Baldwin TD and Hicks TW, Assessment Calculations for Human ...

0977-6Version 1Table 5.1Vault completion dates (dates are rounded to the last year in whichdisposals are assumed to occur).Completion DateCase A Case BVault 15 2086 2087Vault 16 2092 2094Vault 17 2100 2101Vault 18 2106 2107Vault 19 2111 2112Vault 20 2127 21275.1.2 Other Vault ParametersFor the 2011 ESC, optimum use has been assumed to be made of LLWR capacityassociated with the vaults by emplacing packaged wastes to the maximum heightconsistent with the overall cap profile. Profiling material will fill the space betweenthe waste package stacks and the engineered cap. The stacking arrangement is asshown in Figure 5.1. For inventory Case A, waste packages are stacked up to sevenhigh in Vault 15, six high in Vaults 16 and 17, and up to four high in Vaults 18, 19and 20. For inventory Case B, waste packages are stacked up to eight high in Vaults15 and 16, seven high in Vault 17, and up to five high in Vaults 18, 19 and 20.Sufficient waste is available to fill the vaults to capacity for each inventory case.The thickness of cap and profile material above the stacks of waste packages will varyacross the vaults, with little profiling material being present above the waste packagestowards the edges of the package layers. A cautious approach has been taken for thehuman intrusion assessment in that, for each vault grid cell shown in Figure 3.1,intrusion is assumed to occur where the waste packages are stacked highest and wherethere is minimal profiling material. For the calculations only the 3-m-thickengineered cap 2 is assumed to be present as indicated in Table A.4. Thus, the amountof waste excavated by intrusive activities is maximised 3 .The free space volumes for waste in each vault, the maximum depth of waste in eachvault (based on an individual half-height International Standards Organisation(HHISO) waste package height of 1.36 m) and the average bulk density of materials2 In a relatively late change to the engineering design, it was specified that there should be a minimumof 1 m thickness of profiling over the stacked waste in the vaults in order to buffer the cap against anydifferential settling effects (LLWR, 2011, §8.3.10). This additional 1 m of material is cautiouslyneglected in the human intrusion calculations presented here.3 Note that the addition of Vaults 15 to 20 would result in a greater thickness of profiling material beingpresent towards the southern end of the trenches, which would reduce the potential for human intrusioninto the trenches.Galson Sciences Ltd 14 21 March 2011