Meeting the Industry Challenge to Achieve Leak Free Performance

摘要

Deployment of highly reliability fuel products is one of AREVA NP's overarching philosophies. Any fuel defect brings appreciable burden to utility and fuel vendors alike Consistent with the INPO challenge to eliminate fuel failures, AREVA NP's own culture of "Zero Tolerance for Failure" has led to historic levels of leaker free performance. In the past 5 years, the failure rate for AREVA NP fuel products has decreased by around an order of magnitude resulting in a number of reliability milestones being achieved in each of AREVA NP's United States, French, and German regions and global operators they serve. AREVA NP's achievements in leaker free performance are direct results of rigorous investigations and development of innovative products and solutions to address longstanding industry fuel reliability concerns. This multifaceted commitment to excellence has not only manifest itself in every aspects of AREVA NP's fuel business (including design, manufacturing, and operations), but is the direct result of experience feedback from a robust failure identification and resolution program. An illustrative example of this commitment can be found in the AREVA NP's BWR fuel product line. PCI had been a leading failure mechanism in BWR fuel supplied in the United States. In response, AREVA NP implemented improved pellet designs, tighter manufacturing standards, and industry-leading power maneuvering methodologies that have eliminated PCI failures altogether Likewise, failures resulting from small debris forms in the primary system have been a leading failure mechanism in the BWR fuel The implementation of advanced debris filters such as the Improved FUELGUARD~(™) and 3~(rd) Generation FUELGUARD~(™) have virtually eliminated debris-related failures AREVA NP's commitment to fuel reliability is not limited to the BWR fuel products Grid-to-Rod Fretting (GTRE) has long been a dominant PWR failure mechanism in the industry and results from challenging cross-flows within specific reactor designs that excite and ultimately cause the fuel rod to fret against the spacer contacts to the point of failure. In 2010 alone, 32 PWR fuel rods were discharged in the United States region that had failed due to fretting -related conditions. To eliminate this longstanding industry challenge, a suite of fuel products developed around the HTP~(™) (High Thermal Performance) spacer platform were implemented. The HTP~(™) grid design, with its multiple line contacts, serves to cradle the fuel rod and dampen vibrations in the presence of challenging flow conditions When coupled with the Alloy 718 HMP~(™) (High Mechanical Performance) lower grid, HTP~(™) fuel has never experienced a GTRF failure. Looking at these examples from the United States market in totality, marked improvement is evident, in 2010 a total of 41 failed fuel rods were discharged from reactors in the United States whereas in 2015 no failed fuel rods were discharged out of the approximately 1 3 million fuel rods in operation. The German and French regions have achieved similar reliability gains through comparable illustrative examples leading to all-time leaker free performance world-wide.