The Research On The Application Of LBB For The Design Of Nuclear Pipes Beyond Creep Temperature

LBB (Leak-Before-Break) is an important analysis method for insuring the structure safety and reliability of nuclear reactor. The analysis on the crack propagation is the core of LBB. The affection of fatigue and creep to the crack growth must be considered when LBB is applied on the nuclear pipes in the high temperature reactors (as fast reactor) beyond the creep temperature. The paper summarizes a set of LBB method applying for the safe analysis of the nuclear pipes beyond the creep temperature, basing on A16 in the France RCC-MR standard and carrying on LBB analysis for a section of pipe in the heat drainage system in Fast Reactor. The result of calculation shows that creep affects the crack growth greatly beyond the creep temperature. It is demonstrated that the pipe 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.