The Fort Calhoun Station, Omaha Public Power District’s (OPPD’s) 478-MW nuclear reactor that was offline for nearly three years to address longstanding issues, including flooding from the  Missouri River in 2011, is ready to restart, the Nuclear Regulatory Commission (NRC) has deemed. 

The federal regulatory body on Tuesday concluded OPPD was ready to safely restart the 1973-built plant (a 2007 POWER Top Plant) located about 19 miles north of Omaha, Neb., on the basis of more than 23,000 hours of extensive NRC inspections and detailed evaluations to independently review more than 450 restart action items and major improvements made by OPPD.

OPPD heated up the plant to normal operating temperature and pressure to inspect for any leaks in October. “NRC inspectors observed these activities and determined that the plant and personnel performed satisfactorily with no significant issues,” it said.

The plant’s single reactor was shut down in April 2011 for scheduled refueling, but it remained offline after floodwaters surrounded the plant between June and September that year amid massive flooding along the Missouri River.

On June 7, 2011, meanwhile, the plant also suffered an electrical fire in a switchgear room that was later found to have started in a replacement electrical breaker where poor alignment between components increased electrical resistance on some parts, causing them to heat up and fail. The fire, not thought to be flood-related, knocked out power to the redundant electrical system, resulting in the loss of spent fuel pool cooling for about 90 minutes (during which time plant officials said temperatures in the pool increased by only two degrees).

The NRC later determined the incident could be characterized as “red”—the highest safety significance—saying it “could have resulted in the loss of a safety function or multiple failures in systems used to mitigate a severe accident.” An inspection showed “inadequate maintenance” was to blame in part for the incident.

In 2012, OPPD contracted Exelon Nuclear Partners, a division of Chicago-based power company Exelon Generation, to manage Fort Calhoun nuclear operations until the plant’s operation license expires in August 2033. OPPD will remain the owner and licensed operator of the plant, but,under the agreement, plant staff will be a blended team of OPPD and Exelon employees.

“Safety was and is the top priority as OPPD brings the plant online. The startup will be accomplished carefully and slowly, with operators gradually increasing power. A great deal of refurbishing and upgrading was done to bring the plant back, all under the watchful eye of the nation’s independent regulator, the [NRC],” said OPPD on Tuesday.

The Fort Calhoun Station will remain under special NRC oversight until it meets certain criteria as laid out by the panel that is overseeing the process.

 

Sonal Patel, associate editor(@POWERmagazine, @sonalcpatel)