BRIDGMAN, Mich., July 13, 2016 – Indiana Michigan Power’s Cook Nuclear Plant Unit 2 returned to service at 6:00 p.m. yesterday. A rupture in a steam expansion joint bellows shut down the unit on July 6 and damaged the Turbine Building exterior wall.
The cause of the failure is believed to be vibration-induced metal fatigue. During the repairs, improvements were made to the expansion joint to ensure reliability until the unit is taken off line this fall for refueling. More comprehensive design change improvements will be made then.
Plant operators manually shut down the reactor immediately following the rupture and briefly entered the site’s emergency plan at the lowest level following the incident. There were no injuries and Cook Unit 1 remained at full power through the period.