannonbridge are within the range of
natural variations,although clearly in the upper part of this
range.5. Discussion5.1. Peat harvestingRadiation dose arising from
exposure to external gamma radiation of terrestrialorigin for
workers involved in the harvesting of the peat all year round
should belower than the natural background value. It should also be
lower than the dosearising from a normal outdoor work activity.
This is because activityconcentrations measured in the raw peat are
lower than in average Irish soils.Harvesting is carried out in
open-air by machineries and workers are wearingfacial masks and
protective clothing to protect them from any windborne peatdust.
Radiation dose arising from inhalation of peat dust is therefore
minimized.5.2. Enrichment factorsEnrichment factors calculated in
this study are not significant compared to otherpublished values
[16]. It is recognised that the levels of enhancement
ofradionuclide concentrations in ash are very variable. This is
mostly due todifferences in the raw peat, the type of furnace, the
combustion temperature andthe operational characteristics of the
plant [6]. For example, the temperature in thefurnace at
Shannonbridge is 1000-1100C, which is lower than the
combustiontemperature of 1250-1350C quoted in Mustonen and Jantunen
[4].Page 42 of 894NORM IV Conference May 2004, Szczyrk POLAND5.3.
Inhalation of airborne peat dust in the bunkerRadiological
assessments usually refer to the inhalation of contaminated dust as
amajor pathway by which workers dealing with NORM are likely to be
receiving thelargest radiation dose. Calculations were undertaken
to determine the committedeffective dose arising from inhalation of
peat dust likely to be received by anemployee in the bunker over
the working year. A sample of airborne peat dust thathad settled on
shelving adjacent to the personal sampling pump was collectedand
analyzed by gamma spectrometry. This enabled the amount and type
ofradionuclides likely to be in the airborne peat dust to be
determined (Table 1, dustin bunker). The committed effective dose
from inhalation of peat dust wascalculated using the formula:( ) =
r r inh inh c g V t D, exp(2)where texp is the exposure duration
(assumed to be 100 hours over the year), V isthe breathing rate
(1.18 m3h-1 for light work, [6]), ginh,r is the inhalation dose
factorfor the nuclide r (in SvBq-1, [19]) and cr is the ambient air
activity concentration forthe radionuclide r (Bqm-3). Results of
the calculations are shown in Table 5. Thecommitted effective dose
resulting from inhalation of peat dust in the bunker overthe
working year is less than 1 Sv (0.89 Svy-1) and therefore
insignificant. Itshould be noted that this dose is the maximum
likely to be received by any workeras it was calculated assuming no
PPE.Page 43 of 894NORM IV Conference May 2004, Szczyrk POLANDTable
5. Committed effective dose from inhalation of airborne peat dust
in the bunker area;(1) See Table 1. 210Pb and 210Po are assumed to
be in equilibrium; (2) Dust concentration isequal to A / v where A
is the amount of peat dust breathed in during an 8-hour shift
(23.78mg) and v is the flow rate of the pump (2 lmin) multiplied by
the duration of the experiment(465 min) and divided by 1000; (3)
Ambient air activity concentration for the radionuclide r(Bqm-3) is
the product of the assumed activity concentration by the dust
concentration; (4)Inhalation dose factor for the nuclide r (AMAD 5
m, [19])Radionuclide r226Ra210Pb210Po228Ra228Th UnitAssumed
activityconcentrations in peat dust(1)15 50 50 1 1 Bqkg-1Dust
concentration (2) 25.6 mgm-3cr (3)
3.810412.810412.81042.61052.56105Bqm-3ginh,r (4)
1.21051.11067.11071.71062.3105SvBq-1ginh,r cr
4.61091.41099.110104.310115.91010Svm-3 ginh,r cr 7.5
109Svm-3Exposure duration texp 100 hy-1Breathing rate V 1.18
m3h-1Dinh 0.89 Svy-15.4. Radon and radon daughters
inhalationAnother significant exposure pathway in workplaces where
NORM materials areprocessed is radon inhalation from storage of
