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Miyahara, Shinya*; Kawaguchi, Munemichi; Seino, Hiroshi; Atsumi, Takuto*; Uno, Masayoshi*
Proceedings of 28th International Conference on Nuclear Engineering (ICONE 28) (Internet), 6 Pages, 2021/08
In a postulated accident of fuel pin failure of sodium cooled fast reactor, a fission product cesium will be released from the failed pin as an aerosol such as cesium iodide and/or cesium oxide together with a fission product noble gas such as xenon and krypton. As the result, the xenon and krypton released with cesium aerosol into the sodium coolant as bubbles have an influence on the removal of cesium aerosol by the sodium pool in a period of bubble rising to the pool surface. In this study, cesium aerosol removal behavior due to inertial deposition, sedimentation and diffusion from a noble gas bubble rising through liquid sodium pool was analyzed by a computer program which deals with the expansion and the deformation of the bubble together with the aerosol absorption considering the effects of particle size distribution and agglomeration in aerosols. In the analysis, initial bubble diameter, sodium pool depth and temperature, aerosol particle diameter and density, initial aerosol concentration in the bubble were changed as parameter, and the results for the sensitivities of these parameters on decontamination factor (DF) of cesium aerosol were compared with the results of the previous study in which the effects of particle size distribution and agglomeration in aerosols were not considered. From the results, it was concluded that the sensitivities of initial bubble diameter, the aerosol particle diameter and density to the DF became significant due to the inertial deposition of agglomerated aerosols. To validate these analysis results, the simulation experiments have been conducted using a simulant particles of cesium aerosol under the condition of room temperature in water pool and air bubble systems. The experimental results were compared with the analysis results calculated under the same condition.
Miyahara, Shinya*; Kawaguchi, Munemichi; Seino, Hiroshi
Proceedings of 2020 International Conference on Nuclear Engineering (ICONE 2020) (Internet), 6 Pages, 2020/08
In a postulated accident of fuel pin failure of sodium cooled fast reactor, a fission product cesium will be released as an aerosol such as cesium iodide and/or oxide together with xenon and/or krypton. In this study, cesium aerosol removal behavior due to inertial deposition, sedimentation and diffusion was analyzed by a computer program which deals with the expansion and the deformation of the bubble together with the aerosol absorption. Initial bubble diameter, sodium pool depth and temperature, aerosol particle diameter and density, initial aerosol concentration were changed as parameter. From the results, it was concluded that the initial bubble diameter was most sensitive parameter to the decontamination factor (DF). It was found that the sodium pool depth, the aerosol particle diameter and density have also important effect on the DF, but the sodium temperature has a marginal effect. To meet these results, the experiments are under planning to validate the results.
Nakata, Kotaro*; Hasegawa, Takuma*; Solomon, D. K.*; Miyakawa, Kazuya; Tomioka, Yuichi*; Ota, Tomoko*; Matsumoto, Takuya*; Hama, Katsuhiro; Iwatsuki, Teruki; Ono, Masahiko*; et al.
Applied Geochemistry, 104, p.60 - 70, 2019/05
Times Cited Count：8 Percentile：38.40(Geochemistry & Geophysics)no abstracts in English
Abe, Hitoshi; Tashiro, Shinsuke; Morita, Yasuji
JAERI-Conf 2005-007, p.199 - 204, 2005/08
Source term data for estimating release behavior of radioactive nuclides is necessary to evaluate synthetic safety of nuclear fuel cycle facility under accident conditions, such as fire and criticality. In JAERI, the data has been obtained by performing some demonstration tests. In this paper, the data for the criticality accident in fuel solution obtained from the TRACY experiment, will be mainly reviewed. At 4.5 h after the transient criticality, the release ratio of the iodine were about 0.2% for re-insertion of transient rod at just after transient criticality and about 0.9% for not re-insertion. Similarly the release coefficient and release ratio for Xe were estimated. It was proved that the release ratio of Xe-141 from the solution was over 90% in case that the inverse period was over about 100 (1/s). Furthermore, outline of the study on the fire accident as future plan will be also mentioned.
Bakhtiari, M.; Tamai, Hiroshi; Kawano, Yasunori; Kramer, G. J.*; Isayama, Akihiko; Nakano, Tomohide; Kamiya, Kensaku; Yoshino, Ryuji; Miura, Yukitoshi; Kusama, Yoshinori; et al.
Nuclear Fusion, 45(5), p.318 - 325, 2005/05
Times Cited Count：46 Percentile：79.20(Physics, Fluids & Plasmas)In the previous works we had shown that injecting a mixture of large amounts of hydrogen and small amounts of argon can terminate a tokamak discharge quickly with avoiding runaway electron generation. In this work we have done the same experiments but with different gases in addition to argon. In fact we compared the effect of the puffing of argon, krypton, and xenon gases with and without simultaneous hydrogen gas puffing on disruption mitigation. We observed that injecting all impurities in the form of an admixture in hydrogen lead to faster plasma shutdowns with less runaway electron generation. We also found that injecting krypton gas (with or without hydrogen) seems to be a good candidate for plasma shutdown purposes since it induces low heat flux to divertor plates and avoids runaway electron generation more effectively.
