Structural Integrity Lessons Learned in WWER RPV Surveillance Specimen Programs

Abstract

Surveillance specimen programs in reactor pressure vessels (RPVs) are an important part of monitoring material property changes during reactor operations. Results of testing such specimens in surveillance programs, if properly designed and operated, should be the basis for assessing RPV integrity and lifetime. This paper describes special features of surveillance programs in individual water-water energetic reactors (WWERs)—V-230 and V-213 for WWER-440s and V-320 for WWER-1000s—that lead to changes in normative embrittlement trend curves of base and weld metals in these RPVs. Finally, VERLIFE procedures for evaluating test results of surveillance specimens are described together with their application to RPV integrity assessment with the use of both types of transition temperatures: critical temperature of brittleness, Tk, and reference temperature, T0.