important quantities of materials in awarehouse [20]. In our case,
it could be possible that the peat (bunker area) andpeat ash
(bottom ash in the boiler area) stored onsite may contribute
significantlyto the total occupational exposure due to the
quantities involved. Anotherexposure situation which would arise
from large quantities of fly ash stored in anPage 44 of 894NORM IV
Conference May 2004, Szczyrk POLANDenclosed space would be the
cleaning of the grit arrestors or the freeing ofblockages in the
hoppers. The radiological assessment of these work activitieswas
not carried out as they did not occur at the time of our site
visits. Thismaintenance work would arise 3 times in a year
approximately, would take up to 5days to be completed and would be
undertaken under very strict conditions(obligation to wear
respiratory equipment, over clothing, gloves, etc) using
watersprays for dust suppression. The annual effective dose from
inhalation of radonand radon daughters at different locations
throughout the plant (Figure 1) wascalculated for the levels
measured across the plant and by taking into account theexposure
duration at each location (Table 3). The highest dose calculated
wouldbe received in the maintenance room and is 0.11 mSvy-1, which
is only 10% of theannual limit under S.I. 125 of 2000.5.5. Exposure
to external gamma radiation in the plant and on the
landfillsitesThe annual effective dose arising from exposure to
external gamma radiation wascalculated on the basis of the maximum
dose rate measured at each location inthe plant (Figure 1)
multiplied by the exposure duration at each location (Table 4),They
are all below the annual effective dose calculated for the control
site(Shannonbridge church).Page 45 of 894NORM IV Conference May
2004, Szczyrk POLAND6. ConclusionsTable 6 summarises all the doses
arising from different pathways calculated in theframework of this
study.Table 6. Occupational radiation doses calculated for workers
at Shannonbridge; (1)calculated assuming outdoor radon
concentration of 10 Bqm-3 [7] and a F factor of 0.8(instead of 0.4
indoors)Location / exposuredurationDustinhalation(Sv)Inhalation
ofradon andprogeny (Sv)External gammairradiation
(Sv)TOTAL(Sv)Tippler / 100 hy-13 6 9Bunker area / 100 hy-10.89 4 8
13Boiler area / 680 hy-132 102 134Bottom ash pile(inactive) / 50
hy-13 (1) 4 7Bottom ash pile (active) /500 hy-132 (1) 40 72Wet ash
pond / 400 hy-125 (1) 52 77Maintenance duties / 170hy-1undetermined
undetermined undeterminedundeterminedTOTAL / 2000 hy-1312The total
annual effective dose likely to be received by a worker involved in
theprocessing of the peat and handling of the peat ash in
Shannonbridge isapproximately 0.3 mSv (312 Sv). The exposure
pathways taken into account arethe peat dust inhalation in the
bunker area, the inhalation of radon and radonprogeny and the
external gamma irradiation at different locations in the plant.Page
46 of 894NORM IV Conference May 2004, Szczyrk POLANDTherefore, most
of the exposure situations where workers are involved on aregular
basis are covered, with the exception of maintenance duties like
thecleaning of the hoppers and the freeing of blockages in the grit
arrestors. Theseduties are the only ones where workers are directly
in contact with the peat flyash. One would not expect the annual
effective dose associated with these dutiesto be significant as
this type of work is always carried out with PPE, is undertakenin
wet conditions, occurs non-routinely (3 times in a year) and is
usually completedwithin a week. Another exposure situation not
covered in this study is theinhalation of peat ash dust on the
landfill sites arising from the generation ofwindborne ash on the
ash pond. However the top layer of the pond, when driedout, usually
forms a crust underneath which the ash is trapped. It is
thereforeunlikely to be wind blown.References1. Stationery Office,
Radiological Protection Act, 1991 (Ionising Radiation)Order.
