Combustion properties of glove-box panel resins under fire accidents

Tashiro, Shinsuke; Uchiyama, Gunzo; Ono, Takuya; Amano, Yuki; Yoshida, Ryoichiro; Watanabe, Koji*; Abe, Hitoshi; Yamane, Yuichi

Nuclear Technology, 211(3), p.429 - 438, 2025/03

https://doi.org/10.1080/00295450.2024.2329832

Contributing to the confinement safety evaluation of glove-box (GB) connected with high efficiency particle air (HEPA) filters for radioactive materials under fire accidents, combustion tests of a flammable polymer, Polymethyl methacrylate (PMMA), and a flame retardant polymer, Polycarbonate (PC), as typical GB panel resins have been conducted with an engineering-scale combustion apparatus. The combustion properties such as the mass loss rate (MLR) and the heat release rate (HRR) of PMMA and PC were investigated in the combustion tests. In the tests with the same shapes, it was found the followings; MLRs and HRRs of PMMA were larger than those of PC under the same supply flow rate into the combustion cell (Fv); MLRs and HRRs of PMMA and PC were constant under different Fv. Moreover, in the tests of PMMA with different cross section areas (S), MLRs and HRRs were found to be proportional to S. Using these results, the relationships of MLR and HRR to S of PMMA and PC were deduced.

Power profile analysis of criticality accidents involving fissile solution boiling with considering evaporation

Watanabe, Tomoaki; Yamane, Yuichi

Journal of Nuclear Science and Technology, 61(7), p.958 - 966, 2024/07

https://doi.org/10.1080/00223131.2023.2290711

The total fission energy released in a criticality accident involving fissile solution boiling tends to be high because the relatively high fission power continues during boiling. Simulating fission power change correctly during boiling seems essential to estimate the total fission energy. Fission power during boiling changes depending on fissile concentration and volume as the solution evaporates. In this study, we investigated the effect of concentration and volume change on estimated total fission energy for a long time of boiling. We introduced a model calculating the evaporation of fissile solution into the modified quasi-steady-state method to simulate power change during boiling. Three CRAC experiments and the Idaho Chemical Processing Plant (ICPP) criticality accident in 1959 were analyzed. As a result, the calculated energy considering concentration and volume change during boiling reproduced the measured energy well.

Overview of development program for engineering scale extraction chromatography MA(III) recovery system

Watanabe, So; Takahatake, Yoko; Hasegawa, Kenta; Goto, Ichiro*; Miyazaki, Yasunori; Watanabe, Masayuki; Sano, Yuichi; Takeuchi, Masayuki

Mechanical Engineering Journal (Internet), 11(2), p.23-00461_1 - 23-00461_10, 2024/04

https://doi.org/10.1299/mej.23-00461

Utilization of gamma ray irradiation at the WASTEF Facility

Sano, Naruto; Yamashita, Naoki; Watanabe, Masaya; Tsukada, Manabu*; Hoshino, Kazutoyo*; Hirai, Koki; Ikegami, Yuta*; Tashiro, Shinsuke; Yoshida, Ryoichiro; Hatakeyama, Yuichi; et al.

JAEA-Technology 2023-029, 36 Pages, 2024/03

JAEA-Technology-2023-029.pdf:2.47MB

At the Waste Safety Testing Facility (WASTEF), the gamma ray irradiation device "Gamma Cell 220" was relocated from the 4th Research Building of the Nuclear Science Research Institute in FY2019, and the use of gamma ray irradiation has begun. Initially, Fuel Cycle Safety Research Group, Fuel Cycle Safety Research Division, Nuclear Safety Research Center, Sector of Nuclear Safety Research and Emergency Preparedness, the owner of this device, conducted the tests as the main user, but since 2022, other users, including those outside the organization, have started using it. The gamma ray irradiation device "Gamma Cell 220" is manufactured by Nordion International Inc. in Canada. Since it was purchased in 1989, the built-in Co radiation source has been updated once, and safety research related to nuclear fuel cycles, etc. It is still used for this purpose to this day. This report summarizes the equipment overview of the gamma ray irradiation device "Gamma Cell 220", its permits and licenses at WASTEF, usage status, maintenance and inspection, and future prospects.

Study on criticality safety control of fuel debris for validation of methodology applied to the safety regulation

Suyama, Kenya; Ueki, Taro; Gunji, Satoshi; Watanabe, Tomoaki; Araki, Shohei; Fukuda, Kodai; Yamane, Yuichi; Izawa, Kazuhiko; Nagaya, Yasunobu; Kikuchi, Takeo; et al.

Proceedings of 12th International Conference on Nuclear Criticality Safety (ICNC2023) (Internet), 6 Pages, 2023/10

To remove and store safely the fuel debris generated by the severe accident of the Fukushima Daiichi Nuclear Power Station in 2011 is one of the most important and challenging topics for decommissioning of the damaged reactors in Fukushima. To validate the adopted method for the evaluation of criticality safety control of the fuel debris through comparison with the experimental data obtained by the criticality experiments, the Nuclear Regulation Authority (NRA) of Japan funds a research and development project which was entrusted to the Nuclear Safety Research Center (NSRC) of Japan Atomic Energy Agency (JAEA) from 2014. In this project, JAEA has been conducting such activities as i) comprehensive computation of the criticality characteristics of the fuel debris and making database (criticality map of the fuel debris), ii) development of new continuous energy Monte Carlo code, iii) evaluation of criticality accident and iv) modification of the critical assembly STACY for the experiments for validation of criticality safety control methodology. After the last ICNC2019, the project has the substantial progress in the modification of STACY which will start officially operation from May 2024 and the development of the Monte Carlo Code "Solomon" suitable for the criticality calculation for materials having spatially random distribution complies with the power spectrum. We present the whole picture of this research and development project and status of each technical topics in the session.

