2015 Q3 Environmental (redacted).pdf

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DISTRIBUTION

Head of Health Physics and Chemistry (1 copy)

4 copies for distribution to:

1. Environment Agency Site Inspector (Email)

2. Natural Resources Wales (Email)

3.

Head of Radiological Protection and Research Management, Food Standards Agency (Email)4. Head of Profession-Environment (Email)

Original report to be filed in Dosimetry Office.


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ENVIRONMENTAL MONITORING PROGRAMME RESULTS

3rd

QUARTER 2015

C O N T E N T S

SECTION TITLE PAGE NO

1. PURPOSE 1

2. SCOPE 1

3. RESPONSIBILITIES 1

4. PROCEDURE 1

5. NOTEWORTHY RESULTS 3

6. UNCERTAINTIES 3

7. DEFINITIONS 4

8. REFERENCES 4

9. RECORDS 4

Appendix A Terrestrial Programme: Environmental TLD Results

Appendix B Terrestrial Programme: Environmental Gamma Doserates

Appendix C Terrestrial Programme: Passive Shade Gamma Activity Analysis

Appendix D Terrestrial Programme: Milk Activity Analysis

Appendix E Terrestrial Programme: Herbage Activity Analysis

Appendix F Terrestrial Programme: Soil Core Activity Analysis

Appendix G Marine Programme: Beach Gamma Doserate Monitoring

Appendix H Marine Programme: Marine Samples Activity Analysis

Appendix I Marine Programme: Fishing Equipment Monitoring

Appendix J Initial Assessment of Uncertainties


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ENVIRONMENTAL MONITORING PROGRAMME RESULTS

3rd

QUARTER 2015

1. PURPOSE

This report provides the results of the programme of environmental monitoring for radioactivity

around the Wylfa site, to ensure compliance with the conditions within the Environmental Permit(ref. 1) issued by the Environment Agency (EA) and the Environmental Permit (ref. 5) issued by

Natural Resources Wales (NRW) for Wylfa Power Station under the Environmental Permitting

(England & Wales) Regulations 2010.

2. SCOPE

This report covers all statutory environmental monitoring identified by the Environment Agency in

the Compilation of Environment Agency Requirements, Approvals and Specifications (CEARAS)

(ref. 2) as in force at the time of sampling and analysis for the 3rd

Quarter 2015.

3. RESPONSIBILITIES

3.1 The Head of Health Physics and Chemistry is responsible for reviewing and authorising this

report and for the provision of expert advice on the monitoring of radioactivity in the vicinity

of the Wylfa site.

4. PROCEDURE

All environmental monitoring was carried out in accordance with the procedures listed in the Wylfa

Power Station Health Physics Departmental Instruction WYA/RHI/017/005 “Management of the

Environmental Monitoring Programme” (ref. 3), with the exception of Soil Core reporting which has

been completed in accordance with the previous CEARAS (ref. 2). Further details can be found in

Appendix F.

All reasonably practicable measures have been taken to achieve the detection limits specified in the

CEARAS. Unless otherwise noted, all positive results (i.e. those exceeding the detection limit) are

quoted with uncertainties at the 95% confidence level based upon counting statistics only. Where

results are less than, or equal to, the detection limit, the detection limit value has been reported. If any

result has exceeded the mean of the previous 12 results plus 3 standard deviations then this will be

noted in the “remarks” column of a particular sample, and, as far as reasonably practicable, an

explanation provided for any such value.

Analysis is carried out locally at the station or at a Contract Laboratory. All analytical methods are

validated and controlled in a manner consistent with the requirements of ISO 17025 that are specified

in the CEARAS.

4.1 Terrestrial Environmental Monitoring Programme

The terrestrial programme includes measurements of radiation dose rates over pasture,

radiation doses at the site perimeter fence and at set distances from the station, passive shade

deposition collectors, grass samples, soil cores and milk samples.

4.1.1 TLDs are deployed quarterly at locations on the perimeter fence with one TLD per 30°

sector, and in three arcs around Wylfa; at approx. 5, 10 and 30 km distances with at


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least one per 30° sector. Exposed TLDs are sent to the Approved Dosimetry Service for

processing and analysis. Previous results used a Vinten TLD, but following a period of

inter-comparison, the reported results are now the Harshaw type TLD only. The results

are listed in Appendix A.

