Encroaching Clams Choke Nuclear Reactor

A nuclear reactor at Three Mile Island shut down during an effort to rid it of clams, releasing steam and trace amounts of radiation, officials said. A spokeswoman for the Nuclear Regulatory Commission said there was no threat to public safety.

Unit 1 shut off Friday evening when three water circulating pumps stopped running as operators adjusted pressure switches to cope with an infestation of Asiatic clams in the outermost of the plant’s three circulating water systems.