Consideration of creep relaxation initial stress setting method used to inelastic analysis for fast reactor components design

Abstract

In the structural design of fast reactor components, internal pressure is low and stress due to heat is dominant therefor stress relaxation with elastic follow-up due to creep is considered. In calculating the creep damage from elastic analysis in accordance with the JSME standard for fast reactor, the initial stress for calculation of stress relaxation behavior during high temperature holding has appropriate conservative. This initial stress is estimated based on elastic analysis result, and to be larger than the actual behavior in order to conservatively consider nonlinear behavior due to creep and plasticity. Therefore, more rational design can be achieved by calculating the creep damage from inelastic analysis. In this study, the initial stress (thermal load condition in stress analysis) for creep damage calculation by inelastic analysis considering appropriate conservative is specified and its effectiveness is shown.