Late Sunday night, Unit 1 at the St. Lucie nuclear power plant had to be manually shut down after technicians noticed “anomalous behavior” after a Control Element Assembly continued to insert control rods with no instructions to do so. The reactor was at 1 per cent output at the time and was undergoing Low Power Physics Testing.
To illustrate how much of the verbiage in Event Reports is pure boilerplate, the report noted: “The trip was uncomplicated and all CEAs fully inserted when the reactor was tripped.” Considering that control rod insertion was the source of the problem, to say that the CEA’s fully inserted seems redundant. The Event Report also notes: “RCS Heat Removal is being maintained with Auxiliary Feedwater and Atmospheric Dump Valves. ”
No word on when restart of the reactor is expected. Tuesday’s Reactor Status Report still has Unit 1 at 0 per cent output.