Safety analysis for the revised fuel rod internal pressure design basis

The safety implications of the proposed revision to the Westinghouse fuel rod internal pressure design basis have been investigated. The revised design basis was developed as a more realistic basis for satisfying stress/strain limits while increasing the flexibility of the designer and enhancing reactor operation capability in areas such as reduced pressure operation and cycle stretchout. As a result of the revised design basis, a small percentage of the fuel rods in the core are allowed to exceed the nominal coolant design pressure. The safety implications of the revised design basis were investigated using a conservative, bounding approach in order to make the results applicable to all present and future Westinghouse designed and fueled plants. The potential concerns, which were addressed during normal operation and accident conditions, are: fuel rod integrity, DNB propagation, and clad ballooning and degradation of heat transfer following DNB