Disaggregation of collective dose—a worked example based on future discharges from theSellafield nuclear fuel reprocessing site, UK

Abstract

Collective dose has long been advocated as an important measure of the detrimentassociated with practices that involve the use of radioactivity. Application of collective dosein the context of worker protection is relatively straightforward, whereas its application inthe context of discharges to the environment can yield radically different conclusionsdepending upon the population groups and integration times that are considered. Thecomputer program PC-CREAM98 has been used to provide an indicative disaggregationinto individual dose bands of the collective dose due to potential future radioactivedischarges from the nuclear fuel reprocessing site at Sellafield in the UK. Two alternativedischarge scenarios are considered, which represent a ‘stop reprocessing early,minimum discharge’ scenario and a ‘reprocessing beyond current contracts’ scenario.For aerial discharges, collective dose at individual effective dose rates exceeding0.015 µSv y−1 is only incurred within the UK, and at effective dose rates exceeding1.5 µSv y−1 is only incurred within about 20 km of Sellafield. The geographical distribution ofcollective dose from liquid discharges is harder to assess, but it appears that collectivedose incurred outside the UK is at levels of individual effective dose rate below1.5 µSv y−1, with the majority being incurred at rates of0.002 µSv y−1 or less. In multi-attribute utility analyses, the view taken on the radiological detriment tobe attributed to the two discharge scenarios will depend critically on the weight ormonetary value ascribed to collective doses incurred within the differing bands of individualdose rate.