Paper ID Number: D3-A1-US Title: Latest Advances in Fatigue Monitoring Technology Using EPRI's FatiguePro Software

In 1985, EPRI embarked upon the development of an on-line fatigue monitoring system for nuclear power plant components. The resultant system, FatiguePro, has been successfully implemented and operated at approximately thirty operating nuclear units worldwide over the past twelve years. Significant efforts have been expended on the development of the FatiguePro software over the past twelve years, and improvements are continuing. These include: (1) enhancements in personal computer capabilities and operating system improvements, (2) lessons learned by the large population of users, and (3) the incorporation of new technical algorithms to address regulatory requirements. This paper describes the most recent advancements made to the FatiguePro software, including: (1) sophisticated thermal hydraulic models to remove the reliance on conservative, design basis, thermal " step " transients, (2) analytical models and extensive field data that address the effects of thermal stratification, (3) advanced thermal stress solutions that accommodate more complex fracture mechanics solutions for fatigue crack growth assessments, (4) environmental fatigue assessments, including those that require difficult strain rate determinations, and (5) a FatiguePro User's Group (FPUG) that directs the future enhancement of the software and provides a valuable forum for sharing, solving and responding to industry fatigue-related issues.