ENS 53196: Difference between revisions
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| emergency class = Non Emergency | | emergency class = Non Emergency | ||
| notification date = 02/04/2018 12:00 | | notification date = 02/04/2018 12:00 | ||
| retracted = Yes | |||
| notification by = Brian Mcilnay | | notification by = Brian Mcilnay | ||
| NRC officer = Mark Abramovitz | | NRC officer = Mark Abramovitz | ||
| event date = 02/04/2018 04:45 EST | | event date = 02/04/2018 04:45 EST | ||
| last update date = | | last update date = 03/29/2018 | ||
| title = Failure of Containment Penetration Thermal Relief Check Valves to Meet Surveillance Acceptance Criteria | | title = Failure of Containment Penetration Thermal Relief Check Valves to Meet Surveillance Acceptance Criteria | ||
| event text = At 0445 [EST] on February 4, 2018, Watts Bar Unit 1 entered Technical Specification 3.6.1 condition A and 3.6.3 condition A.1 and A.2 due to inoperable containment penetration thermal relief check valves 1-CKV-31-3407 and 1-CKV-31-3421 associated with one train of the Containment Incore Instrument Room Chiller system. During surveillance testing, the thermal relief check valves failed to open and pass flow as required by acceptance criteria. The two penetrations were subsequently drained and isolated in accordance with the surveillance procedure to remove any thermal expansion concerns. Technical Specification 3.6.1 was exited February 4, 2018 at 0512 once the two penetrations were drained and isolated. | | event text = At 0445 [EST] on February 4, 2018, Watts Bar Unit 1 entered Technical Specification 3.6.1 condition A and 3.6.3 condition A.1 and A.2 due to inoperable containment penetration thermal relief check valves 1-CKV-31-3407 and 1-CKV-31-3421 associated with one train of the Containment Incore Instrument Room Chiller system. During surveillance testing, the thermal relief check valves failed to open and pass flow as required by acceptance criteria. The two penetrations were subsequently drained and isolated in accordance with the surveillance procedure to remove any thermal expansion concerns. Technical Specification 3.6.1 was exited February 4, 2018 at 0512 once the two penetrations were drained and isolated. | ||
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This event is being reported pursuant to 10 CFR 50.72(b)(3)(v)(C). | This event is being reported pursuant to 10 CFR 50.72(b)(3)(v)(C). | ||
NRC Resident Inspector has been notified. | NRC Resident Inspector has been notified. | ||
| URL = https://www.nrc.gov/reading-rm/doc-collections/event-status/event/2018/ | * * * RETRACTION AT 1336 EST ON 03/29/2018 FROM TONY PATE TO TOM KENDZIA * * * | ||
The purpose of this notification is to retract ENS notification 53196 made on 2/4/2018 for Watts Bar Nuclear Plant. The previous notification reported a surveillance failure of two containment penetration thermal relief check valves that, at the time of discovery, could have prevented the fulfillment of the safety function of structures or systems that are needed to control the release of radioactive material. | |||
After Engineering evaluation, it has been determined there is reasonable assurance the two thermal relief check valves (1-CKV-31-3407 and 1-CKV-31-3421) were capable of performing their specified safety function to isolate containment and act as a thermal relief device during a design basis accident. The basis of the evaluation included: | |||
1. No maintenance activities or interactions with the check valves had occurred since last tested. | |||
2. All surveillance testing for the valves was within required frequency. | |||
3. The opening force for a new check valve of the same size and similar to 1-CKV-31-3407 and 1-CKV-31-3421 is 0.38 pounds. Engineering analysis has determined the minimum failure pressure of the piping systems associated with the containment penetration in question is 450 psig. If it is assumed the force applied on the check valve seat reaches 450 psig, the force applied on the seat would reach 111 pounds or 300 times the force required to open a new, clean check valve. Based on engineering judgement of previous operating experience where the pressure required to open the same stuck check valve was within a safety factor of 6 to potential equipment damage, the thermal relief check valves would have opened prior to equipment damage and thus the identified condition would not have resulted in adversely affecting the containment isolation boundary. | |||
Entry into Technical Specification (TS) 3.6.1 condition A on 2/4/2018 at 0445 has been retracted. Although not a loss of safety function, the containment penetrations associated with 1-CKV-31-3407 and 1-CKV-31-3421 remain inoperable and are being tracked by TS 3.6.3 condition A.1 and A.2. | |||
The NRC Resident Inspector has been notified. | |||
Notified the R2DO (Rose). | |||
| URL = https://www.nrc.gov/reading-rm/doc-collections/event-status/event/2018/20180330en.html#en53196 | |||
}}{{unit info | }}{{unit info | ||
| Unit = 1 | | Unit = 1 | ||
Latest revision as of 06:30, 30 March 2018
| Where | |
|---|---|
Watts Bar  Tennessee (NRC Region 2) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | |
| Time - Person (Reporting Time:+2.25 h0.0938 days <br />0.0134 weeks <br />0.00308 months <br />) | |
| Opened: | Brian Mcilnay 12:00 Feb 4, 2018 |
| NRC Officer: | Mark Abramovitz |
| Last Updated: | Mar 29, 2018 |
| 53196 - NRC Website
| |