[en] This paper will focus on recent progress in the Containment Integrity Programs, which are managed by Sandia National Laboratories for the US Nuclear Regulatory Commission. The overall objective of these programs is to develop reliable methods for predicting the performance of LWR containment buildings for loadings beyond their design basis. The basic assumptions and an outline of the analysis methodology are presented. The mechanics of strain concentrations that lead to liner tearing in reinforced concrete containments are explained in terms of an analytical model that accurately represents the behavior of 1:6-scale model that was tested to failure. New insights into the leakage potential of personnel airlocks and equipment hatches based on test results and analyses are described. 20 refs., 20 figs., 5 tabs