Discharges of krypton from Sellafield, 1951-1997, and the resultant doses to members of the public.

The radionulide 85Kr, which has a half-life of 10.72 years, is produced, almost exclusively, by reprocessing operations during which the fission product is released from irradiated nuclear fuel by chemical dissolution. Reprocessing plants at Sellafield, in Cumbria, have released the noble gas to atmosphere since operations commenced in 1952. Historically, krypton discharges were classified for security reasons, although these have been monitored and published by BNFL for each year since 1977. This paper reviews discharges of 85Kr from Sellafield, and consequent radiation doses, since its earliest operations. Over the past three years, discharges of 85Kr have increased due to the operation of the Thermal Oxide Fuel Reprocessing Plant (Thorp). Nonetheless, the associated annual committed effective dose to individuals remains low, peaking around 1.5 microSv a-1 to the identified critical groups, which compares with typical annual committed effective doses from natural sources of radiation of 2200 microSv. Maximum collective doses predicted from any single year of operations are 0.6 man Sv, 2 man Sv and 42 man Sv to the UK, Europe and the world respectively. Comparison may be made to natural background committed effective doses, which are of the order of 130,000 man Sva-1, 750,000 man Sva-1 and 13,000,000 man Sva-1 to the UK, EU and world populations respectively.