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10. Identification of Carbon in Glassy Cesium-Bearing Microparticles Using Electron Microscopy and Formation Mechanisms of the Microparticles.

Author

Hidaka, Akihide

Abstract

The author previously proposed that glassy cesium-bearing microparticles [resulting uniquely from the Fukushima Daiichi nuclear power station (FDNPS) accident] may have been formed by melting and atomization of glass fibers (GFs) of the high-efficiency particulate air filter in the standby gas treatment system line due to the flame and blast during the hydrogen explosion in Unit 3. Assuming that this hypothesis is correct, Type A could contain or accompany carbon, which ignites spontaneously above 623 K, because of the limited time to be heated up, the inclusion of carbon in the binder applied on the GF surface, and the closely located charcoal filter. As previous studies have not identified carbon, the present analyses were performed with an electron probe microanalyzer to determine whether Type A contains carbon. The results show that Type A contained carbon originating from the binder. Some nonspherical particles were accompanied by Type A, and the film surrounding Type A contained more carbon, 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 only by the author's proposed hypothesis. Although it may be premature to determine Type A formation mechanisms, this information enables one to limit the temperature conditions of Type A formation. [ABSTRACT FROM AUTHOR]

Published
2022
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11. 環境モニタリングデータとWSPEEDIコードで逆算した福島第一原子力発電所事故時ソースタームの131I/137Cs比を用いた事故後期の131I及び137Cs放出挙動に関する考察

Author

Hidaka, Akihide and Yokoyama, Hiroya

Abstract

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 $^{131}$I and $^{137}$Cs release behaviors during the late phase of the accident based on $^{131}$I/$^{137}$Cs ratio of the source terms that were recently evaluated backward by WSPEEDI code based on environmental monitoring data. The $^{131}$I release from the contaminated water in the basement of 1F2 and 1F3 reactor buildings was evaluated to be about 10\% of $^{131}$I source term. The increase in $^{137}$Cs release from March 21 to 23 and from March 30 to 31 could be explained by the release of CsBO$_{2}$ which is formed as a result of chemical reactions of Cs with B$_{4}$C due to re-ascension of the core temperature caused by slight shortage of the core cooling water., 福島第一原子力発電所事故の評価では、炉内事象と環境モニタリング測定との結びつきの議論が重要であるが、事故から6年近く経過した現在でも、両者の事象を統合的に扱った研究は必ずしも進んでいない。WSPEEDIコードと環境モニタリングデータから逆算で詳細化された$^{131}$I/$^{137}$Cs比に基づき、福島事故後期における原子炉建家等の地下汚染水からの気液分配に基づく$^{131}$I放出量を再評価するとともに、これまで検討が行われなかった$^{137}$Cs放出挙動に関して化学形や放出機構等について検討した。原子炉建屋等の地下汚染水からの$^{131}$I放出量に関する再評価では、全ソースタームに対する地下汚染水からの$^{131}$I放出の寄与分は約10\%となった。また、3/21$\sim$3/23及び3/30$\sim$3/31の$^{131}$I放出量に対する$^{137}$Cs放出量の超過は、炉心冷却水がわずかに不足したことに伴う炉心温度の再上昇により、制御材を起源として生成するCsBO$_{2}$の放出でほぼ説明できる見通しを得た。

Published
2017

13. Japan - IAEA Joint Nuclear Energy Management School 2016

Author

Yamaguchi, Mika, Hidaka, Akihide, Ikuta, Yuko, Murakami, Kenta, Tomita, Akira, Hirose, Hiroya, Watanebe, Masanori, Ueda, Kinichi, Namaizawa, Ken, Onose, Takatoshi, Yamashita, Kiyonobu, Uesaka, Mitsuru, Kita, Tomohiko, Toba, Akio, Kitabata, Takuya, and Sawai, Tomotsugu

