The operability of the
HPCI system with a degraded pipe support was indeterminate because the licensee did not repair the support, took no action to prevent recurrence of the hydraulic
transient that had damaged the support, and did not evaluate the system for recurrence of the
transient. The system remained in this degraded condition for at least 70 days, without assurance that it could perform its safety function until, through intervention by the NRC, additional support discrepancies were identified, the degraded support was repaired, and a significant amount of air was vented from the discharge piping. The support damage had been caused by a
water hammer due to voids in the discharge piping. The
HPCI system would have experienced another
water hammer because no actions were taken to eliminate the voids, and the damage to the system from another
water hammer may have rendered the system
inoperable. The significance of the finding has not yet been determined by the licensee, and this item is considered an Unresolved Item.
