Standardization of EQ program limitorque valve actuator configurations

Motor operated valves (MOVs) of a wide variety of configurations and sizes are used in a large number of diverse nuclear plant applications. The primary manufacturer is Limitorque Corporation, although Rotork remains an option. A notable fraction of these MOVs require compliance with 10 CFR 50.49 "The Environmental Qualification (EQ) Rule" in order to assure safety function performance when exposed to the harsh environment effects of a pipe break type accident. Over the past 30 years, industry efforts to achieve qualification have evolved and changed dramatically. When a nuclear plant Owner procures an MOV, it is certified to a given EQ test report, which delineates the required (tested) configuration. Despite years of operational experience, serious challenges still remain with respect to maintaining the required qualified configuration in the field. This paper discusses an approach used by a midwestern nuclear power plant to simplify the maintenance requirements through the use of a standardization process that ensures that all installed actuators are maintained in a configuration that is equal to or better than the individual test configuration.