BRIDGMAN — The Unit 2 reactor at the Cook nuclear power plant was up and running again Monday night, Jan. 2, after being down since late Septem­ber for a planned refueling and maintenance outage.
Indiana Michigan Pow­er’s Cook plant completed its refueling at 7:20 p.m. Monday allowing its Unit 2 reactor to reconnect to the transmission grid.
In addition to refueling the reactor and perform­ing regular maintenance and testing work, the out­age was extended due to the replacement of the main turbine and the in­spection and replacement of baffle bolts, which sup­port internal components of the reactor vessel.
The outage lasted 89 days.
Replacement of the high-pressure turbine and all three low-pressure turbines is the largest of Cook’s Life Cycle Man­agement projects.
The $250 million tur­bine replacement has been in the planning stages for more than five years.
Originally, plans called for the reactor to be gain­ing in power and connect­ed to the electric grid by late December. However, an unexpected snag occurred as problems with defective fuel pump injectors for emergency diesel generators used as backup power supply for both Units 1 and 2 were discovered, plant spokes­man Bill Schalk said.
“That caused about a week delay from the sched­ule as we were hoping to be up around Christmas Eve,” Schalk said on Jan. 3, “but it was a longer out­age because of the baffle bolts and the turbine.”
The baffle bolt inspec­tions were previously planned for 2019, but were moved forward based on industry initiatives follow­ing the discovery of de­graded baffle bolts at two plants last spring.
Ultrasonic inspection was performed on all 832 bolts, and 201 bolts were replaced. Based on the inspections, AEP deter­mined there was no im­pact on the safety of Unit 2 during the previous cycle of operation.
Cook’s Life Cycle Man­agement includes 114 up­grade and replacement projects as part of the 20-year operating license extension granted by the Nuclear Regulatory Com­mission in 2005.
“Thanks to all our em­ployees and local and re­gional craft workers for their safe and hard work during this longer than usual outage,” Joel Gebbie, senior vice president and chief nuclear officer, said in a news release. “We also appreciate the support of our families and the community as we work to secure the long-term viability and reliability of our plant.”
Additional baffle bolt inspections and replacements, and a potential design change to minimize stress on baffle bolts, may also take place in subsequent outages for both Cook units.