Three Mile Island unit 1 was out of service for repairs on Friday following a reactor trip the previous afternoon.
A reactor coolant pump tripped at 2:16 p.m., Thursday, creating a flux-to-flow imbalance that caused the plant's safety systems to automatically shut down the reactor from full power, according to a Nuclear Regulatory Commission event report. The automatic control function of a turbine bypass valve also malfunctioned during the trip, the report said. All other systems responded as designed. No radiation was released, although non-radioactive steam discharged into the atmosphere made a loud noise audible by neighbors.
On Friday, an Exelon spokesman told Reuters plant workers were repairing the reactor coolant pump. He declined to estimate when the plant would restart.