GNF defense in depth 2010 update

GNF's Defense-in-Depth (DID) Program focuses attention on aspects of fuel design, fabrication, performance, and utilization that affect fuel reliability as well as on the key methods that govern the utilization of GNF fuel. Success of the program has been indicated by a decrease in fuel failure rates in prior years; however, continued diligence utilities and vendors will be required to sustain long-term reductions. Mid-exposure results from inspections of GNF2 Advantage™ fuel are available, providing added confirmation of acceptable performance of design features in that product. GNF continues to monitor the effectiveness of the Defender™ lower tie plate debris filter, which is the latest generation of debris mitigation technology installed in GNF fuel. To address channel deformation issues, GNF has employed the Cell Friction Metric methodology for use during core design and is working with customers to transition to alternate channel materials. GNF has also embarked on the implementation of Additive Fuel to further enhance PCl resistance and GNF-Ziron cladding material to provide improved corrosion and hydrogen pickup characteristics at higher burnups relative to Zircaloy-2. PRIME03, an enhanced thermal-mechanical predictive model, is supporting expanded introduction of GNF2 Advantage™ fuel.