Operators shut down Unit 2 of the Prairie Island nuclear power plant near Red Wing, MN, after a turbine trip Sunday.
Minneapolis-based Xcel Energy Inc. said there was no risk to the public or employees from the condition that led to the shutdown.
The company says the unit shut down in response to a turbine trip caused by low oil pressure.
Plans are underway to make repairs and return the unit to service.
During outages, Xcel Energy purchases electricity from the Midcontinent Independent System Operator or other utilities or increases electricity production at its other plants to ensure an adequate power supply for customers.
The two reactors at Prairie Island generate 1,076 megawatts of electricity, enough to power nearly 1 million homes.