Abstract

IAEAは、将来原子力エネルギー計画を運営管理するリーダーとなる人材の育成を目的とした原子力エネルギーマネジメントスクールを2010年より世界各国で開催している。原子力機構は、日本原子力人材育成ネットワークの事務局として、同ネットワークに参加している東京大学、日本原子力産業協会及び原子力国際協力センターとともに、2012年よりIAEAと共催という運営形態で上記スクールを日本で継続的に開催している。2016年は、IAEAの専門家を講師とした講義とともに、日本開催の特徴を生かしつつ、日本人専門家の協力を得て、福島第一原子力発電所事故の教訓、日本の原子力分野における経験・技術の紹介などを含む独自性のある講義を提供した。施設見学では、多様な原子力関連施設の見学を福井県及び神戸市で実施した。本スクールの開催を通して、我が国の若手人材の国際化および新規原子力導入国等の人材育成へ貢献することができ、また、我が国とIAEAとの協力関係の促進に資することができた。加えて、関係機関が一体となって協力し合い開催することにより、国内の原子力人材育成ネットワークの協力関係を強化することができた。, Since 2010, IAEA has held the NEM School to develop future leaders who plan and manage nuclear energy utilization in their county. Since 2012, JAEA together with Japan Nuclear HRD Network, University of Tokyo, Japan Atomic Industrial Forum and JAIF International Cooperation Center have cohosted the school in Japan in cooperation with IAEA. Since then, the school has been held in Japan every year. In 2006, Japanese nuclear technology and experience, such as lessons learned from the Fukushima Daiichi Nuclear Power Plant accident, were provided to offer a unique opportunity for the participants to learn about particular cases in Japan. Through the school, we contributed to the internationalization of Japanese young nuclear professionals, development of nuclear human resource of other countries including nuclear newcomers, and enhanced cooperative relationship with IAEA. Additionally, collaborative relationship within the network was strengthened by organizing the school in Japan.

Published
2017

15. Estimation of the Release Time of Radio-Tellurium During the Fukushima Daiichi Nuclear Power Plant Accident and Its Relationship to Individual Plant Events.

Author

Takahashi, Sentaro, Kawashima, Shigeto, Hidaka, Akihide, Tanaka, Sota, and Takahashi, Tomoyuki

Abstract

A simulation model was developed to estimate the areal (surface) deposition pattern of 129mTe after the Fukushima Daiichi nuclear power plant (FDNPP) accident. Using this model, the timing and intensity of the 129mTe release were reverse estimated from the environmental monitoring data. Validation using 137Cs data showed that the model simulated atmospheric dispersion and estimated surface deposition with relatively high accuracy. The estimated surface deposition pattern of 129mTe was consistent with the actual measured pattern. The estimated time and activity of 129mTe emissions indicated that 129mTe was predominantly emitted from FDNPP Unit 3. [ABSTRACT FROM AUTHOR]

Published
2019
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16. 訂正; 環境モニタリングデータとWSPEEDIコードで逆算した福島第一原子力発電所事故時ソースタームの131I/137Cs比を用いた事故後期の131I及び137Cs放出挙動に関する考察、2017年日本原子力学会欧文誌、図6の縦軸の修正

Author

Hidaka, Akihide and Yokoyama, Hiroya

Abstract

以前に発表した論文(Examination of $^{131}$I and $^{137}$Cs releases during late phase of Fukushima Daiichi NPP accident by using $^{131}$I/$^{137}$Cs ratio of source terms evaluated reversely by WSPEEDI code with environmental monitoring data [Journal of Nuclear Science and Technology, vol.54(8), pp.819-829 (2017)])における図6の縦軸の訂正である。

Published
2017

39. Findings from CSARP; Cooperative Severe Accident Research Program.

Author

SUGIMOTO, Jun, primary, HASHIMO-TO, Kazuichiro, additional, YAMANO, Norihiko, additional, HIDAKA, Akihide, additional, MARU-YAMA, Yu, additional, UEZUKA, Hiroshi, additional, FUKETA, Toyoshi, additional, NAKAMURA, Takehiko, additional, SODA, Kunihisa, additional, and KATANISHI, Masashi, additional

Published
1997
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40. Recent Advances of Thermal Hydraulic Researches in Severe Accident.

Author

NARIAI, Hideki, primary, SUGIYAMA, Kenichiro, additional, KATAOKA, Isao, additional, MISHIMA, Kaichiro, additional, KIKUCHI, Yoshihiro, additional, MONDE, Masanori, additional, SUGIMOTO, Jun, additional, YAMANO, Norihiro, additional, HIDAKA, Akihide, additional, NAGASAKA, Hideo, additional, KAJIMOTO, Mitsuhiro, additional, OHNO, Shuji, additional, and OGATA, Junji, additional

Published
1997
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