Accident consequence analysis for JMTR as a decommission facilities

Nagata, Hiroshi; Omori, Takazumi; Maeda, Eita; Otsuka, Kaoru; Nakano, Hiroko; Hanakawa, Hiroki; Ide, Hiroshi

JAEA-Review 2023-033, 40 Pages, 2024/01

JAEA-Review-2023-033.pdf:1.39MB

Japan Materials Testing Reactor (JMTR) was decided as a one of decommission facilities in April 2017. In order to submit the decommissioning plan to the Nuclear Regulation Authority, the type of accident assumed in the first stage of the decommissioning plan was selected, and the public exposure dose was evaluated. A fuel handling accident and a fire accident during storage of waste were selected as assumed accidents in the first stage of the decommissioning plan. An evaluation of the public exposure dose from the radioactive materials released into the atmosphere due to these accidents was estimated to be a maximum of 0.019 mSv (due to a fire accident during storage of waste). This estimated value was found to be sufficiently smaller than the judging criteria (5 mSv), and not to pose a significant risk of radiation exposure to the general public.

PSTEP: Project for solar-terrestrial environment prediction

Kusano, Kanya*; Ichimoto, Kiyoshi*; Ishii, Mamoru*; Miyoshi, Yoshizumi*; Yoden, Shigeo*; Akiyoshi, Hideharu*; Asai, Ayumi*; Ebihara, Yusuke*; Fujiwara, Hitoshi*; Goto, Tadanori*; et al.

Earth, Planets and Space (Internet), 73(1), p.159_1 - 159_29, 2021/12

https://doi.org/10.1186/s40623-021-01486-1

The PSTEP is a nationwide research collaboration in Japan and was conducted from April 2015 to March 2020, supported by a Grant-in-Aid for Scientific Research on Innovative Areas from the Ministry of Education, Culture, Sports, Science and Technology of Japan. It has made a significant progress in space weather research and operational forecasts, publishing over 500 refereed journal papers and organizing four international symposiums, various workshops and seminars, and summer school for graduate students at Rikubetsu in 2017. This paper is a summary report of the PSTEP and describes the major research achievements it produced.

Development of an external radiation dose estimation model for children returning to their homes in areas affected by the Fukushima Nuclear Accident

Mori, Airi; Takahara, Shogo; Yoshida, Hiroko*; Sanada, Yukihisa; Munakata, Masahiro

Health Physics, 117(6), p.606 - 617, 2019/12

https://doi.org/10.1097/HP.0000000000001100

Amorphization from the quenched high-pressure phase in III-V and II-VI compounds

Mori, Yuki*; Kato, Sayuri*; Mori, Hiroko*; Katayama, Yoshinori; Tsuji, Kazuhiko*

Review of High Pressure Science and Technology, 7, p.353 - 355, 1998/03

http://ci.nii.ac.jp/naid/10002690121

The temperature dependence of phase transitions in GaSb, AlSb, GaAs, GaP, InAs, ZnSe, and CdTe are studied by X-ray diffraction measurements under pressure upto 30 GPa at temperatures of 90-300K. The phase transitions depend on paths in a pressure-temperature phase diagram. The structure of the recovered phase after decompression depends on the ionicity in bonding: amorphous for small ionicity, the stable zincblende structure for large ionicity, and microcrystalline or moderate ionicity. These results are discussed by using a configuration-coordinate model.

Committee on dose assessments of Japanese population

Takahashi, Fumiaki; Ishimori, Yuu; Inagaki, Masayo*; Omori, Yasutaka*; Sanada, Tetsuya*; Sugino, Masato*; Furukawa, Masahide*; Hosoda, Masahiro*; Manabe, Kentaro; Yajima, Kazuaki*; et al.

no journal, , 

The Japan Health Physics Society (JHPS) established a committee on dose assessments of Japanese population in August, 2015. The committee consists of 12 members (researchers and technicians) who are engaged in natural radiation measurements, radiation monitoring, radiation dose assessment and so on. Discussion have been made on dose assessments for daily life exposure in Japan. At the first meeting, stragedy of the committee was discussed and terrestrial radiation, cosmic radiation. Radon and radioactivity in food were defined as the radiological source to be investigated. It was also decided that the committee also would investigate influential factors (e.g., dose assessment model, daily life pattern) on radiation dose assessments. In addition, the committee has a plan to make discussions how JHPS should undertake this issue in future. At the 49th Annual meeting of JHPS, the committee members report their activities and make discussions on radiation dose assessment of Japanese population with the participants to the meeting.

Development of -ray directional radiation dose detector with good efficiency for field survey

Yamamori, Ryo*; Kobayashi, Hikaru*; Honta, Shohei*; Yoshino, Hiroshi*; Nozaki, Atsuo*; Ichijo, Yusuke*; Hijikata, Yoshio*; Yoshida, Hiroko*; Furuta, Takuya

no journal, , 

Understanding radiation field is important to predict radiation dose rate in newly constructing buildings in an area widely contaminated by radioactive nuclei. Directional spectra of the radiations are important to consider the shielding effect of the building. We adopts a method to measure the directional spectra by adopting a plate of lead collimator in front of the scintillator and subtract the values from the spectra measured without lead collimator. We investigated a possible weight saving detection system having sufficient detection efficiency. The investigation was carried out for the condition of the collimator radius ( = 10, 15, 20 cm) and the distance between collimator and detector ( = 1, 3, 5 cm). We found that three combinations satisfied the 90 field view and the detection efficiency became better with larger collimator radius. On the other hand, larger collimator radius indicate heavier detection system. Therefore, we developed an optimum detection system for field survey with the 15 cm diameter plate (10kg), the scintillator (3.4kg), and the folder (1.0kg).