The following is a synopsis of information received from the licensee:
On March 6, 2020, while at zero percent power and in Cold Shutdown - Mode 4, Nine Mile Point Unit 2 (NMP2) determined through surveillance testing that three Main Steam Isolation Valves (MSIVs) did not meet their Technical Specification closure time.
The cause of the MSIV failures has been determined to be delayed Air Pack response. The delay was caused by a buildup of corrosion product and waxy foreign material believed to be dried pipe thread sealant or O-ring assembly lube that accumulated on the internal surfaces of the Air Pack during refurbishment by the vendor Trillium (previously Hiller).
The following is action taken or planned to be taken to prevent recurrence: A note will be added to the procurement requirement evaluation form and purchase order for MSIV Air Pack refurbishments to minimize use of O-ring lubricant and thread sealant to limit likelihood of capturing foreign material on Air Pack valve internals.
The Energy Industry Identification System (EIIS) component function identifier and system name of each component or system referred to above is:
Component - Main Steam Isolation Valves, Air Pack.
IEEE 803 Function Identifier - VOP.
IEEE805 System Identification - SB.
The licensee notified the NRC Resident Inspector.
For further information contact:
Todd Tierney
Plant Manager
Nine Mile Point Nuclear Station
Exelon Generation Company, LLC
Brandon Shultz
Site Regulatory Assurance Manager
Nine Mile Point Nuclear Station
(315) 349-7012
.
