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Goto, Yuichi; Inada, Satoshi; Kuno, Takehiko; Mori, Eito*
Nihon Hozen Gakkai Dai-16-Kai Gakujutsu Koenkai Yoshishu, p.221 - 224, 2019/07
Test equipment, containers, and analytical wastes, generated by experiments using spent fuel pieces in hot cell of Operation Testing Laboratory and by analysis of highly active liquid wastes in hot analytical cell line of Tokai Reprocessing Plant, are treated as highly radioactive solid wastes. These wastes are stored in specific shielded containers called waste cask and then transport to the storage facility. The treatment of these highly radioactive solid wastes have been carried out for 40 years with upgrading waste taking out system and transportation device. As a results, automation of several procedures have been achieved utilizing conventional equipment, and work efficiency and safety have been improved.
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.
Dozaki, Koji*; Yukinori, Shigeru*; Takaya, Shigeru; Wachi, Eiji*; Aoki, Takayuki*
no journal, ,
It is important for maintenance of nuclear power station facilities in the future to promote mathematical techniques which support judgement to modify maintenance practices, such as maintenance tasks, maintenance implementation timing, and so on. Mathematical Maintenance Working Group, which has been established by Maintenance Standardization Committee since July 6, 2018, is investigating application examples of such mathematical techniques in maintenance planning as influence evaluation of changing maintenance tasks based on inspection results, or evaluation of optimized maintenance implementation timing, and so on. The status of these investigation examples are reported.
Nakai, Satoru; Kaneko, Yoshihisa
no journal, ,
Prototype fast breeder reactor "Monju" accumulated maintenance, the repair experience more than 25 years after a test operation and got the knowledge that became extremely useful for the design of the fast reactor and operation and maintenance in the future. A maintenance program was introduced as a fast reactor power plant at the Stage of Research and Development, and problems such as the maintenance management became clear and examined the way of the maintenance management based on these experiences.
Yamada, Tomonori; Daido, Hiroyuki*; Shibata, Takuya; Nishimura, Akihiko; Tagawa, Akihiro
no journal, ,
no abstracts in English
Katsuyama, Jinya; Lu, K.; Li, Y.
no journal, ,
no abstracts in English
Hayashi, Kenta; Ito, Kenji; Matsuo, Hidehiko; Sakai, Yasuhiro
no journal, ,
no abstracts in English
Asayama, Tai
no journal, ,
This paper presents a future vision for safety and structural code development for advanced non-light water reactors. The most important feature that these codes and standards should have is that they ensure that safety goals are met in the way most appropriate and practical to the characters of new reactors which could be significantly different from those of light water ones. For this purpose, the author proposes a universal structure which consists of goals, codes and standards and knowledge base. The goals will be defined in terms of safety, reliability and economy. Codes and standards will form a seamless structure which provides multiple pathways with intermediary targets that correlate the goals and candidate technical options for structure and component design. Margins will be allocated in a plant lifecycle utilizing the System Based Code Concept. Knowledge bases will support codes and standards and allows for timely technical updates. As a future vision, a concept of digitalized autonomous code in which autonomous technical updates of provisions are realized is presented.
Hashidate, Ryuta; Toyota, Kodai; Takahashi, Keita; Yada, Hiroki; Takaya, Shigeru
no journal, ,
In order to achieve both safety and economic efficiency of a nuclear power plant, it is necessary to realize rational maintenance based on characteristics of the plant. The fast breeder prototype reactor, Monju, spent most of the year for the maintenance. It is important to identify causes of the prolonged maintenance of Monju and to investigate countermeasures for implementation of rational maintenance of a next fast reactor. In this study, causes of the prolonged maintenance of Monju during reactor cold shutdown were investigated based on the plant operation of Monju. In addition, proposals for the maintenance optimization idea of a next generation fast reactor were presented to address the revealed issues.
Aizawa, Kosuke; Enuma, Yasuhiro; Yamada, Kazuhiko*
no journal, ,
An evaluation of failure probability for facilities in a real plant subjected to tornado missiles was introduced based on simple calculation. Impact speeds of the tornado missiles to the plant facility were calculated, assuming several initial locations for them and Rankine's model or Fujita's model as a tornado vortex model. Failure probability of each facility subjected to the tornado missiles was quantitatively evaluated, taking account of probabilities of tornado strike to the plant, number of missiles and so on. The results show that we can reduce the failure probability of the facilities by appropriate management of prospective missiles especially at the building roof.
Toyota, Kodai; Hashidate, Ryuta; Takahashi, Keita; Yada, Hiroki; Takaya, Shigeru
no journal, ,
In order to achieve both safety and economic efficiency of a nuclear power plant, it is necessary to realize rational maintenance based on characteristics of the plant. The fast breeder prototype reactor, Monju, spent most of the year for the maintenance. It is important to identify causes of the prolonged maintenance of Monju and to investigate countermeasures for implementation of rational maintenance of a next fast reactor. In this study, causes of the prolonged maintenance of Monju during reactor cold shutdown were investigated based on the plant maintenance plan of Monju. In addition, proposals for the maintenance optimization idea of a next generation fast reactor were presented to address the revealed issues.
Suzuki, Masaaki*; Ito, Mari*; Hashidate, Ryuta; Takahashi, Keita; Yada, Hiroki; Takaya, Shigeru
no journal, ,
Nishimura, Akihiko; Morishita, Hideki*; Yamada, Tomonori; Yoshida, Minoru*; Tagawa, Akihiro
no journal, ,
For decommissioning of the Fukushima Daiichi Nuclear Power Station, installation of an optical fiber seismic vibrometer using a specially designed robotic system was demonstrated. A water tank with 4.5m diameter and5m depth was used as a demo plant of tank type critical assembly. Micro earthquake response of a water tank was detected by the optical fiber seismic vibrometer. Vibration characteristic of the window of the water tank was monitored by laser Doppler interferometer.