ENS 47444
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ENS Event | |
|---|---|
08:01 Nov 16, 2011 | |
| Title | Unusual Event Due to Drywell Leakage Greater than 10 Gpm |
| Event Description | On 11/16/11 at 0208 EST, Brunswick Nuclear Plant, Unit 2 calculated a drywall floor drain 42 minute leak rate of 5.88 gpm, following several hours of gradually rising floor drain leakage during a plant startup. Tech Spec 3.4.4 A was entered, requiring floor drain leakage to be restored below 5 gpm within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />. At 0253 EST, a 45 minute leak rate of 10.11 gpm was calculated. At 0301 EST, Unusual Event SU 6.1 was declared for unidentified leakage exceeding 10 gpm, and at 0309 EST, a manual reactor scram was inserted from approximately 7% power [10 CFR 50.72(b)(2)(iv)(B)]. Following the scram, the reactor was depressurized at a maximum cooldown rate of 92.5 deg F/hr, and the unidentified leak rate fell less than 10 gpm within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> and less than 5 gpm within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />. Leak rate at 0614 EST on 11/16/11 is 3.82 gpm with reactor pressure at 228 psig.
The exact nature of the leak is unknown at this time. The current plan is to continue to depressurize and cool down the reactor to Mode 4, such that a full drywall inspection can commence. At present, Brunswick has not terminated the Unusual Event. Level control is currently being maintained with control rod drives (CRD). The MSIVs were manually closed to control cooldown. The maximum cooldown was observed to be 92.5 F/hour. The plant plans to reopen MISIVs and depressurized to condensate booster pump injection pressure of 350 psig. The plan is to achieve Mode 4 for a leak inspection. The licensee has notified the NRC Resident Inspector.
The leakage rate is currently 3.73 gpm. The decrease is due to lower pressure which is currently at 258 psig. There are no additional changes. The leakage source is not identified at this time. The licensee has notified the NRC Resident Inspector. Notified R2DO (Vias).
The leakage rate is currently below the T.S. limit due to lower pressure which is currently at 210 psig. There are no additional changes. The plant will remain in an Unusual Event (UE) until further notice. The licensee has notified the NRC Resident Inspector. Notified R2DO (Vias).
The leakage rate is stable. The leak rate is calculated at 3.04 gpm at 183 psig at 0708 EST. The current reactor pressure is 162 psig. The licensee has notified the NRC Resident Inspector. Notified R2DO (Vias).
The licensee terminated from their Unusual Event at 0815 EST. The leakage is still unidentified. The licensee has notified the NRC Resident Inspector. Notified R2DO (Vias). |
| Where | |
|---|---|
Brunswick  North Carolina (NRC Region 2) | |
| Reporting | |
| Emergency class: | Unusual Event |
| 10 CFR 50.72(a) (1) (i), Emergency Class Declaration 10 CFR 50.72(b)(2)(iv)(B), RPS Actuation | |
| Time - Person (Reporting Time:+-4.47 h-0.186 days <br />-0.0266 weeks <br />-0.00612 months <br />) | |
| Opened: | David Fashcher 03:33 Nov 16, 2011 |
| NRC Officer: | John Knoke |
| Last Updated: | Nov 16, 2011 |
| 47444 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | Yes, Manual Scram |
| Before | Power Operation (7 %) |
| After | Hot Shutdown (0 %) |
Brunswick with 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | |
WEEKMONTHYEARENS 567972023-10-16T02:56:00016 October 2023 02:56:00
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2008 16:08:00 Other Unspec Reqmnt, 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Scram Due to Spurious Srv Opening ENS 444532008-08-30T19:03:00030 August 2008 19:03:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Turbine Electro-Hydraulic Control Malfunction Leads to Reactor Scram ENS 430622006-12-25T10:39:00025 December 2006 10:39:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation, 10 CFR 50.72(b)(2)(iv)(A), System Actuation - ECCS Discharge Reactor Scram Due to Trip from Neutron Monitoring System ENS 429862006-11-11T17:43:00011 November 2006 17:43:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Reactor Scram Due to Conductivity Excursion ENS 429552006-11-01T23:37:0001 November 2006 23:37:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration, 10 CFR 50.72(b)(3)(iv)(A), System Actuation, 10 CFR 50.72(b)(2)(iv)(A), System Actuation - ECCS Discharge Unit 2 Declared an Unusual Event Due to Loss of Offsite Power to the 4Kv Emergency Buses ENS 419832005-09-13T03:14:00013 September 2005 03:14:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event Declared Due to Hurricane Ophelia Warning ENS 418372005-07-13T13:17:00013 July 2005 13:17:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Turbine Trip/Reactor Trip ENS 415822005-04-09T05:50:0009 April 2005 05:50:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Reactor Scrammed from 61% Power Due to Low Reactor Water Level ENS 409532004-08-14T17:08:00014 August 2004 17:08:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Notice of Unusual Event Emergency Declared Due to Loss of Offsite Power ENS 409542004-08-14T16:59:00014 August 2004 16:59:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Rps Actuation Due to Loss of Offsite Power ENS 409512004-08-13T22:20:00013 August 2004 22:20:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Notice of Unusual Event Declared Due to Hurricane Warning ENS 402972003-11-04T22:32:0004 November 2003 22:32:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation, 10 CFR 50.72(b)(2)(iv)(A), System Actuation - ECCS Discharge Brunswick Unit 2 Scram Due to Generator/Turbine Trip ENS 401642003-09-17T02:40:00017 September 2003 02:40:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event at Brunswick Due to Hurricane Warning 2023-04-20T05:48:00 | |
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