Fuel operating experience in Westinghouse PWRs

Westinghouse fuel experience from a data base of 29 plants with Zircaloy fuel clad demonstrates a continued high reliability. On-site surveillance programs indicate that previous defect mechanism such as clad hydriding due to moisture, fuel densification, clad flattening and clad defects following a rapid initial startup after refueling have been virtually eliminated. The class of potential defect mechanisms which have not compromised fuel performance (fuel rod bow, pellet-to-clad interaction at high power operation, corrosion and fretting) is undergoing extensive evaluation to verify the adequacy of the current designs and to develop design improvements. 6 refs