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Hidaka, Akihide
Journal of Radioanalytical and Nuclear Chemistry, 332(6), p.1607 - 1623, 2023/03
Times Cited Count：0 Percentile：0.00(Chemistry, Analytical)no abstracts in English
Tashiro, Shinsuke; Ono, Takuya; Amano, Yuki; Yoshida, Ryoichiro; Watanabe, Koji*; Abe, Hitoshi
Nuclear Technology, 208(10), p.1553 - 1561, 2022/10
Times Cited Count：1 Percentile：16.36(Nuclear Science & Technology)To contribute to the confinement safety evaluation of the radioactive materials in the Glove box (GB) fire accident, combustion tests with the Polymethyl methacrylate (PMMA) and the Polycarbonate (PC) as typical panel materials for the GB have been conducted with a relatively large scale apparatus. As the important data for evaluating confinement safety, the release ratio and the particle size distribution of the soot generated from the burned materials were obtained. Furthermore, the rise of the differential pressure (
P) of the high efficiency particle air (HEPA) filter by the soot loading was also investigated. As results, the release ratio of the soot from the PC was about seven times as large as the PMMA. In addition, it was found that the behavior of the rise of the P with soot loading could be represented uniformly regardless of kinds of combustion materials by considering effect of the loading volume of the soot particle in the relatively low loading region.
Hidaka, Akihide
Nuclear Technology, 208(2), p.318 - 334, 2022/02
Times Cited Count：6 Percentile：58.63(Nuclear Science & Technology)The author previously proposed that the Cs bearing microparticle (Type A) may have been formed by melting and atomization of glass fibers (GF) of the HEPA filter in the SGTS due to flame and blast during the hydrogen explosion in Unit 3. If this hypothesis is correct, the Type A could contain or accompany carbon (C), that ignites spontaneously above 623 K, because of the limited time to be heated up, inclusion of C in the binder applied on the GF surface and closely located charcoal filter. As the previous studies did not focus on C, the present analyses were performed with EPMA whether the Type A contains C. The results showed that the Type A contained C originating from the binder, and non-spherical particles accompanied by the Type A and the film surrounding the Type A contained more C, which is thought to originate from the charcoal filter. These results cannot be explained by the other mechanisms proposed so far, and can be explained consistently by the author proposed hypothesis.
Hidaka, Akihide
Journal of Nuclear Science and Technology, 56(9-10), p.831 - 841, 2019/09
Times Cited Count：12 Percentile：74.06(Nuclear Science & Technology)The insoluble Cs particles (Type A) were firstly observed in Tsukuba-city on the morning of March 15. The particles have been considered to be generated in RPV of Unit 2 by evaporation/condensation based on the measured 
Cs/
Cs ratio and the core temperatures of each unit. However, the Type A particles with smaller diameter than the Type B particles of Unit 1 origin, are covered by almost pure silicate glass and have a trace of the quenching. This indicates that the particles could have been generated due to the melting of the HEPA filter in SGTS by the fire of H
detonation at Unit 3, and atomization followed by quenching of the molten materials by air blast of the explosion. Although the particles were mostly dispersed to the sea because of the wind direction, some of them deposited onto the lower elevation of R/B at Unit 3, could have been subsequently re-suspended and released into the environment, by the steam flow in the R/B caused by restart of the Unit 3 core cooling water injection at 2:30 of March 15.
Ono, Takuya; Watanabe, Koji; Tashiro, Shinsuke; Amano, Yuki; Abe, Hitoshi
Proceedings of 25th International Conference on Nuclear Engineering (ICONE-25) (CD-ROM), 7 Pages, 2017/07
After the Fukushima-Daiichi accident, countermeasures against the severe accident are newly required as regulatory items for nuclear facilities. Organic solvent fire in cell was defined as one of the accidents in the fuel reprocessing plant. When the solvent burns, aerosols including soot are released. The substances clog HEPA filters in the ventilation system and their breakthrough may happen because of differential pressure rising. Moreover, the fire can also release volatile radioactive gaseous species, which can pass through HEPA filters. These phenomena are important for evaluation of confinement capability of the facility and public exposure. We have investigated, in relating to the clogging behavior, release behavior of aerosols as well as of volatile materials from burnt solvent. In the presentation, we will report experimental data and evaluation results obtained from recent research.
Ikezawa, Yoshio
Saikin No Kenkyu Shisetsu, 0, p.304 - 311, 1995/00
no abstracts in English
Ikezawa, Yoshio
Kurin Tekunoroji, 3(4), p.41 - 45, 1993/04
no abstracts in English
Hashimoto, Kazuichiro; Nishio, Gunji; Soda, Kunihisa
Nuclear Technology, 101, p.218 - 226, 1993/02
Times Cited Count：8 Percentile：63.29(Nuclear Science & Technology)no abstracts in English
Suzuki, Motoe; Nishio, Gunji; Takada, Junichi; Tsukamoto, Michio; Koike, Tadao
JAERI 1328, 90 Pages, 1993/01
no abstracts in English
Hashimoto, Kazuichiro; Nishio, Gunji
Aerosols: Science,Industry,Health and Environment,Vol. 2, p.1159 - 1162, 1990/00
no abstracts in English
M.Y.Ballinger*; P.C.Owczarski*; ; ; S.Jordan*; W.Lindner*
Nuclear Technology, 81, p.278 - 292, 1988/00
Times Cited Count：15 Percentile：77.60(Nuclear Science & Technology)no abstracts in English
; ;
Hoken Butsuri, 19(1), p.25 - 32, 1984/00
no abstracts in English
; ;
Proc.5th Int.Symp.on Contamination Control, p.23 - 26, 1980/00
no abstracts in English
Tashiro, Shinsuke
no journal, ,
In such as reprocessing facilities, radioactive materials with easy scattering into air are usually treated in the Glove-box (GB). Under the fire accident with GB panels burning, radioactive materials and soot will be together released within the facilities. When the high efficiency particle air (HEPA) filter in the ventilation system, which plays role of the confinement equipment for radioactive materials within the facilities, is damaged during such accident, it may lead to enhance the release of radioactive materials outside them. Based above background, the relationship between the quantity of soot loading onto the HEPA filter and the differential pressure (P) across the one was investigated. The tests with burning of major GB panels materials were performed using the large test apparatus (ACUA, Apparatus for Evaluating Clogging Effect of HEPA Filter on Confinement Capability Under Fire Accident), which enables to burn GB panels materials used as the GBs components in the actual facilities. The rising behavior of P has been evaluated with the increase of loading mass of soot, however, the relationship between loading volume of soot and P was newly examined in this study because the loading volume would be more appropriate than the loading mass as the index for expressing the progress of HEPA filter's clogging by soot loading. As a result, it was found that the rising behavior of P with soot loading in the relatively low region of loading volume could be uniformly represented regardless of combustion conditions such as the kind of GB panels materials and the ventilation in the cell for burning the material.
