NASHVILLE, Tenn. (AP) — The nation’s largest public utility has appointed an independent panel to look into power failures that spurred the decision to implement rolling blackouts during dangerously cold conditions late last year, the Tennessee Valley Authority announced Thursday.

The public utility said the panel will include American Public Power Association President Joy Ditto, former Republican U.S. Sen. Bob Corker from Tennessee and retired Electric Power Research Institute CEO Mike Howard.

“These leaders bring tremendous experience and expertise not only in public power and energy systems, but also an understanding of the growing energy needs of the region,” Don Moul, TVA chief operating officer, said in a statement.

TVA has said it takes full responsibility for the Dec. 23 and 24 rolling blackouts and is undergoing an internal review of what happened.

TVA experienced its highest ever winter peak-power demand on Dec. 23.

The utility said a combination of high winds and freezing temperatures caused its coal-burning Cumberland Fossil Plant in Cumberland City to go offline when critical instrumentation froze up. The Bull Run coal-burning plant in Clinton also went offline, TVA spokesman Scott Brooks said. The utility “had issues at some of our natural gas units” as well, Brooks said.

TVA said most of the local power companies it supplies were able to keep the rolling blackouts to “relatively short durations” for the people dependent on its electricity.

TVA told all 153 local power companies to reduce their load on the electric grid by 5% or 10%, depending on the timing and the day, Brooks said. It was up to local power companies to decide how to make the reductions, and the rolling temporary power reductions were an option — not a requirement — for them, Brooks said.

The Nashville Electric Service, for example, said on Dec. 24 that customers should expect approximately 10-minute outages every 1.5 to 2 hours.

Brooks said TVA doesn’t have a way to track how many people lost their power due to rolling blackouts, or when. He said the local utilities that interrupted people’s power kept them to less than 30 minutes at a time “unless there were other issues on the local grid.”

TVA is also expected to factor in a review by the Federal Energy Regulatory Commission and the North American Electric Reliability Corporation, which are investigating how power systems across the country operated during the winter storm.

Additionally, TVA’s inspector general office said it is monitoring the utility’s investigation to help decide what kind of inspector general reviews will be appropriate.

The rolling blackouts are certain to come up during the TVA board meeting on Feb. 16 in Muscle Shoals, Alabama — the first with a new majority of members picked by President Joe Biden.

TVA provides power to 10 million people in parts of seven Southern states.