OAK HARBOR, Ohio -- The Davis-Besse nuclear power plant was up and running again Wednesday after it was shut down May 6 for refueling and maintenance, according to FirstEnergy Nuclear Operating Corp.

A minor cooling system leak found last week during inspections before the restart "may have contained trace amounts of reactor water" but was properly contained and did not pose a public hazard, the Nuclear Regulatory Commission reported.

The 908-megawatt Davis-Besse began producing electricity at 3:37 a.m. Wednesday. It is operating at about 30 percent and is expected to be at full power by the end of the week.

During the outage, 68 of the plant's 177 fuel assemblies were exchanged.

The detected leak occurred in a three-quarter-inch weld on a cooling system pipe. The water, for which flow was estimated at 0.1 gallon a minute, was collected in a containment-sump system designed to capture and process such water, a spokesman said. No water was released from the plant, she said.

The leak occurred as the company is applying for a renewal of the plant's license. Relicensing opponents have a petition pending that asks the NRC to consider as a factor in its decision the October discovery of hairline cracks in Davis-Besse's outer concrete shield, or containment, building.

A statement released Wednesday by the company regarding the restart addressed that issue.

"... Inspections of the station's shield building revealed that the tight cracks in the building's wall discovered during the fall 2011 reactor head replacement outage do not appear to have grown, nor were any new cracks identified," the statement said.

-- Ignazio Messina

First Published June 14, 2012, 5:02 a.m.