Sawa, Kazuhiro; Yoshimuta, Shigeharu*; Tobita, Tsutomu*;
JAERI-Research 97-036, 23 Pages, 1997/05
JAERI-Research-97-036.pdf:0.72MB
no abstracts in English
Matsumoto, Mikio; Endo, Yasuichi; ; Itabashi, Yukio; ; Yokouchi, Iichiro; Ando, Hiroei
JAERI-M 92-212, 62 Pages, 1993/01
no abstracts in English
Sawa, Kazuhiro; Shiozawa, Shusaku; Fukuda, Kosaku;
Journal of Nuclear Science and Technology, 29(9), p.842 - 850, 1992/09
no abstracts in English
Ogawa, Toru; Kobayashi, Fumiaki; Tobita, Tsutomu; Fukuda, Kosaku; Saito, Takashi; Yokouchi, Iichiro;
Nucl. Eng. Des., 132, p.31 - 37, 1991/00
Times Cited Count：10 Percentile：71.83(Nuclear Science & Technology)no abstracts in English
;
Nihon Genshiryoku Gakkai-Shi, 29(7), p.656 - 663, 1987/07
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)no abstracts in English
; ; ; ; Tobita, Tsutomu; ; ; Yamamoto, Katsumune
JAERI-M 86-146, 21 Pages, 1986/10
no abstracts in English
; ;
JAERI-M 85-012, 42 Pages, 1985/02
no abstracts in English
; Numakunai, Takao; ;
JAERI-M 8966, 50 Pages, 1980/07
no abstracts in English
; ; Ono, Shinichi
Bulletin of the Chemical Society of Japan, 48(5), p.1411 - 1416, 1975/05
Times Cited Count：12no abstracts in English
Tamura, Hajimu; Kokubu, Yoko; Umeda, Koji
no journal, ,
JAEA installed an IsotopX NGX noble gas mass spectrometer with an water sample oriented preparation system in Tono Geoscience Center to measure helium accumulation age and neon isotope ratio of ground water for estimation of ground water stability on long term geological stability survay on geological disposal of nuclear waste. High precision isotope analysis by multi-collector mass spectrometer is neccessary tool for neon isotope analysis of young ground water due to small isotopic variation of neon for nucleogenic reaction or mixing of volcanic fluids in ground water. NGX-004 was configured for simultanous measurement of neon isotopes with 2 faradays for 
Ne and 
Ne, and 1 SEM for 
Ne spaced out 1 m/z each other. 10.084 
0.002 of Ne/Ne and 0.02598 0.00004 of Ne/Ne were obtained by 
ohm faraday and 
ohm faraday, and ion count and ohm faraday, which is able to resolve 0.2% difference.
Yamamoto, Yoichi; Kijima, Yuichi; Tomita, Yutaka
no journal, ,
Based on repeated DPRK's nuclear tests, the Japanese government contributed funds for the noble gas measurement project in February 2017 for the purpose of strengthening CTBTO's detection capability for nuclear tests. The CTBTO decided to conduct measurements in Hokkaido and Tohoku regions of Japan for the time being, and to enhance JAEA with experiences and performance of measurements in Japan as the responsible organization. In response to this, the JAEA has installed two mobile noble gas measurement systems at Horonobe, Hokkaido and JAEA Ohminato site in Mutsu, Aomori, and been carrying out the joint measurement project with the CTBTO. The current status of this project will be presented.
Tomita, Yutaka; Kumata, Masahiro; Wakabayashi, Shuji; Kijima, Yuichi; Yamamoto, Yoichi; Oda, Tetsuzo
no journal, ,
Furuno, Akiko; Tateoka, Hisanori*; Yamamoto, Yoichi; Kurihara, Toshiyuki; Tomita, Yutaka
no journal, ,
Our team operates and manages the Takasaki Radionuclide Monitoring Station of the CTBT International Monitoring System, as well as the monitoring stations of the Noble gas joint measurement project with CTBT. Radioactive xenon is observed irregularly and frequently at these stations, and it is very important to identify the source of the emissions in order to ensure detection of nuclear tests. Xe-133 is the most frequently detected of the four nuclides. However, it is difficult to identify the release source of Xe-133 because it has a half-life of 5.2 days and may affected by Xe-133 from distant facilities (e.g., Europe or Russia) due to meteorological conditions and release amounts. Xe-135, on the other hand, is detected less frequently, but its short half-life of 9.1 hours limits possible sources to a relatively narrow range. We estimated the source of Xe-135 for two examples observed in 2021 at the past conference. In this presentation, we focus on the Xe-135 detection events to date and discuss possible release sources that could affect the background of radioactive noble gases in Japan.
Yamamoto, Yoichi; Kijima, Yuichi; Tomita, Yutaka
no journal, ,
This presentation summarizes JAEA's recent activities related to CTBT verification regime. To establish the global verification regime of CTBT for the nuclear tests, JAEA has been operating provisionally three facilities (two monitoring stations and one radionuclide laboratory) of the CTBT international monitoring system and a national data center for radionuclide monitoring. For the 6th nuclear test conducted by North Korea in September 2017, JAEA reported the analysis and evaluation results of data observed at the CTBT radionuclide monitoring stations to the national government etc. in a timely manner and thereby contributed to the evaluation by the national government based on the CTBT operation system in Japan. For the purpose of strengthening CTBTO's detection capability for nuclear tests, JAEA started new noble gas joint measurement project with CTBTO in Horonobe (Hokkaido) and Mutsu (Aomori) based on the Japanese government contribution in 2017.
Yamamoto, Yoichi; Kijima, Yuichi; Tomita, Yutaka
no journal, ,
Radionuclide monitoring is the only way to judge whether the target explosion event was a nuclear test. Among the radionuclides produced by the nuclear explosion, the noble gases are particularly important because they are inert and more likely to leak to the ground rather than other substances in an underground nuclear test. Only 4 radioxenon isotopes as the noble gases are monitored for the CTBT verification. It was after the first nuclear test of North Korea in October 2006, when a radioxenon monitoring system installed at the Takasaki radionuclide monitoring station in Japan and the radioxenon monitoring has been carried out since January 2007. We report on the past observation results of the radioxenon at the Takasaki radionuclide monitoring station and the characteristics of radioxenon background.
