ENS 40134
ENS Event | |
|---|---|
13:33 Sep 5, 2003 | |
| Title | High Pressure Coolant Injection (Hpci) Declared Inoperable. |
| Event Description | At 09:30 EDT, Unit 1 was performing the HPCI Quarterly Flow verification surveillance. Shortly after the initiation of the system an abnormally loud bang was heard. System flow of approximately 5200 gpm and discharge pressure of approximately 1300 psi was achieved at approximately 09:33. Approximately 4 seconds after reaching rated system flow HPCI discharge pressure increased to approximately 1675 psi and system flow dropped to approximately 2700 gpm. HPCI had been declared inoperable at 08:35 EDT to perform the surveillance and will remain inoperable until the cause of the loss of system flow is corrected. Because HPCI is a single train ECCS [Emergency Core Cooling System] safety system, this event results in the loss of an entire safety function which requires an 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> ENS notification in accordance with 10CFR50.72(b)(3)(v) and the guidance provided under NUREG-1022, rev. 2.
There are no other ECCS systems presently out of service. Reactor Core Isolation Cooling (RCIC) is fully operable and HPCI entered Tech Spec 3.5.1 (14 day Limiting Condition of Operation). All other ECCS systems are fully operable. The NRC Resident Inspector was notified of this event by the licensee.
On 09/05/2003, PPL Susquehanna LLC made an ENS notification per 10CFR50.72(b)(3)(v) in response to an apparent loss of the HPCI [High Pressure Coolant Injection] safety function. In the event, results of HPCI Quarterly Flow Surveillance testing did not meet acceptance criteria established for the system. Investigation into the cause of the failed HPCI surveillance revealed a 360-degree weld crack on the HPCI Test Line to Condensate Storage Tank [CST] Valve, HV155F008. HV155F008 is not in the reactor vessel injection flowpath. The impact of this crack, which was located between the valve seat cage assembly and the valve body, was that the HPCI Test Line to CST valve was not capable of throttling over the full range of HPCI system flows. Valve performance became erratic at higher flows because the valve seat cage was lifted out of the valve body into the flow path, increasing system resistance, and preventing attainment of design flow in the HPCI test loop. While the ability to effectively test the HPCI system using the test return path to the CST was compromised, the HPCI injection flowpath to the reactor vessel was not adversely affected by the damaged valve. Accordingly, the HPCI system maintained full capability for providing sufficient coolant to the reactor vessel in the event of a small break loss-of-coolant accident. Because the HPCI safety function was not compromised by the identified test path obstruction, this ENS notification is being retracted. The Licensee has notified the NRC Resident Inspector. Notified R1DO (Cobey). |
| Where | |
|---|---|
Susquehanna  Pennsylvania (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
| Time - Person (Reporting Time:+-2.18 h-0.0908 days <br />-0.013 weeks <br />-0.00299 months <br />) | |
| Opened: | Gordon E. Robinson 11:22 Sep 5, 2003 |
| NRC Officer: | John Mackinnon |
| Last Updated: | Oct 2, 2003 |
| 40134 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |