05000247/FIN-2005005-01
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Finding | |
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| Title | Emergency Diesel Generator Building Flooding |
| Description | On November 29, 2005, the inspectors reviewed the internal flood protection measures for the EDG building. All three 480 VAC EDGs are located in this building in a common area separated by installed fire barrier walls. The EDGs are approximately five feet above the concrete floor of the building and access to the EDGs is afforded by metal grate flooring. The major sources of potential flooding for the space are fire protection piping and the essential service water (ESW) system piping in the building. The building is designed such that water drains toward five shallow sumps that are connected to a common 12-inch-diameter drain line that discharges to the site drainage system. Each sump has two 3-inch-diameter openings that have backwater ball check valves to prevent back-leakage into the EDG building. Inspectors observed between 30 and 50 oil absorbent pads on the concrete floor underneath the EDGs. These pads were not fixed to the floor by any means, and would be free to migrate to the building sumps along with water during a flooding event. The pads were of sufficient size to effectively block the 3-inch holes in each of the building sumps as water level rises in the building. The IPEEE credits the building drains being sufficiently sized to prevent significant accumulation of water due to a break of fire protection piping in the room. This assumes that the function of these drains is not impeded by foreign material blockage. In addition, both the IPEEE and the IP2 Probabilistic Safety Assessment (PSA) state that a break of an ESW line is bounded by the fact that the EDGs are cooled by ESW and would be the only equipment negatively impacted by the flooding, and that this occurrence is analyzed by the total loss of service water event. There are inconsistencies between the IPEEE, dated 1995, and the PSA, which was completed in the 1998 time frame. The PSA does not account for the fire protection header as being a potential source of flooding for the EDG building, whereas the IPEEE does. Both analyses credit open ventilation louvers along the building north wall at grade level to drain water if the buildings installed drain capacity is insufficient. However, during the winter months these louvers are maintained shut. In addition, the IPEEE mentions an EDG building flood alarm in the control room and specific isolation procedures in the event of flooding. Neither the alarm, nor the specific isolation procedures, currently exist. Finally, the inspectors identified that 480 VAC normal feeder breaker control power exists in each EDG control cabinet. Flood water that reaches the bottom of the EDG control cabinets due to insufficient building drain capacity, and can not be relieved through closed building doors and closed ventilation louvers, could potentially render all three EDGs unavailable and trip the normal feeder breakers to all 480 VAC vital AC buses. In response to the , Entergy removed the oil absorbent pads from the EDG building and entered the issue into the corrective action program (CR-IP2-05-4868). This issue will be treated as a URI pending additional licensee evaluation and inspector review of the potential impact of flooding in the EDG building on the normal and emergency vital AC power sources |
| Site: | Indian Point  |
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| Report | IR 05000247/2005005 Section 1R06 |
| Date counted | Dec 31, 2005 (2005Q4) |
| Type: | URI: |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.06 |
| Inspectors (proximate) | B Wittick D Dempsey D Jackson F Arner G Bowman G Dentel J Josey J Kottan J Lilliendahl J Noggle L Scholl M Cox M Snell R Codell S Barr T Burns T Hipschman T Nicholson T Setzert Fisht Hipschman T Sicola C Long D Jackson D Johnson D Silk G Bowman J Noggle M Cox R Fuhrmeister R Kahler S Barr |
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Finding - Indian Point - IR 05000247/2005005 | |||||||||||||||||||||
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Finding List (Indian Point) @ 2005Q4
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