ENS 57615
ENS Event | |
|---|---|
14:26 Mar 18, 2025 | |
| Title | Secondary Containment Boundary Inoperable |
| Event Description | The following information was provided by the licensee via phone and fax:
At 1026 [EDT] on March 18, 2025, it was discovered that the secondary containment boundary door was found fully open, rendering the secondary containment boundary inoperable, therefore, this condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72 (b)(3)(v). The door was closed at 1029 on March 18, 2025, and the secondary containment boundary was declared operable. There is no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. There has been no impact to Unit 2 and Unit 3 continues to operate at 100 percent power.
The following information was provided by the licensee via phone and fax: This report retracts the 8-hour notification made on March 18, 2025, for NRC Event Number EN#57615. NRC Event 57615 describes a condition at Millstone Power Station Unit 3 (MPS3) where a secondary containment boundary door was found fully open, rendering the secondary containment boundary inoperable. This condition was reported in accordance with 10CFR 50.72(b)(3)(v)(D) as a condition that could have prevented the fulfillment of a safety function to mitigate the consequences of an accident. Upon further review of the conditions that existed at the time, MPS3 has concluded that the door was not blocked open. The time duration from the activation of the door security alarm to the arrival of security personnel and the subsequent closure of the door was less than four minutes. The door was left unattended for less than 40 seconds, which is less than the five-minute criteria for entry and egress without special provisions. The supplementary leak collection and release system drawdown test has sufficient margin to accommodate this unattended door time. The evaluation concluded that the secondary containment boundary remained operable throughout this event and did not lose the ability to perform its safety function to control the release of radioactive material and mitigate the consequences of an accident. The basis for this conclusion will be provided to the NRC Resident Inspector. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: This event was originally reported in accordance with 10CFR 50.72(b)(3)(v)(D) and 10CFR 50.72(b)(3)(v)(C). The licensee confirmed that the retraction is applicable to both notifications. Notified R1DO (Bickett) |
| Where | |
|---|---|
Millstone  Connecticut (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident 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: | Kevin Woods 16:59 Mar 18, 2025 |
| NRC Officer: | Ernest West |
| Last Updated: | Apr 4, 2025 |
| 57615 - NRC Website
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