YAKIMA, Wash. (AP) — The Nuclear Regulatory Commission has extended the license for the Northwest's only commercial nuclear power plant by an additional 20 years, the plant's operator announced Wednesday.

The license extends operations at south-central Washington's Columbia Generating Station through 2043. The plant had been operating on a 40-year license that expires at the end of 2023.

The plant is operated by Energy Northwest, a public power consortium composed of 28 member utilities.

Commission officials and Energy Northwest CEO Mark Reddemann attended a small signing ceremony in Washington, D.C., on Tuesday afternoon, Energy Northwest said in a statement. An on-site announcement was scheduled for Thursday at the plant north of Richland.

The 1,150-megawatt plant located provides about 3 percent of the region's power — roughly enough electricity for 1 million homes — and 10 percent of the power supply for Washington state.

Energy Northwest began pursuing license renewal in 2007. A formal application of more than 2,200 pages was submitted to the Nuclear Regulatory Commission in January 2010. The renewal follows a lengthy review process that required the plant to demonstrate that it meets technical, safety and environmental requirements through the additional 20 years of operation.

Gov. Chris Gregoire endorsed relicensing of the plant as a reliable and affordable power source, without greenhouse gas emissions, over the long term.

"Nuclear power has its place in the current and future production of electrical power for our nation," Gregoire said in a statement. "It is a cornerstone of power production in the Pacific Northwest."

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