1216 軽水炉中靱性配管に対する Z 係数の策定

Abstract

To achieve a rational maintenance program for aged light water reactor components, it is important to establish and to improve the flaw evaluation criteria. Current flaw evaluation criteria are focused on Class 1 piping with high toughness, while flaw evaluation criteria suitable for Class 2 and 3 piping with moderate-toughness are also required from the viewpoints of in-service inspection request, reduction of operating cost, and systematization of consistent code/standard. In this study, cracked pipe fracture tests as well as finite element analysis and simplified fracture analysis by the reference stress method were conducted using typical moderate-toughness pipe materials. The experimental and analytical results were reduced to the Z-factor to predict fracture loads of cracked pipes. Fracture loads for Class 2 and 3 piping were smaller than those for Class 1 piping, consequently Z-factors for Class 2 and 3 piping were about 25% higher than those for Class 1 piping.