Review of experience with water reactor fuels 1968–1973

This review of water reactor fuel performance from 1968 to 1973 shows that defect levels in Zircaloy-clad UO2 fuels have, at times, been up to 1 in 3 bundles/reactor yr or ∼1 in 100 pins. Among the consequences of such events, are considerable efforts by manufacturers, designers and operators to understand the mechanisms of defection. As a result it has been possible to feed back the operating experience to give improvement in defect level to ∼1 in 200 bundles/reactor yr or between 1 in 103 and 1 in 104 fuel pins. The various types of defects and limiting features of Zircaloy clad fuel have been classified and fitted to well established reliability technology. There is justification for establishing a statistical data bank on water reactor fuel performance, to establish models and confirm acceptable defect levels, similar to those available on reactor plant. Few defects can yet be described as ‘life limiting’ in that incore lifetime is currently decided on economic grounds. Some potential life-limiting features have been identified during the review which should be the subject of further work to improve the long term performance of water reactor fuel.