Nuclear containment vessels are potentially one of the most seismically vulnerable structures. In light of the Fukushima Daiichi accident, it is becoming increasingly important to more accurately predict the ultimate capacity of containment vessels under high temperature and pressure followed by an extreme earthquake event. The improved accuracy can not only provide important data for decision makers during an unexpected nuclear accident but also provide valuable data for decommissioning reactors after an accident. The following components are studied to improve the ultimate capacity prediction: (1) The effect of high temperature on structural materials; (2) Parameters to characterize structural damage resulting from earthquake motions; (3) The effect of high temperature and pressure time history on containment failure mode; (4) The effect of thermal boundary conditions (adjoining top slab and other floors affecting containment vessel thermal behavior), not fully understood for BWR reinforced concrete containment vessels; (5) The structural behavior of reinforced concrete containment vessels differ from that of post-tensioned concrete, in that the concrete wall section is in tension while transferring the radial shear force; (6) Cracks are more likely to develop around large openings during a seismic event; and (7) other heat sources (such as heat transfer from fire at a spent fuel pool, adjacent fires and/or explosions, and convection from hydrogen gas) alter the thermal distribution. The proposed material model identifies damage parameters as a function of seismic loading history, and includes mechanistic physical behavior. This paper includes an extensive list of components and necessary experimental data that need to be included in a new material model in order to increase accuracy in ultimate capacity prediction.
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