An alert was declared on June 7th, 2011, at the Fort Calhoun nuclear generating plant north of Omaha, NE.  The plant is next to the Missouri River which has been at some level of flood stage recently.  According to the NRC, a fire ocurred briefly affecting some electrical equipment necessary for safe operation of the plant. Within a few hours the plant operators exited the alert when the necessary access to equipment was regained. 

For a short time the plant lost its ability to cool the spent fuel pool cooling water.  While the incident did not result in any unsafe temperature rise in the pool, the licensee was obligated to declare the alert. The plant remained safely shut down during the event, though afterward the plant remained under an Unusual Event Declaration due to the condition of the Missouri River. The FAA issued a temporary flight restriction within two nautical miles of the plant.

Ft Calhoun Nuclear Plant in the Missouri River