Short cracks in piping and piping welds

This is the fifth semiannual report of the US Nuclear Regulatory Commission's research program entitled ''Short Cracks in Piping and Piping Welds.'' This 4-year program began in March 1990. The program objective is to verify and improve fracture analyses for circumferentially cracked large-diameter nuclear piping with crack sizes typically used in leak-before-break analyses or in-service flaw evaluations. During this reporting period, the overall program as well as the results to date were reviewed very critically. It was found that several changes to the current program were needed to meet the final objectives at the end of the 4 years. Hence, the program was restructured. As a result, several activities were put on hold during this reporting period until restructuring was finalized. The changes to the existing program as well as the deliverables from the additional activities are detailed in this report. In the surface- cracked pipe evaluations, work progress involved: (1) evaluating the tensile and Charpy V-notch data for a carbon-manganese submerged arc weld metal (Plate DP2-F49W), and (2) conducting 3D finite-element (FE) analyses of uncracked stainless steel pipe experiments conducted in Japan to resolve the discrepancies between experimental data and FE predictions. Significant efforts during this period involved quantifying the leak rate from cracked pipe using advanced probabilistic analysis. A new PC-based version of the code to evaluate circumferential surface-cracked pipe, NRCPIPES Version 1.0, was completed and sent to the NRC for testing along with a user's manual. Most of the analysis of the influence of the residual stress field on cracks in welds, being conducted under a subcontract to the University of Michigan, was completed during this reporting period and is included here