ENS 57010
ENS Event | |
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13:20 Mar 5, 2024 | |
Title | Accident Mitigation - Loss of UPS Cooling |
Event Description | The following information was provided by the licensee via email:
On March 5, 2024, at 0720 CST, the X-02 118V uninterruptible power supply air conditioning (UPS A/C) unit tripped with the associated emergency fan coil units (EFCUs) shut down for planned maintenance in the area. The X-01 UPS A/C unit was declared inoperable upon discovery due to a scheduled outage of support systems (Unit 1 station service water) via the safety function determination process. This placed the site in technical specification 3.7.20 condition A, B, and C to restore the UPS A/C system within one hour. The EFCUs were restarted at 0729 which satisfied condition B and C, and X-01 UPS A/C unit was aligned to Unit 2 cooling water at 0801, exiting condition A. The condition that could have prevented the fulfillment of the safety function lasted for approximately nine minutes. Area temperatures had no notable change based on field observations during the condition. The UPS HVAC system provides temperature control for the safety related UPS and distribution rooms during all normal and accident conditions. The UPS HVAC system consists of (a) a dedicated UPS room EFCU in each safety-related UPS and distribution room, and (b) two electrically independent and redundant A/C trains either of which can support all four safety related UPS and distribution rooms; each train consists of an air conditioning unit, ductwork, dampers, and instrumentation. The NRC Resident Inspector has been notified. |
Where | |
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Comanche Peak Texas (NRC Region 4) | |
Reporting | |
10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
Time - Person (Reporting Time:+5.9 h0.246 days <br />0.0351 weeks <br />0.00808 months <br />) | |
Opened: | Damon Schroeder 19:14 Mar 5, 2024 |
NRC Officer: | Adam Koziol |
Last Updated: | Mar 5, 2024 |
57010 - NRC Website
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Unit 1 | |
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Reactor critical | Critical |
Scram | No |
Before | Power Operation (100 %) |
After | Power Operation (100 %) |
Unit 2 | |
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Reactor critical | Critical |
Scram | No |
Before | Power Operation (100 %) |
After | Power Operation (100 %) |