Levels of 99Tc in Seawater and Biota Samples from Norwegian Coastal Waters and Adjacent Seas

In 1994, the Enhanced Actinide Removal Plant at British Nuclear Fuelsʹ Sellafield began operation, treating the backlog and continuous throughput of radioactive wastes from reprocessing. This led to a significant increase in the levels of technetium-99 (99Tc) discharged from Sellafield compared with the early 1990s. This study was conducted in order to establish the levels of 99Tc in sea water and biota (calculating concentration factors where possible) arising from these newly increased discharges. sea water activity levels of 0.9–8.5 Bq/m3 were recorded in 1996 compared with levels <1 Bq/m3 in the period 1990–1992. A clear increase in 99Tc levels in seaweed samples was observed in Outer Oslofjord between 1996 and 1997. For all sites, highest levels of 99Tc were observed in seaweed and lobster samples (maximum levels of 170 and 270 Bq/kg, dry weight, respectively). The results suggest that the initial plume of 99Tc from the increased discharges, had reached the Norwegian coast sometime before November 1996.