Engineering J Estimation Methods for Leak-Before-Break Analyses of Nuclear Piping

Abstract

The present work presents a method to estimate elastic-plastic J for circumferential through-wall cracked pipes for the Leak-Before-Break (LBB) analysis of pressurized piping. The proposed method is based on the GE/EPRI approach and the key issue is to propose a robust Ramberg-Osgood fitting procedure. Two different estimation schemes are given, one for the case when full stress-strain data are available, and the other for the case when only yield and ultimate tensile strengths are available. The proposed J estimates are compared with those from extensive elastic-plastic finite element (FE) analyses. Experimental validation is also performed by comparing maximum moments predicted by fracture mechanics analysis using the proposed J estimates with those from full-scale pipe test. Both results show sufficient confidence in the accuracy of the proposed J estimates.

Development and validation of a leak before break criterion for cylindrical pressure vessels

“…Yun-Jae 10 has proposed an approach for non-linear fracture mechanics analyses (elastic-plastic and creep fracture mechanics) based on reference stress of circumferential and axial through-wall cracked pipes under various loading conditions for LBB analysis. Kim et al.…”