| The current development of nuclear power not only requires economy but also pays attention to safety. LBB (Leak-Before-Break) is an important analysis method for insuring the structure safety and reliability of nuclear reactor. The Reactor Pressure Vessel (RPV) applicable with LBB conditions can eliminates some of the complex support facilities to save the cost and maintain the safety requirement.The paper summarizes a set of LBB method applying for the safe analysis of the pipes and pressure vessel basing on the appendix A16of the France RCC-MR standard and carrying on LBB analysis for the RPV in API000Reactor. The paper also gives a brief introduction about the structural characteristics, technical specification of the material, design codes and main parameters of AP1000RPV. The affection of fatigue to the crack growth must be considered when LBB is applied on the RPV. Suppose that a circumferential through wall defect had existed where the loads were most serious. According to various category situations, the stability growth of the crack can be calculated under alternate loads by Paris formula. It is necessary to consider the affection of neutron irradiation as well, because it is the characteristic embrittlement damage to RPV. The result of calculation shows that the RPV meets the conditions that the crack is stable and the leakage is detectible which LBB asks for, and it also satisfies the time request from the beginning of leak to the moment at which the crack is unstable.This paper based on the requirement of design specifications of RPV, and adopted a simplified analytical mode. The result cannot be used in engineering project, but provides a viable analytical method for RPV design process. |
