The " unusual event, " the least serious of four emergency classifications, was declared at 5 : 36 a . m . and ended nearly nine hours later at 2 : 05 p . m.
12.
Unit 2 of the plant has been shutdown due to an emergency on 5 March 2015, indicated by a fire alarm at 4 : 00 am CST . Xcel energy plant operators declared a notification of an unusual event, the lowest of four emergency classifications established by the U . S . Nuclear Regulatory Commission.
