The uptake of iron-55 by marine sediment, macroalgae, and biota following discharge from a nuclear power station

Significant quantities of Fe-55, an activation product of stable iron, have been released into the environment following the atmospheric testing of nu clear weapons (mainly in the 1950s and 1960s) as well as through authorized discharges of radioactivity from nuclear power and reprocessing sites. Alt hough some studies have been performed on the behavior of weapons' fallout- derived Fe-55 in the environment and subsequent impact on humans, little ha s been published on the behavior of Fe-55 released as a point source discha rge from nuclear sites. This study presents data on the concentration and t emporal variation of Fe-55 in fucoid seaweeds, shellfish, crab, and lobster collected from Weymouth Bay and adjacent coastal areas, southern England. These areas have received authorized discharges of radionuclides originatin g from the operation of a now decommissioned steam-generating, heavy water- type reactor at AEE Winfrith. The highest activities of Fe-55 are found ass ociated with marine sediments collected nea the discharge pipeline and a ra pid decline occurs away from the pipeline. This is consistent with rapid so rption of Fe-55 by the sediment, and the data show there is only limited re working and remobilization. Activities of Fe-55 in biota generally decrease d over time, due to a reduction in the amount of Fe-55 discharged. The vari ation of Fe-55 activity, revealed from the monthly sampling of seaweed, doe s not reflect the short-term fluctuations seen in the patterns of discharge d Fe-55 activity. Although discharges of Fe-55 from AEE Winfrith exceeded o ther radionuclides, the radiological impact on local seafood consumers is c onsiderably less than for other key radionuclides such as Co-60 and (65) Zn but of comparable magnitude to the global average population dose arising from fallout-derived Fe-55.