Burnup limits in PWR and in BWR fuel

The design of future cores will be based on burnup limits that are currently expanding. The performance parameters that have limited the burnup potential for current fuels in BWRs and in PWRs will be identified. Any changes that are justified through data from lead test assemblies (LTAs) or other improvements will be reported. Performance issues such as Zircaloy growth, pellet-cladding interaction (PCI), corrosion, Zircaloy ductility, fuel rod internal pressure will be discussed relative to potential limits. Some of these are limiting because of fuel rod integrity and others because of licensing or commercial considerations. Potential limits that arise from nuclear design considerations will also be described for general cases where peaking or other limits may be reached at lower values than those due to mechanical integrity, for example. Where representative data are available for classes of BWRs and PWRs, operating limits will be projected for use by those utilities with plants in these categories. (author). 10 figs