The fluidized-bed Waste Calcining Facility (WCF) at the Idaho Chemical Processing Plant has been successfully converted from a liquid-metal heating system to a new system called “in-bed combustion,” where a hydrocarbon fuel is burned directly in the fluidized bed to supply the heat necessary to calcine radioactive wastes. Significant accomplishments demonstrated during the first processing campaign using in-bed combustion heating were an onstream time of 100% over the total run duration of 156 days of radioactive operation, a capacity increase of ∼15%, and demonstration of the safety and reliability of the process and control systems.