Enhanced Component Performance Study: Motor-Operated Valves 1998–2014
This report presents an enhanced performance evaluation of motor-operated valves (MOVs) at U.S. commercial nuclear power plants. The data used in this study are based on the operating experience failure reports from fiscal year 1998 through 2014 for the component reliability as reported in the Institute of Nuclear Power Operations (INPO) Consolidated Events Database (ICES). The MOV failure modes considered are failure to open/close, failure to operate or control, and spurious operation. The component reliability estimates and the reliability data are trended for the most recent 10-year period while yearly estimates for reliability are provided for the entire active period. One statistically significant trend was observed in the data: The frequency of demands per reactor year for valves with fail-to-open/close failure modes, for valves with greater than twenty demands per year, was found to be decreasing.