NRC inspects crack at Progress Florida nuclear unit

HOUSTON, Oct 9 (Reuters) - The U.S. Nuclear Regulatory Commission has launched a special inspection of a crack in a containment building wall at Progress Energy's (PGN.N) 838-megawatt Crystal River nuclear power station in Florida, the agency said late Thursday.

The unit shut Sept. 26 for an extended refueling outage that will include replacement of two steam generators and other work to increase the unit's output.

A crack was found as workers began removing concrete to create an opening for new generators, Progress told the NRC in a report.

The gap was found about nine inches from the outer wall of the 42-inch steel-reinforced concrete containment wall, according to the NRC.

"The discovery of this crack in the concrete does not appear to represent a major reduction in safety, and there are no immediate concerns because the plant is shut down," said Luis Reyes, the NRC Regional II Administrator, in a statement.

"However, we want to make sure we have the right inspection resources to fully understand any safety implications before the plant restarts," he said.

Progress has been investigating the cause of the crack, said a Progress spokeswoman, adding that it is too early to know if repairs will be needed that would extend the outage beyond a mid-December return estimate from electricity traders.

"If we learn we need to do additional repairs, we'll look at the schedule then," she said.

The NRC said Chairman Gregory Jaczko and Reyes, who were already scheduled to visit Crystal River on Friday, will get a first hand look at the problem.

NRC's special investigators are expected to arrive next week, the Progress spokeswoman said. The NRC said it may contract one or more independent experts to assist in the inspection.

The inspection will continue for several weeks during the plant's outage. The NRC said the plant will not restart until the agency "is satisfied that the analyses and all work completed provide the required safety margin."

Crystal River is located in Red Level, Florida, about 85 miles north of Tampa.

The 3,151-MW Crystal River station also includes the 379-MW coal Unit 1, the 491-MW coal Unit 2, the 721-MW coal Unit 4 and the 722-MW coal Unit 5 as well as the nuclear unit.

Progress Energy operates the reactor which is 90-percent owned by Progress. Minority owners include a number of Florida electric coops and municipalities.

(Reporting by Eileen O'Grady)