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Hidaka, Akihide
Insights Concerning the Fukushima Daiichi Nuclear Accident, Vol.4; Endeavors by Scientists, p.341 - 356, 2021/10
Hidaka, Akihide; Yokoyama, Hiroya
Journal of Nuclear Science and Technology, 54(8), p.819 - 829, 2017/08
Times Cited Count:13 Percentile:74.66(Nuclear Science & Technology)To clarify what happened during the Fukushima accident, the phenomena within RPV and the discussion of ties with the environmental monitoring are very important. However, the previous study has not necessarily advanced until the present that passed almost six years from the accident. The present study investigated I and
Cs release behaviors during the late phase of the accident based on
I/
Cs ratio of the source terms that were recently evaluated backward by WSPEEDI code based on environmental monitoring data. The
I release from the contaminated water in the basement of 1F2 and 1F3 reactor buildings was evaluated to be about 10% of
I source term. The increase in
Cs release from March 21 to 23 and from March 30 to 31 could be explained by the release of CsBO
which is formed as a result of chemical reactions of Cs with B
C due to re-ascension of the core temperature caused by slight shortage of the core cooling water.
Hidaka, Akihide; Yokoyama, Hiroya
Journal of Nuclear Science and Technology, 54(8), P. i, 2017/08
Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)no abstracts in English
Hidaka, Akihide
Nihon Genshiryoku Gakkai Wabun Rombunshi, 14(1), p.51 - 61, 2015/03
BC used mainly for BWR and EPR absorbers could cause phenomena which never happen in PWR with Ag-In-Cd absorbers during severe accident. B
C would make a eutectic interaction with stainless steel and enhance melt relocation. Boron oxidation could increase H
generation and change of liberated carbon to CH
could enhance CH
I generation. HBO
generated during B
C oxidation could be changed to CsBO
by combining with Cs. This may increase Cs deposition in reactor coolant system. There could be differences in configuration, surface area, stainless steel-B
C weight ratio between B
C powder and pellet absorbers. Present issue is to clarify effect of these differences on full scale melt progression, B
C oxidation and source term. Advancement of this research domain could contribute to further sophistication of prediction tool for melt progression and source terms, and treatment of organic iodide formation in safety evaluation.
Miwa, Shuhei; Shinada, Masanori; Osaka, Masahiko; Sugiyama, Tomoyuki; Maruyama, Yu
no journal, ,
In order to acquire the data on fission product chemical behavior during transport in a reactor for the improvement of source term evaluation method, we performed the chemical reaction tests of cesium (Cs) and iodine (I) deposits and boron oxide (BO
) vapor/aerosol using the apparatus which can simulate temperature conditions of reactor coolant system under a sever accident. The volatile I compounds were formed by the reaction of B
O
vapor/aerosol and deposit, and significant amount of I was revaporized from the deposit.