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Goto, Yuichi; Yamamoto, Masahiko; Kuno, Takehiko; Inada, Satoshi
Nihon Hozen Gakkai Dai-15-Kai Gakujutsu Koenkai Yoshishu, p.489 - 492, 2018/07
Radioactive liquid waste from the Tokai Reprocessing Facility Analytical Laboratory is temporarily stored in intermediate waste storage tank by using receiving valves. Then, the liquid waste is transferred to liquid treatment facility by using liquid feed valves. The deterioration of the gasket part of these valves (leakage of waste liquid) was confirmed in 2004. Since then, the material of gaskets was changed from polyethylene to Teflon. In 2016, the gaskets were replaced by periodical update. Therefore, physical properties of used gaskets were investigated, and the relevance between radioactive level and degradation degree was evaluated.
Ishikuro, Yasuhiro; Nemoto, Tsutomu; Yamada, Yusuke; Oyama, Koji
Nihon Hozen Gakkai Dai-15-Kai Gakujutsu Koenkai Yoshishu, p.501 - 505, 2018/07
After operating until December 2010, JRR-4 was under periodical self-inspection for the next operation. After that, it suffered from the Great East Japan Earthquake on March 11, 2011. But it recovered almost a year later. However, we determined to decommission JRR-4 in September 2013. After that, we received the approval of the decommissioning plan of JRR-4 on June 7, 2017. And we received the approval of the change of the safety regulations related to it. Subsequently JRR-4 was shifted to decommission phase in December 2017. This report describes the outline of the decommissioning plan of JRR-4 and the implementation status.
Ueda, Masashi; Ishiguro, Takahiro*; Hattori, Shushi*; Hattori, Tsukasa*; Shirahama, Takuma*
no journal, ,
Sodium-cooled fast reactors need special maintenance technologies such as remote maintenance, under sodium viewer etc., because sodium is opaque, chemically active and the maintenance works must be performed in high temperature. To acquire basic knowledge for remote maintenance technology in liquid sodium, a trial product of recover device for loose parts was fabricated and tested in sodium. The positions of loose parts were approximately estimated by using ultrasound, and the parts were recovered by the device successfully.
Tokoro, Hayate; Miyoshi, Ryuta; Matsuki, Takuya; Yasuda, Takeshi; Tsutagi, Koichi
no journal, ,
High active liquid waste (HAW) of about 340 m
is stored in the HAW tanks at the Tokai Reprocessing Plant. However there is no effective observation method inside the cell installing the HAW tank since no one can enter because of its high dose rate. This time, by utilizing the existing guide rail, design and manufacture of the new device for observation, optimization of the device by mockup, inside the cell observation and dose rate distribution measurement inside the cell were conducted. As the result, we were succeeded in observation of the HAW tank and measurement of the dose rate distribution inside the cell for the first time. Here we report the results of those approaches.
powder) in mechanical treatment cell at Tokai Reprocessing PlantFuruuchi, Yuta; Sato, Shinji; Yatabe, Hitoshi; Yokota, Satoru; Yamada, Takashi; Yahagi, Fumio; Terunuma, Hirotaka; Tokoro, Takeshi; Takahashi, Akihiro; Iijima, Shizuka; et al.
no journal, ,
Clean-up activity of spent fuel powder (UO powder) in mechanical treatment cell was performed for the purpose of the preparation of decommissioning at TRP. For the clean-up activity, we selected an inexpensive vacuum cleaner and made tools, that was improved taking into account of use by means of a crane or a manipulator in the high dose cell, and applied it after a mock-up test. We report our experience and knowledge provided through this clean-up activity.
Yokota, Satoru; Hatanaka, Akira; Fujimori, Masahito; Shimoyamada, Tetsuya; Nakamura, Yoshinobu
no journal, ,
Three batch-type dissolvers in the Tokai Reprocessing Plant are a device for dissolving spent fuel. The dissolver is composed of one slab and two barrels (stainless steel 310s). Install a fuel basket (stainless steel 304L) in the barrel and accept the sheared spent fuel to dissolve it. The insoluble fuel cladding is taken out of the barrels with the basket. The dissolution time of operation for one batch is approximately 10 hours. During dissolution operation, nitric acid was added to the dissolver into the spent fuel in the basket with water. The solution was heated with steam. Corrosion failure has occurred in the past because the dissolver is exposed to a high corrosive environment (high temperature, high acid concentration). Therefore, we carry out the periodical wall thickness measurement of the barrel by the remote control. On the other hand, the wall thickness measurement of the fuel basket was carried out only once by destructive measurement at the time of renewal in 1999. The details of the corrosion tendency of the fuel basket are unknown, and it is urgent to establish a non-destructive measurement method by remote handling. Therefore, we examined the method of wall thickness measurement of the fuel basket and established the measuring technique.