ENS 53485: Difference between revisions
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| emergency class = Non Emergency | | emergency class = Non Emergency | ||
| notification date = 07/03/2018 19:07 | | notification date = 07/03/2018 19:07 | ||
| retracted = Yes | |||
| notification by = Jeremy Czeschin | | notification by = Jeremy Czeschin | ||
| NRC officer = Vince Klco | | NRC officer = Vince Klco | ||
| event date = 07/03/2018 00:00 CDT | | event date = 07/03/2018 00:00 CDT | ||
| last update date = 07/ | | last update date = 07/31/2018 | ||
| title = | | title = En Revision Imported Date 8/1/2018 | ||
| event text = On July 3, 2018, while performing a review of Emergency Operating Procedures, a concern was identified regarding the potential for excessive loss of ultimate heat sink inventory (UHS) through the auxiliary feedwater (AFW) system mini-flow recirculation pathway. This condition would have the potential to prevent the ultimate heat sink from providing an adequate inventory of water for a 30-day mission time. | | event text = EN Revision Text: DISCOVERY OF AN UNANALYZED CONDITION THAT SIGNIFICANTLY DEGRADES PLANT SAFETY | ||
On July 3, 2018, while performing a review of Emergency Operating Procedures, a concern was identified regarding the potential for excessive loss of ultimate heat sink inventory (UHS) through the auxiliary feedwater (AFW) system mini-flow recirculation pathway. This condition would have the potential to prevent the ultimate heat sink from providing an adequate inventory of water for a 30-day mission time. | |||
The normal water supply for the Callaway AFW system is the condensate storage tank (CST). The CST is a non-safety grade component. The safety-grade supply for AFW is the essential service water (ESW) system. The ESW system is supplied by the UHS. The UHS thermal performance analysis accounts for a loss of UHS inventory to the AFW system up until the point of the accident sequence that the AFW pumps would be secured. The analysis did not include an allowance for loss of UHS inventory through the AFW mini-flow recirculation pathway following the AFW pumps being secured. The EOP guidance that secures the AFW pumps does not isolate the mini-flow recirculation pathway. | The normal water supply for the Callaway AFW system is the condensate storage tank (CST). The CST is a non-safety grade component. The safety-grade supply for AFW is the essential service water (ESW) system. The ESW system is supplied by the UHS. The UHS thermal performance analysis accounts for a loss of UHS inventory to the AFW system up until the point of the accident sequence that the AFW pumps would be secured. The analysis did not include an allowance for loss of UHS inventory through the AFW mini-flow recirculation pathway following the AFW pumps being secured. The EOP guidance that secures the AFW pumps does not isolate the mini-flow recirculation pathway. | ||
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This condition is reportable per 10 CFR 50.72(b)(3)(ii)(B) for an unanalyzed condition that significantly degrades safety. | This condition is reportable per 10 CFR 50.72(b)(3)(ii)(B) for an unanalyzed condition that significantly degrades safety. | ||
The NRC Resident Inspectors have been notified of this condition. | The NRC Resident Inspectors have been notified of this condition. | ||
| URL = https://www.nrc.gov/reading-rm/doc-collections/event-status/event/2018/ | * * * RETRACTION ON 07/31/2018 AT 1430 EDT FROM LEE YOUNG TO ANDREW WAUGH * * * | ||
Event Notification (EN) 53485, made on July 3, 2018, is being retracted because re-evaluation performed subsequent to the notification has demonstrated, based on actual plant equipment and environmental conditions, that the unanalyzed inventory losses previously reported by EN 53485 would not have depleted the UHS inventory to an unacceptable level during its 30-day mission time. | |||
The re-evaluation has led to the conclusion that the previously unanalyzed losses of UHS inventory would not have prevented the UHS from performing its specified safety functions and meeting its 30-day mission time requirements. With the UHS capable of performing its specified safety functions and meeting its 30-day mission time requirements, the systems supported by the UHS would have remained capable of performing their specified safety functions. Based on these considerations, it has been determined that the condition reported in EN 53485 did not result in the plant being in an unanalyzed condition that significantly degraded safety. Consequently, the condition did not meet the criteria for an 8-hour notification per 10 CFR 50.72(b)(3)(ii)(B) for an unanalyzed condition that significantly degrades safety. | |||
The NRC Resident Inspector has been notified of the Event Notification retraction. | |||
Notified R4DO (Gaddy). | |||
| URL = https://www.nrc.gov/reading-rm/doc-collections/event-status/event/2018/20180801en.html#en53485 | |||
}}{{unit info | }}{{unit info | ||
| Unit = 1 | | Unit = 1 | ||
Latest revision as of 07:30, 1 August 2018
| Where | |
|---|---|
Callaway  Missouri (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| Time - Person (Reporting Time:+14.12 h0.588 days <br />0.084 weeks <br />0.0193 months <br />) | |
| Opened: | Jeremy Czeschin 19:07 Jul 3, 2018 |
| NRC Officer: | Vince Klco |
| Last Updated: | Jul 31, 2018 |
| 53485 - NRC Website | |