Leak Before Break Analysis of Steam Generator Shell Nozzle Junction for Sodium Cooled Fast Breeder Reactor

Abstract

The steam generators (SG) control the capacity factor of sodium cooled fast reactor plants and hence they are designed with high reliability. One of the strategies to enhance the reliability is to demonstrate leak before break (LBB) justification. LBB analysis is reported for 500 MWe sodium cooled fast reactor (SFR) in this paper. The material of construction is modified 9 Cr-1 Mo and the critical location is the shell nozzle junction. The initial surface crack is postulated at the critical locations at the shell nozzle junction. The critical crack length is computed by adopting the philosophy of CEGB-R6 procedure, for which Jintegral is computed by finite element method. For determining the detectable through-wall crack length, the crack opening area is also determined by finite element method. Finally, it is demonstrated that it is possible to justify leak before break argument for SFR SG with adequate margins. The required material properties are extracted from French Design Code RCC-MR-2002 and validated with tests on plates.