4.1.2 Quarterly doserate measurements are carried out using a Mini 6-80/MC70 at 9 or more

inner (3km) locations, and 9 or more outer (10km) locations. The dose rate (nGy/h) is a

measurement of air kerma rate in the environment due to natural terrestrialradioactivity, cosmic contribution, inherent instrument background and man-made

sources (WYA/RHI/017/005 (ref. 3) and TGN-M5 refer (ref. 4)).

The results are listed in Appendix B (Environmental Gamma Doserate measurements).

4.1.3 Passive shades are deployed at eight sites (two shades per site) in two arcs at

approximately 1km and 10km. The shades are collected monthly and analysed by

Gamma Spectrometry at Wylfa. The results are listed in Appendix C.

4.1.4 A sample of milk is collected from each farm on a quarterly basis. The samples are then

analysed by gamma spectrometry at Wylfa. Quarterly samples are bulked to give Inner(farms 1,3 & 4) and Outer (farms 5-8) quarterly samples which are sent to the Contract

Laboratory for quarterly Sulphur 35 analysis and annual Carbon 14 analysis (completed

in Quarter 2). The results are listed in Appendix D.

4.1.5 Grass (herbage) samples are collected from the inner four farm sites and Wylfa Head

(the nearest site to the station) once per quarter and are analysed by gamma

spectrometry. A bulked sample is forwarded to the Contract Laboratory, for quarterly

Sulphur-35 analysis and annual Carbon-14 analysis (completed in Quarter 2). The

results are listed in Appendix E.

4.1.6 Soil cores are collected from one of the herbage locations once per annum, and are

analysed by gamma spectrometry and for gross beta activity. The results are listed inAppendix F.

4.2 Marine Environmental Monitoring Programme

The marine programme includes measurements of radiation dose rates over shoreline or

sediment, measurements of contamination of fishing equipment and the beach and analysis of

seaweed, sediment, fish, crustacean, and mollusc samples.

4.2.1 Quarterly spot gamma radiation dose rates were measured at 5 or more Beach sites (as

evenly spaced as far as practicable, with at least two locations either side of the

station). The results are listed in Appendix G.

4.2.2 Six monthly contamination surveys of the strandline at Porth yr Ogof are conducted

using portable contamination monitors. The results of the next survey will be reported

in the 4th quarter 2015.

4.2.3 Marine sediment samples are collected quarterly and are analysed by gamma

spectrometry and for gross beta activity. The results are listed in Appendix H.

4.2.4 Seaweed, Fish, crustacean and mollusc samples are collected from local fishermen on a

quarterly basis, when available, and are analysed by gamma spectrometry and for gross

beta activity. The results are listed in Appendix H.

4.2.5 Annual contamination monitoring of fishing equipment used by local fishermen is


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carried out using a contamination probe and ratemeter. The results are listed in

Appendix I.

5. NOTEWORTHY RESULTS

The Am-241 activity in the sample of Silt from Cemaes has exceeded the mean plus 4 standard

deviations of the previous 12 results. The Cs-137 activity in the same sample, and the sample of

seaweed from Cemlyn, exceeds the mean plus 3 standard deviations of the previous 12 results. Theactivity in the Cemlyn Seaweed is below the required detection limit, and therefore by implication, of

no regulatory concern.

The silt sample from Cemlyn historically has higher levels of Am-241 and Cs-137, and the activity in

the Q3 2015 Cemlyn silt sample is quite typical. The Am-241 activity in the Cemaes silt sample is

similar to the Am-241 activity in the Cemlyn silt sample, and the Cs-137 activity is less than half the

Cs-137 activity in the Cemlyn silt sample. The activity observed in the Cemlyn silt is generally not

considered to be attributed to the site but instead thought to more likely originate from Sellafield. If

the Cemaes activity had originated from the site we would have expected to see an increase in

activity at Cemlyn also, as this is the closer and more likely location to observe such an increase.

6. UNCERTAINTIES

Requirement No. 4.2.2/P2/v002 of the Wylfa site Compilation of Environment Agencies

Requirements, Approvals and Specifications (CEARAS) that accompanies Permit No.

EPR/GB3235DL/V002, newly issued on 11th November 2015, requires that the operator reports the

results of the environmental monitoring programme in accordance with the following:

“…all positive results (i.e. those exceeding the detection limit) shall be reported with an uncertainty

which is at the 95% confidence level (i.e. 1.96 standard deviations) and includes all analytical

uncertainties in accordance with ISO 17025…..”

