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Nanjo, Kotaro; Shiotsu, Hiroyuki; Maruyama, Yu; Sugiyama, Tomoyuki; Okamoto, Koji*
Journal of Nuclear Science and Technology, 60(7), p.816 - 823, 2023/07
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)Nanjo, Kotaro; Ishikawa, Jun; Sugiyama, Tomoyuki; Pellegrini, M.*; Okamoto, Koji*
Journal of Nuclear Science and Technology, 59(11), p.1407 - 1416, 2022/11
Times Cited Count：7 Percentile：79.63(Nuclear Science & Technology)
C absorber material on melt progression and chemical forms of iodine or cesium under severe accident conditionsHidaka, Akihide
Insights Concerning the Fukushima Daiichi Nuclear Accident, Vol.4; Endeavors by Scientists, p.341 - 356, 2021/10
Kido, Kentaro; Hata, Kuniki; Maruyama, Yu; Nishiyama, Yutaka; Hoshi, Harutaka*
NEA/CSNI/R(2016)5 (Internet), p.204 - 212, 2016/05
-rayOkagawa, Seigo; Nagai, Hitoshi*; Abe, Hitoshi*; Tashiro, Shinsuke
JAERI-Tech 2003-068, 17 Pages, 2003/08
JAERI-Tech-2003-068.pdf:0.78MB
To study the release mechanism of iodine from the dissolver solution in the nuclear fuel reprocessing plants to the atmosphere at criticality accidents, the characteristics of redox of iodine species in various solutions must be examined. In the present work, the effect of -ray irradiation on the redox reaction was examined in the nitric acid solution of 1M and 3M. Without irradiation, most of iodine in 1M nitric acid solutions were exist in the form of I
. In 3M nitric acid solutions, iodine was oxidized to I
. When the solutions were irradiated by -ray with exposure of more than 4C/kg, I was disappeared regardless of nitric acid concentration. At exposure of 120C/kg, iodine was oxidized to IO. At exposure of 4800C/kg, iodine was exist in the form of IO in 1M nitric acid solution. On the other hand, iodine in 3M nitric acid solution was reduced to I at the same exposure. In the irradiated solution, nitrous acid was found, which would be produced from nitric acid by -ray irradiation.
Hidaka, Akihide
no journal, ,
During core cooling at Fukushima Daiichi NPP accident, large amount of contaminated water was accumulated in the basements of reactor buildings at Units 1 to 4. The estimated ratios of 
I and 
Cs quantities in water to the core inventories are 0.51%, 0.85% at Unit 1, 74%, 38% at Unit 2 and 26%, 18% at Unit 3, respectively. According to the Henry's law, certain fraction of iodine in water could be released to atmosphere. Many evaluations for I-131 release have been performed so far by MELCOR or the reverse estimation with SPEEDI. The SPEEDI reverse predicted significant release until March 26 while no prediction in MELCOR after March 17. The present study showed that iodine release from accumulated water due to radiolytic conversion from I to I and gas-liquid partition of I may explain the release between March 17 and 26. This strongly suggests a need for improvement of current MELCOR approach which treats the release only from containment breaks.
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 BO vapor/aerosol and deposit, and significant amount of I was revaporized from the deposit.
