Development of SPEEDI-MP, comprehensive simulation system for circulation of environmental pollutants, 11; Application of atmospheric models to the environmental assessment of the Rokkasho Reprocessing Plant, 2

Terada, Hiroaki  ; Nishizawa, Masato; Nagai, Haruyasu  ; Chino, Masamichi; Sasaki, Koichi*

SPEEDI-MP has been developed for comprehensive prediction of migration of radionuclides in the atmosphere, ocean, and terrestrial region. In this study, we made attempt to distinguish the contributions to observed air dose rate between natural and artificial radionuclides from the reprocessing facility in Rokkasho, Aomori. For the purpose, two atmospheric dispersion models of SPEEDI-MP were applied, which were an Eulerian model for natural radionuclides and a Lagrangian particle model for artificial radionuclides. During the period of 10 September 2007, the model prediction performance was improved by using the observation data at the height of 250 m and 300 m above ground in addition to those from the surface to 150 m level for data assimilation in meteorological prediction. We could also generally reproduce the monitoring results observed at the monitoring stations approximately 4 km distant from the main stack in 12 September 2007 with the same calculation method.