Short cracks in piping and piping wells

This is the sixth semiannual report of the US Nuclear Regulatory Commission's 4-year research program ''Short Cracks in Piping and Piping Welds'' which began in March 1990. The objective is to verify and improve fracture analyses for circumferentially cracked nuclear piping with cracks sizes typically found during in-service flaw evaluations. Progress is the through-wall-cracked pipe efforts involved (1) verification of deformation plasticity under nonproportional loading, (2) evaluation of the effect of weld metal strength on various J-estimation schemes, and (3) development of new GE/EPRI functions. Surface-cracked pipe evaluations involved (1) material characterization of B ampersand W C-Mn-Mo submerged arc weld metal, and (2) 3D finite-element mesh refinement study. The toughness of the bimetallic weld fusion line was evaluated and showed unusual fracture behavior based on the results of the Charpy tests. The dynamic strain aging J-R tests confirmed the screening criterion developed earlier in the program. The results from this program to date necessitated several additional efforts. These were initiated and have been reported here. Presentation of the results from this program to the ASME Section XI Pipe Flaw Evaluation Working Group is also summarized here