Plutonium: the legacy of Sellafield

摘要

Plutonium has been discharged from the Sellafield (Windscale) UK site since 1952. The total decay-corrected, cumulative discharge of plutonium (α) up to 1995 was 717 TBq, of which most resides in the sub-tidal sediments within the Irish Sea. The observed inventory in the sub-tidal sediments, combined with that in the other environmental compartments (intertidal sediments, water column and exported from the Irish Sea), accounts for about 70% of the reported cumulative discharge. However, this fraction increases to about 90% if upper estimates are used for the fraction associated with intertidal sediments and the quantity exported. Plutonium is being remobilised from the seabed and exported via the northern exit of the Irish Sea, and is being transported in solution to the Barents Sea and beyond. Past releases contribute significantly to present radiation doses from seafood consumption and this is likely to continue. The environmental impact of plutonium has been assessed and found to be negligible.