HOUSTON (Bloomberg) - As Hurricane Harvey bore down on them, workers remained at the controls of Texas' biggest nuclear power plant, keeping the lights on for two million customers even while some of their own homes were flooded.

Teams of employees have been stationed at the South Texas Project power plant since early Friday (Aug 25). While the site is 145km south-west of Houston and avoided the worst of the deadly storm, it had to cope with heavy rain and flooding on nearby roads that made it difficult for people to get around.

Plant technicians and engineers were organised into special storm-team crews, working rotating 12-hour shifts, washing clothes in the showers and sleeping on cots set up before Harvey hit. Throughout the storm, the concrete-domed twin reactors have continued operating at full capacity, providing electricity for Texans who can still get service amid a historic flood.

"Really, it's a matter of getting the sleep you need so you are prepared and ready for the next shift," said Mr Bob Tatro, a 30-year veteran at the plant and a shift manager for a storm crew that's kept the plant operating.

When the "Gator Grill" cafeteria ran short of food, operators convinced a local grocery store manager to open up to replenish supplies despite a mandatory evacuation order.

Another run was made to a local branch of Wal-Mart Stores Inc to buy US$2,000 (S$2,717.20) of underwear, clean socks and other essentials for plant workers.

"One of the things we'll review after the storm is having washing machines on site," said Mr Buddy Eller, a spokesman for the facility, which is owned by NRG Energy Inc, CPS Energy and Austin Energy.

Despite as much as 25.4cm of rain on Monday, the nuclear plant near the Gulf of Mexico hasn't been threatened by the rising waters in nearby tributaries, Mr Eller said. Winds from Harvey never reached hurricane force at the site, which would have required the plant to shut down, he said.

There was no flooding at the facility, which is near a wildlife nature preserve.

Workers have been making sure the site's storm drains are clear and there is enough potable water, said Mr Kurt Moorefield, a shift manager who has been at the plant since Friday.

"The biggest issue is finding other employees who can safely make it back to the site," Mr Eller said.

Some workers' homes have flooded and the company was focused not only on keeping the plant running but helping to assist employees displaced by the storm, he said.

Mr Tatro, 55, said he had been texting with loved ones to get brief updates. His family evacuated to stay with relatives and friends near Austin, he said. His house in Bay City is near the Colorado River, which was expected to crest on Thursday.

"There are some things that are within my control, flooding isn't one of them," he said by phone from the plant. "I just chose to not let it wear me down."

About 250 operators, engineers, maintenance and other support staff have been stationed at the 2,700-megawatt plant since the storm hit. Additional workers were trickling in to provide help as the weather permitted, and the company was looking to transition back to normal staffing levels, Mr Eller said.

Harvey could end up being the most costly weather disaster in US history, with its relentless rains flooding thousands of homes, crippling the energy hub around Houston and killing at least 46 people, according to the Austin American-Statesman.

Shift manager Moorefield, 48, said that he had heard on Wednesday from his wife that there was water up to his house but no water in it. "So far, so good," he said by phone.