On Monday, federal regulators renewed the operating licenses for Xcel Energy Inc.’s Prairie Island Nuclear Generating Plant, Units 1 and 2, which will allow the plant to run for 20 more years. Four days earlier, Xcel shut down its other nuclear plant in Minnesota to repair a valve.

Xcel plans to invest at least $500 million in the relicensed units, which are equipped with pressurized water reactors, over the next four years to support life extension, said Judy Poferl, CEO of Xcel subsidiary Northern States Power Co.-Minnesota. Additional investments will be made if the NRC approves an increase in generating capacity at the site, which Xcel Energy plans to apply for late this year, she said.

"Continuing to operate the Prairie Island reactors through 2033 and 2034 is a cost-effective option for meeting our customers’ demand for electricity," Poferl said in a statement.

The Prairie Island Indian Community had raised objections to the license renewal, but the NRC rejected those arguments.

On Friday, Xcel shut down the 579-MW Monticello Nuclear Generating Plant (licensed through 2030), to replace a valve that protects the plant’s main steam line system from overpressure conditions. The shutdown of the boiling water reactor, located 35 miles northwest of Minneapolis, was not expected to be lengthy, and the situation posed no danger to the public or plant workers, the company said.

Earlier this year, Minnesota, where Xcel is based, voted to lift a 17-year ban on new nuclear plants. Monticello and Prairie Island are the state’s only existing nuclear plants.

Sources: NRC, Xcel Energy, Minnesota Public Radio, POWERnews