A reactor at Three Mile Island, the site of the nation’s worst nuclear accident, shut down unexpectedly on Thursday afternoon when a coolant pump tripped and steam was released, the Nuclear Regulatory Commission told NBC News.

The system tripped when “the pump stopped operating and created a power/flow imbalance,” said NRC spokesman Neil Sheehan.

The plant responded as designed and is stable with no impact on public health or safety, added NRC spokeswoman Diane Screnci.

If any radiation was in the released steam, Screnci said, it would be below detectable levels.

Continue Reading…