Statutory Instrument 125 of 2000, Department of Public
Enterprise,Government Publications Office, Dublin (2000).2. Council
of the European Union, Basic Safety Standards for the
HealthProtection of the General Public and Workers Against the
Dangers of IonisingRadiation, Council Directive 96/29/EURATOM,
Luxembourg (1996).3. Madden, J.S., Radon in dwellings in selected
areas of Ireland, Report RPII-94/3, Radiological Protection
Institute of Ireland, Dublin (1994).4. Mustonen, R., Jantunen, M.,
Radioactivity of size fractionated fly-ashemissions from a peat-
and oil-fired power plant. Health Physics, 49:1251-1260,(1985).5.
McAulay, I.R., Department of Physics, Trinity College Dublin.
Unpublisheddata (1986-1990) 6. Smith, K.R., Crockett, G.M., Oatway,
W.B., Harvey, M.P., Penfold, J.S.S.,Mobbs, S.F., Radiological
impact on the UK populations of industries which use orPage 47 of
894NORM IV Conference May 2004, Szczyrk POLANDproduce materials
containing enhanced levels of naturally occurring
radionuclides:Part I: Coal-fired Electricity Generation, Report
NRPB-R327, National RadiologicalProtection Board, Chilton, Didcot
(2001).7. United Nations Scientific Committee on the Effects of
Atomic Radiation,Sources and Effects of Ionizing Radiation. Report
to the General Assembly, withScientific Annexes. United Nations,
New York (2000).8. Finch, E.C., A radiological analysis of peat ash
samples supplied by ESBInternational, Unpublished report to the
Electricity Supply Board, Trinity College,Ireland (1998).9.
Mustonen, R., Building Materials as sources of indoor exposure to
ionisingradiation. Report STUK-A105, Strlskerhetscentralen,
Helsinki (1992).10. Von Philipsborn, H., Kuhnast, E., Gamma
spectrometric characterisation ofindustrially used African and
Australian bauxites and their red mud tailings. Rad.Prot. Dos.,
45:741-744, (1992).11. International Atomic Energy Agency,
Radioactivity in material not requiringregulation for purposes of
radiation protection, Draft Safety Guide DS-161, SafetyStandards
Series, IAEA, Vienna (2003).12. European Commission, Practical use
of the concepts of clearance andexemption Part II Application of
the concepts of exemption and clearance tonatural radiation
sources. Radiation Protection 122. EC
Directorate-GeneralEnvironment, Luxembourg (2001).13. Hofmann, J.,
Leicht, R., Wingender, H.J., Worner, J., Natural
radionuclideconcentrations in materials processed in the chemical
industry and the relatedradiological impact, Report EUR 19264,
Nuclear Safety and the Environment,European Commission, Luxembourg
(2000).14. OGrady, J., Radioactivity and fertilisers. Technology
Ireland, 24:41-45,(1992).15. Marsh, D., Radiation mapping and soil
radioactivity in the Republic ofIreland, MSc. Thesis, Trinity
College, National University of Ireland, Dublin (1991).16. European
Commission, Enhanced radioactivity of building materials.Radiation
Protection 96. EC Directorate-General Environment,
Luxembourg(1999).Page 48 of 894NORM IV Conference May 2004, Szczyrk
POLAND17. National Authority for Occupational Safety and Health,
Code of Practice forthe Safety Health and Welfare at Work (Chemical
Agents) Regulations 2001,Government Publications Office, Dublin
(2002).18. International Commission on Radiological Protection,
Protection againstRadon-222 at home and at work. Publication 65.
Annals of the ICRP, 23, No. 2,Pergamon Press, Oxford (1994).19.
