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Published:July 1st, 2007 12:23 EST
The Fort Calhoun nuclear plant will receive additional oversight from the U.S. Nuclear Regulatory Commission

The Fort Calhoun nuclear plant will receive additional oversight from the U.S. Nuclear Regulatory Commission

By SOP newswire

The Fort Calhoun nuclear plant will receive additional oversight from the U.S. Nuclear Regulatory Commission based on a performance indicator and an inspection finding involving the improper installation of a valve that degraded the condition of a safety system for 454 days. The plant, located near Omaha, Neb., is operated by the Omaha Public Power District (OPPD).

“The NRC remains confident in the ability of the Omaha Public Power District to operate Fort Calhoun safely," said NRC Region IV Administrator Bruce S. Mallett. “But there are performance problems that need to be addressed by the licensee."

The NRC uses a color-coded system to categorize inspection findings and performance indicators, which are objective measures of plant performance. The colors range from “green" and then increase to “white," “yellow" and “red" depending on the safety significance of the issue. In this case, the Fort Calhoun performance indicator and inspection finding were determined by the NRC staff to be “white," or a safety issue of low to moderate significance.

Both of these “white" inputs into the NRC’s reactor oversight process involved mitigating systems, a group of components, like valves, pumps or electrical breakers, that are designed to mitigate, or minimize the consequences of an accident. As a result, Fort Calhoun is being moved to the Degraded Cornerstone Column of the NRC’s Action Matrix, which will result in a higher level of scrutiny by the NRC. This is the third highest level of NRC oversight and eight other nuclear power plants in the U.S. are currently in this category. The NRC Action Matrix is available on the NRC web site at: An NRC inspection, described in a report released on March 2, determined a valve in the containment spray system was improperly installed on May 11, 2005. The system sprays water in the building containing the reactor to reduce pressure under some accident conditions.

The valve remained improperly positioned for 454 days until the problem was discovered during a refueling outage in October 2006. The NRC staff is satisfied that the licensee completed a thorough review and analysis of the event and has taken appropriate corrective actions.

“The improper installation resulted in a condition in which the actual position of the valve was nearly opposite of the indicated position," Mallett said. “The violation involved the conduct of maintenance activities and a failure by the licensee to conduct appropriate post-maintenance testing prior to returning the valve to service."

At the request of the licensee, a regulatory conference was held on April 16 to discuss OPPD’s position on the safety significance of the finding and corrective actions. In response to questions, the licensee submitted additional information to the NRC on April 23. Nevertheless, the NRC has determined that the safety significance of the violation is best characterized as “white."

Fort Calhoun has also accumulated seven reportable failures of various components in mitigating systems that count towards the safety system functional failure performance indicator. This performance indicator tracks the number of events or conditions that alone prevented, or could have prevented the fulfillment of the safety function of structures or systems.

The NRC will conduct a supplemental inspection at a future date to provide assurance that the causes for the performance issues are understood, to independently assess the extent of the problems, to determine if safety culture contributed to the problems, and to verify that corrective actions are sufficient to prevent recurrence.