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Okano, Masanori; Akiyama, Kazuki; Taguchi, Katsuya; Nagasato, Yoshihiko; Omori, Eiichi
Dekomisshoningu Giho, (57), p.53 - 64, 2018/03
The construction of Tokai Reprocessing Plant (TRP) was initiated in June 1971, and its hot test using spent fuel started in September 1977. Thereafter TRP had been operated to reprocess 1,140 tons of spent fuel for approximately 30 years until May 2007, according to the reprocessing contract with domestic electric power companies. JAEA announced a policy of TRP in report of JAEA reform plan published in September 2014. The policy shows that TRP will shift to a decommissioning stage by economic reasons. Based on the policy, application of approval for TRP decommissioning plan was submitted to Nuclear Regulation Authority (NRA) in June 2017. This plan provides basic guidelines such as procedures for decommissioning and specific activities for risk reduction, and implementation divisions of decommissioning, management of spent fuels and radioactive wastes, decommissioning budget, and decommissioning schedule. The process of TRP decommissioning is planned to continue for approximately 70 years until the release of controlled areas of approximately 30 facilities.
Shirai, Nobutoshi; Miura, Yasushi; Tachibana, Ikuya; Omori, Satoru; Wake, Junichi; Fukuda, Kazuhito; Nakano, Takafumi; Nagasato, Yoshihiko
JAEA-Technology 2016-007, 951 Pages, 2016/07
The periodic safety review of TRP is to confirm the safety activities and get effective additional measures the facility safety and its reliability. We implemented 4 items; for (1) evaluation of safety activity implementation, we confirmed we are adequately expanding its safety activities by the necessary documents and schemes. For (2) evaluation of status of safety activities reflecting the latest technical knowledges, we confirmed we reflect latest knowledges for improvement of safety and reliability. For (3) technical evaluation about aging degradation, we can keep the safety of the facilities important to safety and the sea discharge line, under assumption of the present maintenance, because of "focuses for aging degradation". For (4) planning measures about a 10-years-plan that the operator shall implement to keep the facility condition, by the technical evaluation, we found no additional safety plans into maintenance strategies.
Fukuda, Kazuhito; Tomioka, Kenichiro*; Omori, Satoru; Nakano, Takafumi; Nagasato, Yoshihiko
JAEA-Technology 2014-032, 566 Pages, 2014/11
The Periodic Safety Review of TRP is assessment of the validity of safety activities in order to get assurance for continuous operation by adding effective items to extract and to execute for TRP safety. We performed 4 items; for (1) evaluation of safety activity at TRP, as we confirmed organization was ordered and managed. For (2) evaluation of status of safety activities reflecting the latest knowledge, we confirmed improvement of safety was continued adequately reflecting from the experience for safety. For (3) technical review on aging for the safety related structures, systems and components, we evaluated the guaranty of safety under assumption of continuous maintenance till the next Periodic Safety Review. For (4) establishment of long term maintenance program, we found no additional activities into maintenance programs, however, for several installations we established a plan and utilized them for reliability.
