BRIDGMAN, Mich., November 12, 2013 – Indiana Michigan Power’s Cook Nuclear Plant Unit 2 returned to service today at 8:26 a.m. following a refueling outage that began October 2. The outage duration was 41 days and 8 hours. 

“We completed some complicated large-scale Life Cycle Management projects this outage that will continue to support the safe, reliable and economic operation of the Cook units for many years to come,” said Larry Weber, senior vice president and chief nuclear officer. “Cook has been operating extremely well thanks go to our talented employees and the local and regional workers who supplement our workforce.”

Prior to the outage, the unit ran at 100.6 percent capacity factor and generated 13,551 net gigawatthours during the previous 18 months. This included a 452 consecutive-day run that was 19 days short of the unit record of 471 days. It is possible to run at greater than 100 percent capacity when lake water temperatures are cooler than normal.

Aside from refueling the reactor and performing regular maintenance and testing work, the current outage also included completion of several activities associated with the plant’s Life Cycle Management Project. These include replacement of two Feedwater Heaters, a new Control Room Annunciator System, replacement of two Unit Auxiliary Transformers and significant Transmission Switchyard improvements including replacement of a large transformer.

More than 1,900 contracted workers supplemented the regular 1,198-person plant staff at various periods. This is several hundred more than a typical refueling due to the additional major projects. More than 12,600 maintenance, inspection and equipment modification job activities totaling more than 310,000 work-hours were scheduled.

The two 62-ton Feedwater Heaters installed pre-heat water before it enters the Steam Generators. Steam passes around 1,358 three-quarter inch U-tubes that run the length of the 61-foot shell. There is also a new digital control system. The plant was not originally designed to replace these large components so some structural adjustments were made to accommodate the replacement.

The new Control Room Annunciator System monitors almost 1,600 plant parameters and will alarm when the status of equipment or systems is outside pre-set limits. The new digital computer-screen system will replace existing push-button analog controls. An identical system was installed in Unit 1 during its spring refueling outage. Operators have been training with the new system on the Control Room Simulator for almost a year.

The Unit Auxiliary Transformers reduce voltage on a small portion of the output of the Main Generator to power plant equipment during normal operation. Two transformers and one spare were installed during Unit 1’s last outage. Unit 2 will get two new transformers this outage.

Switchyard upgrades are part of a five-year project to increase capability and reliability for connections between the plant and the switchyards, and between the switchyards and the transmission grid. The Unit 1 345kv switchyard and Unit 2 765kv switchyards are regional transmission hubs with multiple connections to the AEP extra-high voltage grid as well as with other utilities. A new transformer being installed this outage replaces a 30-year old one connecting the two switchyards. Switchyard connections are made by three semi-truck-sized breakers. Two new breaker banks have already been added and one more will be completed this outage.

Life Cycle Management replacements and improvements support the 20-year extended operation of the two units. The license extensions to operate Unit 1 until 2034 and Unit 2 until 2037 were granted in 2005 by the Nuclear Regulatory Commission. The Michigan Public Service Commission and Indiana Utility Regulatory Commission have both approved these projects as reasonable and necessary.

At full capacity, the 1,030-net MW Unit 1 and 1,077-net MW Unit 2 combined produce enough electricity for more than one and one half million average homes.

            Indiana Michigan Power is a wholly owned subsidiary of American Electric Power (NYSE:AEP). American Electric Power is one of the largest electric utilities in the United States, delivering electricity to more than 5.3 million customers in 11 states. AEP ranks among the nation’s largest generators of electricity, owning nearly 38,000 megawatts of generating capacity in the U.S. AEP also owns the nation’s largest electricity transmission system, a 40,000-mile network that includes more 765 kilovolt extra-high voltage transmission lines than all other U.S. transmission systems combined. AEP’s transmission system directly or indirectly serves about 10 percent of the electricity demand in the Eastern Interconnection, the interconnected transmission system that covers 38 eastern and central U.S. states and eastern Canada, and approximately 11 percent of the electricity demand in ERCOT, the transmission system that covers much of Texas. AEP’s utility units operate as AEP Ohio, AEP Texas, Appalachian Power (in Virginia and West Virginia), AEP Appalachian Power (in Tennessee), Indiana Michigan Power, Kentucky Power, Public Service Company of Oklahoma, and Southwestern Electric Power Company (in Arkansas, Louisiana and east Texas). AEP’s headquarters are in Columbus, Ohio.