Analysis of shell-rupture failure due to hypothetical elevated- temperature pressurization of the Sequoyah Unit 1 steel containment building

Abstract

Sandia National Laboratories, as part of the Containment Integrity Programs under the sponsorship of the Nuclear Regulatory Commission (NRC), has developed analytical techniques for predicting the performance of light water reactor steel containment buildings subject to loads beyond the design basis. The analytical techniques are based on experience with large-scale steel containment model tests that provided important insights and experimental validation of the analytical methods. As a means of demonstrating these analytical techniques, the NRC asked Sandia to conduct a structural evaluation of an actual steel containment building. The objective of the analysis was to determine the actual pressure capacity and the mode, location, and size of failure, where a functional definition of failure is used. The purpose of this report is to document the calculations performed to determine the pressure limits for the shell- rupture mode of failure. General failure of the containment shell is predicted by application of a failure criterion to the results from finite element structural analyses. The failure criterion relates the calculated values of strain in the containment plates, due to internal-pressurization loading, to the ultimate strain limit of the steel. Included in the failure criterion are adjustments for factors inherent in finite element analysis, such as level of detail and element size of the finite element model and variations in material property data. Separate finite element models were used to evaluate the overall free-field behavior of the structure and the localized behavior at a specific penetration location. 18 refs., 68 figs., 10 tabs.