Nuclear hydrogen demonstration project using the HTTR; Demarcation of nuclear-industrial laws and design standards

Aoki, Takeshi; Shimizu, Atsushi; Ishii, Katsunori; Morita, Keisuke; Mizuta, Naoki; Kurahayashi, Kaoru; Yasuda, Takanori; Noguchi, Hiroki; Nomoto, Yasunobu; Iigaki, Kazuhiko; et al.

Annals of Nuclear Energy, 220, p.111503_1 - 111503_7, 2025/09

https://doi.org/10.1016/j.anucene.2025.111503

Aiming to establish coupling technologies between a high temperature gas cooled reactor and a hydrogen production plant, JAEA has initiated the HTTR Heat Application Test Project and is conducting the safety design and the safety analysis for the licensing of the HTTR Heat Application Test Facility. The present study proposed a relative evaluation methodology for the demarcation of applicable laws and design standards for the nuclear hydrogen production system and applied it to the HTTR Heat Application Test Facility. The evaluation results showed that a candidate applying the High Pressure Gas Safety Act to the Heat Application Test Facility (hydrogen production plant) and design standards established under the High Pressure Gas Safety Act to the steam reformer did not show the lowest category in any of the metrics, and was proposed as the most superior demarcation option for the HTTR Heat Application Test Facility.

Development of portable VR system for radiation work environment using 3-D environmental map visualizing radiation information as input data

Sato, Yuki; Minemoto, Kojiro*; Nemoto, Makoto*; Matsuura, Yasutaka*; Hayashi, Keisuke*

Proceedings of International Conference on Nuclear Decommissioning; Addressing the Past and Ensuring the Future 2023 (Internet), 4 Pages, 2025/00

The development of technology to visualize the distribution of radioactive substances at the decommissioning site of the Fukushima Daiichi Nuclear Power Station (FDNPS) is important for reducing worker exposure and developing a detailed work plan. Sato, one of the authors, developed an integrated Radiation Imaging System (iRIS) that combines a Simultaneous Localization and Mapping (SLAM) device, a Compton camera (a type of gamma-ray imager), and a survey meter, and have successfully produced a 3-D map of the working environment inside the FDNPS that visualizes the location of radioactive hot spots and the distribution of air dose rates. In addition, the authors are developing a system that enables users to experience the radiation environment of the FDNPS in virtual reality (VR) using the 3-D map visualizing such radiation information as input data. This VR system can use a commercially available portable VR head-mounted display, which not only displays the location of the radiation source in a virtual space, but also has the ability to calculate the exposure dose according to the working time. The development status of this VR system, which is expected to be effective in educating inexperienced workers and planning work, will be presented at the conference.

Study on microwave power dependency of electron spin resonance spectrum of carbonate radicals in teeth

Iwami, Satone*; Yamashita, Takuma*; Mitsuyasu, Yusuke*; Ono, Kenta*; Oka, Toshitaka; Takahashi, Atsushi*; Kino, Yasushi*; Sekine, Tsutomu*; Shimizu, Yoshinaka*; Chiba, Mirei*; et al.

KEK Proceedings 2024-6, p.91 - 95, 2024/12

We aim to improve the detection limit of the ESR dosimetry method. In this study, the saturation behavior of each radical was investigated by varying the microwave power during ESR measurement. Based on the difference in spin relaxation time between carbonate radicals and native radicals, it is expected that the signal-to-noise ratio improves and the detection limit can be lowered when the microwave power is increased to 4.0 mW.

Development of a control system for core-sampling USV that combines sliding mode control and neural network

Morito, Makoto*; Fujii, Shun*; Yoshimura, Koki*; Sanada, Yukihisa; Baba, Shoichiro*; Matsunaga, Hiroshi*; Mori, Takami*; Sato, Keiichiro*; Tahara, Junichiro*

Proceedings of 34th International Ocean and Polar Engineering Conference (ISOPE-2024), p.3754 - 3761, 2024/06

This study proposes a method that combines sliding mode control and neural networks as a control method for unmanned surface vehicle to measure radiation in submarine soil. Sliding mode control is used as the base of control input, and corrective inputs are added using a neural network controller so that one of the parameters of sliding mode control, , and its rate of change are reduced. After producing a control system using this method, we conducted simulation tests and sea area tests to evaluate whether the survey could be conducted using this method.

Development of coupling technology for high temperature gas-cooled reactors and hydrogen production facility; HTTR heat application test project plan

Ishii, Katsunori; Morita, Keisuke; Noguchi, Hiroki; Aoki, Takeshi; Mizuta, Naoki; Hasegawa, Takeshi; Nagatsuka, Kentaro; Nomoto, Yasunobu; Shimizu, Atsushi; Iigaki, Kazuhiko; et al.

