05000424/FIN-2010005-02
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Finding | |
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| Title | Depressurization of Main Firewater Header |
| Description | The resident inspectors identified an unresolved item (URI) related to the inadvertent depressurization of the main firewater header. On November 1, 2010, Plant Vogtle operations personnel inadvertently depressurized the main firewater header. For a period of 13 hours1.50463e-4 days <br />0.00361 hours <br />2.149471e-5 weeks <br />4.9465e-6 months <br /> and 21 minutes, the facility lost all automatic sprinkler system capability. If there had been an automatic actuation of the sprinkler system or a demand from any of the hose stations in the facility during that time period, there would have been no water available for fire suppression. At 0339 on November 1, 2010, both of the diesel firewater pumps and the north jockey pump were placed out of service and danger tagged to permit replacement of the relief valves on the diesel-driven pumps. As part of the tagout, the remote indicator in the control room for fire header pressure was also removed from service. The licensee entered the appropriate 7-day fire protection LCO action statement at that time. When the operators secured the north jockey pump for the tagout, they incorrectly assumed that the south jockey pump was in operation. In reality, the south jockey pump was also not operating and its hand switch was in the off position. This was in accordance with the governing procedure as the facility only needs to run one of the two jockey pumps to maintain 120 psig in the firewater header. As pressure in the firewater header began to decrease, the motor-driven firewater pump failed to start automatically at 100 psig. It was later discovered that the auto-start pressure switch had failed on demand. Two independent firewater header low pressure alarms were received in the control room, but the operators incorrectly assumed that the alarms were due to the tagout of the diesel-driven pumps. At approximately 1700 on November 1, a third party inspector, who was inspecting the fire protection system as part of an assistance team, noticed that several of the local firewater header pressure gauges were reading very low. He brought this fact to the attention of a system operator who immediately contacted the control room. The shift supervisor immediately dispatched an operator to the south firewater station, where he reported that the firewater header was depressurized, and neither the south jockey pump nor the motor-driven firewater pump were running. The shift supervisor directed that the operator start the jockey pump, and within a few minutes system pressure was restored. Several minutes after that, the shift supervisor directed that the motor-driven firewater pump be started manually to verify operability. The motor-driven firewater pump was started and ran for several minutes while maintenance personnel tried to determine why the pump had failed to automatically start at 100 psig. This issue will remain under review pending coordination with regional fire protection inspectors to appropriately identify the fire protection standard, apparent root cause and determine if a performance deficiency exists. This issue is being documented as URI 05000424,425/2010005-02, Depressurization of Main Firewater Header. |
| Site: | Vogtle  |
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| Report | IR 05000424/2010005 Section 4OA5 |
| Date counted | Dec 31, 2010 (2010Q4) |
| Type: | URI: |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | |
| Inspectors (proximate) | S Shaeffer M Cain B Caballero T Chandler R Williams W Russell |
| INPO aspect | |
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Finding - Vogtle - IR 05000424/2010005 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Vogtle) @ 2010Q4
Self-Identified List (Vogtle)
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