ENS 41753
ENS Event | |
|---|---|
18:37 Jun 7, 2005 | |
| Title | Unusual Event Declared Due To Unidentified Drywell Leakage Greater Than 10 Gpm |
| Event Description | Hope Creek manually scrammed the reactor from 100% power at 1413 and declared an Unusual Event due to unidentified drywell leakage exceeding 10 gpm (EAL 2.1.1.b) at 1437. The drywell unidentified leak rate peaked at approximately 15 gpm and is currently 12 gpm and slowly lowering. All safety systems were operable prior to the transient and responded as expected. Drywell pressure peaked at approximately 0.5 psig and is steady using normal drywell cooling (the normal pressure band is 0.1 to 0.7 psig). Drywell and suppression pools sprays were not required to mitigate the drywell pressure transient. Reactor vessel level lowered to approximately -30 inches following the scram and was returned to the normal level band using the feedwater and condensate systems. The expected vessel level 3 (setpoint +12.5 inches) ESF actuations occurred. The plant is proceeding to cold shutdown to investigate the drywell leak.
The licensee notified the NRC Resident Inspector.
As of 0330, Region I IRC in consultation with NRC/IRD (McGinty) secured from Monitoring Mode based on the plant being stable at about 55 psig (about 300 degrees F) and preparing to initiate shutdown cooling. The leak rate remains at about 8 gpm, and an initial drywell entry determined the source of the leakage to be from the A-loop of shutdown cooling testable check valve (50A ). The valve was found with the position indication failed/separated and an approximate 20 foot plume of steam/liquid coming out. Plans are to continue to cool down the plant, go onto the B-loop of shutdown cooling , and isolate valve 50A. The licensee has conservatively remained in the UE and plans to exit when leak rate is assured to remain below 10 gpm (EAL entry condition) or cold shutdown is achieved and the EAL is no longer applicable. The licensee's outage center remains manned, and an NRC inspector remains on site around the clock. DHS (Hoisington), FEMA (Sweetser), DOE (Turner) EPA (Crews), USDA (Pimmons), HHS (Williams) were notified.
The licensee has placed RHR loop B into service and reached Mode 4 (cold shutdown) at 0455. Preparations are in progress to isolate the leak by closing manual valve 183.
The licensee terminated the Unusual Event at 0515 EDT based on reaching cold shutdown with the leak rate less than 10 gpm. The licensee notified the NRC Resident Inspector. DHS (Hoisington) and FEMA (Sweetser), R1D0 (Jackson), NRR EO (Hannon), and IRD (Leach) notified.
On the morning; of 06/08/05, investigation into a previously reported increase in unidentified drywell leakage (Event #41753) identified the leak location as the F050A residual heat removal (RHR) check valve. The F050A check valve is on the return line to the 'A' recirculation loop,. The F050A check valve was isolated at approximately 0545 hours0.00631 days <br />0.151 hours <br />9.011243e-4 weeks <br />2.073725e-4 months <br />. The position indication magnatrol assembly for the F050A check valve appears to be the source of the leakage. Additional investigation is proceeding to identify the exact location of the leak as well as address the structural integrity of the valve. This updated report is being made in accordance with 10CFR50.72(b)(3)(ii). At the time of this notification Hope Creek Generating station is in OPCON 4 [Cold Shutdown] at 122 degrees reactor coolant temperature. The licensee notified the NRC Resident Inspector. R1DO (Jackson) and NRR EO (Jung) notified. |
| Where | |
|---|---|
Hope Creek  New Jersey (NRC Region 1) | |
| Reporting | |
| Emergency class: | Unusual Event |
| 10 CFR 50.72(a) (1) (i), Emergency Class Declaration | |
| Time - Person (Reporting Time:+-3.12 h-0.13 days <br />-0.0186 weeks <br />-0.00427 months <br />) | |
| Opened: | Andrew Schirmer 15:30 Jun 7, 2005 |
| NRC Officer: | Mike Ripley |
| Last Updated: | Jun 8, 2005 |
| 41753 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | Yes, Manual Scram |
| Before | Power Operation (100 %) |
| After | Hot Shutdown (0 %) |
WEEKMONTHYEARENS 531012017-11-30T21:57:00030 November 2017 21:57:00
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