Reliability analysis of containment strength

The Sequoyah and McGuire ice condenser containment vessels were designed to withstand pressures in the range of 12 to 15 psi. Since pressures of the order of 28 psi were recorded during the Three Mile Island incident, a need exists to more accurately define the strength of these vessels. A best estimate and uncertainty assessment of the strength of the containments were performed by applying the second moment reliability method. Material and geometric properties were supplied by the plant owners. A uniform static internal pressure was assumed. Gross deformation was taken as the failure criterion. Both approximate and finite element analyses were performed on the axisymmetric containment structure and the penetrations. The predicted strength for the Sequoyah vessel is 60 psi with a standard deviation of 8 psi. For McGuire, the mean and standard deviations are 84 psi and 12 psi, respectively. In an Addendum, results by others are summarized and compared and a preliminary dynamic analysis is presented