Numerical analysis for 137CS on seabed sediment including atmospheric deposition near the Fukushima coastal area

Description

Radionuclides were released into the atmosphere and ocean from the accident at the Fukushima Daiichi Nuclear Power Plant (NPP) in March 2011. Numerical simulations were performed to evaluate the distribution of 137Cs in the ocean with considering directly release and deposition from the atmosphere. Calculated concentrations of 137Cs in the sea water and seabed are compared with the measured data, and atmospheric transport model has been also used to calculate the rates of atmospheric deposition on the sea surface. Lots of atmospheric deposition was occurred on sea surface in northeast direction from Fukushima NPP due to westerly wind and precipitation on March 15-31, 2011. Most modelling for the marine dispersion of 137Cs after Fukushima accident was considered as a perfectly conservative radionuclide, thus scavenging processes and adsorption on seabed sediments are neglected. The processes of the non-conservative from the numerical simulations have been well described and the calculated results are also in agreement with the measured data. The concentrations of 137Cs in seabed sediments were mainly contributed by the atmospheric deposition and long residence time showed in northeast coastal area off Fukushima NPP.

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