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梶野 瑞王*; 足立 光司*; 五十嵐 康人*; 佐藤 志彦; 澤田 壮弘*; 関山 剛*; 財前 祐二*; 佐谷 茜*; 鶴田 治雄*; 森口 祐一*
Journal of Geophysical Research; Atmospheres, 126(1), p.e2020JD033460_1 - e2020JD033460_23, 2021/01
被引用回数：12 パーセンタイル：72.21(Meteorology & Atmospheric Sciences)The dispersion and deposition of radio-cesium (
Cs) carried by the two types (type A and type B) of water-insoluble Cs-bearing solid microparticles (CsMPs) released due to the Fukushima nuclear accident were simulated for the first time. The presence of type B CsMPs (70-400 
m found in soil and 1-5 m found in air), associated with the hydrogen explosion of Unit 1 in the afternoon of March 12, could partly explain the simulated underestimation of total deposition over land by assuming that 100% of the Cs carriers were water-soluble submicron particles (WSPs). Type A CsMPs (0.1-10 m), released from Units 2 or 3 in the midnight between March 14 and 15, travelled over the Kanto Plain, the most populated plain in Japan. Differences in the size distribution of type A CsMPs altered the surface air concentration over Kanto substantially, by up to more than one order of magnitude. The major deposition mechanisms varied among dry, wet, and fog depositions depending on the size distribution. The simulated activity fractions due to the CsMPs in the total deposition were compared to those observed in surface soil for the first time. The observations could be explained by the simulations for the locations under the influence of type B CsMPs. However, the simulations were substantially underestimated for the locations influenced by type A CsMPs. There could be more fractions of type A CsMPs emission in the source term and/or the simulated deposition rates of type A CsMPs were underestimated.
梅田 浩司; 大井 貴夫; 大澤 英昭; 大山 卓也; 小田 治恵; 亀井 玄人; 久慈 雅栄*; 黒澤 英樹; 小林 保之; 佐々木 康雄; et al.
JAEA-Review 2007-050, 82 Pages, 2007/12
JAEA-Review-2007-050.pdf:28.56MB
本報告書は、2006年度(平成18年度)の地層処分技術に関する各々のプロジェクトにおける研究開発の現状とトピック報告を示した年度報告書である。
杉田 裕; 川上 進; 油井 三和; 牧野 仁史; 澤田 淳; 三原 守弘; 栗原 雄二
原子力バックエンド研究, 10(1), p.103 - 112, 2004/00
高レベル放射性廃棄物の地層処分における処分場の閉鎖技術に関して、第2次取りまとめで示した閉鎖概念に基づき、閉鎖性能と処分場から大規模な破砕帯を伴う断層にいたる核種移行の存在との関係に着目した検討を行った。検討の結果、「連絡坑道から小規模の破砕帯を伴う断層を経由する卓越的な核種移行が存在する」というシナリオは、閉鎖要素においてその機能が発揮されること、その存在のためにはいくつもの条件を同時に満たすことが必要であるからその可能性は低く、第2次取りまとめの「母岩を経由して大規模な破砕帯を伴う断層に至る」というシナリオが妥当であることを示した。
梶野 瑞王*; 関山 剛*; 五十嵐 康人*; 足立 光司*; 財前 祐二*; 澤田 壮弘*; 佐藤 志彦; 森口 祐一*
no journal, ,
A great number of atmospheric simulations have been conducted to understand the consequences of FDNPP accident. We came to know wet deposition is important but don't know to what extent. We know simulations vary but we don't know why. Meteorological model comparison with a single dispersion model was conducted to evaluate the magnitude of uncertainty in meteorological simulations. Among the deposition processes, rainout by liquid precipitation was the most important process. The fog deposition was the next, which was not considered in any other models but Katata et al., ACP (2015) and this study. Fog deposition is the main cause for the deposition in Gunma and Tochigi prefecture. All the simulation underestimated the airborne observation of Cs deposition, which amounted to 2.6 PBq. The underestimation is approximately 1.5 PBq (1 PBq in Hamadori and 0.4 PBq in Nakadori). It is due to underestimation of deposition process, which is the main finding of the meteorological model ensemble study: Some model overestimated while others underestimated both the precipitation and surface concentration, and therefore the precipitation and source term estimation should be reasonable and not be the cause of underestimation. By considering the A-type (Adachi et al., Sci. Rep., 2014) and S-type (Satou et al., Anthropocene, 2016) of Cs-ball particles, associated with the SRV opening of Unit 2 and Hydrogen explosion of Unit 1, respectively, the underestimation of simulated Cs deposition could be significantly improved. The maximum estimation of the additional deposition due to Cs-ball amounted approximately 1 PBq.
