JAEA's modeling studies on radionuclides transport in the terrestrial environment

Ota, Masakazu  ; Terada, Hiroaki   ; Koarashi, Jun   ; Nagai, Haruyasu  

We present the Japan Atomic Energy Agency (JAEA)'s work regarding the development of a land surface model and its applications to transport of radionuclides around nuclear facilities, such as the Rokkasho reprocessing plant of Japan Nuclear Fuel Limited. In particular, we focus on the environmental transfers of C and I - the major radionuclides of concern in respect to their potential impacts on radiological doses and long-lasting contamination of the terrestrial environment. JAEA has been developing a land surface model, named SOLVEG-II, that predicts transfer and exchange of water and CO in an atmosphere-vegetation-soil system. We have introduced dynamics of C and I into SOLVEG-II; the developed model is therefore able to calculate the dynamics of C and I under realistic conditions with influences from water and CO cycles in the target land surface ecosystem. Through applying the model to the transfer of C and I discharged from the Rokkasho reprocessing plant, key processes affecting contamination of vegetation were identified. In the presentation, some other applications (e.g. transfers of tritium and radiocesium) of the model will also be viewed.