BYRON – With significant upgrades and large-scale projects among the work scheduled – and more than 2,200 workers called in to help – Byron Generating Station began a refueling outage Monday.

During a refueling outage, which usually occurs in the spring or fall when electricity demand is low, spent fuel rods are replaced with new fuel and other routine maintenance is done.

Earlier this year, Exelon officials said silt and debris had collected on the grooved plastic sheets that cool the water inside the towers over the more than 20 years they have been in operation.