乾式キャスクを積載した使用済核燃料輸送船の線量率分布測定

概要

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An well prepared on board experiment was performed in the spent fuel shipping vessel PACIFIC SWAN loaded with eight dry-type casks of the TN-type. The casks contained the spent fuel of a pressurized water reactor (PWR). The burn-up was approximately 15,000 MWD/MTHM, and the cooling time was 475 days. The measurements of neutron and gamma-ray dose rate distributions were concentrated on the cask surface, in the hold, on the hatch cover, and also along the pass way. The neutron dose rates were measured with a rem counter and the gamma-ray with an ionization-type survey meter. The measured neutron dose rates are distributed like a 'haze', while the gamma-ray dose rates are distributed like a 'sward' at any places measured. From the above result, it is recomended that the difference of these distributions of dry-type casks is taken into account to a shielding design or to shielding analysis of spent fuel shipping vessels. Referring to the detailed results, the maximum dose rate on the cask surface was approximately 3 mR/hr for gamma rays and 0.6 mrem/hr for neutrons at the middle of the cask. It was 0.8 mR/hr for gamma rays and 0.13 mrem/hr for neutrons on the hatch cover of the No.3 hold; these maximum values were observed just above the No.2 cask. Along the pass way on the main deck, the maximum dose rate was 0.3 mR/hr for gamm rays and 0.14 mrem/hr for neutrons.
独立行政法人海上技術安全研究所の論文
1983-03-31