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Li, Y.*; Hasegawa, Kunio*; Onizawa, Kunio; Shimomoto, Masayoshi*
Proceedings of 2009 ASME Pressure Vessels and Piping Division Conference (PVP 2009) (CD-ROM), 9 Pages, 2009/07
When a flaw is detected in a stainless steel piping system of a nuclear power plant during in-service inspection, the fracture estimation method provided in the codes such as the ASME Code Section XI or the JSME S NA-1-2004 can be applied to evaluate the integrity of the pipe. However, in these current codes, the fracture estimation method is only provided for the pipe containing a single flaw, although multiple flaws such as stress corrosion cracks have actually been detected in the same circumference of stainless steel piping systems. In this paper, a fracture estimation method is proposed by formula for multiple independent circumferential flaws with any number and arbitrary distribution in the same circumference of the pipe. Using the proposed method, the numerical solutions are compared with the experimental results to verify its validity, and several numerical examples are provided to show its effectiveness.
Onizawa, Kunio; Ito, Hiroto*; Shimomoto, Masayoshi*; Nishikawa, Hiroyuki*
no journal, ,
At nuclear power plants under operation in Japan, it is important for the assessment of safety of the plants to evaluate the structural integrity of components consisting of the plant. It is also required for maintaining the structural integrity of components due to aging degradation by stress corrosion cracking and fatigue crack growth to take suitable measures. From these viewpoints, probabilistic fracture mechanics (PFM) analysis method which treats the scatter and uncertainty of material properties is the most rational method. We have developed a PASCAL-SP which is a PFM analysis code for welded joints of reactor piping. Two kinds of application of PFM analysis results by PASCAL-SP to safety regulation are presented. The first one is a comparison of the safety margins provided for defect evaluation under operating conditions in JSME Fitness-for-Service Rule. Another is an application to the calculation of failure rate for piping used in PSA.