Performance of containment penetrations under severe accident loadings

The objective of the present paper is to provide a complete summary of efforts to date to better understand the behavior of containment penetrations when subjected to severe accident conditions. The research activities discussed herein are a part of the Containment Integrity Programs, which are managed by Sandia National Laboratories for the US Nuclear Regulatory Commission. The overall goal of the Containment Integrity Programs is to develop test validated methods to predict the ultimate pressure capacity, at elevated temperatures, of light water reactor (LWR) containment structures. In order to accomplish this goal, a series of scale model containment tests have been conducted including a 1:8-scale steel model and a 1:6-scale reinforced concrete model. Because of the reduced scale and limited number of tests, the model tests could not include all of the various penetration designs. Thus, several separate test programs have been conducted in which various features of containment penetrations were tested in order to determine their leakage behavior when subjected to severe accident conditions. Past containment penetration research programs have included testing of typical compression seals and gaskets, electrical penetration assemblies (EPAs), and a personnel airlock. Recently, a series of tests were conducted to determine the leakage behavior of inflatable seals when subjected to postulated severe accident combinations of containment pressure and temperature. Also, there is an ongoing research activity to determine the capacity of bellows that are used at some containment penetrations. These three research programs will form the major portion of this paper