Waterford — A nuclear reactor unit was shut down at noon Saturday to address a leak in the plant's component cooling water system, said Dominion Energy spokesperson Ken Holt.

Holt said this was a planned shutdown and not an emergency. 

"The component cooling water system provides cooling to equipment that supports the production of electricity," he said. "The leak of water is located within Unit 2's containment building and poses no threat to the public or the environment."

The water inside the containment building is collected in drains and discharged through tested and approved release paths as part of a system that was explained to two reporters who visited the nuclear site in September.

Holt said the federal Nuclear Regulatory Commission as well as state and local officials were all notified of the shutdown. Millstone also sent an email to residents who live near the plant and who have asked to be notified of events at the plant.

He said the unit will remain offline while repairs are made.