Nagasato, Yoshihiko
Nihon Genshiryoku Gakkai-Shi ATOMO, 55(11), p.661 - 662, 2013/11
no abstracts in English
; ; ; Omori, Eiichi
JNC TN8410 2001-021, 33 Pages, 2001/09
Carbon-14 released from the nuclear facilities is an important radionuclide for the safety assessment, because it tends to accumulate in environment through food chain and has as a significant impact to personal dose. Carbon-14 has been monitored routinely as one of the main gaseous radionuclides exhausted from the Tokai Reprocessing Plant (TRP) since OCtober of 1991. Furthermore, behavior of carbon-14 in TRP has been investigated through the reprocessing operation and the literature survey. This report describes the result of investigation about the behavior of carbon-14 in TRP as followings. (1)Only a very small amount of carbon-14 in the fuel was liberated into the shear off-gas and most of it was liberated into the dissolver of-gass. Part of the carbon-14 was trapped at the caustic scrubber installed in the of-gas treatment process, and untrapped carbon-14 was released into the environment from the main stack. Amount of carbon-14 released from the main stack was about 4.16.5GBq every ton of uranium reprocessed. (2)Carbon-14 trapped at the caustic scrubbers installed in the dissolver off-gas and in the vessel off-gas treatment process is transferred to the low active waste vessel. Amount of carbon-14 transferred to the low active waste vessel was about 5.4 9.6GBq every ton of uranium reprocessed. (3)The total amount of carbon-14 input to TRP was summed up to about 11.915.5 GBq every ton of uranium reprocessed considering the released amount from the main stack and the trapped amount in the off-gas treatment devices. The amount of nitrogen impurity in the initial fuel was calculated about 1522ppm of uranium metal based on the measured carbon-14. (4)The solution in the low active waste vesselis concentrated at the evaporator.Most of the carbon-14 in the solution was transferred into concentrated solution. (5)Tokai vitrification Demonstration Facility (TVF) started to operate in 1994. Since then, carbon-14 has been measured in the ...
Sudo, Toshiyuki; ; ;
Donen Giho, (99), p.99 - 104, 1996/09
None
Fukuda, Kazuhito; Tomioka, Kenichiro*; Tachibana, Ikuya; Shirai, Nobutoshi; Kosaka, Ichiro; Nakano, Takafumi; Nagasato, Yoshihiko
no journal, ,
no abstracts in English
Nakano, Takafumi; Fukuda, Kazuhito; Sato, Fuminori; Kosaka, Ichiro; Nagasato, Yoshihiko
no journal, ,
no abstracts in English
Sato, Fuminori; Nakanishi, Ryuji; Kosaka, Ichiro; Nakano, Takafumi; Nagasato, Yoshihiko
no journal, ,
no abstracts in English
Koshino, Katsuhiko; Shirai, Nobutoshi; Sakaguchi, Shinobu; Shirozu, Hidetomo; Otaki, Miyuki*; Kosaka, Ichiro; Nakano, Takafumi; Nagasato, Yoshihiko; Tachibana, Ikuya
no journal, ,
no abstracts in English
Nakanishi, Ryuji; Sato, Fuminori; Kosaka, Ichiro; Nakano, Takafumi; Nagasato, Yoshihiko
no journal, ,
no abstracts in English
Akiyama, Kazuki; Taguchi, Katsuya; Nagasato, Yoshihiko
no journal, ,
Tokai Reprocessing Plant is the chemical plant having approximately 30 facilities. Moreover TRP has the particularity that must start the decommissioning while treating radioactive waste. Especially it is important to vitrify high radioactive waste. JAEA worked out the decommissioning schedule for TRP having these particularities. In this presentation, the basic thought of 70-years-schedule is described.
Hashimoto, Kowa; Okano, Masanori; Taguchi, Katsuya; Nagasato, Yoshihiko
no journal, ,
The Tokai Reprocessing Plant has many facilities, various installation and complicated systems, which are contaminated by radioactive materials. Based on this feature, JAEA estimated its waste generation and the cost for decommissioning by using common and reasonable condition for many and complicated facilities.
Taguchi, Katsuya; Hashimoto, Kowa; Akiyama, Kazuki; Nagasato, Yoshihiko
no journal, ,
The TRP had been operated to reprocess 1,140 tons of spent-fuel for approximately 30 years until May 2007. TRP finished the role of reprocessing, and it shift to a decommissioning stage. In this presentation, particularity and challenging-issues of TRP decommissioning are presented, before report a related consideration of TRP.
Nakazawa, Yutaka; Murakami, Manabu; Taguchi, Katsuya; Nakano, Takafumi; Nagasato, Yoshihiko
no journal, ,
JAEA will make a TRP safety policy necessary to adequate the new standard of legal regulation for nuclear facilities and to improve the action based on the decommissioning phase of TRP that counting the nuclear material and importance to control it. I will explain the present TRP situation, selection of important facilities in viewpoint of safety and credible accidents, and the safety policy now planning.