ENS 57804
ENS Event | |
|---|---|
19:45 Jul 7, 2025 | |
| Title | Residual Heat Removal Complex Pump Room Damper Fully Closed |
| Event Description | The following information was provided by the licensee via phone and email:
On 7/7/2025 at 1545 EDT, one of the division 2 residual heat removal (RHR) complex pump room dampers was noted to be full-closed instead of at the expected full-open position based on outside air temperatures. An operator walkdown confirmed that the division 2 RHR pump room temperature controller was attempting to open the damper. Per plant procedures, the affected RHR service water (RHRSW), emergency equipment service water (EESW), and emergency diesel generator service water pumps (DGSW) were declared inoperable. Division 2 EESW supports the safety function for all division 2 safety systems, including high pressure coolant injection (HPCI). Therefore, HPCI was also declared inoperable. Since HPCI is a single-train safety system, this meets the criterion for event notification per 10 CFR 50.72(b)(3)(v)(D). The damper will be blocked to the position required based on current and projected outside air temperature, this will return the systems to operable. The cause of the damper failure is unknown and under investigation. The NRC Resident Inspector has been notified. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: Multiple technical specification limiting conditions for operation (LCOs) were entered as a result of this event. Fermi Unit 2 expects to be able to exit the LCOs within the required timeframes.
The following retraction was provided by the licensee via phone and email: Following the initial event notification, further analysis of the condition identified that since the residual heat removal complex room temperature (85 degrees F) was less than the limit bounded by a calculation (<104 degrees F), and the dampers were blocked in a position in accordance with plant procedures within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of the event, there is reasonable assurance that the high pressure coolant injection (HPCI) system would be able to perform its safety function. Therefore, HPCI is considered operable for the condition. No other concerns were noted during the event. HPCI remained operable and there was no loss of safety function. The event did not involve a condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident under 10 CFR 50.72(b)(3)(v)(D). Therefore, the NRC non-emergency 10CFR50.72(b)(3)(v)(D) report was not required and the NRC event 57804 can be retracted and no licensee event report under 10 CFR 50.73(a)(2)(v)(D) is required to be submitted." Notified R3DO (Zurawski) |
| Where | |
|---|---|
Fermi  Michigan (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:+2.85 h0.119 days <br />0.017 weeks <br />0.0039 months <br />) | |
| Opened: | Glenn West 22:36 Jul 7, 2025 |
| NRC Officer: | Ernest West |
| Last Updated: | Jul 22, 2025 |
| 57804 - NRC Website
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