Special NRC Oversight at Fort Calhoun Station

As a result of the continuous performance assessment of Fort Calhoun Station (FCS), the U.S. Nuclear Regulatory Commission (NRC) modified its regulatory oversight of FCS, effective December 13, 2011, to address several performance issues that were identified during an extended shutdown of the plant. FCS initially shut down for a scheduled refueling outage in April 2011, but that outage was subsequently extended to address longstanding technical issues, as well as issues associated with the Missouri River flooding that affected the plant from June through September 2011. Because the identified performance issues will require additional oversight, the NRC will now follow Inspection Manual Chapter 0350 (IMC 0350), "Oversight of Reactor Facilities in a Shutdown Condition Due to Significant Performance and/or Operational Concerns," rather than the usual IMC 0305, "Operating Reactor Assessment Program."

The following table lists the publicly available documents that the NRC has issued in connection with the special oversight of FCS.

Also on this page:

• Electrical Switchgear Fire Event

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Electrical Switchgear Fire Event

• A fire occurred on June 7, 2011, in electrical switchgear that distributes power to vital systems and components needed for the safe shutdown of the plant. This fire affected two independent trains of the system and resulted in the NRC issuing a preliminary red finding on March 12, 2012, following a special inspection. The special inspection report is found in the below documents.

• The fire started in a replacement electrical breaker that was modified to fit inside the existing electrical switchgear. The replacement breaker was installed and in service for about 18 months before the fire occurred.

• Poor alignment between electrical components and inadequate cleaning of the connections (hardened grease at the interface) increased the electrical resistance at their junction. These conditions created a buildup of heat that caused a fire affecting one train; electrically conductive soot and smoke spread past a barrier and tripped the breaker on the opposing train. This electrical fault resulted in the complete loss of spent fuel pool cooling for approximately 90 minutes, resulting in a 3°F temperature rise in the pool.

• Fort Calhoun Station staff has taken compensatory measures to ensure that high resistance connections were corrected in the other affected load centers, and reactor shutdown cooling systems were not directly affected. The NRC is in the process of reviewing Fort Calhoun Station's actions in response to the fire. The reactor at Fort Calhoun Station is currently shutdown and will not be allowed to restart until the IMC 0350 Panel grants approval.