Analysis of bellows expansion joints in containment buildings

Failure of a containment building to perform its function takes place when a leak path is formed. Bellows expansion joints, that are used at the penetrations where piping systems penetrate the containment structures, are one of the potential points of failure. In the event of a severe accident, they can be simultaneously subjected to internal pressure, temperature and gross end displacements as the containment experiences large deformations. Current design and analysis criteria address bellows in only the small strain range. To understand its behavior during a severe accident, a universal bellows expansion joint in the Sequoyah containment vessel was analyzed for large displacements, and high pressures and temperatures. The bellows were analyzed with a three-dimensional finite element model using the ABAQUS finite element code. The model included rigid surfaces and interface elements to model the interaction of the convolutions as they touched each other. 3 refs., 6 figs