Operating experience review of service water system problems

In a recent paper, selected results of a comprehensive review and evaluation of service water system problems conducted by the Office for Analysis and Evaluation of Operational Data (AEOD) of the US Nuclear Regulatory Commission (NRC) were presented. The results of this review and evaluation indicated that service water system problems have significant safety implications. These system problems are attributable to a great variety of causes and have adverse impacts on a large number of safety-related systems and components. To provide additional feedback of operating experience, this paper presents an overview of the dominant mechanisms leading to service water system degradations and failures. The failures and degradations of service water systems observed in the 276 operating events are grouped into six general categories. The six general categories are (1) fouling due to various mechanisms, (2) single-failure and other design deficiencies, (3) flooding, (4) equipment failures, (5) personnel and procedural errors, and (6) seismic deficiencies