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Grambow, B.; Nitta, Ayako; Shibata, Atsuhiro; Koma, Yoshikazu; Utsunomiya, Satoshi*; Takami, Ryu*; Fueda, Kazuki*; Onuki, Toshihiko*; Jegou, C.*; Laffolley, H.*; et al.
Journal of Nuclear Science and Technology, 59(1), p.1 - 24, 2022/01
Times Cited Count：15 Percentile：71.66(Nuclear Science & Technology)Yin, X.; Zhang, L.*; Meng, C.*; Inaba, Yusuke*; Wang, X.*; Nitta, Ayako; Koma, Yoshikazu; Takeshita, Kenji*
Journal of Hazardous Materials, 387, p.121677_1 - 121677_10, 2020/04
Times Cited Count：12 Percentile：54.1(Engineering, Environmental)Inaba, Yoshitomo; Nishihara, Tetsuo; Groethe, M. A.*; Nitta, Yoshikazu*
Nuclear Engineering and Design, 232(1), p.111 - 119, 2004/07
Times Cited Count：26 Percentile：82.77(Nuclear Science & Technology)It is important to grasp the explosion characteristics of object gases: natural gas and methane, in order to evaluate the influence of a gas explosion accident in the HTTR hydrogen production system on the reactor. Thus, we carried out explosion experiments of the object gases in semi-open space, and verified a numerical analysis code for the simulation of the explosion accident. It was confirmed that NG-air mixture or methane-air mixture in semi-open space didn't result in DDT although 10 g of C-4 explosive was used as an ignition source, and the numerical results agreed relatively with the experimental results. As a result, we could have the prospects for predicting the influence of the explosion accident on the reactor.
Inaba, Yoshitomo; Nishihara, Tetsuo; Nitta, Yoshikazu*
Nuclear Technology, 146(1), p.49 - 57, 2004/04
Times Cited Count：4 Percentile：29.26(Nuclear Science & Technology)One of the most important safety design issues for a hydrogen production system coupling with a High Temperature Gas-cooled Reactor (HTGR) is to ensure reactor safety against fire and explosion accidents because a large amount of combustible fluid is dealt with in the system. The Japan Atomic Energy Research Institute (JAERI) has a demonstration test plan of a hydrogen production system by steam reforming of methane coupling with the High Temperature engineering Test Reactor (HTTR). In the plan, we developed the P2A code system to analyze event sequences and consequences in detail on the fire and explosion accidents assumed in the HTGR or HTTR hydrogen production system. This paper described the three accident scenarios assumed in the system, the structure of P2A, the analysis procedure with P2A and the results of the numerical analyses based on the accident scenarios, and it was showed that P2A was a useful tool for the accident analysis in the system.
Nitta, Ayako; Oki, Keiichi; Koma, Yoshikazu
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Various radioactive wastes generated in Fukushima Daiichi Nuclear Power Station should be safely disposed of. The properties of the wastes are required to understand. For that, the wastes are sampled and performed analyses. To utilize obtained analytical data, the database "FRAnDLi" was made to provide the data through the Internet.
Nitta, Ayako; Hinai, Hiroshi; Sato, Yoshiyuki; Aono, Ryuji; Oki, Keiichi; Koma, Yoshikazu; Shibata, Atsuhiro
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no abstracts in English
Murakami, Erina; Oki, Keiichi; Takahatake, Yoko; Nitta, Ayako; Shibata, Atsuhiro; Koma, Yoshikazu
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no abstracts in English
Nitta, Ayako; Hinai, Hiroshi; Shibata, Atsuhiro; Nomura, Kazunori; Oki, Keiichi; Koma, Yoshikazu
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Hinai, Hiroshi; Nitta, Ayako; Shibata, Atsuhiro; Koma, Yoshikazu; Kaneko, Masaaki*; Ichikawa, Masashi*
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no abstracts in English
Ichikawa, Masashi*; Kaneko, Masaaki*; Koma, Yoshikazu; Hinai, Hiroshi; Nitta, Ayako; Shibata, Atsuhiro
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To study on treatment and disposal of solid waste generated at Fukushima Daiichi NPS (1F), radionuclide composition of sample taken from the bottom of primary containment vessel (PCV) of unit 1 was acquired by radioactivity analysis. It was the first time that nuclide composition data of samples taken from the inside of the reactor had been acquired, and the acquisition of these data will make it possible to estimate the origin of contaminants.
Kaneko, Masaaki*; Ichikawa, Masashi*; Hinai, Hiroshi; Nitta, Ayako; Shibata, Atsuhiro; Koma, Yoshikazu
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no abstracts in English
Ichikawa, Masashi*; Kaneko, Masaaki*; Hinai, Hiroshi; Nitta, Ayako; Shibata, Atsuhiro; Koma, Yoshikazu
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no abstracts in English
Nitta, Ayako; Hinai, Hiroshi; Ichige, Yoshiaki; Koma, Yoshikazu; Shibata, Atsuhiro
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no abstracts in English
Kitatsuji, Yoshihiro; Ouchi, Kazuki; Yomogida, Takumi; Oka, Toshitaka; Nitta, Ayako; Hinai, Hiroshi; Koma, Yoshikazu; Konno, Katsuhiro*
no journal, ,
In order to clarify the chemical species of alpha nuclides in the contaminated water of the Fukushima Daiichi Nuclear Power Station, sludge was classified by particle size. The concentration of alpha radioisotope was measured and the particles were investigated. Most alpha particles were larger than 10 micrometers and settled at the bottom of the torus chamber.
and 
spectrometry and elemental composition by ICP-AESNitta, Ayako; Hinai, Hiroshi; Shibata, Atsuhiro; Koma, Yoshikazu
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no abstracts in English
-emitting nuclides analysis of the stagnant water including sediments in Fukushima Daiichi NPS, 5; Estimation of Pu and Am behavior in the stagnant water of Unit #3 reactorNitta, Ayako; Hinai, Hiroshi; Kitawaki, Shinichi; Koma, Yoshikazu
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no abstracts in English
-emitting nuclides analysis of the stagnant water including sediments in Fukushima Daiichi NPS, 6; Chemical state analysis of -emitting nuclide particles obtained from unit #3 stagnant water sludge (Part 2)Nitta, Asahi; Usui, Akane; Yamaguchi, Yukako; Sekio, Yoshihiro; Maeda, Koji; Koma, Yoshikazu; Konno, Katsuhiro*
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no abstracts in English
-emitting nuclides analysis of the stagnant water including sediments in Fukushima Daiichi NPS, 8; Behavior of moving to sediment of Pu and AmNitta, Ayako; Hinai, Hiroshi; Kitawaki, Shinichi; Koma, Yoshikazu
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no abstracts in English
-emitting nuclides analysis of the stagnant water including sediments in Fukushima Daiichi NPS, 10; Chemical state analysis of -emitting nuclide particles obtained from stagnant water sludge sampled from Unit #1 and centralized radioactive waste treatment facilityToyota, Chihiro; Nitta, Asahi; Usui, Akane; Sekio, Yoshihiro; Maeda, Koji; Koma, Yoshikazu; Konno, Katsuhiro*
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no abstracts in English
