ENS 43942
ENS Event | |
|---|---|
19:41 Jan 29, 2008 | |
| Title | High Pressure Coolant Injection System Not Available for Safe Shutdown Capability |
| Event Description | The D/C power supply for the Unit 1 High Pressure Coolant Injection (HPCI) system instrumentation has failed resulting in the inability of HPCI to meet its requirement to support safely shutting down the reactor during a Station Blackout (Complete Loss of A/C Power) situation. The Emergency Core Cooling System (ECCS) function of HPCI is still available with the alternate A/C power supply.
The licensee is actively troubleshooting the power supply. The HPCI unavailability places the licensee in a 14-day Limiting Condition for Operation action statement. The licensee has notified the NRC Resident Inspector.
This is a retraction of the event notification made on 1/29/08 at 21:50 EST hours. This event (#43942) was initially reported as a safety system functional failure under the requirement of 10 CFR 50.72(b)(3)(v)(A). The notification stated that the D.C. power supply for the Unit 1 High Pressure Coolant Injection (HPCI) system instrumentation failed resulting in the inability of HPCI to meet its requirement to support safely shutting down the reactor during a Station Blackout (SBO) (Complete Loss of A/C Power) situation. The Emergency Core Cooling System (ECCS) function of HPCI is still available with the alternate A/C power supply. A review of the station's current licensing basis determined that HPCI is not credited with a safety function during a Station Blackout (SBO) event. Operating procedures direct securing HPCI early in an SBO event to minimize the discharge rate on the Class 1E batteries. The Reactor Core Isolation Cooling (RCIC) system is credited with maintaining reactor inventory during a SBO event. HPCI remained capable of completing its safety function to inject coolant into the reactor pressure vessel during a loss of coolant accident (LOCA) concurrent with loss of offsite power (LOOP) event. The Division 2 automatic initiation logic was inoperable but the Division 4 automatic initiation logic was unaffected by the Division 2 instrument power supply failure. Division 2 instrument power is required for HPCI automatic flow control and would not have been initially available during a LOOP event. However, the Division 2 instrument power would have been restored when the 480 VAC load center is re-energized approximately 13 seconds into the event. The 13 second delay in HPCl injection is offset by existing margin in HPCI's capability to meet the Technical Specification response time of 60 seconds. Therefore, a condition did not exist at the time of discovery that could have prevented the fulfillment of the HPCI safety function. The licensee notified the NRC Resident Inspector. Notified R1DO (Bellamy). |
| Where | |
|---|---|
Limerick  Pennsylvania (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor | |
| Time - Person (Reporting Time:+2.15 h0.0896 days <br />0.0128 weeks <br />0.00295 months <br />) | |
| Opened: | Daniel Semeter 21:50 Jan 29, 2008 |
| NRC Officer: | Howie Crouch |
| Last Updated: | Mar 27, 2008 |
| 43942 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (98 %) |
| After | Power Operation (98 %) |
WEEKMONTHYEARENS 439422008-01-29T19:41:00029 January 2008 19:41:00
[Table view]10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor High Pressure Coolant Injection System Not Available for Safe Shutdown Capability 2008-01-29T19:41:00 | |