NRC (Nuclear Regulatory Commission) Leak-Before-Break (LBB.NRC) Analysis Method for Circumferentially Through-Wall Cracked Pipes under Axial Plus Bending Loads.

摘要

The fracture mechanics analysis procedure used by the NRC to evaluate utility leak-before-break submittals is described in the report. This methodology is an estimation technique based on J-tearing theory. This approach is intended to provide a conservative approximation of the applied crack driving parameter, J, for postulated through-wall leakage-size cracks in nuclear power plant pipes. Piping integrity evaluations can then be accomplished for various loading conditions and assumed flaw sizes. Because the method can be used to obtain a rather rapid computer generated approximation of the applied crack driving parameters, NRC evaluation of applicant or licensee submittals can be accomplished in an expeditious manner without resorting to elaborate finite element techniques. The NRC program should not be considered as fixed in time. As piping fracture mechanics technology matures, it may be refined in the future.