SEISMIC RESPONSE PREDICTION OF AN ADVANCED GAS-COOLED REACTOR CORE MODEL WITH DEGRADED COMPONENTS

The Advanced Gas-cooled Reactors (AGRs), graphite-cored nuclear reactors are the second-generation reactor design and satisfy around 15% of the total electricity demand of the UK. As the graphite cores age, AGR core components have degraded and become cracked due to internal stresses that result from neutron irradiation. An extensive shaking table test campaign was conducted on a quarter-size AGR Core model to investigate the global dynamic behaviour of the system with degraded graphite components under seismic excitation. Thirteen different array configurations had been shaken more than 3000 times to characterise the displacement response of the AGR core model under seismic excitations with emphasis on array distortion and the shape of the column profiles. A response prediction algorithm is developed, based on linear correlations between the intensity measures of the input motions and the recorded seismic response of the AGR core model, to estimate column distortions and expand the output of experimental or numerical studies by saving time, effort and cost. The algorithm identifies the optimal intensity measures, which are best suited to characterise and describe the structural demand of an AGR core-like structure by using the experimental dataset and predicts the column displacement profiles for any given input motion. The response prediction algorithm was trained by using the intact array, 30% cracked array and 50% cracked array experimental results. Statistical analysis indicates that predicted column distortions, compared against direct experimental displacements, are significant, repeatable and accurate.