Feasibility of the Leak-Before-Break (LBB) Application to the Ulchin 3 and 4 Pressurizer Surge Line

Abstract

This report describes the application method, the analysis process and the results of the leak-before-break (LBB) concept for the Ulchin (UCN) 3 and 4 pressurizer surge line. The LBB analysis for the pressurizer surge line was performed for the portion of the line that has a large stress value as obtained from the static and dynamic analyses of the piping system. The hypothetical crack size was determined with the loads that are exhibited during a normal plant operational condition. The detection capability of the leak detection devices that are installed in the containment was assumed to be 1.0 gpm. The LBB analysis of the surge line was performed based on the requirements of NUREG-1061, Volume 3, and Standard Review Plan (SRP) 3.6.3. The result of the analysis showed that the LBB application satisfied all the requirements of the codes and regulations.