Assessment of BWR fuel-channel lifetimes. Final report

The factors potentially limiting BWR fuel channel lifetimes are reviewed including interaction with control rod blades, interaction with incore instruments, bypass flow, and corrosion. Interaction with control rod blades - channel deformation resulting in encroachment on control rod blades, with potential adverse effects on the control rod blades' ability to move freely - is identified as the mechanism most likely to limit channel lifetime. In addition, interaction of channels with incore instruments can result in indicated core power asymmetries; precluding such interaction can permit re-use of some channels. Increased bypass flow can affect thermal-hydraulic safety limits when re-used channels are placed on new high power fuel assemblies, and this effect could potentially limit re-use of channels. Channel management methods suitable to extend fuel channel lifetimes to two full fuel assembly lifetimes are identified. Recommendations for further work to permit a larger percentage of channels to be used for two full fuel assembly lifetimes are identified