Dai-27-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Koen Rombunshu (Internet), 4 Pages, 2023/09

https://doi.org/10.1299/jsmepes.2023.27.A242

Intruder configurations in Ne at the transition into the island of inversion; Detailed structure study of Ne

Wang, H.*; Yasuda, Masahiro*; Kondo, Yosuke*; Nakamura, Takashi*; Tostevin, J. A.*; Ogata, Kazuyuki*; Otsuka, Takaharu*; Poves, A.*; Shimizu, Noritaka*; Yoshida, Kazuki; et al.

Physics Letters B, 843, p.138038_1 - 138038_9, 2023/08

https://doi.org/10.1016/j.physletb.2023.138038

Detailed -ray spectroscopy of the exotic neon isotope Ne has been performed using the one-neutron removal reaction from Ne. Based on an analysis of parallel momentum distributions, a level scheme with spin-parity assignments has been constructed for Ne and the negative-parity states are identified for the first time. The measured partial cross sections and momentum distributions reveal a significant intruder p-wave strength providing evidence of the breakdown of the N = 20 and N = 28 shell gaps. Only a weak, possible f-wave strength was observed to bound final states. Large-scale shell-model calculations with different effective interactions do not reproduce the large p-wave and small f-wave strength observed experimentally, indicating an ongoing challenge for a complete theoretical description of the transition into the island of inversion along the Ne isotopic chain.

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

Nuclear Science Research Institute Meteorological Statistics (2017-2021)

Futagawa, Kazuo; Kashimura, Keita; Sato, Daiki*; Kawasaki, Masatsugu

JAEA-Data/Code 2022-011, 75 Pages, 2023/03

JAEA-Data-Code-2022-011.pdf:1.49MB

These statistical results are based on the meteorological data observed at the Nuclear Science Research Institute in Japan Atomic Energy Agency and statistically processed according to "The guideline of meteorological statistics for the safety analysis of nuclear power reactor" (Nuclear Safety Commission on January 28, 1982; revised on March 29, 2001). The statistics are based on 5 years of meteorological data, from January 2017 to December 2021. These are statistical results of wind direction, wind speed, atmospheric stability, etc., which are used for dose assessment of the general public due to radioactive materials discharged into the atmosphere from nuclear reactor facilities.

Mesospheric ionization during substorm growth phase

Murase, Kiyoka*; Kataoka, Ryuho*; Nishiyama, Takanori*; Nishimura, Koji*; Hashimoto, Taishi*; Tanaka, Yoshimasa*; Kadokura, Akira*; Tomikawa, Yoshihiro*; Tsutsumi, Masaki*; Ogawa, Yasunobu*; et al.

Journal of Space Weather and Space Climate (Internet), 12, p.18_1 - 18_16, 2022/06

https://doi.org/10.1051/swsc/2022012

We identified two energetic electron precipitation (EEP) events during the growth phase of moderate substorms and estimated the mesospheric ionization rate for an EEP event for which the most comprehensive dataset from ground-based and space-born instruments was available. The mesospheric ionization signature reached below 70 km altitude and continued for ~15 min until the substorm onset, as observed by the PANSY radar and imaging riometer at Syowa Station in the Antarctic region. We also used energetic electron flux observed by the Arase and POES 15 satellites as the input for the air-shower simulation code PHITS to quantitatively estimate the mesospheric ionization rate. Combining the cutting-edge observations and simulations, we shed new light on the space weather impact of the EEP events during geomagnetically quiet times, which is important to understand the possible link between the space environment and climate.

Annual report on the environmental radiation monitoring around the Tokai Reprocessing Plant FY2020

Nakada, Akira; Nakano, Masanao; Kanai, Katsuta; Seya, Natsumi; Nishimura, Shusaku; Nemoto, Masashi; Tobita, Keiji; Futagawa, Kazuo; Yamada, Ryohei; Uchiyama, Rei; et al.

JAEA-Review 2021-062, 163 Pages, 2022/02

JAEA-Review-2021-062.pdf:2.87MB

Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed by the Nuclear Fuel Cycle Engineering Laboratories, based on "Safety Regulations for the Reprocessing Plant of Japan Atomic Energy Agency, Chapter IV - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitant due to the radioactivity discharged from the plant to the atmosphere and the sea during April 2020 to March 2021. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Co., Inc. (the trade name was changed to Tokyo Electric Power Company Holdings, Inc. on April 1, 2016) in March 2011. Appendices present comprehensive information, such as monitoring programs, monitoring methods, monitoring results and their trends, meteorological data and discharged radioactive wastes. In addition, the data which were influenced by the accidental release and exceeded the normal range of fluctuation in the monitoring, were evaluated.