Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Terunuma, Tomohiro; Ozeki, Tatsuya; Iwasaki, Shogo
Proceedings of 7th International Conference on NDE in relation to Structural Integrity for Nuclear and Pressurized Components (CD-ROM), p.424 - 429, 2010/00
After spent fuel is chopped mechanically, the pieces of spent fuel are dissolved with high temperature nitric acid in a dissolver. Uranium, plutonium and fission products dissolved in this solution are separated through extraction process, respectively. Although the dissolver is made of stainless steel, corrosion might occur because the dissolver is always exposed to high temperature nitric acid and the nitric acid hume, etc. The dissolver is installed in a hot cell where is under high radiation environment, and it is difficult for operators it to approach. Therefore, the remote-controlled equipment has been developed to repair and inspect the dissolver.
Yasuo, Kiyoshi; Seto, Nobuhiko; Watahiki, Seiichi; Iwasaki, Shogo; Inami, Shinichi
Nihon Hozen Gakkai Dai-6-Kai Gakujutsu Koenkai Yoshishu, p.506 - 509, 2009/08
The air purge method is applied to measure a liquid level and its density of a radioactive solution in a tank in the Tokai reprocessing plant. In this method, air purge tubes soaked in nitric acid solution are often blocked by depositing salt of nitrate. Dried air is usually used for the air purge system and this can be one of the reasons for generating salt on the tube point. Therefore, a series of experiment using a humidifier to humidify the air has been performed to prevent the blocking with salt, and the effect has been experimentally confirmed.
Nishida, Kyosuke; Hiyama, Hisao; Shibata, Satomi; Iwasaki, Shogo; Inami, Shinichi
Nihon Hozen Gakkai Dai-6-Kai Gakujutsu Koenkai Yoshishu, p.294 - 297, 2009/08
Uninterruptible power supply systems are installed in the Tokai reprocessing plant in preparation for the emergency case that the commercial power supply is stopped by an accidental or intentional interruption in the supply of electricity. The uninterruptible power supply system particularly provides a temporary power source to the important devices for the radiation control of nuclear critical monitoring in the plant. Thus, the system is potentially important and essential for nuclear plants. The paper repots the current activities such as regular inspections, replacement of parts and system update, to maintain the function of uninterruptible power supply systems.
Aoki, Kenji; Hiyama, Hisao; Shibata, Satomi; Iwasaki, Shogo; Inami, Shinichi
no journal, ,
There are plural facilities having a radiation controlled area in the Tokai reprocessing plant, and an uninterruptible power supply system which considered a blackout is necessary for the power supply to each facility from the viewpoint of radiological management and nuclear material containment. In addition, at the time of the power supplying abnormality, intelligence gathering is necessary for prompt measures and restoration. In this report, the intensive monitoring system, which aimed for the unification of the power supply monitor place and the acceleration of the intelligence gathering to detect a power supply abnormality point, is described.
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.
Nishida, Kyosuke; Sukigara, Koji; Terunuma, Tomohiro; Iwasaki, Shogo; Inami, Shinichi
no journal, ,
no abstracts in English
Aoki, Kenji; Shimizu, Kazuyuki; Yamamoto, Masahiko; Takeuchi, Kenji; Hiyama, Hisao; Iwasaki, Shogo
no journal, ,
no abstracts in English
Noguchi, Koji; Yasuo, Kiyoshi; Seto, Nobuhiko; Iwasaki, Shogo; Inami, Shinichi
no journal, ,
At the Tokai reprocessing plant, release of the low radioactive fluid to the ocean is carried out using sea release facilities. It was confirmed that there was a leak point on the sea release facilities. Therefore, check and investigation were performed and the leak point was identified. The leak part was cut and the part was then collected to investigate the cause of the leak. As a result, it was estimated that the leak occurred after the pipe was mechanically damaged and a successive change occurred on the part. For this leak point, a series of works for the cause investigation was carried out in detail, the repair work was performed, and preventive measures were taken against recurrences. This paper describes the summary of the sea release facilities, the situation of the outbreak of the leak, and the process that confirmed the leak point.
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.