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Terada, Atsuhiko; Nagaishi, Ryuji
Nuclear Technology, 210(10), p.1871 - 1887, 2024/10
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)In order to understand dispersion of H
leaked in packed beds of non-porous/porous particles in a partially open space practically, the dispersion of H in the particle layers of glass beads and soil was analytically studied using a CFD code to be compared with the experiments and to elucidate the effects of particle layer. H flowed out from a single leak point in the particle layer of non-porous glass beads was affected by buoyancy around the leak point, and diffused directly above the leak point in an elliptical shape faster than in the horizontal direction. After that, when it reached the air layer in the head space above the particle layer, H spread horizontally, formed a large concentration gradient near the boundary between the particle layer and the air layer, and further diffused in the air layer until the H concentration became about 1/3 or less of the concentration near the surface of particle layer. The calculations largely reproduced the experimental concentration distributions. When the particle layer was porous decomposed granite soil, the diffusion behavior of H in the particle layer proceeded in the same manner as in the case of glass beads. However, a large concentration gradient was formed near the boundary between the particle layer and the air layer, and then H diffused in the air layer until the H concentration became below the lower combustion limit. It was suggested through sensitivity analysis that the air permeability coefficient had a large effect on the time course of H concentration distribution. Based on the above, we further simulated H behavior in the vessel containing the H leaked particle layer. By inserting multiple vent pipes without considering H generation distribution and particle properties in the particle layer, H accumulated from one pipe was discharged by buoyancy without depending on the H generation distribution and particle properties in the particle layer, and air flowed in from the other pipe.
Hirouchi, Jun; Takahara, Shogo; Komagamine, Hiroshi*; Watanabe, Masatoshi*; Munakata, Masahiro
Proceedings of Asian Symposium on Risk Assessment and Management 2017 (ASRAM 2017) (USB Flash Drive), 11 Pages, 2017/11
no abstracts in English
Tashiro, Shinsuke; Abe, Hitoshi; Morita, Yasuji
JAERI-Conf 2005-007, p.348 - 350, 2005/08
Hot test at Rokkasho Reprocessing plant has been started since last year. In addition, construction of the MOX fuel fabrication facility at Rokkasho site is planning. So, the importance of safety evaluation of the nuclear fuel cycle facility is increasing. Under the fire accident, one of the serious postulated accidents in the nuclear fuel cycle facility, the equipments (glove-box, ventilation system, ventilation filters etc.) for the confinement of the radioactive materials within the facility could be damaged by a large amount of heat and smoke released from the combustion source. Therefore, the fundamental data and models calculating for the amount of heat and smoke released from the combustion source under such accident are important for the safety evaluation of the facility. In JAERI, the study focused on the evaluation of amount of heat and smoke released from the combustion source is planning. In this paper, the outline of experimental apparatus, measurement items and evaluation terms are described.
Watanabe, Koji; Tashiro, Shinsuke; Abe, Hitoshi; Takada, Junichi; Morita, Yasuji
JAERI-Tech 2004-029, 48 Pages, 2004/03
JAERI-Tech-2004-029.pdf:3.19MB
In a part of building ventilating installation of a nuclear fuel facility, a reprocessing plant for example, the pre-filters are adopted as one of the ventilation filters. In a fire accident, it is supposed that, because of the pre-filter clogging by large smoke, its differential pressure (
p) is evolved up to the value at its breakage. Therefore, in regard to maintaining the confinement of radioactive materials, it is important to predict the time course of p of the pre-filter accurately. In the current study, it was assumed that the empirical equation for the DF of the pre-filter as function of smoke particle diameter (SPD), between 0.7-2 
m, could be applied to estimating its DF for SPD above 2 m. Under this assumption, the time corresponding to its p at its breakage, calculated by CELVA-1D, was agreed well with the experimental result.
Takada, Hiroshi; Maekawa, Fujio; Honmura, Shiro*; Yoshida, Katsuhiko*; Teraoku, Takuji*; Meigo, Shinichiro; Sakai, Akio*; Kasugai, Yoshimi; Kanechika, Shuji*; Otake, Hidenori*; et al.
Proceedings of ICANS-XVI, Volume 3, p.1115 - 1125, 2003/07
no abstracts in English
Oikawa, Akira; Miya, Naoyuki
Purazuma, Kaku Yugo Gakkai-Shi, 78(12), p.1308 - 1312, 2002/12
Tritium experience over decade in DD operation of JT-60 is summarized.Effluent of tritium in vacuum exhaust through the stack to environment always remains a level below detectable levels. Tritium concentration of drain is also below the limit of regurations of the local agreement amd the law. For a scheduled maintenance work of the in-vessel components, following an annual deuterium plasma discharge campaign, a 4-week no-deuterium plasma discharge campaign and the succeeded ventilation by room air allow to reduce tritium concentration on the surface of in-vessel components. A cooperative endeavour is underway for analysis of tritium behavior in JT-60.
Ino, Hiroichi*; Ueta, Shohei; Suzuki, Hiroshi; Tobita, Tsutomu*; Sawa, Kazuhiro
JAERI-Tech 2001-083, 46 Pages, 2002/01
JAERI-Tech-2001-083.pdf:6.31MB
no abstracts in English
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：63.06(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
