BRIDGMAN, Mich. (AP) — A reactor at a nuclear power plant in southwestern Michigan is shutting down this week for refueling, maintenance and testing.

Indiana Michigan Power says power has been reduced at Cook Nuclear Plant’s Unit 1 and the unit will be shut down starting Wednesday. The anticipated length of the outage isn’t being disclosed. About 1,750 contracted workers will supplement the plant’s 1,100-person staff for the work.

The utility says the outage will be extended due to inspection and replacement of baffle bolts, which support internal components of the reactor vessel.

The plant is along Lake Michigan in Berrien County’s Lake Township, near Bridgman. Cook’s Unit 2, which was returned to service last year following a refueling outage , will remain in operation during the shutdown.