UPDATE: Cook Nuclear Plant Unit 2 up and running after shut down for repairs

UPDATE: On the afternoon of July 2, Indiana Michigan Power announced that Cook Nuclear Plant Unit 2 was returned to service at 11:59 a.m., after completing repairs for a leak on a charging pump discharge control valve.

"Plant Operators discovered the leak in the charging pump discharge control valve at 11:02 p.m. Wednesday, June 26. The charging pump provides additional water to the unit’s reactor coolant system," plant officials said.

"After carefully assessing the leak, it was determined the unit needed to be removed from service to safely perform the necessary repair work. Operators began reducing power in Unit 2 at 2 a.m., Thursday, June 27, and safely executed the controlled manual shutdown at 8:03 a.m., according to normal procedures. There were no impacts to customer service and Cook Unit 1 remained at 100 percent."

ORIGINAL: BRIDGMAN, Mich. -- Indiana Michigan Power announced operators at their Cook Nuclear Plant safely manually removed Cook Unit 2 from service to repair a charging pump discharge control valve leak.

I&M officials say Unit 1 remains at 100 percent power, and service to customers has not been affected.

Officials discovered the leak at 11:02 p.m. on Wednesday, June 26.

The charging pump provides additional water to the unit’s reactor coolant system.

Officials say after assessing the leak, operators began reducing power at 2 a.m., Thursday, June 27, in preparation to perform a controlled shutdown using normal shutdown procedures, so crews can safely make the repairs.

They add a timeline for service to return will not be provided for competitive reasons.

"When a power company’s generation has the potential to be impacted, either positively or negatively -- for example, a generating unit of any kind being removed from service -- it also has the potential to influence the buying and selling of power on the market," AEP Communication Manager Bill Downey said.

"Much like insider trading, market brokers who have advanced or enhanced knowledge about the future trends of a company’s generation capacity may have an unfair advantage per the rules of FERC. This would even include power purchasing brokers who work on behalf of AEP. Such advanced information must legally be kept confidential to prevent any company, even AEP itself, from having what may be seen as an unfair advantage in the marketplace.

"Therefore, specific generation return to service information is withheld to keep it separate and apart from the marketplace side of the power business."