[3C05-07] Technologies for Dismantling, Decontamination & Evaluation 1

[3C07] Development of dose evaluation method for confirmation of completion of decommissioning

(2)Evaluation method of radioactivity distribution change for safety assessment

*Kazuji Miwa¹, Masakazu Namekawa², Taro Shimada¹, Takeda Seiji¹ (1. JAEA, 2. NAIS)

Keywords:decommissioning, radionuclide migration, surface water, soil migration, radionuclide distribution, dose evaluation

Radionuclide which have high distribution ratio in surface soil migrates on ground surface by rainfall. Migration of radionuclides causes local accumulation in site and outflow to the ocean. Therefore, we are developing a comprehensive evaluation method for surface water and soil migration, radionuclides migration by surface water and soil migration, and effects on exposure dose to public. Evaluation model which estimates surface radionuclides migration in considering vertical radionuclide concentration profile and radionuclides concentration in each soil particle size is developed. Result of trial analysis of Cs-137 migration assuming high precipitation region in japan shows that air dose rate rising in a depression due to accumulation of Cs-137. This result corresponds to the trend of high air dose rate in a depression observed in Fukushima.