05000285/FIN-2009006-03
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Finding | |
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| Title | Failure to Update Flood Protection for Safety Related Buildings |
| Description | The team determined flood elevations at Fort Calhoun Station by reviewing USAR Chapter 2.7, Hydrology, USAR Chapter 9.8, Raw Water System, and Technical Specifications 2.16, River Level. USAR Section 2.7.1.2 states, in part: The design flood elevation of 1,006 feet based on a 0.1 percent probability flood is considered conservative. Without special provisions, the plant can accommodate flood levels of up to 1,007 [feet mean sea level]. Steel flood gates are permanently mounted above and adjacent to openings in structures containing equipment required for a safe and orderly plant shutdown. In the event of high water levels, these flood gates can be installed to provide protection to a level of 1,009.5 [feet mean sea level]. In the Intake Structure, protection to 1009.5 [feet] msl is accomplished with flood gates and sandbagging. The plant can be protected by sandbags, temporary earth levees and other methods to allow a safe shutdown with a flood elevation of 1,013 [feet mean sea level].USAR Section 9.8.6 states, in part: Protection for the raw water pumps and their drives against floods is provided at three elevations as indicated on Figure 9.8-1. The pumps are permanently protected against any water level up to elevation 1007.5 feet by the Class I concrete substructure of the intake building. Protection is provided to elevation 1009.5 feet by sandbags around the traveling screen areas and by gasketed steel closures at exterior doorway openings in the intake structure reinforced concrete perimeter walls. Protection to elevation 1014.5 feet is provided by additional sandbags around the traveling screen areas, and by supplementing the intake structure perimeter walls with sandbags. The water level inside the intake cells can be controlled by positioning the exterior sluice gates to restrict the inflow into the cells. Technical Specification 2.16, Basis, states: The maximum Missouri River level of 1009 feet is the level at which the installed flood gates will protect the plant. Any increase in river level will require sand bagging to repel the water to a maximum flood level of 1014 feet or greater. When the licensee determines it is necessary to protect the plant at flood levels greater than 1009.3 feet, the licensee implements procedure GM-RR-AE-1002, Flood Control Preparedness for Sandbagging. Step 7.4 of the procedure states: The primary focus for flood protection should be directed to those facilities which are considered vital with respect to nuclear safety and credited with flood protection in the IPEEE Flooding evaluation, Reference 2.3. These facilities shall be protected at the sacrifice of the other facilities if site conditions warrant. The vital facilities are: Auxiliary Building, Intake Structure, and Turbine Building Basement. Reference 2.3 of procedure GM-RR-AE-1002 is the IPEEE for Fort Calhoun Station Section 5.2, External Flooding, Table 5.2.3, which credits flood protection up to1013.5 feet mean sea level by sandbagging for the switchyard, auxiliary building, intake structure, and turbine building. Table 5.2.3, Impact of Periodic Flood due to Rain and Snow, comments that severe core damage results if either intake or auxiliary buildings and bagging fails. Attachment 9.5 of procedure GM-RR-AE-1002 gives specific instructions that plant operators would use to protect from flood crest above 1009 feet mean sea level. The attachment notes that sandbags would be tied and draped over the top of floodgates to supplement the protection capability to the projected flood crest. Specifically, the attachment states, Place additional sandbags on top of the floodgates to raise the protection against the expected crest of the flood. During the inspection, the team discussed, with the licensee, how protection of vital facilities against floods would occur at flood levels above the probable maximum flood level of 1009 feet mean sea level. As a result of this discussion, the team determined that stacking and draping sandbags at a height of four feet over the top of floodgates would be insufficient to protect the vital facilities. The sandbags would be insufficient because the cross section on the top of the floodgates is too small to support a stacked sandbag configuration that would retain four feet static head of water. The team determined that the failure to protect the auxiliary building, intake structure, and turbine building to an external flood height of 1013 feet mean sea level is a performance deficiency. Specifically, the licensee failed to meet the self imposed standards of USAR Section 2.7.1.2 and USAR Section 9.8.6. In addition, the licensee failed to meet the self imposed standard of Step 7.4 in procedure GM-RR-AE-1002, Flood Control Preparedness for Sandbagging. The licensee disagreed with the teams determination that this is a performance deficiency because Fort Calhoun Station is designed to protect to the design basis probable maximum flood height of 1009.3 feet mean sea level. The licensee believes that any flooding above the probable maximum flood level is incredible because it would involve a dam break upstream of the site and dam failure was considered incredible based on Army Corps of Engineers letter to Omaha Public Power District, dated December 12, 1967. However, the team believes, because the licensee stated flood protection would occur up to 1013 feet mean sea level in the USAR and station procedures, the licensee self-imposed a standard to provide flood protection up to1013 feet mean sea level. Additionally, in November 2003, the licensee received new information from the Army Corps of Engineers that determined flood levels could be potentially higher than what was evaluated in 1967.Because more inspection is necessary to resolve this issue, the issue is considered an unresolved item pending further NRC Region IV review. The NRC Region IV review willdetermine:1. If the failure to meet the self imposed standard of flood protection up to 1013 feet is a performance deficiency in accordance with NRC Manual Chapter 0612.2. If a violation of NRC requirements is associated with the performance deficiency because the licensee did not update the flooding design basis when new information was received in November 2003.This unresolved item is identified as URI 05000285/2009006-03, Failure to Update Flood Protection for Safety Related Buildings |
| Site: | Fort Calhoun  |
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| Report | IR 05000285/2009006 Section 1R21 |
| Date counted | Dec 31, 2009 (2009Q4) |
| Type: | URI: |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.21 |
| Inspectors (proximate) | D Loveless G George G Replogle J Kirkland M Williams T Farnholtzd Lovelessg George G Morris N Okonkwo P Goldberg S Hedger S Wong T Farnholtz W Sherbin |
| INPO aspect | |
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Finding - Fort Calhoun - IR 05000285/2009006 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Fort Calhoun) @ 2009Q4
Self-Identified List (Fort Calhoun)
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