International Commission on Radiological Protection, Dose
coefficients forintakes of radionuclides by workers. Publication
68. Annals of the ICRP, 24, No. 4,Pergamon Press, Oxford (1994).20.
Penfold, J.S.S., Mobbs, S.F., Degrange, J.P., Schneider, T.,
Establishmentof reference levels for regulatory control of
workplaces where materials areprocessed which contain enhanced
levels of naturally-occurring radionuclides.Radiation Protection
107. EC Directorate-General Environment, Luxembourg(1999).Page 49
of 894NORM IV Conference May 2004, Szczyrk POLANDEXPOSURE FROM AN
IGNEOUS PHOSPHATEMINE OPERATIONSEE ALSO: ABSTRACTAJ vd
WesthuizenTechnical Manager: Radiation Protection &
AuditingNOSA InternationalPO Box 26434Pretoria0007South
Africae-mail: [email protected] facility under
discussion is a South African Open Cast Mine that producesigneous
phosphate rock, with intermediate and final products for the
domestic andinternational markets. It provides the following
strategic advantages:Make South Africa self-sufficient from
phosphate imports.Earn foreign currency from the export of the
mineral.Page 50 of 894NORM IV Conference May 2004, Szczyrk
POLANDCreate approximately 2000 direct job opportunities, with
associated indirect jobopportunities in the Greater Phalaborwa
region. Approximately 3.0 million tons of phosphate rock is
produced annually and theproduct is a finely ground apatite mineral
from a coarsely crystalline calcium-fluoride-phosphate compound of
magmatic origin. The mine is located adjacent to the towns of
Phalaborwa, Namakgale andLulekani, bordering on the Kruger National
Park in the Limpopo Province. The company obtained a Nuclear
Authorisation in terms of the South AfricanNuclear Energy Act, No
131 of 1993 in 1993 and has been holder of anauthorisation since.
It changed in 2002 to a Certificate of Registration, issuedunder
the auspices of the National Nuclear Regulatory Act, No 47 of
1999.Page 51 of 894NORM IV Conference May 2004, Szczyrk
POLANDPRODUCTION PROCESSThe following is a simplified diagram of
the mining and beneficiation process.Open Cast MineCrushingTailings
from neighboringmineWet MillingFlotationDispatchDry
MillingFlotationFiltrationDryingOld Production Line New Production
LineInterim Storage Interim StorageInterim StorageTailings
DamsTransport by trucksWaste Rock DumpsOverburdenTailingsTailings
ProductSPECIFIC ACTIVITYTable 2.2-1 below summarises the known
specific activities of the major sourcesof material involved in the
process, e.g. Phosphate Rock and Phosphate Tailings.Page 52 of
894NORM IV Conference May 2004, Szczyrk POLANDTable 3-1: Nuclide
specific activity of the process materialNuclideSpecific Activity
(Bq.g-1)Phosphate Rock TailingsU-238 0.14 0.26Ra-226 0.14
0.27Pb-210 0.12Th-232 0.47 0.31Ra-228 0.55 0.33Th-228 0.55
0.35ISOTOPES CONSIDERED The following isotopes were considered in
the assessment process.Table 4-1 Isotopes of the natural decay
series used in the calculation of the doseconversion factorUranium
- Series Actinium - Series Thorium SeriesU-238 U-235 Th-232U-234
Pa-231 Ra-228Th-230 Ac-227 Th-228Ra-226 Th-227 Ra-224Pb-210 Ra-223
Bi-212Po-210The National Nuclear Regulator does not generally
require the inclusion of U-235and daughter isotopes in the
assessment process and for the initial screeningsurvey, it was
excluded. However, where the gross alpha activity is used for
dosedetermination, it was deemed appropriate to include the
Actinium Series whencalculating its dose conversion factor as it
may have a measurable effect. Page 53 of 894NORM IV Conference May
2004, Szczyrk POLANDMETHODOLOGYOccupational ExposureOccupational
exposure consisted of two pathways for the purpose of
thisassessment, namely External Exposure from the gamma component
andInhalation [1, 2]. Ingestion was excluded, as it is not a
regulatory requirement inSouth Africa. The external exposure was
measured at various locations in aspecific section and the doserate
at 1 meter used in this assessment process.Two methods of
determining internal dose were used to calculate the
occupationaldose, one more suitable for screening assessment
purposes and the other a morerealistic calculation.Method 1The
screening assessment utilized area air concentrations as collected
though anOccupational Hygiene program and the average isotope
specific activity ofphosphate or tailings (See Table 3-1). An
occupancy factor of 1 is used, alsoassuming 250 shifts per year,
each lasting 9.5 hours.Method 2The assessment was repeated but
base
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