Historically, uncertainties have been either reported as counting uncertainty alone or directly as

reported from contract laboratories. In order to meet the requirement of the new CEARAS, an initialassessment of all uncertainties has been carried out and is included as Appendix J of this report.

The methods for identifying and combining uncertainty employed are in line with those detailed

within ‘M3003 – The expression of Uncertainty and Confidence in Measurement’. All numbers,

where quoted within the table in Appendix J, are at the 95% confidence level.

In order to provide a bounding estimate of uncertainty, the random component has been evaluated.

Where available and applicable, data such as K-40 has been trended to provide an estimate of the

random uncertainty in other nuclides for the same reportable quantity. When no applicable reference

data is identifiable, then the data itself has been trended to provide a bounding estimate of

uncertainty. It is recognised that this will overestimate the random component due to spatial andtemporal variations in sampling.

For the majority of reportable quantities, the dominant component is in fact the random component.

There may be scope for refining this parameter in future if relevant data sets can be identified from

which trending can be undertaken. The next most significant quantity is generally the Counting

Uncertainty. This is typically reported on gamma spectrometry software and there exists little scope

for further refinement. Other quantities such as instrument calibration, source calibration, weight or

area measurements offer only a minor contribution to combined uncertainty.

Where contract laboratories are employed, the reports provided contain an uncertainty according to

the relevant accreditation standard for the measured quantity. To provide a total uncertainty, this

number is then combined with the random uncertainty.


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7. DEFINITIONS

Where “N/A” is noted under results, it indicates that the quantity is “not applicable” for the sample

type or not required to be performed in this quarter (“not assessed”).

Where “N/S” is noted under results, no sample was available from the location or for the sample type.

8. REFERENCES

1. Environment Agency Environmental Permit Number EPR/GB3235DL/V001

2. Compilation of Environment Agency Requirements, Approvals and Specifications (made under

Permit number EPR/GB3235DL/V001) Issue 1.

3. WYA/RHI/017/005 – “Management of the Environmental Monitoring Programme”.

4. Routine Measurement of Gamma Ray Air Kerma Rate in the Environment - Technical Guidance

Note (Monitoring) M5, HMIP, September 1995.

5. Natural Resources Wales Environmental Permit Number EPR/GB3235DL/V002

9. RECORDS

This Technical Report is the statutory record of environmental monitoring results.


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Site Exposure Exposure Exposure Exposure Exposure

Start End Period (µSv) (µSv/day)

