Containment integrity and leakage evaluation

As part of a Probabilistic Risk Assessment (PRA) of the Yankee Atomic Electric Company plant at Rowe, MA, an evaluation was made of the ultimate pressure capability of the reactor containment structure. Design features of the structure that had the potential to limit the ultimate capability were investigated in detail. Data was not available to calculate the capability of electrical penetrations and a test program to qualify these components is described. The ultimate capability is determined to be approximately three times the design pressure. An evaluation is presented for leakage characteristics at pressures in excess of design. The leakage rate at the ultimate pressure is extrapolated and data from previous tests up to the design pressure is compared to the developed extrapolation curve