Evaluation of crack opening area and leak rate in various PHT pipings for LBB analysis of Indian PHWRs

The advent of Leak Before Break (Lb) concept has replaced the traditional design basis event of Double Ended Guillotine Break (Deg) in the design of high energy piping systems of a nuclear reactor. The LBB analysis shows that if there is any undetected flaw on the inside surface of the pipe it will not grow through wall during the inservice inspection/repair interval period and even if it grows through wall it will lead to detectable leakage before any catastrophic break occurs. Determination of crack opening area which decides the Leakage Size Crack (LSC) is one of the key element in LBB analysis. In this paper, the leakage areas have been evaluated using Bartholom'e et al. Model by the integration of crack opening displacement along the crack front, considering plasticity and geometrical effects using Dugdale's model. Crack opening area using this method has been compared with well-known Tada Paris Method and Numerical Integration Method based on Finite Element Method Analysis for various PHT piping. Also, leak flow rates using Henry's non-equilibrium model have been evaluated for all the above leakage areas and the results have been compared with published results. (author)