A transformer at a nuclear plant caught fire Tuesday morning, but the smoky blaze was confined to the non-nuclear side of the plant, company officials said.

The fire, reported at 9:40 a.m., did not pose a threat to the public, said Craig Nesbit, a spokesman for Exelon Nuclear in Warrenville, Ill., which shares ownership of the Peach Bottom nuclear power plant with New Jersey-based PSE&G.

"The fire itself was very small," Nesbit said. "It was mostly smoke."

Power from one of the plant's generating units was reduced following the fire, but it remained online, Nesbit said. Delta is in south-central Pennsylvania.