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Ishiyama, Toru; Kawasaki, Ichio; Matsumoto, Takenari; Terada, Hideyuki; Kikuchi, Akio; Mizoguchi, Tsuyoshi*; Ikede, Hiroyuki*
Nihon Hozen Gakkai Dai-8-Kai Gakujutsu Koenkai Yoshishu, p.82 - 87, 2011/10
In the undergrounding pipe-space, there are many pipes for utility (electronic cable, water, gas, steam, etc.). These pipes are kept to safe by daily inspection. But hot environment of the pipe-space affects badly the device and a laborer's health. The investigation of the heat distribution was carried on, therefore it was found that the radiant heat around the valve was very much. The method of thermal insulation was examined from the view point of the shape, cost, and effect. Then some of valves were covered with flexible thermal insulation, and the temperature of the area around the covered valves was decreased about 10
C.
Watashi, Katsumi
no journal, ,
The insulation degradation can be appeared in cables which were installed at radiation and air environment in aged LWRs. It is implicated that the behavior is related to decrease of an antioxidant among the stabilizers which was caused by thermal oxidation and radiation induced oxidation. JNES has prepared a diagnostics method of insulation degradation for safety related low voltage cable used in aged LWRs. This paper shows a degradation indicator, for which nondestructive test and, then, probability of insulation degradation. A reliability analysis method applied in the paper is based on level 2 reliability analysis method. A degradation master curve, critical values of the indicator and the nondestructive test performance were referred form JNES report. Importance of nondestructive test performance was concluded.
Watashi, Katsumi
no journal, ,
Research on irradiation embrittlement of heat affected zone, HAZ, in weldment of RPV was experimentally studied in JAEA. Test pieces simulated HAZ was used in the study, and the result showed no significant difference between the HAZ and base metal in microscopic and mechanical properties. This report shows the result of statistical analysis of HAZ ductile brittle transition temperature shift compared with that shown as an unified equation constructed from a database of surveillance test specimens.
Watashi, Katsumi
no journal, ,
A Poisson distribution well represents SCC initiation and subsequent small scale growth in material tests. This report describes the Poisson distribution application to LWR SCC database which was arranged from NUCIA. Frequencies were plotted against operated duration, then a Poisson's parameter was set to represent SCC aspect. In subsequent step, for only case, IASCC, a crack propagation was calculated. Fitting degrees of the distributions and a major parameter on failure probability were emphasized.
Nakai, Satoru; Kaneko, Yoshihisa; Uchihashi, Masaya
no journal, ,
FBR can breed fuel and use minor actinide in the radioactive waste as a fuel, so that reduce environmental burden. Monju play a key role in the development of demonstration reactor in the aspects of demonstration of reliable operability and establishment of operation and maintenance method of FBR. In this paper describes the activities towards the establishment of Monju maintenance program and FBR maintenance method.
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.
Terada, Takaya; Nishimura, Akihiko; Oka, Kiyoshi
no journal, ,
no abstracts in English
Iwata, Mitsunao*; Sugiyama, Yuichi*; Murata, Yoshinori*; Takaya, Shigeru
no journal, ,
Microstructural states of metallic materials can be expressed by system free energy, and the estimation of the system free energy is useful for damage analysis of the materials. In this study, change with creep time in the system free energy of the FG-HAZ in 9Cr heat resistant ferritic steels is estimated on the basis of a series of experiments such as chemical analysis by using extracted residues, X-ray diffraction, and scanning transmission observations. The change in the system free energy is expressed quantitatively by rate constants depending on applied stress. It is observed that the steel ruptures when the applied stress exceeds the allowable stress. The relationship between allowable stress and system free energy makes it possible to predict the rupture time in the long term.
Takaya, Shigeru; Okajima, Satoshi; Asayama, Tai; Chitose, Hiromasa*; Machida, Hideo*; Yokoi, Shinobu*; Kamishima, Yoshio*
no journal, ,
An evaluation method of the occurrence probability of a through-wall crack in a reactor vessel of a fast breeder reactor due to fatigue-creep interaction has been proposed. Input data were prepared for a trial evaluation and the proposed evaluation method was applied. The result was compared with the allowable occurrence probability derived from the safety requirements for FBR.
Nishimura, Akihiko; Terada, Takaya; Yamada, Tomonori; Takenaka, Yusuke*; Furuyama, Takehiro*
no journal, ,
We are developing the inspection technology for laser micro spot welding. Butt welding for the inner wall of heat exchanger tubes were successfully carried out by a composite-type optical fiber scope. The related technologies are the following: (1) Rapid inspection by eddy current testing (2) Fiber endoscope observation (3) Synchrotron X-ray absorption contrast method. These technologies are versatile to be applied in maintenance for industrial production plants.