The U.S. Nuclear Regulatory Commission on Feb. 14 issued three violations to the Palisades nuclear power plant. One violation is for a “substantial safety significance” issue and two others are for a “low to moderate safety significance” issue. These violations will result in additional NRC inspections and oversight of the facility. The single-unit, 798 MW plant in Covert, Mich. is operated by Entergy Nuclear Operations (NYSE: ETR).
The violation resulting in a substantial significance to safety is related to a Sept. 25 electrical fault caused by personnel at the site which resulted in a reactor trip, the loss of half of the control room indicators, and actuation of safety systems that were not warranted by actual plant conditions. The NRC said this made the reactor trip more challenging for the operators and increased the possibility of a serious event occurring. The NRC conducted a Special Inspection and determined the plant failed to have adequate work procedures for the electrical panel maintenance work to ensure the job was done successfully.
The violations resulting in a low to moderate significance to safety are related to a coupling failure in the service water system. The system is comprised of three motor driven pumps which provide cooling to safety related equipment such as containment air coolers and diesel generators. Last August one of the service water pumps failed due to cracking in one of the couplings. This was a repeat of a previous equipment failure that occurred in 2009. The NRC conducted a Special Inspection and copncluded the plant failed to prevent recurrence of the cracking condition and failed to completely consider the properties of the steel used in a past modification of the couplings.
After consideration of the information the NRC staff has characterized the Sept. 25 violation as “yellow” or as a finding of substantial significance and the Aug. 9 violations as “white” or having a low to moderate safety significance.
The yellow and white inspection findings will place the plant in the “Degraded Cornerstone Column” of the NRC’s Action Matrix as of the fourth quarter of 2011. This will not only result in additional oversight at Palisades, but will also include a NRC supplemental team inspection to independently determine whether Palisades understands the root cause and contributing causes of the risk significant issues; has identified the extent of the condition and extent of cause; and has taken the appropriate corrective actions to prevent recurrence. In addition, the NRC will evaluate if the site considered whether any safety culture component caused or significantly contributed to the issues.
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