Dose-reduction effects of vehicles against gamma radiation in the case of a nuclear accident

原子力事故時の線に対する自家用車の被ばく低減効果

高原 省五  ; 渡邊 正敏*; 廣内 淳 ; 飯島 正史*; 宗像 雅広 

Takahara, Shogo; Watanabe, Masatoshi*; Hirouchi, Jun; Iijima, Masashi*; Munakata, Masahiro

The aim of this paper is to evaluate the dose-reduction effects of vehicles. To achieve this aim, a model for calculating the dose reduction factor (DRF) was developed based on the actual shape and weight of Japanese vehicles. This factor is defined as the ratio of dose rate inside a vehicle to that outside. In addition to model calculation, we evaluated the DRFs by actual measurements in the areas contaminated by the Fukushima accident. A comparison between the simulated and the measured results revealed that the DRFs obtained using the developed models were in good agreement with the results of actual measurements. Using this model, we also evaluated the DRFs for cloudshine and groundshine in the case of a nuclear accident. The evaluations were performed for four vehicle models whose weights were 800-1930 kg. The DRF for cloudshine with photon energy of 0.4-1.5 MeV was 0.66-0.88, and that for groundshine from Cs was 0.64-0.73.