Disaggregation and valuation of collective dose and global circulation dose

This study is an extension of earlier work (Jones et al 2004 J. Radiol. Prot. 24 13-27) using an adaptation of the PC-CREAM computer model (Mayall et al 1997 NRPB-SR296 (EUR 17791 EN) (Chilton: NRPB)) applied to future discharge scenarios for the nuclear fuel reprocessing plant at Sellafield, Cumbria, UK. This work showed that, of the total 3700 person-Sv collective dose delivered to the world population over 500 years integration from a particular scenario (SF3), 95% is at levels of individual dose below 0.015 microSv y(-1). The collective dose delivered at individual dose rates below 0.015 microSv y(-1) reflects the contribution from globally circulating radionuclides, namely (3)H, (14)C, (85)Kr and (129)I. The methodology used in the earlier work could not break down the dose from globally circulating radionuclides into bands of individual dose; the principal aim of this study is to achieve such a breakdown. The results confirm that the global circulation dose is received in the very lowest bands i.e. all below 0.015 microSv y(-1) for atmospheric discharges, and all below 0.0015 microSv y(-1) for discharges to the sea in the SF3 scenario. If account is taken of the argument that the monetary value of the detriment associated with collective dose should reduce with decreasing levels of individual dose or risk (Jackson et al 2004 J. Radiol. Prot. 24 41-59; NRPB 1993 Doc. NRPB 4 (2) 75-80) then it can be shown that the value of the detriment associated with discharges in the SF3 scenario would be substantially reduced compared with that derived from current conventional assumptions.