複数亀裂付き平板の破壊評価法の開発

抄録

Stress corrosion cracking (SCC) has been detected in the welded components of nuclear power plants. The components of nuclear power plants consist of highly ductile materials such as austenitic stainless steels, and their failure mode is expected to be plastic collapse due to ductile fracture. The limit load analysis, which is applied to fracture assessment for ductile materials, is employed in the fitness-for-service (FFS) codes such as JSME Code “Rules on Fitness-for-Service for Nuclear Power Plants”. The FFS codes provide flaw characterization rules for multiple flaws, and the technical basis seems to be based on interaction of stress intensity factors which are linear elastic fracture mechanics parameters based on small scale yielding. Thus, the applicability of current flaw characterization rules for multiple flaws to limit load analysis is unclear. The limit load analysis for non-aligned multiple flaws was developed based on the net-section approach and the test results of flat plates with two flaws in the past studies. The test results can be represented by using the defined net-section of non-aligned multiple flaws. Finite element analyses were conducted to interpolate the test conditions. The effect of flaw positions on collapse load was estimated by the test and analysis results.