ENS 42912
ENS Event | |
|---|---|
02:26 Oct 17, 2006 | |
| Title | Unusual Event - Identified Leakage Greater than 25 Gpm |
| Event Description | At 2126, PBNP Unit 2 had a inadvertent PORV (431C) lift. This was a momentary event, however, a PRT level change of 60 gallons was noticed. This event is classifiable per C.U.1.2 identified leakage greater than 25 GPM on Unit 2.
This event has been terminated at 2139. This event was caused by a momentary loss of power to the PORV controller. Power was immediately restored. The event was caused when a manually operated breaker (MOB) was inadvertently operated while the licensee was working inside the panels on the "B" train RHR system. The licensee notified the NRC Resident Inspector, State and local officials.
Unit 2 was in Mode 5 at ~150 psig, ~112 degrees F and the pressurizer (PZR) was in a water-solid condition per plant procedures. The following is a timeline of the event for clarification: 20:47:49 A manually operated breaker (MOB-281) inadvertently opened while removing a caution tag resulting in an increase of flow in the RHR system. 20:48:43 MOB-281 was reclosed correcting the RHR flow perturbation, however the adjacent breaker (MOB-282) inadvertently opened due to the vibration of MOB-281 being manipulated. This resulted in the loss of power to the RCS pressure instrumentation providing an input to a power-operated relief valve (PORV) causing the affected PORV to open. The PORV opening provided a flow path from the PZR to the Pressurizer Relief Tank (PRT). 20:49:06 MOB-282 was reclosed resulting In the PORV shutting and isolating the flow path from the PZR to the PRT. 20:55 The PRT level indication was checked on the Main Control Board, no change in level was observed as compared to prior to the event. While additional actions to stabilize the plant were being taken, the Shift Manager directed additional data to be obtained from the Plant Process Computer System (PPCS) regarding PRT parameters as the amount of water transferred was not large enough to be identified on the control board level Indication due to meter resolution. 21:26 Analysis of the PPCS data indicated that 62.5 gallons of RCS inventory had been transferred from the PZR to the PRT while the PORV was open. It was identified that this exceeded allowable RCS leakage limits, and the Emergency Plan was implemented. 21:32 An Unusual Event was declared per EAL CU 1.2, identified leakage greater than 25 gpm. It was recognized that this was a transient event and would be promptly terminated as the leakage flow path had been secured. 21:39 The Unusual Event was terminated. 21:43 State and County agencies were notified. 21:50 NRC Resident notified. 22:15 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> ENS Notification for Unusual Event and subsequent termination completed. The licensee notified the NRC Resident Inspector. Notified R3DO (Skokowski). |
| Where | |
|---|---|
Point Beach  Wisconsin (NRC Region 3) | |
| Reporting | |
| Emergency class: | Unusual Event |
| 10 CFR 50.72(a) (1) (i), Emergency Class Declaration | |
| Time - Person (Reporting Time:+-3.18 h-0.133 days <br />-0.0189 weeks <br />-0.00436 months <br />) | |
| Opened: | Ricky Robbins 23:15 Oct 16, 2006 |
| NRC Officer: | Joe O'Hara |
| Last Updated: | Oct 17, 2006 |
| 42912 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Not Critical |
| Scram | No |
| Before | Cold Shutdown (0 %) |
| After | Cold Shutdown (0 %) |
WEEKMONTHYEARENS 530042017-10-09T12:37:0009 October 2017 12:37:00
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