ENS 57912
ENS Event | |
|---|---|
02:50 Sep 10, 2025 | |
| Title | Enclosure Building Boundary Inoperable |
| Event Description | The following information was provided by the licensee via phone and fax:
Entry into shutdown technical specification action statement due to an identified breach in ventilation ductwork. At 2250 EDT on September 9, 2025, it was discovered that there was degraded manway sealant on the manway to fire damper HV-298A. This degraded sealant results in a direct path from the enclosure building to the atmosphere, challenging the enclosure building boundary. This condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v)(C). There is no impact on the health and safety of the public or plant personnel. The plant is currently in a 24-hour technical specification action statement (3.6.5.2) for Unit 2. Unit 3 is not impacted and continues to operate at 100 percent power. The Resident Inspector has been notified.
The following information was provided by the licensee via phone and fax: Millstone Unit 2 is retracting NRC Event Notification57912, made on September 10, 2025, at 0523 EDT, regarding a condition identified at Millstone Power Station Unit 2. The condition involved degraded sealant on manways to fire dampers HV-298A/B/G, which resulted in a direct path from the enclosure building to the atmosphere, challenging the integrity of the enclosure building boundary. This condition was initially reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v)(C) for an event or condition that could have prevented the fulfillment of a safety function (control of release of radioactive material). A subsequent review using additional information on hatch design and actual seating surface determined that there is reasonable assurance the enclosure building boundary remained operable and retained its safety function to control the release of radioactive material and mitigate the consequences of an accident. Based on this assessment, Unit 2 exited Technical Specification action statement 3.6.5.2, and the condition is not reportable under 10 CFR 50.72(b)(3)(v)(C). Therefore, NRC EN 57912 is being retracted. The Resident Inspector has been notified. Notified R1DO (Ford). |
| Where | |
|---|---|
Millstone  Connecticut (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | |
| Time - Person (Reporting Time:+2.55 h0.106 days <br />0.0152 weeks <br />0.00349 months <br />) | |
| Opened: | Josh Lindsey 05:23 Sep 10, 2025 |
| NRC Officer: | Eric Simpson |
| Last Updated: | Sep 12, 2025 |
| 57912 - NRC Website
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