W1 25/07/2015 10/10/2015 77.00 175.38 2.28

W2 25/07/2015 10/10/2015 77.00 188.49 2.45

W3 25/07/2015 10/10/2015 77.00 151.13 1.96

W4 25/07/2015 10/10/2015 77.00 183.19 2.38

W5 25/07/2015 10/10/2015 77.00 173.78 2.26

W6 25/07/2015 10/10/2015 77.00 194.22 2.52

W7 25/07/2015 10/10/2015 77.00 248.83 3.23

W8 25/07/2015 10/10/2015 77.00 193.71 2.52

W9 25/07/2015 10/10/2015 77.00 169.63 2.20

W10 25/07/2015 10/10/2015 77.00 198.34 2.58

W11 25/07/2015 10/10/2015 77.00 171.05 2.22

W12 25/07/2015 10/10/2015 77.00 174.35 2.26

W13 25/07/2015 10/10/2015 77.00 206.09 2.68

W14 25/07/2015 10/10/2015 77.00 175.77 2.28W15 25/07/2015 10/10/2015 77.00 172.41 2.24

W16 25/07/2015 10/10/2015 77.00 170.33 2.21

W17 28/07/2015 10/10/2015 74.00 153.89 2.08

W18 25/07/2015 10/10/2015 77.00 226.44 2.94

W19 25/07/2015 10/10/2015 77.00 191.90 2.49

W20 26/07/2015 11/10/2015 77.00 197.14 2.56

W21 26/07/2015 11/10/2015 77.00 211.24 2.74

W22 26/07/2015 11/10/2015 77.00 197.48 2.56

W23 26/07/2015 11/10/2015 77.00 180.93 2.35

W24 26/07/2015 11/10/2015 77.00 162.80 2.11

W25 26/07/2015 11/10/2015 77.00 212.09 2.75

W26 26/07/2015 11/10/2015 77.00 218.08 2.83

W27 26/07/2015 11/10/2015 77.00 229.82 2.98

W28 26/07/2015 11/10/2015 77.00 202.34 2.63

W29 26/07/2015 11/10/2015 77.00 221.59 2.88W30 26/07/2015 11/10/2015 77.00 229.61 2.98

W31 26/07/2015 11/10/2015 77.00 273.74 3.56

W32 26/07/2015 11/10/2015 77.00 210.15 2.73

W33 26/07/2015 11/10/2015 77.00 199.64 2.59

W34 26/07/2015 11/10/2015 77.00 287.05 3.73

W35 25/07/2015 11/10/2015 78.00 287.72 3.69

W36 26/07/2015 11/10/2015 77.00 224.17 2.91

W37 25/07/2015 11/10/2015 78.00 206.25 2.64

W38 25/07/2015 11/10/2015 78.00 213.39 2.74

W39 25/07/2015 11/10/2015 78.00 178.20 2.28

W40 26/07/2015 11/10/2015 77.00 197.69 2.57

W41 25/07/2015 14/10/2015 81.00 191.62 2.37

W42 25/07/2015 11/10/2015 78.00 145.70 1.87

W43 25/07/2015 11/10/2015 78.00 201.12 2.58W44 25/07/2015 11/10/2015 78.00 192.38 2.47

APPENDIX A

ENVIRONMENTAL TLD RESULTS

Third Quarter 2015


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Site Exposure Exposure Exposure Exposure Exposure

Start End Period (µSv) (µSv/day)

F1 25/07/2015 10/10/2015 77.00 204.27 2.65

F2 25/07/2015 10/10/2015 77.00 249.75 3.24

F3 25/07/2015 10/10/2015 77.00 155.76 2.02

F4 25/07/2015 10/10/2015 77.00 194.56 2.53

F5 25/07/2015 10/10/2015 77.00 186.78 2.43

F6 25/07/2015 10/10/2015 77.00 267.07 3.47

F7 25/07/2015 10/10/2015 77.00 240.60 3.12

F8 25/07/2015 10/10/2015 77.00 243.64 3.16

F9 25/07/2015 10/10/2015 77.00 235.38 3.06

F10 25/07/2015 10/10/2015 77.00 220.48 2.86

F11 25/07/2015 10/10/2015 77.00 213.05 2.77

F12 25/07/2015 10/10/2015 77.00 174.44 2.27

Remarks:

Only the new Harshaw type TLDs were exposed in Quarter 3.

The Dose recorded by the TLDs at locations W7 and W34 exceeded the mean plus three standard deviations of the previous

twelve results. Due to the change of TLDs the past data consisted of 2 Harshaw type TLD results and 10 Vinten type TLD

results, and due to the general step increase in results using the Harshaw TLDs this was as expected.

The annual means and ranges to be reported with the Q4 2015 results will be those measured by the Harshaw TLDs.

Third Quarter 2015

APPENDIX A Continued

ENVIRONMENTAL TLD RESULTS


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600 SEC INNER GRID REF. DATE

