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Journal Articles

Factors controlling the spatiotemporal variation of $^{137}$ Cs in seabed sediment off the Fukushima coast; Implications from numerical simulations

Misumi, Kazuhiro*; Tsumune, Daisuke*; Tsubono, Takaki*; Tateda, Yutaka*; Aoyama, Michio*; Kobayashi, Takuya; Hirose, Katsumi*

Journal of Environmental Radioactivity, 136, p.218 - 228, 2014/10

https://doi.org/10.1016/j.jenvrad.2014.06.004

Times Cited Count：22 Percentile：54.1(Environmental Sciences)

Major controls on spatiotemporal variations of $^{137}$ Cs activity in seabed sediments derived from the Fukushima Dai-ichi Nuclear Power Plant accident during the first year after the accident were investigated by using numerical simulations. The model successfully reproduced major features of the observed spatiotemporal variations of $^{137}$ Cs activity in sediments. The spatial pattern of $^{137}$ Cs in sediments, which mainly reflected the history of $^{137}$ Cs activity in the bottom water overlying the sediment and the sediment particle size distribution, became established during the first several months after the accident. Taking $^{137}$ Cs activities in sediments in the coastal area and in the vicinity of the power plant into account, increased the simulated total inventory of $^{137}$ Cs in sediments off the Fukushima coast to a value on the order of 10 $^{14}$ Bq.

Journal Articles

Hydrogen absorption/desorption behavior through oxide layer of fuel claddings under accidental conditions

Sakamoto, Kan*; Shibata, Hiroki; Une, Katsumi*; Ouchi, Atsushi*; Aomi, Masaki*; Kurata, Masaki

Proceedings of 2014 Water Reactor Fuel Performance Meeting/ Top Fuel / LWR Fuel Performance Meeting (WRFPM 2014) (USB Flash Drive), 7 Pages, 2014/09

The depth profiles of hydrogen were measured at outer surface of fuel claddings corroded in high temperature steams at 1073-1473 K to examine the barrierness of surface oxide layer against the hydrogen absorption/desorption. The results indicated that the oxide layer would be no longer the barrier against the hydrogen under some conditions although it remained as the barrier against the oxidation.

Journal Articles

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Katsumi, Muto,; Koakutsu, Masayuki; Nakazawa, Osamu; Hayafune, Hiroki; Kato, Hiroshi

Saikuru Kiko Giho, (22), 103 Pages, 2004/00

https://rdreview.jaea.go.jp/gihou/pdf2/n22-16.pdf

https://rdreview.jaea.go.jp/gihou/pdf2/n22-17.pdf

https://rdreview.jaea.go.jp/gihou/pdf2/n22-20.pdf

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Journal Articles

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Katsumi, Muto,; Koakutsu, Masayuki; Nakazawa, Osamu; Hayafune, Hiroki; Kato, Hiroshi

Saikuru Kiko Giho, (23), 119- Pages, 2004/00

https://rdreview.jaea.go.jp/gihou/pdf2/n23-17.pdf

The application of the fluoride volatility process in the reprocessing of fuel from the fast breeder reactor is regarded as one of the economical methods. Plutonium hexafluoride (PuF6), however, reacting with fluorine (F2) and plutonium dioxide (PuO2) as the raw material, is in an unstable condition and tends to remain as a solid compound in the process after decomposing into plutonium tetrafluoride (PuF4). Suitable conditions should be established for the practical use of this process. One of them is to enhance the stability of PuF6. The behaviour of plutonium fluorination and relevant chemical reactions were investigated by referring to sundry literature and by thermodynamic calculation. It was then compared with recent data from laboratory scale experiments for this paper. Results from the theoretical analysis agreed with experimental observation that PuF6 could be formed stably under a high temperature condition (approx.1000 K) with over supply of figher concentration of F2.

Journal Articles