Northern Ohio's Davis-Besse nuclear plant will remain closed until an investigation of hairline cracks in the outer concrete building is completed, Nuclear Regulatory Commission officials said.

The cracks were found during repair work to replace the plant's reactor head. During the maintenance, FirstEnergy Nuclear Operating Co. workers cut a hole in the 2-foot concrete structures surrounding the reactor. After the hole was cut, workers found what could be a 30-foot hairline crack in the decorative concrete on the outside of the building.

Later investigations found different types of cracks, according to FirstEnergy. The nuclear plant was offline when the cracks were discovered.

"Until we have confidence that the cracks in the Shield Building don't have any safety implications, the plant won't go back online," said Viktoria Mytling, spokeswoman at NRC's regional office in Chicago.

The company announced Wednesday that workers will this week patch the hole that was cut for repair work. On Wednesday, however, a minor electrical fire occurred when a water valve leaked on electric equipment. The fire "is not a safety concern," Mytling said (David Patch, Toledo Blade, Nov. 17). -- AP