COUNT GROSS NET Annual Mean

1079 1 354945 24-Sep-15 82.1 27.3 ***** *** - ***

1107 2 358944 24-Sep-15 84.2 29.5 ***** *** - ***

1109 3 361939 24-Sep-15 84.4 29.6 ***** *** - ***

1099 4 362936 24-Aug-15 83.6 28.8 ***** *** - ***

1102 5 358932 24-Aug-15 83.9 29.1 ***** *** - ***

1117 6 353930 25-Sep-15 85.0 30.2 ***** *** - ***

1115 7 350928 25-Sep-15 84.9 30.1 ***** *** - ***

1139 8 343930 25-Sep-15 86.7 31.9 ***** *** - ***

1105 9 343934 25-Sep-15 84.1 29.3 ***** *** - ***

1229 10 349939 25-Sep-15 93.5 38.7 ***** *** - ***

1149 11 350943 25-Sep-15 87.4 32.6 ***** *** - ***

1218 12 350942 25-Sep-15 92.7 37.9 ***** *** - ***

OUTER

1253 13 425945 24-Aug-15 95.4 40.6 ***** *** - ***

1269 14 425931 24-Aug-15 96.6 41.8 ***** *** - ***

1053 15 419902 08-Sep-15 80.1 25.3 ***** *** - ***

1107 16 412895 08-Sep-15 84.2 29.5 ***** *** - ***

1098 17 392875 08-Sep-15 83.6 28.8 ***** *** - ***

1109 18 382867 08-Sep-15 84.4 29.6 ***** *** - ***

1135 19 354858 08-Sep-15 86.4 31.6 ***** *** - ***

1148 20 347858 08-Sep-15 87.4 32.6 ***** *** - ***

1127 21 327864 08-Sep-15 85.8 31.0 ***** *** - ***

1149 22 313866 17-Sep-15 87.4 32.6 ***** *** - ***

1136 23 303877 17-Sep-15 86.5 31.7 ***** *** - ***

1091 24 305911 17-Sep-15 83.0 28.2 ***** *** - ***

1118 25 297928 22-Sep-15 85.1 30.3 ***** *** - ***

1077 26 332939 22-Sep-15 82.0 27.2 ***** *** - ***

RATIO MEAN INNER = 1.00

MEAN OUTER

REMARKS:

Calibration factor c.p.s./(microGy/h) 21.9 Cal Cert. 1512293GJ

Cosmic component c.p.s. 0.8

Inherent background component c.p.s. 0.4

Annual Range

APPENDIX B

ENVIRONMENTAL GAMMA DOSERATES

Third Quarter 2015

DOSERATE nGy/h NET DOSERATE nGy/h


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Grid Ref Be-7 Uncertainty Cs-137 Uncertainty Co-60 Uncertainty

H1TS 342932 11.19 7.1%


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Time of count detection limits for each group of radionuclides measured are detailed in the table below.

No specified radionuclides above limits of detection unless stated otherwise.

Co-60, I-131, Cs-134, Cs- 137 Nb-95, Zr-95, Ru-106, Sb-125

Ce-144, Eu-154, Eu-155, Ag-110

Time of count

0.19 0.84Detection Limit

(Bq shade-1

)


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MILK ACTIVITY ANALYSIS

FARM

NUMBER K-40 Uncertainty Cs-137 Uncertainty Co-60 Uncertainty

1 35.08 9.13%


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GAMMA SPECTROMETRY ANALYSIS

Gamma Activity (Bq kg-1

wet)

K-40 Uncertainty Cs-137 Uncertainty Co-60 Uncertainty

138.20 3.9%


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Gross Beta Analysis

Gross Beta Activity Gross Beta Activity Sample

Sample Code Date of on date counted on date counted Analysis

Collection Bq kg-1

(Dry weight) Bq m-2

Date

HO/CO/04/*/5 24/09/2015 471 ± 47 N/A 10/11/2015

HO/CO/04/*/30 24/09/2015 459 ± 46 135000 ± 14000 10/11/2015

Gamma Activity Analysis

Sample Code 5 cm Earth Core 30cm Earth Core

HO/CO/04/*/5 HO/CO/04/*/30

Nuclide Activity Activity

Bq kg-1

(Dry weight) Bq m-2

Co-60


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600 sec SITE NAME CODE DATECOUNT GROSS NET Annual Mean

1063 Trwyn Cemlyn B1 18-Sep-15 80.9 26.1 ***** *** - ***

1059 Cemlyn B2 18-Sep-15 80.6 25.8 ***** *** - ***

1029 Cemlyn Beach B3 18-Sep-15 78.3 23.5 ***** *** - ***

1193 Cerrig Brith B4 24-Sep-15 90.8 36.0 ***** *** - ***

1165 Porth y Pistyll B5 24-Sep-15 88.7 33.9 ***** *** - ***

1109 Porth y Ogof B6 24-Sep-15 84.4 29.6 ***** *** - ***

1070 Porth Wylfa B7 24-Sep-15 81.4 26.6 ***** *** - ***

1217 Cemaes Bay B8 22-Sep-15 92.6 37.8 ***** *** - ***

1197 Porth Padrig B9 22-Sep-15 91.1 36.3 ***** *** - ***

1215 Porth Wen B10 24-Aug-15 92.5 37.7 ***** *** - ***

1304 Porth Llechog B11 24-Aug-15 99.2 44.4 ***** *** - ***

1292 Porth Amlwch B12 24-Aug-15 98.3 43.5 ***** *** - ***

1272 Creek Amlwch B13 24-Aug-15 96.8 42.0 ***** *** - ***

1368 Porth Wnal B14 17-Sep-15 104.1 49.3 ***** *** - ***

REMARKS

Gross Doserates - Uncorrected Doserates

Net Doserates - Measured readings minus the cosmic component and inherent background.

