Development of wide range photon detection system for muonic X-ray spectroscopy

Mizuno, Rurie*; Niikura, Megumi*; Saito, Takeshi*; Matsuzaki, Teiichiro*; Sakurai, Hiroyoshi*; Amato, A.*; Asari, Shunsuke*; Biswas, S.*; Chiu, I.-H. ; Gianluca, J.*; et al.

Nuclear Instruments and Methods in Physics Research A, 1060, p.169029_1 - 169029_14, 2024/03

https://doi.org/10.1016/j.nima.2023.169029

Development of safety design philosophy of HTTR-Heat Application Test Facility

Aoki, Takeshi; Shimizu, Atsushi; Noguchi, Hiroki; Kurahayashi, Kaoru; Yasuda, Takanori; Nomoto, Yasunobu; Iigaki, Kazuhiko; Sato, Hiroyuki; Sakaba, Nariaki

Proceedings of 30th International Conference on Nuclear Engineering (ICONE30) (Internet), 9 Pages, 2023/05

The safety design philosophy is developed for the HTTR (High Temperature Engineering Test Reactor) heat application test facility connecting high temperature gas-cooled reactor (HTGR) and the hydrogen production plant. The philosophy was proposed to apply proven conventional chemical plant standards to the hydrogen production facility for ensuring public safety against anticipated disasters caused by high pressure and combustible gases. The present study also proposed the safety design philosophy to meet specific safety requirements identified to the nuclear facilities with coupling to the hydrogen production facility such as measures to ensure a capability of normal operation of the nuclear facility against a fire and/or explosion of leaked combustible material, and fluctuation of amount of heat removal occurred in the hydrogen production plant. The safety design philosophy will be utilized to establish its basic and detailed designs of the HTTR-heat application test facility.

Development plan for coupling technology between high temperature gas-cooled reactor HTTR and Hydrogen Production Facility, 2; Development plan for coupling equipment between HTTR and Hydrogen Production Facility

Mizuta, Naoki; Morita, Keisuke; Aoki, Takeshi; Okita, Shoichiro; Ishii, Katsunori; Kurahayashi, Kaoru; Yasuda, Takanori; Tanaka, Masato; Isaka, Kazuyoshi; Noguchi, Hiroki; et al.

Proceedings of 30th International Conference on Nuclear Engineering (ICONE30) (Internet), 6 Pages, 2023/05

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.

Safety design philosophy of HTTR Heat Application Test Facility

Aoki, Takeshi; Shimizu, Atsushi; Iigaki, Kazuhiko; Okita, Shoichiro; Hasegawa, Takeshi; Mizuta, Naoki; Sato, Hiroyuki; Sakaba, Nariaki

JAEA-Technology 2022-011, 60 Pages, 2022/07

JAEA-Technology-2022-011.pdf:2.08MB

Japan Atomic Energy Agency is planning a High Temperature Engineering Test Reactor (HTTR) heat application test producing hydrogen with the HTTR which achieved the highest reactor outlet coolant temperature of 950C in the world to realize a massive, cost-effective and carbon-free hydrogen production technology utilizing a high temperature gas cooled reactor (HTGR). In the HTTR heat application test, it is required to establish its safety design for coupling a hydrogen production plant to HTGR through the licensing by the Nuclear Regulation Authority (NRA). A draft of a safety design philosophy for the HTTR heat application test facility was considered taking into account postulated events due to the plant modification and coupling of the hydrogen production plant based on the HTTR safety design which was authorized through the safety review of the NRA against New Regulatory Requirements. The safety design philosophy was examined to apply proven conventional chemical plant standards to the hydrogen production plant for ensuring public safety against disasters caused by high pressure gases. This report presents a result of a consideration on safety design philosophies regarding the reasonability and condition to apply the High Pressure Gas Safety Act for the hydrogen production plant, safety classifications, seismic design classification, identification of important safety system.

