American Electric Power’s 1020MWe Cook 1 nuclear unit in Michigan was back on line generating power on 22 December after a shutdown of more than three years. Both units at the two-unit Cook station had been shut down in 1997 for extensive upgrades to address safety concerns. Unit 2 resumed service first in June 2000.

Remedial work, which was similar at both plants, included restoration of the ice condenser systems, structural modifications of the containment buildings, and refurbishment of motor-operated valves.