Elastic creep-fatigue damage evaluation: less restrictive design rules for SNR 2 components

Abstract

To achieve less conservative design rules for LMFBR Class 1 components in elevated temperatures service, two modifications of the elastic creep-fatigue evaluation in use are proposed: (1) In the creep-damage evaluation, the relaxation of residual stresses during hold-times shall be taken into account; (2) In the fatigue-damage evaluation, the creep effects on the cyclic stress strain hysteresis loop shall be considered by adding the net relaxation strain during holdtimes to the elastic-plastic strain range, and design fatigue curves without hold-time shall apply.