AbstractAnalysis of the mechanical response of the PROMETHEUS inertial fusion energy (IFE) reactor first wall is presented. Time-dependent stress, strain and displacement fields are numerically determined for an SiC-SiC composite first wall structure, in response to two types of pulsed loadings. These are ablation momentum associated with sudden evaporation of the protecting liquid metal film due to X-ray deposition and the interaction of the first wall with the induced pressure shock waves during cavity heat up and cool down phases. Based on these results, a modular first wall concept is recommended. Fatigue life time calculations based on residual stiffness and damage evolution criteria for the SiC-SiC composite first wall structure are presented.