Limer LMC and Thorne MC, Assessment Calculations for Radon for ...

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8 Conclusions and SummaryThe assessment described herein has used an understanding of the physical processesinvolved in the release and transport of Rn-222 through the system, constrained wherepossible by empirical evidence, in order to provide estimates of the potential inhalationdoses resulting from releases of Rn-222 gas from the wastes disposed of at the LLWR.The assumptions made in this assessment are therefore cautiously realistic. Themonitoring data provides an upper bound on fluxes of Rn-222 gas that might beobserved at the surface. Taking account of travel time through the cap, based upon anunderstanding of the physical processes that are expected to dominate bulk gastransport through the cap, enables a more realistic upper limit to be placed uponpotential Rn-222 fluxes to the ground surface as a result of attenuation in the cap.The estimates of Rn-222 concentration in buildings obtained from the empiricalregression relationship are typically a factor of three to six lower than those obtainedusing the ventilation rate method. The calculational approach using ventilation ratesmay be regarded as being unduly cautious (possibly due to neglect of a release fractionof substantially less than 1.0 from the soil surface).The results show that for an intact, undegraded cap, the annual effective doses fromRn-222 inhalation will be negligible. However, in the unlikely event that there to existareas over which the infiltration barrier was substantially degraded (either as a resultof ongoing degradation processes or as a result of intrusive human activities) and werea building to be constructed on those areas, then annual effective doses of > 3 mSvmight be incurred by the occupants. However, if the proposed emplacement strategyfor Ra-226 bearing wastes is adopted within the Vaults, then the additional travel timethrough the higher stacks of waste would be sufficient for the potential exposure todrop by three orders of magnitude.64
QRS-1443ZG-1, Version 3.0ReferencesAppleton J D and Miles J C H (2009). Empirical relationships to assist in the LLWRassessment of radon. British Geological Survey Commissioned Report, CR/09/066.113pp.Appleton J D and Miles J C H (2010). A Statistical Evaluation of the Geogenic Controlson Indoor Radon Concentrations and Radon Risk. Journal of EnvironmentalRadioactivity, 101(10), 799-803.Appleton J D, Cave M R, Miles J C H and Sumerling T J (2011). Soil radium, soil gasradon and indoor radon empirical relationships to assist in post-closure impactassessment related to near-surface radioactive waste disposal, Journal ofEnvironmental Radioactivity, 102, 221-234.Ball M, Willans M, Cooper S and Lennon C (2008). LLWR Lifetime Project: Review ofthe gas pathway. Nexia Solutions (07) 9277 Issue 2, May 2008.Bechelli W and Smith AD (2005). Radon Monitoring at the Drigg Low Level WasteRepository. A Westlakes Scientific Consulting Report, 040276/01.Birchall A and Marsh J W (2005). Radon dosimetry and its implication for risk.International Congress Series, 1276, 81-84.Cliff K D, Green B M R, Mawle A and Miles J C H (1992). Thoron concentrations in UKhomes. Radiation Protection Dosimetry, 45(1/4), 361-366.Cave M R, Appleton J D and Miles J C H (2010). Regression analysis to assist in theLLWR assessment of radon. British Geological Survey Commissioned Report,CR/10/013. 44pp.Cummings R and Huntington A (2010). Optimisation: Packing Ratios and WasteContainer Sizes. LLW Repository Ltd, ESC Project Memo, LLWR/ESC/MeM(10)076,21 st April 2010.Darby S, Hill D, Auvinen A, Barros-Dios J M, Baysson H, Bochicchio F, Deo H, Falk R,Forstiere F, Hakama M, Heid I, Kreienbrock L, Kreuzer M, Lagarde F, Mäkeläinen I,Muirhead C, Oberaigner W, Pershagen G, Ruano-Ravina A, Ruosteenoja E, SchaffrathRosario A, Tirmarche M, Tomášek L, Whitley E, Wichmann H E and Doll R (2005).Radon in homes and risk of lung cancer: collaborative analysis of individual data from13 European case-control studies. British Medical Journal, 330(7485), 223-227.65
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The estimates of Rn-222 concentrati
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References 65Appendix A FEP Audit o
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This assessment provides the basis
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Section 2 describes the current kno
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likely to be extremely limited.Ther
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2.2 The Relationship of Rn-222 Conc
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Rearranging:C1 = 8 ⋅C− 2. 8 ⋅
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Table 2-2: Radon Measurements from
Page 24 and 25: Table 2-3: Radon Measurements from
Page 26 and 27: Figure 2-4: Spatial Distribution of
Page 28 and 29: The Rad 7 is a portable electronic
Page 30 and 31: Probe 1.6Probe 4.6Probe 4.12Probe 4
Page 32 and 33: peak observed concentrations may be
Page 34 and 35: shown in Figure 2-8. Rn-222 concent
Page 37 and 38: QRS-1443ZG-1, Version 3.0ProbeTable
Page 39: QRS-1443ZG-1, Version 3.0would be e
Page 42 and 43: Probe 1.3Probe 2.3Probe 3.4Probe 2.
Page 44 and 45: 3 Radon Migration Processes through
Page 46 and 47: 3.2.1 Rn-222 Fluxes to the Ground S
Page 48 and 49: If there were a pathway comprising
Page 50 and 51: In addition, it is relevant to note
Page 52 and 53: 4 Indoor Concentration of Rn-222In
Page 54 and 55: GM indoor radon Bq m-34003503002502
Page 56 and 57: The analysis of UK data by BGS/HPA
Page 58 and 59: concentration is 39 Bq m -3 and the
Page 60 and 61: SummaryThe values obtained from the
Page 62 and 63: dose per unit EEC of 12.5 nSv per B
Page 64 and 65: 6 Summary of Assessment Assumptions
Page 66 and 67: A case is identified that assesses
Page 68 and 69: constitutes an unquantified conserv
Page 70 and 71: Table 7-3: Potential Annual Effecti
Page 72 and 73: Table 7-5: Potential Annual Effecti
Page 76 and 77: Drever J I (1997). The Geochemistry
Page 78 and 79: McGarry R G (2003). Gas Pathway Res
Page 80 and 81: Appendix AFEP Audit of LLWR 2011 ES
Page 82 and 83: Table 8-3: Biosphere and Exposure F
Page 84: Table 8-4: 2008 R2S9 Submission - C
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