ENS 43177
ENS Event | |
|---|---|
23:20 Feb 20, 2007 | |
| Title | Hpci Declared Inoperable Due to an Apparent Equipment Malfunction |
| Event Description | On February 20, 2007 at 1720 hours0.0199 days <br />0.478 hours <br />0.00284 weeks <br />6.5446e-4 months <br />, the High Pressure Coolant Injection (HPCI) system was declared inoperable. During a system walkdown the HPCI Motor Speed Changer (MSC) was discovered energized. The MSC controls HPCI turbine speed during system startup and shutdown, and should not have been energized at the time of the walkdown. Additional troubleshooting determined the MSC was not functioning properly, rendering the HPCI system inoperable. This event is being reported as a condition that could have prevented fulfillment of a safety function in accordance with 10CFR50.72(b)(3)(v)(D) because the HPCI system is a single train system and the loss of HPCI could impact the plant's ability to mitigate the consequences of an accident. In accordance with Technical Specification Action 3.5.1.F, the Reactor Core Isolation Cooling (RCIC) system was confirmed operable. Further troubleshooting and engineering evaluations are continuing.
The licensee informed the NRC Resident Inspector.
The purpose of this report is to retract the ENS report made on February 20, 2007 at 1720 hours0.0199 days <br />0.478 hours <br />0.00284 weeks <br />6.5446e-4 months <br /> (ENS#43177) under 10CFR50.72(b)(3)(v)(D), a condition that could have prevented fulfillment of a safety function. The initial report was made when the Unit 2 High Pressure Coolant Injection (HPCI) system was declared inoperable following a system walkdown that discovered the HPCI Motor Speed Changer (MSC) was energized. The MSC controls HPCI turbine speed during system initiation, and should not have been energized at the time of the walkdown since the system was not in operation. During troubleshooting the MSC responded slower than expected. Due to this unexpected behavior, it was not certain if HPCI could have met its design basis requirements. However, a subsequent engineering evaluation has determined that at the time of discovery, the HPCI system injection time would have been sufficient to meet its safety function. Repairs to HPCI were completed and the system was declared operable on February 22, 2007 at 0036 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. The licensee notified the NRC Resident Inspector. Notified the R3DO (Orth). |
| Where | |
|---|---|
Quad Cities  Illinois (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
| Time - Person (Reporting Time:+-3.47 h-0.145 days <br />-0.0207 weeks <br />-0.00475 months <br />) | |
| Opened: | Mike Maclennan 19:52 Feb 20, 2007 |
| NRC Officer: | Steve Sandin |
| Last Updated: | Mar 5, 2007 |
| 43177 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (96 %) |
| After | Power Operation (96 %) |