Calibration factor c.p.s./(microGy/h) 21.9 Cal Cert. 1512293GJ

Cosmic component c.p.s. 0.8

Inherent background component c.p.s. 0.4

Annual Range

APPENDIX G

BEACH GAMMA DOSERATE MONITORING

Third Quarter 2015

DOSERATE nGy/h NET DOSERATE nGy/h


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Sediment

Dry/

Sample Location Code Date WetRatio Activity Uncertainty Activity Uncertainty Activity Uncertainty Activity

Silt Cemaes Bay HO/SL/B8 17-Sep-15 0.39 407.55 4.1% 22.45 3.1%


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Date of Survey: 23/09/2015

Instrument used:

Electra/44-10 (6367), Electra/EP15 (3304)

Remarks: No contamination evident

APPENDIX I

Third Quarter 2015

Pots and Nets NIL cps > background

EQUIPMENT

MONITOREDRESULT

MONITORING OF FISHING EQUIPMENT


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Reportable

Quantity

Combined

Uncertainty

(%)

Uncertainty

Component

Component

Magnitude

(%)

Comment

Random 46.8 2SD of all data at all locations from Q2 2000 - Q4 2014

Time 0.8 Half day uncertainty in time of exposure start and time of exposure end

Counting 10 No uncertainty quoted by contract laboratory but unlikely to be >10%

Random 73 Determined from 2SD of all results for all locations for 2003-2014 for Be-7

Counting 9.5 Determined from average counting uncertainty for 2014 results

Calibration Standard 3 Determined from Source Certificate used for efficiency calibration

Random 51.4 Based on 2SD for all farms for K-40 between Q1 2008 and Q3 2015

Counting 4.2 Average of all uncertainties for K-40 for all farms for Q1 2013 - Q3 2015


Weight 0.8 Assume resolution of 1g in 100g and triangular distribution

S-35 Random 202 Based on average of 2 SD uncertainty for each location for all results from Q1 2005 to Q3 2015

Bq/kg (wet) Laboratory 29.6 Average of all uncertainties for each location for Q1 2013 to Q3 2015

Random 241 Based on average of 2 SD uncertainty for each location for all results from Q1 2005 to Q3 2015

Laboratory 27 Average of all uncertainties for each location for Q1 2013 to Q3 2015

Area 1.2 Assume resolution of 1cm (in ~1m) on linear measurement and apply triangular distribution

Random 94.1 Based on average of 2 SD uncertainty for each location for all results from Q2 2006 to Q2 2015

Laboratory 15.9 Average of all uncertainties for each location for Q1 2013 to Q2 2015







Area 1.2 Assume resolution of 1cm (in ~1m) on linear measurement and apply triangular distribution

Random 20.2 Based on 2SD for all data 2012-2015

Laboratory 9.7 Based on average of data quoted by contract lab for 2012-2015




Area 11.5 Assume 0.25cm accuracy in 2.5cm and apply triangular distribution




Random 168 Based on 2SD for all data 2006-2015


Area 11.5 Assume 0.25cm accuracy in 2.5cm and apply triangular distribution

Random 40.5 Based on 2SD of all results for all sites between Q1 2003 and Q3 2015

Counting 8.5 Based on average uncertainty for all sites between Q1 2014 and Q3 2015


Volume 0.8 Assume accuracy of 10ml in 1000ml and apply triangular distribution

S-35 Random 86.4 Based on 2SD for all results for all sites between Q1 2007 and Q3 2015

Bq/m3 Laboratory 0 Too few +ve results to obtain average uncertainty

C-14 Random 42 Based on 2sd for all results for all sample sites between Q2 2003 and Q2 2015

Bq/kg (c) Laboratory 17.4 Average uncertainty for all results 2014-2015

C-14 Random 39.6 Based on 2sd for all results for all sample sites between Q2 2003 and Q2 2015

Bq/m3 Laboratory 17.4 Average uncertainty for all results 2014 - 2015

Random 34.7 Average over all sites of 2SD variance between Q3 1999 and Q3 2015

Instrument Calibration 10 Estimate based on quoted uncertainty of 5% for dose rates >2uG/h

Time 0.1


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Reportable

Quantity

Combined

Uncertainty

(%)

Uncertainty

Component

Component

Magnitude

(%)

Comment

Random 42.2 Average over all sites of 2SD variance between Q1 2000 and Q3 2015

Instrument Calibration 10 Estimate based on quoted uncertainty of 5% for dose rates >2µGy/h

Time 0.1

Documents

2015 Q3 Environmental (redacted).pdf