Development of engineering scale extraction chromatography separation system, 2; Spray drying granulation of silica support for adsorbent

Hasegawa, Kenta; Goto, Ichiro*; Miyazaki, Yasunori; Ambai, Hiromu; Watanabe, So; Watanabe, Masayuki; Sano, Yuichi; Takeuchi, Masayuki

Proceedings of 30th International Conference on Nuclear Engineering (ICONE30) (Internet), 5 Pages, 2023/05

Fact-finding survey on the competencies and literacy of radiological technologists regarding radiation disasters

Arai, Tomohiro*; Murata, Sho*; Watanabe, Yuichi*; Ishihara, Toshihiro*; Fukamizu, Yoshiya*; Takeda, Satoshi*; Ebata, Kiyokadzu*; Watanabe, Yuki; Takashima, Yoshio*; Kaneko, Junichi*

Journal of X-Ray Science and Technology, 31(2), p.237 - 245, 2023/03

https://doi.org/10.3233/XST-221341

Radiological technologists have received specialized education about radiation and serve as risk communicators who aim to lessen patients' anxiety about radiation exposure, in addition to performing radiological examinations in routine clinical practice. Also, Radiological technologists across Japan were dispatched to the affected area to conduct an essential procedure-screening the belongings and body surfaces of evacuees for contamination at the nuclear disaster at the Fukushima Daiichi Nuclear Power Plant operated by Tokyo Electric Power Company in March 2011. In this study, we conducted a fact-finding survey on knowledge and awareness of radiation disasters among radiological technologists at National Hospital Organization facilities in Japan to reveal their literacy and competencies regarding radiation disasters. Also, we compared the knowledge and awareness of radiation disasters among Japanese radiological technologists between nuclear power station areas and non-nuclear power station areas and discuss ideal human resource development for radiological technologists to be ready to serve during a radiation disaster.

Design and actual performance of J-PARC 3 GeV rapid cycling synchrotron for high-intensity operation

Yamamoto, Kazami; Kinsho, Michikazu; Hayashi, Naoki; Saha, P. K.; Tamura, Fumihiko; Yamamoto, Masanobu; Tani, Norio; Takayanagi, Tomohiro; Kamiya, Junichiro; Shobuda, Yoshihiro; et al.

Journal of Nuclear Science and Technology, 59(9), p.1174 - 1205, 2022/09

https://doi.org/10.1080/00223131.2022.2038301

In the Japan Proton Accelerator Research Complex, the purpose of the 3 GeV rapid cycling synchrotron (RCS) is to accelerate a 1 MW, high-intensity proton beam. To achieve beam operation at a repetition rate of 25 Hz at high intensities, the RCS was elaborately designed. After starting the RCS operation, we carefully verified the validity of its design and made certain improvements to establish a reliable operation at higher power as possible. Consequently, we demonstrated beam operation at a high power, namely, 1 MW. We then summarized the design, actual performance, and improvements of the RCS to achieve a 1 MW beam.

Multi-scale turbulence simulation suggesting improvement of electron heated plasma confinement

Maeyama, Shinya*; Watanabe, Tomohiko*; Nakata, Motoki*; Nunami, Masanori*; Asahi, Yuichi; Ishizawa, Akihiro*

Nature Communications (Internet), 13, p.3166_1 - 3166_8, 2022/06

https://doi.org/10.1038/s41467-022-30852-0

Turbulent transport is a key physics process for confining magnetic fusion plasma. Recent theoretical and experimental studies of existing fusion experimental devices revealed the existence of cross-scale interactions between small (electron)-scale and large (ion)-scale turbulence. Since conventional turbulent transport modelling lacks cross-scale interactions, it should be clarified whether cross-scale interactions are needed to be considered in future experiments on burning plasma, whose high electron temperature is sustained with fusion-born alpha particle heating. Here, we present supercomputer simulations showing that electron scale turbulence in high electron temperature plasma can affect the turbulent transport of not only electrons but also fuels and ash. Electron-scale turbulence disturbs the trajectories of resonant electrons responsible for ion-scale micro-instability and suppresses large-scale turbulent fluctuations. Simultaneously, ion-scale turbulent eddies also suppress electron-scale turbulence. These results indicate a mutually exclusive nature of turbulence with disparate scales. We demonstrate the possibility of reduced heat flux via cross-scale interactions.

A Storm-induced flood and associated nearshore dispersal of the river-derived suspended Cs

Uchiyama, Yusuke*; Tokunaga, Natsuki*; Azuma, Kohei*; Kamidaira, Yuki; Tsumune, Daisuke*; Iwasaki, Toshiki*; Yamada, Masatoshi*; Tateda, Yutaka*; Ishimaru, Takashi*; Ito, Yukari*; et al.

Science of the Total Environment, 816, p.151573_1 - 151573_13, 2022/04

https://doi.org/10.1016/j.scitotenv.2021.151573

no abstracts in English