USA member Cook Nuclear Plant’s Unit 1 broke its previous record for capacity factor and completed its second consecutive breaker-to-breaker fuel cycle when it began its 25th refueling outage on September 24.

The capacity factor of 101.4 percent beats the previous record of 101.3 percent that was set in the previous fuel cycle that ended in the spring of 2013. It is possible to run greater than 100 percent capacity by gaining efficiencies through lower than normal lake water temperatures. The unit ran for 493 consecutive days, which is the second longest run ever. Running continuously between refueling outages is known in the industry as a breaker-to-breaker run as the unit’s output circuit breakers remained connected to the transmission grid for the entire 18-month fuel cycle. The total fuel cycle generation is 12,332,534 megawatt-hours.

Cook Unit 2 remains at 100 percent power. That unit has also completed the last two fuel cycles at full capacity.

In addition to refueling the reactor and performing regular maintenance and testing work, the current outage also includes several Life Cycle Management (LCM) projects. In 2005, Cook received license renewals from the Nuclear Regulatory Commission that will allow the units to run to 2034 and 2037 respectively. That is an additional 20 years beyond their original licenses. The new license takes effect for Unit 1 on October 25.

“Both Cook units are running extremely well, in fact, better than ever,” said Larry Weber, AEP Chief Nuclear Officer and Senior Vice President. “We will enter Unit 1’s period of extended operation with safe, reliable and low-cost generation ready to serve our customers for the next 20 years.”

One of the LCM projects this outage is replacement of two 58-ton Feedwater Heaters that pre-heat water before it enters the Steam Generators. Steam passes around 2,915 five-eighth inch U-tubes that run the length of the 41 foot shell. There is also a new digital control system. The plant was not originally designed to replace these large components so some significant structural adjustments have been made to accommodate the replacement.

Over the course of the outage several USA peer employees will be among the approximately 2,500 contracted workers who will supplement the regular 1,198-person plant staff. More than 10,000 maintenance, inspection and equipment modification job activities totaling more than 268,000 work-hours are scheduled for two daily 12-hour work shifts throughout the outage.

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.