NRC CAL – NOV (Yellow)

On April 27, 2015, the NRC issued a Notice of Violation associated with a Yellow Significance Determination Process finding to the Exelon Generation Company, LLC (licensee) for a violation identified at its Oyster Creek Nuclear Generating Station. The violation involved the failure to comply with 10 CFR 50, Appendix B, Criterion III, "Design Control," which required the licensee to establish measures for the selection and review for suitability of application of materials, parts, equipment, and processes that are essential to the safety-related functions of the structures, systems, and components. Specifically, from original installation of electromatic relief valves (EMRVs) in 1969, until the valves were redesigned and reinstalled during the 2014 refueling outage, the EMRV actuators were inadequate because when they were placed in an environment where the actuator was subject to vibration associated with plant operation, the mechanical tolerance between posts and guides created a condition where the springs could wedge between the guides and the posts, jamming the actuator plunger assembly. In addition, given the original design of the valve, the maintenance refurbishing processes were not adequate to maintain the required internal tolerances to prevent excessive fretting and wear of the internal components. As a consequence, two of the five total EMRVs were inoperable for greater than 24 hours in violation of Technical Specification 3.4.B.