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

0977-6Version 16.1.5 B3b – Housing Development: OccupancyFigure 6.19, Figure 6.20 and Figure 6.21 show the total calculated annual dose to anoccupant on a housing development at different locations across the facility in theyears 2230, 7000 and 12000, respectively.The housing development has been assumed to follow construction activities thathave left radioactively contaminated material at the surface. The maximum annualcalculated dose at 2230, resulting from occupancy of a house built on excavatedVault 15 (cell C10) wastes, is 2.6 x 10 -1 mSv. This dose is dominated by exposure toradon and its progeny as a result of the house being constructed on wastes that contain226 Ra (Figure 6.22 and Figure 6.23). Over time, as the dose contribution from 222 Rn(and its daughters) associated with 226 Ra disposals reduces, the inhalation of 222 Rnassociated with the decay of 234 U disposals (via 230 Th and 226 Ra) begins to dominate.The calculated dose ranges from 7.2 x 10 -2 mSv in grid cell A11 (Vault 19) to2.6 x 10 -1 mSv in grid cell C10 (Vault 15) at 2230. By the year 7000, the calculateddose at each location has reduced by almost an order of magnitude, only increasingslightly by the year 12000 to a maximum of 6.0 x 10 -2 mSv in grid cell C10 due toinhalation of radon associated with 234 U decay.0.300.25Dose (mSv)0.200.150.100.050.00A & B10C & D11E & FFigure 6.19Total annual dose to a site occupant (B3b) in the year 2230 (Case A).Galson Sciences Ltd 33 21 March 2011