Luminant's Comanche Peak-2 nuclear power reactor in Glen Rose, Texas, remained offline Monday after operators manually tripped the 1,241-MW unit from 100% of capacity late Saturday, according to a US Nuclear Regulatory Commission event report.
Luminant told NRC the unit experienced a loss of main feedwater.
"Operators observed [that] both main feed pumps tripped and [steam generator] levels decreasing," prompting the manual trip at 8:25 pm CST Saturday (0225 GMT), Luminant said.
It said the reactor trip resulted in a turbine trip and that both motor-driven auxiliary feedwater pumps started and that the low steam generator levels triggered the turbine auxiliary feedwater pump.
NRC spokesman Victor Dricks said Monday that the "loss of the main feedwater pumps would automatically set in motion an automatic reactor trip," but that operators saw the levels decreasing and tripped the unit.
No information was available on what caused the problem with the main feedwater pumps, Dricks said, noting that the unit is being maintained in a safe condition.
"All systems responded as expected," Luminant said. "There was no work in progress at the time of the incident."
The adjacent 1,250-MW Comanche Peak-1 reactor continues to operate at 100% of capacity, according to NRC daily reactor status reports.
