Workers at the plant experienced what is known an automatic scram at 6:43 a.m. Thursday during reactor startup, according to the Nuclear Regulatory Commission. The
scram was due to an invalid intermediate range monitor scram signal, the agency said.
Range monitors are devices inserted into the reactor to measure power
flux levels as a reactor is being returned to service.
reactor was at a "very low power level" at the time and had not yet
synched to the grid, which normally happens at about 30-percent power, according to the NRC.
The plant was operating at zero percent power Friday morning, according to officials.
Plant officials say the facility was taken offline at 10:50 a.m. Monday in
order to perform planned maintenance on a turbine speed controller.