State regulators have approved Xcel Energy's request to increase power and radioactive waste storage at the Prairie Island nuclear plant.
The utility plans to spend $600 million to upgrade the plant so it can handle higher pressure and temperatures that could add 164 megawatts to its output.
Prairie Island currently generates about 1,000 megawatts, which is enough power for about one-fifth of Xcel's customers.
Xcel first asked regulators in May 2008 for permission to store nuclear waste in up to 35 more casks on a concrete pad next to the plant _ it already has authorization for 29 casks. Xcel got approval on Thursday.
State legislators will now take up the matter.
John Howe, the mayor of nearby Red Wing, says he's "deeply disappointed" by the decision.