ENS 57561
ENS Event | |
|---|---|
09:24 Feb 19, 2025 | |
| Title | Two of Three ECCS Trains Declared Inoperable |
| Event Description | The following information was provided by the licensee via phone and email:
On 02/18/2025, at 0400 CST, train `C' essential cooling water was declared inoperable for scheduled maintenance. This cascades down to train `C' emergency core cooling system (ECCS), rendering it inoperable. Train `C' essential cooling water was declared operable on 02/18/2025, at 1207; however, train `C' essential chiller remained inoperable due to ongoing maintenance, which renders train `C' ECCS inoperable. On 02/19/2025, at 0324, train `B' ECCS was declared inoperable due to challenging control room habitability. The mitigating strategy of placing high head safety injection pump `1B' in pull to lock was completed at 0749 on 2/19/2025. On 02/19/2025, at 0324, Technical Specification 3.5.2 action `b' was entered due to two trains of ECCS being inoperable. This action requires that at least two trains of ECCS are restored to operability within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> or apply the requirements of the CRMP (Configuration Risk Management Program). On 02/19/2025, at 0424, the CRMP was entered based on two ECCS trains remaining inoperable for longer than 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />. This condition resulted in the inoperability of two of the three safety trains required for the accident mitigating function including: high head safety injection, low head safety injection, and containment spray. This is an 8-hour reportable condition per 10CFR50.72(b)(3)(v)(D) because it could affect the ability to mitigate the consequences of an accident. Unit 1 remains in mode 1 at 100 percent power. The NRC Resident Inspector has been notified. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: With two ECCS trains inoperable, the licensee will enter a shutdown technical specification action statement on 3/13/2025. |
| Where | |
|---|---|
South Texas  Texas (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
| LER: | 05000498/LER-2025-001 Two Inoperable Emergency Core Cooling System Trains Resulting in Potential Loss of Safety Function |
| Time - Person (Reporting Time:+2.2 h0.0917 days <br />0.0131 weeks <br />0.00301 months <br />) | |
| Opened: | Robert Dewoody 11:36 Feb 19, 2025 |
| NRC Officer: | Josue Ramirez |
| Last Updated: | Feb 19, 2025 |
| 57561 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |