Transferability of results of PTS experiments to the integrity assessment of reactor pressure vessels

The integrity assessment of the reactor pressure vessel (RPV) is based on t he fracture mechanics concept as provided in the code. However, this concep t covers only the linear-elastic fracture mechanics regime on the basis of the reference temperature RTNDT as derived from Charpy impact and drop-weig ht test. The conservatism of this concept was demonstrated for a variety of different materials covering optimized and lower bound material states wit h regard to unirradiated and irradiated conditions. For the elastic-plastic regime, methodologies have been developed to describe ductile crack initia tion and stable crack growth. Tho transferability of both, the linear-elast ic and elastic-plastic fracture mechanics concept was investigated with the help of large scale specimens focusing on complex loading situations as th ey result from postulated thermal shock events for the RPV. A series of pre ssurized thermal shock (PTS) experiments were performed in which the applic ability of the fracture mechanics parameters derived from small scale speci men testing could be demonstrated. This includes brittle (static and dynami c) crack initiation and crack arrest in the low Charpy energy regime as wel l as stable crack initiation, stable crack growth and crack arrest in the u pper shelf toughness regime. The paper provides the basic material data, th e load paths, representative for lat ge complex components as well as exper imental and theoretical results of PTS experiments. From these data it call be concluded that the available fracture mechanics concepts can be used to describe the component behavior under transient loading conditions. (C) 20 00 Elsevier Science S.A. All rights reserved.