An automatic safety system automatically shut down Three Mile Island Generating Station Thursday afternoon after a reactor coolant pump had a mechanical problem.
TMI spokesman Ralph DeSantis said four pumps circulate water through the reactor coolant system to keep the plant operating at proper temperatures. One of them "experienced a problem" around 2:20 p.m. and shut itself down, which automatically shut down the entire plant, he said.
Noise: A loud noise coming from the plant during the shutdown might have drawn attention from nearby residents, he said. Steam was released into the atmosphere, creating an audible "sound of steam rushing through pipe," DeSantis said.
There was no risk to residents, he said, as safety systems remain in place during the shutdown.
Plants don't typically shut down automatically very often, and TMI has
gone as long as 10 years between automatic shutdowns. But that's not a recent record.
Last month: The plant also shut down automatically on Aug. 22, as workers were in the process of manually shutting it down to replace a heating element.
Workers were close to finished when the plant automatically shut down because of a problem with a different pump, he said.
"It's certainly not a common occurrence, but automatic shutdowns do happen in the nuclear industry," he said.
Workers were repairing the reactor coolant pump Friday morning, DeSantis said, but he declined to provide a timeline for when the plant will power up again. In order to operate at full power, all four pumps need to be running.
-- Reach Christina Kauffman at email@example.com.