Radiological implications from the temporal development of radioactivity in marine food from the North Sea

A subject of the revision of authorised limits in 1994 for the discharge of liquid radioactive waste by the reprocessing plant Sellafield (UK) was an increase of these limits for certain radionuclides ( 3 H, 14 C, 60 Co, 99 Tc and 129 I). It is investigated now how the radioactivity in marine biota from the North Sea and subsequently the public radiation exposure of seafood consumers has developed in the years since 1994. This is based on a compartment model for dispersion in the North-East Atlantic. Discharges from the reprocessing plants Dounreay (UK) and La Hague (F) are included in the assessment. It is deduced that about 60 % of 137 Cs in the North Sea originate presently in the remobilisation of old Sellafield discharges from the Irish Sea sediment. A comparison with measured biota data shows that the model is conservative in most cases. The public radiation exposure (artificial radionuclides) from ingestion of fish, crustaceans and molluscs from the central North Sea as the sum over 12 considered radionuclides has decreased from 1992 to 1998 from 0.13 to 0.08 μSv y -1 .