ENS 56928
ENS Event | |
|---|---|
20:04 Jan 18, 2024 | |
| Title | Residual Heat Removal Degraded Due to Service Water Leakage |
| Event Description | The following information was provided by the licensee via email:
On January 18, 2024, at 0030 PST, diesel generator 2 (DG2) was shut down following a monthly surveillance run. Subsequently, a leak was discovered in the DG2 building. Service water pump '1B' was secured at 0117, effectively stopping the leak. The leak was determined to be service water coming from a diesel generator mixed air cooling coil. Service water system 'B' and DG2 were subsequently declared inoperable at 0135. After discussion with engineering, it was identified that the amount of service water leakage from the cooling coil was assumed to be greater than the leakage allowed by the calculation to assure adequate water in the ultimate heat sink to meet the required mission time of 30 days. At 1204, it was determined that entry into Technical Specification 3.7.1 condition D was warranted since the assumed leakage from the cooling coil could exceed the calculated allowed value. At 1238, the control power fuses for service water pump '1B' were removed. DG2 and service water system 'B' were declared unavailable, and the technical specification condition for the inoperable ultimate heat sink was exited. With the control power fuses removed, the pump is kept from auto starting, effectively preventing the leak and ensuring the safety function of the ultimate heat sink is maintained while the cooling coil is repaired or replaced. Due to the leakage assumed greater than the calculated allowable value this condition is reportable per 10 CFR 50.72(b)(3)(ii)(B) as an unanalyzed condition and per 10 CFR 50.72(b)(3)(v)(B) as an event or condition that could have prevented fulfillment of the safety function of structures or systems that are needed to remove residual heat. There was no impact to the health and safety of the public. The NRC Resident has been notified. |
| Where | |
|---|---|
| Columbia Washington (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat | |
| Time - Person (Reporting Time:+1.57 h0.0654 days <br />0.00935 weeks <br />0.00215 months <br />) | |
| Opened: | Jose Valix 21:38 Jan 18, 2024 |
| NRC Officer: | Adam Koziol |
| Last Updated: | Jan 18, 2024 |
| 56928 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
Columbia | |
WEEKMONTHYEARENS 569282024-01-18T20:04:00018 January 2024 20:04:00
[Table view]10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Residual Heat Removal Degraded Due to Service Water Leakage ENS 512012015-07-06T21:20:0006 July 2015 21:20:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Postulated Multiple Spurious Operations Scenario That Could Adversely Impact Post-Fire Safe Shutdown ENS 498982014-03-11T17:01:00011 March 2014 17:01:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Postulated Hot Short Fire Event That Could Adversely Impact Safe Shutdown Equipment ENS 472092011-08-28T03:21:00028 August 2011 03:21:00 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat Shutdown Cooling Temporarily Isolated ENS 429612006-11-03T11:09:0003 November 2006 11:09:00 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat Procedural Error Caused Residual Heat Removal Shutdown Cooling Inboard Containment Isolation Valve to Close. 2024-01-18T20:04:00 | |