Inelastic behavior and creep-fatigue damage evaluation of intermediate heat exchanger for HTGR

Abstract

The intermediate heat exchanger of high-temperature-gas-cooled reactor for hydrogen production is a component that exchanges heat between primary helium gas (950℃) and secondary helium gas (300℃). This component is composed of center pipe, manifold tube plate (perforated structure) and helical heat transfer tubes, all made of nickel-based alloy Hastelloy XR. In this study, detailed inelastic analysis considering 500,000 h operation (100 cycles of 5,000 h hold time) was carried out to clarify the characteristics of inelastic behavior and creep-fatigue damage. Considering the features of these inelastic behaviors, applicability of simplified creep-fatigue evaluation method based on elastic analysis results and elastic-follow-up coefficient, which has been utilized in the Fast Breeder Reactor design guideline, is examined. Creep damage by the simplified creep-fatigue evaluation method is found to give a conservative prediction within a factor of 2, when compared with the prediction by the detailed inelastic FE analysis.