Proposed acceptance criteria for severe accident evaluations of steel containment vessels

Abstract

Containment vessels for commercial nuclear power plants have been viewed as the last engineered barrier against accidental radioactive release to the environment. It has been argued for years that plants equipped with containments could not experience a Chernobyl type disaster. In fact, it was the containment vessel at Three Mile Island which prevented any significant, lasting physical effect on either the public or the environment.However, existing containment vessels were not originally designed to withstand the loadings associated with most of the severe accident scenarios currently being postulated. And thus there is no universally acknowledged acceptance criteria for evaluating containment vessel performance during these postulated severe accident loading scenarios. Yet, studies of such accident scenarios are being encouraged and hence undertaken.This paper proposes that existing, time tested criteria is available to serve as the common denominator for determining whether or not a given steel containment vessel has design features adequate to withstand the effects of a given severe accident loading scenario. It presents results of an effort where state-of-the-art, nonlinear analysis techniques were applied, and computed vessel responses were reviewed in light of basic material failure criteria versus the American Society of Mechanical Engineers' Boiler and Pressure Vessel Code, Section III, Class MC, Service Level C and Service Level D acceptance criteria.