MINNEAPOLIS (AP) - Xcel Energy is investigating why its Monticello nuclear plant shut down.

The Minneapolis utility says there was no danger to the public or plant workers Saturday when relays on the reactor's protection system activated. It's the third unscheduled shut down reported at the Monticello plant this year. The single-reactor plant is about 40 miles northwest of Minneapolis.

Xcel plans to buy power from the grid or other utilities to make up for the lost capacity.

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