EN Revision Text:
MAIN STEAM ISOLATION VALVES EXCEEDED
PRIMARY CONTAINMENT LOCAL LEAK RATE ACCEPTANCE CRITERIA
At 0520 (CDT), on October 05, 2018, it was discovered that a Primary Containment local leak rate test performed on Main Steam Isolation Valves (MSIV) exceeded its acceptance criteria.
During Mode 1, 2, and 3, Surveillance Requirement 3.6.1.3.10 requires MSIV leakage for a single MSIV line to be less than or equal to 106 standard cubic feet per hour (scfh) when tested at 29 psig and Surveillance Requirement 3.6.1.3.12 requires the combined leakage rate for all MSIV leakage paths to be less than or equal to 212 scfh when tested at 29 psig.
As-found for the 'C' MSIV line leakage results were unquantifiable and gave a [minimum] path value greeter than 160 scfh. This leakage rate lead to Surveillance Requirement 3.6.1.3.10 and 3.6.1.3.12 limits to be exceeded. This event is being reported as a condition of the nuclear power plant, including its principal safety barriers, being seriously degraded per 10 CFR 50.72(b)(3)(ii)(A) since the Primary Containment Isolation Valves leakage limits for MSIVs were exceeded.
The NRC Resident Inspector has been notified.
- * * RETRACTION AT 2320 EDT ON 10/24/2018 FROM THOMAS FORLAND TO MARK ABRAMOVITZ * * *
CNS [Cooper Nuclear Station] is retracting the 8-hour non-emergency notification made on October 5, 2018 at 0520 CDT (EN# 53646). Subsequent evaluation concluded that overall as-found 'C' MSIV leakage rate was not at a level that exceeded the surveillance requirement 3.6.1.3.10 and 3.6.1.3.12 limits and thus the Primary Containment Isolation Valve leakage rate limits for the MSIVs were not exceeded.
The NRC Senior Resident Inspector has been notified.
Notified the R4DO (Drake).