Statistical analysis of simulated oceanic dispersion of dissolved radionuclide hypothetically released from the Fukushima Dai-ichi Nuclear Power Plant using long-term oceanographic reanalysis data

We conducted numerical simulations on the oceanic dispersion of dissolved radionuclide hypothetically released from the Fukushima Dai-ichi Nuclear Power Plant using long-term oceanographic reanalysis data. We evaluated the characteristics and trends of dissolved radionuclide behavior in the ocean using statistical analysis based on the simulation results. The surface meridional current at the release point in the Fukushima coastal ocean and the Kuroshio Extension significantly affected the north-south transport of the surface radionuclide in the Fukushima coastal ocean and the eastward transport of the offshore surface radionuclide, respectively. Because the surface kinetic energy in the coastal to the offshore area was larger, the range of the dispersed surface radionuclide tended to be larger. In summer (July-September), the increased frequency radionuclide entrainment by the Kuroshio Extension because of the surface southward radionuclide transport in the Fukushima coastal ocean and the large surface kinetic energy caused a large dispersed surface radionuclide. In winter (January-March), the decreased frequency radionuclide entrainment by the Kuroshio Extension because of the surface northward radionuclide transport in the Fukushima coastal ocean and the small surface kinetic energy caused a small dispersed surface radionuclide.

Automated summary

This study conducted numerical simulations and statistical analysis to investigate the dispersion of dissolved radionuclides released from the Fukushima Dai-ichi Nuclear Power Plant. The results showed that the coastal current and the Kuroshio Extension played a significant role in the transport of these radionuclides. The amount and range of dispersal varied between summer and winter seasons.