Application of Coupling Simulation of Atmospheric, Terrestrial, and Oceanic Transport Models to Predict the Environmental Transport of Radioactive Materials Discharged from the Fukushima Dai-ichi Nuclear Power Plant

The Fukushima Dai-ichi nuclear power plant accident in Japan triggered by a magnitude 9.0 earthquake and resulting tsunami on March 11, 2011 caused the month-long discharge of radioactive materials into the environment. Also, substantial amount of contaminated water remains undisposed within the site, and the environmental impact in case of leakage is a great concern. To cope with these problems, computer simulations on the dispersion of radioactive materials in the environment are useful. Japan Atomic Energy Agency (JAEA) has estimated the source term of radioactive materials discharged to the atmosphere and ocean. We have also carried out simulations by the atmospheric and oceanic transport models to understand dispersion processes. In these simulations, the atmospheric and oceanic dispersion models developed by JAEA have been used separately, so far. As the next step, we are trying to apply a coupling simulation of atmospheric, terrestrial, and oceanic models on the radioactive material transport in the environment. This coupling simulation is necessary to predict the discharge and transport of radioactive materials deposited on the ground to rivers and ocean. It is also effective to predict the transport of tritium in contaminated water that has two-way exchange between the atmosphere and land/sea surface. The method and preliminary results of coupling simulations will be presented.