While performing a High Head Safety Injection (
HHSI) Train-B inservice test, a Plant Operator noted leakage coming through
HHSI Flush Line Isolation Valve #SI-0120B. This valve is located on a flush line coming from the discharge of the
HHSI pump and directs water to the Safety Injection Pump room
sump located within the Fuel Handling Building. The operator investigated and determined that the leakage was due to the valve not being fully seated. The Licensee has come to the conclusion that the estimated leakage through the valve exceeded the allowable value to remain in compliance with
10 CFR 50, Appendix A, GDC 19 limits for
Control Room Envelope during the post
LOCA Containment recirc phase of a large break
LOCA. This condition resulted in an
unanalyzed condition that significantly degraded plant safety requiring a notification to the NRC within eight hours per
10 CFR 50.72 (b) (3) ii. Subsequently, flush line valve #SI-0120B has been fully seated, and the leakage stopped. The licensee considers this valve to be operable.
The Licensee notified the NRC Resident Inspector.
