The 4-GW three-unit Palo Verde Nuclear Generating Station has broken its own generation record, producing the highest electricity output of any nuclear plant in the world.

APS, the Arizona utility that operates the plant, said Palo Verde generated 32.5 million MWh in 2015, making it still the only U.S. power plant to ever produce more than 30 million MWh in a calendar year. The plant has reached that milestone a total of 11 times, including each of the past seven years.

The plant even beat its record of 32.3 million MWh established in 2014, said APS, which owns the plant along with Salt River Project, Southern California Edison, El Paso Electric, Public Service Co. of New Mexico, Southern California Public Power Authority, and the Los Angeles Department of Water and Power.

“Without question, 2015 was our best year ever at Palo Verde,” said Randy Edington, APS executive vice president and chief nuclear officer. “Electricity production records, shorter refueling outages, reduced production costs and an ever-present emphasis on safety helped ensure that electricity customers across Arizona and the Southwest were able to benefit from reliable, low-cost electricity.”

The plant was a POWER Top Plant award winner in 2015. Among its winning attributes was its long-running generation record, and also that it uses only treated wastewater for all plant cooling. (POWER is currently accepting submissions for its prestigious 2016 Top Plant awards.)

The plant whose construction began in 1976 and was completed in 1988 at a cost of $5.9 billion uses Combustion Engineering System 80 pressurized water reactors in a 2 x 4 configuration. The plant employs about 3,000 workers.

Sonal Patel, associate editor (@POWERmagazine, @sonalcpatel)