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Omori, Yasutaka*; Hosoda, Masahiro*; Takahashi, Fumiaki; Sanada, Tetsuya*; Hirao, Shigekazu*; Ono, Koji*; Furukawa, Masahide*
Journal of Radiological Protection, 40(3), p.R99 - R140, 2020/09
Times Cited Count：22 Percentile：77.11(Environmental Sciences)UNSCEAR and the Nuclear Safety Research Association report the annual effective doses from cosmic rays, terrestrial radiation, inhalation and ingestion from natural sources. In this study, radiation doses from natural radiation sources in Japan were reviewed with the latest knowledge and data. Total annual effective dose from cosmic-ray exposure can be evaluated as 0.29 mSv. The annual effective dose from external exposure to terrestrial radiation for Japanese population can be evaluated as 0.33 mSv using the data of nationwide survey by the National Institute of Radiological Sciences. The Japan Chemical Analysis Center (JCAC) performed the nationwide radon survey using a unified method for radon measurements in indoor, outdoor and workplace. The annual effective dose for radon inhalation was estimated using a current dose conversion factor, and the values were estimated to be 0.50 mSv. The annual effective dose from thoron was reported as 0.09 mSv by UNSCEAR and then the annual effective dose from inhalation can be described as 0.59 mSv. According to the report of large scale survey of foodstuff by JCAC, the effective dose from main radionuclides due to dietary intake can be evaluated to be 0.99 mSv. Finally, Japanese population dose from natural radiation can be assessed as 2.2 mSv which is near to the world average value of 2.4 mSv.
Kurihara, Momo*; Yasutaka, Tetsuo*; Aono, Tatsuo*; Ashikawa, Nobuo*; Ebina, Hiroyuki*; Iijima, Takeshi*; Ishimaru, Kei*; Kanai, Ramon*; Karube, Jinichi*; Konnai, Yae*; et al.
Journal of Radioanalytical and Nuclear Chemistry, 322(2), p.477 - 485, 2019/11
Times Cited Count：2 Percentile：21.58(Chemistry, Analytical)We assessed the repeatability and reproducibility of methods for determining low dissolved radiocesium concentrations in freshwater in Fukushima. Twenty-one laboratories pre-concentrated three of 10 L samples by five different pre-concentration methods (prussian-blue-impregnated filter cartridges, coprecipitation with ammonium phosphomolybdate, evaporation, solid-phase extraction disks, and ion-exchange resin columns), and activity of radiocesium was measured. The z-scores for all of the 
Cs results were within 
2, indicating that the methods were accurate. The relative standard deviations (RSDs) indicating the variability in the results from different laboratories were larger than the RSDs indicating the variability in the results from each separate laboratory.
Tamaoki, Yuichi; Omori, Tsuyoshi; Fujishima, Tadatsune; Mizukoshi, Yasutaka; Sakamoto, Naoki
Proceedings of 53rd Annual Meeting of Hot Laboratories and Remote Handling Working Group (HOTLAB 2016) (Internet), 6 Pages, 2016/11
Post irradiation examinations are conducted in hot laboratories in Oarai Research and Development Center of the Japan Atomic Energy Agency in order to develop fuels and materials for fast reactors. These facilities, the majority of which were constructed in the 1970s, have accumulated operating experience over a period of more than 40 years. Continuous operational safety requires the maintenance of important equipment such as electronic devices, manipulators, in-cell cranes, as well as air conditioning and ventilation systems. A method for the periodic safety review for hot laboratories based on the periodic safety review method employed for preventive maintenance at commercialized power reactors in Japan has been developed. In this paper, the status of implementation of the periodic safety review for hot laboratories using the safety review method are introduced.
Fujishima, Tadatsune; Mizukoshi, Yasutaka; Sakamoto, Naoki; Omori, Tsuyoshi
Hozengaku, 13(2), p.115 - 125, 2014/07
In order to develop fuels and materials for fast reactors, five hot laboratories as a facility using nuclear materials for post irradiation examination (PIE) are now in operation at the Oarai Research and Development Centre of Japan Atomic Energy Agency. More than 30 years have passed since the first hot run of these facilities was started, and it has been indispensable to maintain the principal equipment for continuous safe operation. For application to preventive maintenance and the safe operation, a new safety review method that could be applied for these facilities was developed by modification of periodic safety review tools using for Japanese commercialized power reactors. Effective repair or replacement of equipment before malfunction have been performed and the priority for preventive maintenance could be appropriately determined for stable management of hot facility operations by the developed method.
Fujishima, Tadatsune; Sakamoto, Naoki; Mizukoshi, Yasutaka; Amagai, Tomio; Omori, Tsuyoshi
Nihon Hozen Gakkai Dai-5-Kai Gakujutsu Koenkai Yoshishu, p.388 - 392, 2008/07
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Mizukoshi, Yasutaka; Fujishima, Tadatsune; Sakamoto, Naoki; Amagai, Tomio; Omori, Tsuyoshi
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Fujishima, Tadatsune; Mizukoshi, Yasutaka; Sakamoto, Naoki; Amagai, Tomio; Omori, Tsuyoshi
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Fujishima, Tadatsune; Amagai, Tomio; Mizukoshi, Yasutaka; Sakamoto, Naoki; Omori, Tsuyoshi
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Amagai, Tomio; Fujishima, Tadatsune; Mizukoshi, Yasutaka; Sakamoto, Naoki; Omori, Tsuyoshi
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In the site of O-arai research and development center of Japan Atomic Energy Agency (JAEA), five hot laboratories for post-irradiation examination and development of plutonium fuels are operated more than 30 years. A safety review method for preventive maintenance on these hot laboratories includes test facilities and devices are established in 2003. After that, the safety review of these facilities and devices are done and taken the necessary maintenance based on the results in each year. In 2008, 372 test facilities and devices in these hot laboratories were checked and reviewed by this method. As a results of the safety review, repair issues of 38 facilities of above 372 facilities were resolved. This report shows the review results and maintenance experiences based on the results.
Fujishima, Tadatsune; Sakamoto, Naoki; Mizukoshi, Yasutaka; Amagai, Tomio; Omori, Tsuyoshi
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raysYamazaki, Takumi; Takada, Chie; Nakamura, Keisuke; Sagawa, Naoki; Hoshi, Katsuya; Nakagawa, Takahiro; Takimoto, Misaki; Tanimura, Yoshihiko*; Takahashi, Fumiaki; Momose, Takumaro; et al.
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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.
Hosoda, Masahiro*; Saito, Kimiaki; Mikami, Satoshi; Sanada, Tetsuya*; Omori, Yasutaka*; Takeda, Hikaru*; Yamada, Takahiro*; Hirao, Shigekazu*; Tani, Kotaro*; Orita, Makiko*; et al.
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Po-gross alpha countsYamada, Ryohei; Hashimoto, Hiroki*; Tamakuma, Yuki*; Omori, Yasutaka*; Hosoda, Masahiro*; Akata, Naofumi*; Uchiyama, Rei; Nakada, Akira; Endo, Michitaka*; Imajo, Yusuke*; et al.
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no abstracts in English
