The Leak-before-break (LBB) Method Applied In The Analysis Of PWR Piping

A real pipe of the reactor coolant system has been taken as studying object and analyse the LBB echnology application. In nuclear power plant accident, The leak-before-break (LBB) analysis of pressurized piping is an important advanced technology for the safety of structures in nuclear reactors. LBB criterion is a major assessment criterion to prevent catastrophic rupture accident of pressurized piping in nuclear power plant.In this paper, the research and application of LBB technology is described. Some typical LBB analysis methods and the basic steps in LBB analysis are discussed. Through combined method on theory and experiment, the LBB phenomenon of piping in high-pressure case is studied. It is assumed that piping already exist a circumferential crack. Based on the LBB analysis, The crack opening displacement (COD) and leak rate is obtained by theoretical calculation. The LBB test of piping was designed under the conditions of high pressure. Then, LBB test platform was built. The 10 seamless steel piping was used for LBB experiment, as an experimental pipe. And use the ABAQUS software modules determining the crack location and simulating it extended. The crack opening displacement (COD=δ) and leakage rate Q was determined by experiment. The effective of LBB analysis on piping is verified under high pressure.Through these work, the conclusions will be found:this piping with the 10# steel has the LBB characteristics, and the experiment has proved that the LBB analysis on piping under high pressure is effective. The law of the surface crack propagation on experimental piping is presented.