Limer LMC, Assessment Calculations for C-14 Labelled Gas and ...

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Table 5-11: Calculated Effective Inhalation Doses for Case2_InvB (mSv)LocationTime (y)Flux of C-14 Labelled Gas(Bq m -2 y -1 )Calculated Effective InhalationExposure (mSv)CO 2 CH 4 CO 2 CH 4TrenchesRDAVaultsEDAVaults2230 4.83E+02 9.30E+02 5.24E-07 4.72E-072330 1.97E+02 3.95E+02 2.14E-07 2.00E-072430 1.45E+02 3.00E+02 1.57E-07 1.52E-072530 8.71E+01 2.30E+02 9.44E-08 1.16E-072630 6.64E+01 1.90E+02 7.20E-08 9.63E-082230 8.35E+00 8.80E+04 9.05E-09 4.46E-052330 2.36E-01 8.81E+03 2.56E-10 4.47E-062430 1.61E-01 2.64E+03 1.74E-10 1.34E-062530 1.54E-01 7.27E+02 1.68E-10 3.69E-072630 1.25E-01 3.88E+02 1.35E-10 1.97E-072230 4.06E-02 1.17E+05 4.41E-11 5.93E-052330 3.19E-02 4.74E+04 3.46E-11 2.40E-052430 1.28E-02 8.08E+03 1.39E-11 4.10E-062530 1.48E-02 6.57E+02 1.60E-11 3.33E-072630 9.74E-03 3.27E+02 1.06E-11 1.66E-075.2 Rn-222The assessment of the potential impacts of Rn-222 gas released from the wastesdisposed of at the LLW repository relies upon the following key aspects:Known activities and concentrations of Ra-226 to be disposed of at the LLWR(Table 3-2);Rn-222 concentrations in the wastes will be around 10% of the Ra-226concentrations (with a range of 7 to 15%; see Section 2.1.2);Any Rn-222 attenuation in the cap will greatly reduce the concentration of Rn-222in soil gas and the overlying atmosphere (Section 2.2); andRn-222 concentrations in indoor air can be calculated based on either empiricalrelationships between soil gas and indoor air concentrations of Rn-222, or onventilation rates of buildings (Section 2.3.2).36
QRS-1443ZH-1, Version 3.0The cases summarised in Table 5-12 have been derived to explore the implications ofassumptions associated with attenuation in the cap, and the implications of the methodused for deriving the Rn-222 concentration in indoor air for calculated inhalationdoses.Table 5-12: Calculation Cases for Assessing Potential Impacts of Rn-222 Releasefrom the CapRegion of the LLWR Case Name Assumption About CapAll EDA Vaults (15-20)Vaults 15 to 16EDAVaults_1mCoarseEDAVaults_1.5mCoarseEDAVaults_2mCoarseEDAVaults_AsDesignVaults1516_1mCoarseVaults1516_1.5mCoarseVaults1516_2mCoarseVaults1516_AsDesign1 m coarse material1.5 m coarse material2 m coarse material2.1 m coarse, 0.9 m fine1 m coarse material1.5 m coarse material2 m coarse material2.1 m coarse, 0.9 m fineFrom these cases, consistent with the RDA assessment, a reference case for exposuremay be selected as follows.The possibility that the low permeability layer could be disturbed through the creationof a domestic dwelling or light building with a cellar that could extend to a depthsufficient to penetrate the low permeability layer and make connection with theunderlying coarse layers requires consideration. The reference case is thereforedefined, cautiously, on the following basis.The impermeable layer is disturbed as a result of the creation of a building on thecap, with a cellar extending to sufficient depth.Average thicknesses of coarse material of 1.5 m above the vaults provideattenuation.An emanation fraction of 7% for the vaults is assumed (as the wastes arecontainerised and grouted, and the range is based upon trench monitoring; seeLimer and Thorne, 2011).For all the cases defined, the calculated annual effective doses are summarised in Table5-13 and Table 5-14 for the PIER A2 and B2 inventories respectively. An indooroccupancy of 0.8 (7,013 h) and an indoor equilibrium factor of 0.4 are assumed37
Page 3: Les thèmes du portail Leçon 3Néa
Page 7: QRS-1443ZH-1, Version 3.0SummaryThe
Page 11 and 12: QRS-1443ZH-1, Version 3.01 Introduc
Page 13 and 14: QRS-1443ZH-1, Version 3.02 Summary
Page 15 and 16: QRS-1443ZH-1, Version 3.0case, it i
Page 17 and 18: QRS-1443ZH-1, Version 3.0consumed d
Page 19 and 20: QRS-1443ZH-1, Version 3.0relation t
Page 21 and 22: QRS-1443ZH-1, Version 3.0In the RDA
Page 24 and 25: Table 3-2: Rn-222 Inventory Informa
Page 26 and 27: Please see Table 5-1 of Limer et al
Page 28 and 29: contribute substantially to the tot
Page 30 and 31: Calculated Effective Ingestion Dose
Page 32 and 33: (a)Annual Effective IngestionExposu
Page 34 and 35: calculated annual ingestion dose fo
Page 36 and 37: Figure 5-7: Average Decay Corrected
Page 38 and 39: Figure 5-9: Calculated Effective An
Page 40 and 41: Table 5-5: Calculated Annual Effect
Page 42 and 43: Table 5-7: Calculated Annual Effect
Page 44 and 45: Table 5-9: Calculated Effective Inh
Page 48 and 49: throughout. The reference case is h
Page 50 and 51: EDAVaults_NoCap@10000y and Vaults15
Page 52 and 53: area of the cap over vault 8 were t
Page 54: the Nuclear Decommissioning Authori

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