Fracture Assessment for Weldment of Piping for BWR Reactor Internal With Circumferential Through Wall Crack Available to Purchase

A fracture assessment method for piping of BWR reactor internals with a circumferential crack is described in the JSME Code, Rules on Fitness-for-Service for Nuclear Power Plants 2004 Edition. According to this code, limit load is calculated assuming a/t = 1 for through wall crack. It has been desired to demonstrate the adequacy of this equation experimentally. Furthermore, the crack path in weld HAZ between a header and a piping is not straight and has some curvature. It is important to assure the applicability of fracture assessment method to such a case. The fracture tests were conducted for pipes with a circumferential through wall crack between header and pipe to demonstrate the applicability of the current JSME method. Limit load analyses by FEM were also conducted. It was confirmed that the limit load equation in the current JSME Code is possible to apply to the pipe with a circumferential through wall crack even if the crack path was curved along the weld line between header and sparger pipe. In the JSME FFS Code, limit load analysis is required for piping of reactor internals. On the other hand, elastic-plastic fracture mechanics using Z-factor is required for class 1 piping. The present results show that it is enough to assume Z = 1 for the fracture assessment of weldment in austenitic steel piping with medium diameter.