The two nuclear reactors at the South Texas Project plant 90 miles from Houston are operating at full capacity despite calls from watchdog groups for the facility to shut due to Tropical Storm Harvey, a spokesman for the plant said on Tuesday.

"We've got significant rain but flooding has not been an issue here," spokesman Buddy Eller said in a phone call.

The reactors, 44 percent of which are owned by NRG Energy Inc, provide 2,700 megawatts of power to 2 million customers in Texas. The rest of the reactors are owned by the city of San Antonio's CPS Energy utility, with 40 percent, and the city of Austin's Austin Energy, with 16 percent.