ICONE19-43175 Simplified Evaluation Method of Strain Rate Being Generated on Structural Materials During Plant Start-up

抄録

The dynamic aspects of loading conditions for reactor internals, piping and the other components are thought to play important roles in the initiation of failures due, for example, to stress corrosion cracking (SCC) and environmental fatigue. In the design of Light Water Reactors (LWR), however, the strain rate of components is not evaluated, because time-dependent or rate-dependent failure modes are not considered quantitatively in LWR design. The Finite Element Method (FEM) can be used, of course, to evaluate strain rate, but it is more important to know the major factors determining the strain rate magnitude. To investigate such kinds of sensitivity of transient conditions to the magnitude of strain rate, it is helpful to develop a simplified evaluation method of strain rate. For this purpose, a simple strain rate evaluation method based on Green's function was developed for a specific point of a component with a given design condition. Furthermore, a generalized simplified method was developed based on shell theory to evaluate thermal stress and strain rate.