Service Water Life Cycle Management

Nuclear plant service water systems are a critical part of the facility's infrastructure. System integrity and performance are vital for plant reliability and essential to achieving a plant life of 40 years and beyond. Corrosion, fouling (macrofouling, microfouling and sedimentation) and other effects that are detrimental to the reliability of the service water system led to the issue of NRC Generic Letter 89-13 "Service Water System Problems Affecting Safety-Related Equipment." This generic letter continues to be a fundamental guideline for safety related service water systems at all U.S. nuclear plants. The low temperature and pressure service water piping systems are primarily degraded by corrosion. Because of the complexity and random nature of corrosion processes, it is nearly impossible to develop a mathematically deterministic model that accurately predicts pipe wall loss. However, if statistical distributions are used to describe the various corrosion processes, mathematical algorithms that incorporate all of the distributions, iterated a statistically significant number of times, can be used to forecast the most probable number of leaks. This paper predicts the condition of service water piping at Kewaunee Nuclear Power Plant using the described model and includes the expected number of through-wall leaks as a function of operating time.