Plutonium, americium and radiocaesium in the marine environment close to the Vandellos I nuclear power plant before decommissioning

The Vandellos nuclear power plant (NPP), releasing low-level radioactive li quid waste to the Mediterranean Sea, is the first to be decommissioned in S pain, after an incident which occurred in 1989. The presence, distribution and uptake of various artificial radionuclides (radiocaesium, plutonium and americium) in the environment close to the plant were studied in seawater, bottom sediments and biota, including Posidonia oceanica, fish, crustacean s and molluscs. Seawater, sediments and Posidonia oceanica showed enhanced levels in the close vicinity of the NPP, although the effect was restricted to its near environment. Maximum concentrations in seawater were 11.6 +/- 0.5 Bq m(-3) and 16.9 +/- 1.2 mBq m(-3) for Cs-137 and Pu-239,Pu-240, respe ctively. When sediment concentrations were normalized to excess (210)pb, th ey showed both the short-distance transport of artificial radionuclides fro m the Vandellos plant and the long-distance transport of Cs-137 from the As co NPP. Posidonia oceanica showed the presence of various gamma-emitters at tributed to the impact of the Chernobyl accident, on which the effect of th e NPP was superimposed. Seawater, sediment and Posidonia oceanica collected near the plant also showed an enhancement of the plutonium isotopic ratio above the fallout value. The uptake of these radionuclides by marine organi sms was detectable but limited. Pelagic fish showed relatively higher Cs-13 7 concentrations and only in the case of demersal fish was the plutonium is otopic ratio increased. The reported levels constitute a set of baseline va lues against which the impact of the decommissioning operations of the Vand ellos I NPP can be studied. (C) 2000 Elsevier Science Ltd. All rights reser ved.