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Goto, Sho; Aoki, Kenji; Morimoto, Kenji; Tsuboi, Masatoshi; Isozaki, Naohiko; Furukawa, Ryuichi; Kitagawa, Osamu; Fukaya, Yasuhiro*
Nihon Hozen Gakkai Dai-17-Kai Gakujutsu Koenkai Yoshishu, p.517 - 520, 2021/07
no abstracts in English
Isozaki, Naohiko; Morimoto, Kenji; Furukawa, Ryuichi; Tsuboi, Masatoshi; Yada, Yuji; Miyoshi, Ryuta; Uchida, Toyomi; Ikezawa, Kazumi*; Kurosawa, Kenji*
Nihon Hozen Gakkai Dai-16-Kai Gakujutsu Koenkai Yoshishu, p.225 - 228, 2019/07
Highly active liquid waste, which is generated by the reprocessing of spent nuclear fuel, is stored in storage tank of Tokai Reprocessing Plant until it is vitrified. The waste solution in the tank is periodically agitated to avoid the precipitation of insoluble residues during the storage. Three way valves and ball valves have been located at the tank for agitation. Radiation dose rate at the valve location is high and operator's radiation exposure become a problem. Therefore, measures to reduce radiation exposure are performed and reported in this presentation.
Domura, Kazuyuki; Morimoto, Kenji; Seto, Nobuhiko; Iwasaki, Shogo; Fukuari, Yoshihiro; Inami, Shinichi
no journal, ,
A leak occurred from the sea release pipe buried in the bottom of the sea of the Tokai reprocessing plant. The plumbing of the leak point was cut to investigate the cause of the leak and was collected ashore. Then the investigations such as surface observation and other analyses were performed. As a result of this investigation, the plumbing was scratched at the time of construction from the outside. In the service of approximately 17 years, a damaged part changed with age, and it was estimated that it led to a crack. It was estimated for the leak of the plumbing that hydrogen produced with electrolytic protection caused hydrogen embrittlement cracking and hydrogen induced cracking. This paper reports the details of the investigations.
Wakimoto, Fumitsugu; Morimoto, Kenji; Terunuma, Tomohiro; Ozeki, Tatsuya; Iwasaki, Shogo; Inami, Shinichi
no journal, ,
To investigate the cause of the leak phenomenon from the sea release facilities of the Tokai reprocessing plant, the part of the pipe having the leak point was collected, and the investigations such as surface observation, chemical analysis etc. were performed. As a result, following things were shown as estimated causes; the leak point of the release pipe was mechanically damaged during the construction, breaking occurred on the damaged part by a successive change; and the leak occurred. This paper reports the details of the identified cause that the initial damage by external force would affect the leak phenomenon of the sea release piping.
Yasuo, Kiyoshi; Morimoto, Kenji; Seto, Nobuhiko; Watahiki, Seiichi
no journal, ,
JP, 2009-105389 
Patent publication (In Japanese)
Cells and vessels as well as buildings have maintained as a negative pressure to keep nuclear materials inside. Differential pressure switches, detecting change of liquid level and pressure at reprocessing plant, have been required airtightness for the nuclear materials containment under negative pressure. Problem of using the conventional airtight switch is, however, that could not meet the acceptable range with deep negative pressure. We have designed and made a prototype airtight switch applying a new type of pressure detection component. The prototype switch has been reliable on the actual usage, which has been evaluated by an operation, a vibration and an endurance test. We are improving its quality for adapting to the reprocessing process.
Morimoto, Kenji; Isozaki, Naohiko; Yasuo, Kiyoshi
no journal, ,
no abstracts in English
Omori, Kazuki; Morimoto, Kenji; Isozaki, Naohiko
no journal, ,
no abstracts in English