ENS 40576
ENS Event | |
|---|---|
16:30 Mar 8, 2004 | |
| Title | Hpci System Inoperable Due to Failure of Torus Suction Valve to Fully Open |
| Event Description | U2 HPCI was declared inoperable to fulfill its safety function to mitigate the consequences of an accident.
U2 HPCI torus suction valve MO-2-23-058 failed to fully open, during performance of ST-O-023-301-2 'HPCI Pump, Valve, Flow, and Unit Cooler Functional and In-Service Test.' The valve stopped in a mid-position. HPCI flow path from Condensate Storage Tank remains available for HPCI injection. Investigation into cause is continuing. The licensee notified the NRC Resident Inspector.
The purpose of this notification is to retract a previous report made on 3/8/04 at 1130 hours0.0131 days <br />0.314 hours <br />0.00187 weeks <br />4.29965e-4 months <br /> (EN# 40576). Notification of the event to the NRC was initially made as a result of declaring the Unit 2 High Pressure Coolant Injection (HPCI) system inoperable when unexpected conditions were found during performance of routine surveillance testing of HPCI. Specifically, it was noted that a motor-operated Suppression Pool suction valve for HPCI (MO-58) did not complete its stroke in the open direction during testing. The HPCI system was not operating at the time of the discovery. Since the initial report, Engineering has determined that HPCI was capable of performing its safety function. The evaluation has determined that the MO-58 valve was operable for continued operations. The MO-58 stopped in the mid-stroke position due to motor operator torque switch operation. During design events, the torque switch is bypassed and would not have interrupted valve operation. The torque switch is only in the valve logic for remote manual valve operations (e.g. testing). The torque switch was adjusted and HPCI was returned to service on 3/10/04 by approximately 1500 hours0.0174 days <br />0.417 hours <br />0.00248 weeks <br />5.7075e-4 months <br /> [ET]. During adjustments to the HPCI MO-58 motor operator, the suction source from the Suppression Pool was isolated in accordance with Technical Specifications since MO-58 is considered as a Primary Containment Isolation Valve. This occurred on 3/8/04 by approximately 1340 hours0.0155 days <br />0.372 hours <br />0.00222 weeks <br />5.0987e-4 months <br />. This action was performed in accordance with station procedures and is considered planned maintenance. Throughout the time period of repairs to the MO-58, HPCI was available for operations with its suction source from the normally aligned Condensate Storage Tank. The NRC resident has been informed of the retraction. Notified R1 DO (D. Silk). |
| Where | |
|---|---|
Peach Bottom  Pennsylvania (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
| Time - Person (Reporting Time:+0.57 h0.0238 days <br />0.00339 weeks <br />7.80786e-4 months <br />) | |
| Opened: | Daniel Forry 17:04 Mar 8, 2004 |
| NRC Officer: | Mike Ripley |
| Last Updated: | Apr 20, 2004 |
| 40576 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |