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A high flying drone was used in July to inspect Minnesota’s Prairie Island Nuclear Plant’s two landmark reactor buildings. This was the first time an Unmanned Aircraft System (UAS) was deployed at one of Xcel Energy’s nuclear plants to fulfill a technical function, and based on the mission team’s enthusiasm, it won’t be the last.

“I read a story last year about ways Xcel Energy was using drones to inspect transmission lines,” said Dileep Cherlopalle, senior nuclear engineer. “I realized the reactor building inspection could be a great application of the technology and an innovative way to effectively use the tool.”

After weighing the options between using a drone instead of the usual approach of bringing in a huge crane for the inspection, Cherlopalle and his manager, Tim LaHann, crunched the numbers. The drone would save almost $145,000. Eliminating the crane also vastly reduced the safety risks to the inspection crew and plant personnel, while shortening the entire process from hours instead of days. With all that in mind, the opportunity was too good to pass up. A cross-functional team across Xcel Energy business units was created to make the mission possible.

“The inspection showcased Xcel Energy partnerships working hand-in-hand for high value results,” said Eileen Lockhart, Xcel Energy’s Unmanned Aircraft Systems program manager. “The Nuclear Department owned the mission, the company owned the drone, and the Energy Supply Department flew it with support from top leadership in the company. We streamlined work, reduced costs and optimized the results. That’s the kind of innovation we’re trying to foster everywhere at Xcel Energy.”

Drone program is taking off
Xcel Energy began using UAS outdoors in 2015, expanding the fleet to 16 drones for indoor and outdoor inspections in just three years. An early enthusiast for the program was Tom Stegge, a planner at Xcel Energy’s King Generating Station in Bayport, Minn. He is now certified by the FAA to fly drones for the company and was at the controls for the Prairie Island inspection. Stegge said he believes that sharing the news of a mission like this can inspire other departments to apply the technology, too.

“The successes we achieved at Prairie Island are repeatable at multiple Xcel Energy sites,” said Stegge. “Our customers want us to find ways to keep their energy bills low. Using drones is one beneficial way to help ease those cost pressures without sacrificing safety or results.”

Inspections of Prairie Island’s reactor building’s domes and walls are conducted regularly. The drone was able to see areas that the crane couldn’t reach, sending crisp video imagery that enables Engineering personnel to document the building’s structural health. With this mission complete, the team is eager to find other nuclear applications that are costly and challenging to inspect to reap the benefits of UAS technology.