Conclusions of the EPRI concrete containment research program

Six years of EPRI sponsored research aimed at studying the overpressure behavior of reinforced and prestressed concrete containments has brought about the development of a test-validated methodology for the prediction of concrete containment capacity and leakage. The results of many large scale panel tests in the EPRI program and the Sandia 1:6 Scale Reinforced Concrete Containment Test have been instrumental in supporting this work. This paper describes the development of the leakage prediction criteria and analysis guidelines by summarizing the EPRI research program and the conclusions that have been reached regarding concrete containment overpressure behavior. The methodology for predicting liner tearing consists of using ABAQUS-EPGEN (a general purpose finite element program co-sponsored by EPRI and Hibbitt, Karlsson, and Sorensen, Inc.) to perform 2D global analyses and then applying curves of liner strain magnification factors to the global liner strains. The 2D axisymmetric analysis procedure has been automated by the development of 'library models' for two families of concrete containments commonly found in the United States. Post test conclusions of the Sandia 1:6 Scale Model experiment are also discussed in support of the leakage prediction methodology. Finally, the conclusions that have been reached with regard to liner tearing and subsequent equilibrium leakage in a quasi-static pressurization scenario are reviewed in the context of current industry operasting procedures and regulatory requirements. The paper introduces the most recent work in the EPRI program which evaluates the uncertainties of the leakage prediction procedure and recasts the procedure in a probabilistic risk assessment framework for use with recent U.S. regulatory documents. (orig.)