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Takaya, Shigeru; Sasaki, Naoto*; Tomobe, Masato*
JAEA-Data/Code 2015-002, 54 Pages, 2015/03
JAEA-Data-Code-2015-002.pdf:25.53MB
Many efforts have been made to implement the System Based Code concept of which objective is to optimize margins dispersed in several codes and standards. Failure probability is expected to be a promising quantitative index for optimization of margins, and statistical information for random variables is needed to evaluate failure probability. Statistical information of material strength has not been provided enough yet. In this report, the statistical properties of material strength was estimated for SUS304, 316FR steel and some other austenitic stainless steels. These materials are registered in the JSME code of design and construction of fast reactors, so test data used for developing the code were used as much as possible in this report.
Hashidate, Ryuta; Yada, Hiroki; Takaya, Shigeru; Futagami, Satoshi; Yamano, Hidemasa; Kurisaka, Kenichi; Enuma, Yasuhiro
no journal, ,
If components can be maintained according to a target reliability of nuclear power plants, plant safety and economic efficiency could be improved by avoiding excessive or insufficient margins. This approach can rationalize the maintenance of low target reliability components and concentrate resources (people, money, and time) on the maintenance of high target reliability components. It would take a long time to evaluate the target reliability for all components in the plant by quantitatively using probabilistic risk assessment. This paper, therefore, proposed at a first step a simple screening method which determines necessity of quantitative risk assessment for maintenance rationalization using risk information. Specifically, this method was applied to determining necessity of quantitative risk assessment to the laundry system whose function has little contributor to the plant safety of nuclear power plant, and we proposed the maintenance rationalization of the laundry system.
Takaya, Shigeru
no journal, ,
Effective and efficient ISI is crucial for safety, stable operation, and economic efficiency of nuclear power plants. ISI rules need to be developed rationally by considering features of the reactor type and design of an individual nuclear power plant. SFRs have several desirable features while traditional ISI methods are not as easily performed as in light water reactors. ASME Boiler and Pressure Vessel Code, Section XI, Division 3 had provided ISI rules for liquid-metal cooled reactors. However, several parts of the Code were left as being in the course of preparation, thus it was practically difficult to apply. To address this situation, a new Code Case, N-875, was developed based on the SBC concept in cooperation between ASME and JSME. One of key features of the Case is the logic flow to determine ISI requirements by using reliability targets for components. Recently, a new Section XI, Division 2, Reliability and Integrity Management (RIM), has been developed for advanced nuclear reactors. RIM shares some key concepts with SBC, and the Case has been partially incorporated. JSME has also developed a new fitness-for-service code for SFRs by referring the Case, and it will be published soon.