Influence of temperature and primary stress on creep damage in HTGR components

Abstract

High Temperature Gas-cooled Reactor (HTGR) components are characterized by dominant creep damage depending on primary stress and thermal stress. In the JSME M&M2023 conference, a simplified creep-fatigue damage evaluation method based on elastic analysis has been proposed, in which both an elastic follow-up coefficient and a post-relaxation stress are considered. In this paper, the influence of temperature, the elastic follow-up coefficient and the post-relaxation stress on the predicted creep damage is discussed. The simplified method was applied to heat-transfer helical tube with distribution of temperature, primary stress and thermal stress. Predicted creep damages along the tube were conservative within a factor of 3 compared with the results of detailed inelastic analysis. Difference of creep damage during relaxation were analyzed between Hastelloy XR and 316FR assuming HTGR and Fast Reactor (FR) respectively; rapid relaxation and high creep damage were found to be to the special characteristics of HTGR components. Influence of the elastic follow-up coefficient on creep damage was also studied.