One of the two units at the Prairie Island nuclear power plant near Red Wing is temporarily out of service.
The plant's owner and operator, Xcel Energy, says about 600 contractors are helping Prairie Island staff do maintenance tasks and replace one-third of the unit's fuel. Each of the two reactors at Prairie Island is refueled about once every 18 months. Unit 2 remains at full power.
The outage is expected to last four to six weeks.