ENS 56620: Difference between revisions
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| emergency class = Non Emergency | | emergency class = Non Emergency | ||
| notification date = 07/12/2023 12:49 | | notification date = 07/12/2023 12:49 | ||
| retracted = Yes | |||
| notification by = Todd Stringfellow | | notification by = Todd Stringfellow | ||
| NRC officer = Kerby Scales | | NRC officer = Kerby Scales | ||
| event date = 07/12/2023 04:49 EDT | | event date = 07/12/2023 04:49 EDT | ||
| last update date = 07/ | | last update date = 07/31/2023 | ||
| title = ECCS Potentially Inoperable | | title = ECCS Potentially Inoperable | ||
| event text = The following information was provided by the licensee via email: | | event text = The following information was provided by the licensee via email: | ||
At 0449 [EDT] on 7/12/2023, Millstone Unit 3 declared the 'B' train of the emergency core cooling system (ECCS) inoperable due to a degraded damper associated with the ventilation support system for the 'B' charging pump. At the time of this event, the 'A' train of service water was already inoperable due to planned maintenance on a breaker that would have prevented an 'A' service water valve powered from this breaker from closing on a safety signal. This configuration resulted in the possibility that the 'A' train of ECCS would not have been available to fulfill its design function under all postulated accident conditions. This event is being reported under 10 CFR 50.72(b)(3)(v)(B), '[any event or condition that at the time of discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to: (B) remove residual heat].' | At 0449 [EDT] on 7/12/2023, Millstone Unit 3 declared the 'B' train of the emergency core cooling system (ECCS) inoperable due to a degraded damper associated with the ventilation support system for the 'B' charging pump. At the time of this event, the 'A' train of service water was already inoperable due to planned maintenance on a breaker that would have prevented an 'A' service water valve powered from this breaker from closing on a safety signal. This configuration resulted in the possibility that the 'A' train of ECCS would not have been available to fulfill its design function under all postulated accident conditions. This event is being reported under 10 CFR 50.72(b)(3)(v)(B), '[any event or condition that at the time of discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to: (B) remove residual heat].' | ||
Subsequently, the 'A' train of service water was restored to operable at 0548 on 7/12/2023. Repairs and investigation continue on the 'B' train ECCS damper. The NRC resident has been notified. This event did not impact Millstone Unit 2. There was no impact to the public. | Subsequently, the 'A' train of service water was restored to operable at 0548 on 7/12/2023. Repairs and investigation continue on the 'B' train ECCS damper. The NRC resident has been notified. This event did not impact Millstone Unit 2. There was no impact to the public. | ||
| URL = https://www.nrc.gov/reading-rm/doc-collections/event-status/event/2023/ | * * * RETRACTION ON 7/31/2023 AT 1400 EDT FROM JAMES KELLY TO JOHN RUSSELL* * * | ||
The following information was provided by the licensee via email: | |||
The condition was reported to the NRC pursuant to 10 CFR 50.72(b)(3)(v)(B), via an 8-hour report as an event or condition that at the time of discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to remove residual heat. | |||
A subsequent engineering review of the conditions that existed at the time determined that, based on area temperature response, any impact on ventilation flows into and out of the `B' charging pump cubicle did not generate an observable change in the temperature trend. Based on this, it is concluded with reasonable assurance that the functional requirement of the support system was maintained and the `B' charging pump would have continued to perform its safety function until the `A' train of service water was restored to operable and as a result safety function was not lost. | |||
Therefore, this condition is not reportable and NRC Event Number 56620 is being retracted. | |||
The basis for this conclusion has been provided to the NRC Resident Inspector." | |||
Notified R1DO (Bicket). | |||
| URL = https://www.nrc.gov/reading-rm/doc-collections/event-status/event/2023/20230801en.html#en56620 | |||
}}{{unit info | }}{{unit info | ||
| Unit = 3 | | Unit = 3 | ||
Latest revision as of 06:30, 1 August 2023
| Where | |
|---|---|
Millstone  Connecticut (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat | |
| Time - Person (Reporting Time:+4 h0.167 days <br />0.0238 weeks <br />0.00548 months <br />) | |
| Opened: | Todd Stringfellow 12:49 Jul 12, 2023 |
| NRC Officer: | Kerby Scales |
| Last Updated: | Jul 31, 2023 |
| 56620 - NRC Website
| |