ENS 45784
ENS Event | |
|---|---|
01:11 Mar 23, 2010 | |
| Title | Notification of Unusual Event Due to Unidentified Leakage Greater than 10 Gpm |
| Event Description | The following event description is based on information currently available. If through subsequent reviews of this event, additional information is identified that is pertinent to this event or alters the information being provided at this time, a follow-up notification will be made via the ENS or under the reporting requirement of 10CFR50.73.
On March 22, 2010 at approximately 1756 MST, Palo Verde Nuclear Generating Station (PVNGS) Unit 1 identified a rising level and temperature trend in the Reactor Drain Tank (RDT). PVNGS Unit 1 was in Mode 1 (Power Operation) at 93% power with normal RCS temperature and pressure at the time of discovery. Containment temperature and humidity trends are normal. Technical Specification Limiting Condition for Operation 3.4.14 (RCS Operational Leakage), Condition 'A' was entered at 1811 due to unidentified leakage >10 gpm and the LCO allows 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> to restore leakage to <1 gpm. Also at 1811, a Notification of Unusual Event (NOUE) was declared due to unidentified leakage >10 gpm (MU5.1). PVNGS Unit 1 remains at power with all normal systems in operation; periodic pumping of the RDT is occurring. No automatic or manual reactor protection system or engineered safety features actuations occurred and none were required. There were no other component failures, testing or work in progress that contributed to the leak. The leak is located within the containment building, therefore there is no release of radioactivity to the environment and no impact to the health and safety of the public. There is no elevated RCS activity and heat removal is via normal steaming to the main turbine condenser. The electric grid is stable. Current plans are to enter containment and identify the source of leakage. State and Local authorities have been notified. The NRC Senior Resident Inspector has been notified. The licensee notified the following state and local agencies: Maricopa County Sheriff, Arizona Department of Public Safety, Buckeye Police Department, Arizona Radiation Regulatory Agency, Arizona Division of Emergency Management, and the Maricopa County Emergency Management Agency.
At 2112 MST, the shift manager advised that the Pressurizer Main Spray Valve, 100E, packing leakage has been manually isolated. As of 2125 MST, the level trend in the RDT has stabilized. The licensee is working to verify the leakage rate, and remains in an Unusual Event. The plant remains stable in Mode 1 at 93% power. The licensee has notified the NRC Resident Inspector, and the NRC Resident Inspector remains on site.
At 2146 MST, the licensee exited Technical Specification Limiting Condition for Operation 3.4.14, RCS Operational Leakage. At 2219 MST, the Unusual Event was terminated. The licensee will notify the NRC Resident Inspector. Notified R4DO (Deese), NRR EO (Brown), IRD (McDermott), DHS (Moore), and FEMA (Canupp). |
| Where | |
|---|---|
Palo Verde  Arizona (NRC Region 4) | |
| Reporting | |
| Emergency class: | Unusual Event |
| 10 CFR 50.72(a) (1) (i), Emergency Class Declaration | |
| Time - Person (Reporting Time:+-3.1 h-0.129 days <br />-0.0185 weeks <br />-0.00425 months <br />) | |
| Opened: | Bradford Robinson 22:05 Mar 22, 2010 |
| NRC Officer: | Donald Norwood |
| Last Updated: | Mar 23, 2010 |
| 45784 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (93 %) |
| After | Power Operation (93 %) |
WEEKMONTHYEARENS 576592025-04-10T14:11:00010 April 2025 14:11:00
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