Numerical reproduction of dissolved U concentrations in a PO-treated column study of Hanford 300 area sediment using a simple ion exchange and immobile domain model

Saito, Tatsuo; Sato, Kazuhiko; Yamazawa, Hiromi*

Journal of Environmental Radioactivity, 237, p.106708_1 - 106708_9, 2021/10

https://doi.org/10.1016/j.jenvrad.2021.106708

We succeeded at numerical reproduction of dissolved U concentrations from column experiments with PO-treated Hanford 300 Area sediment. The time-series curves of dissolved U concentrations under various Darcy flow rate conditions were reproduced by the numerical model in the present study through optimization of the following parameters:(i) the mass of U in mobile domain (on surface soil connected to the stream) and the rest of the total U left as precipitation in immobile domain (isolated in deep soil);(ii) the mixing ratio between immobile and mobile domains, to fit the final recovering curve of concentration; and (iii) the cation exchange capacity (CEC) and equilibrium constant (k) of the exchange reaction of UO and H on simulated soil surface (), to fit the transient equilibrium concentration, forming the bed of the bathtub curve.

Structural and compositional characteristics of Fukushima release particulate material from Units 1 and 3 elucidates release mechanisms, accident chronology and future decommissioning strategy

Martin, P. G.*; Jones, C. P.*; Bartlett, S.*; Ignatyev, K.*; Megson-Smith, D.*; Satou, Yukihiko; Cipiccia, S.*; Batey, D. J.*; Rau, C.*; Sueki, Keisuke*; et al.

Scientific Reports (Internet), 10, p.22056_1 - 22056_17, 2020/12

https://doi.org/10.1038/s41598-020-79169-2

Classification of the insoluble particles including radioactive Cs found in Okuma town and Futaba town, Fukushima prefecture

Igarashi, Junya*; Zhang, Z. J.*; Ninomiya, Kazuhiko*; Shinohara, Atsushi*; Satou, Yukihiko; Minowa, Haruka*; Yoshikawa, Hideki

KEK Proceedings 2019-2, p.54 - 59, 2019/11

no abstracts in English

Activity of Sr in fallout particles collected in the difficult-to-return zone around the Fukushima Daiichi Nuclear Power Plant

Zhang, Z.*; Igarashi, Junya*; Satou, Yukihiko; Ninomiya, Kazuhiko*; Sueki, Keisuke*; Shinohara, Atsushi*

Environmental Science & Technology, 53(10), p.5868 - 5876, 2019/05

https://doi.org/10.1021/acs.est.8b06769

The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident released abundant radioactive particles into the surrounding environment. Herein, we analyzed the activity of Sr in these particles to estimate the contribution of this radionuclide to the overall radiation exposure and shed light on the processes that occurred during the accident. Seven radioactive particles were isolated from the dust and soil samples collected from areas surrounding the FDNPP, and the minimum/maximum Cs activities were determined as 224/4,100 Bq. Based on the size, specific activity, and Cs/Cs activity ratios, we concluded that six of the seven radioactive particles were released from the Unit 1 reactor, while one particle was released from the Unit 3 reactor by a hydrogen explosion. Strontium-90 was detected in all radioactive particles, and the minimal/maximal Sr activities were determined as 0.046/1.4 Bq. Cs/Sr activity ratios above 1000 were observed for all seven particles, that is, compared to Cs, Sr had negligible contribution to the overall radiation exposure. The Cs/Sr activity ratios of the radioactive particles were similar to those of terrestrial environmental samples and were higher for particles released from the Unit 1 reactor than for samples collected from the Unit 1 reactor building, which indicates possibility of additional Sr -rich contamination after release of the particles.

Local structure study of the iron-based systems of BaFeAs and LiFeAs by X-ray PDF and XAFS analyses

Li, S.*; Toyoda, Masayuki*; Kobayashi, Yoshiaki*; Ito, Masayuki*; Ikeuchi, Kazuhiko*; Yoneda, Yasuhiro; Otani, Akira*; Matsumura, Daiju; Asano, Shun*; Mizuki, Junichiro*; et al.

Physica C, 555, p.45 - 53, 2018/12

https://doi.org/10.1016/j.physc.2018.10.003

-dependence of local distortions in BaFeAs and LiFeAs by X-ray PDF and XAFS methods. Although PDF data exhibit anomaly at the structure transition temperature, EXAFS data exhibit no anomaly. Data supporting the local orthorhombicity at 300 K in the tetragonal phase for BaFeAs. Arguments on the origins of the 4-fold symmetry breaking in the ground average structure of the tetragonal phase.