Dried powder of radioactive wastes cannot be disposed of as such unless it is solidified by an appropriate solid-ification agent. However, the volume of the solidified waste form increases to a large extent due to certain limi-tations (incorporation ratio) while mixing the wastes with a solidification agent. As a result, the cost of waste disposal increases and filling up the disposal facility's capacity occurs fast. To address this problem, roll compac-tion technology can be used to reduce the physical volume of the powdered wastes. Powdered wastes (contam-inated soil and bio-shield concrete) were converted to rigid pellets of certain shape and size (H 6.5 x W 9.4 mm) by a special roll compactor. The operating parameters (hydraulic pressure, roll speed, feeding rate, roll gap) of the roll compactor were evaluated, and the volume reduction factor of each waste powder and the strength of the pellet were estimated. ? 2021 Elsevier B.V. All rights reserved. Dried powder of radioactive wastes cannot be disposed of as such unless it is solidified by an appropriate solidification agent. However, the volume of the solidified waste form increases to a large extent due to certain limitations (incorporation ratio) while mixing the wastes with a solidification agent. As a result, the cost of waste disposal increases and filling up the disposal facility's capacity occurs fast. To address this problem, roll compaction technology can be used to reduce the physical volume of the powdered wastes. Powdered wastes (contaminated soil and bio-shield concrete) were converted to rigid pellets of certain shape and size (H 6.5 x W 9.4 mm) by a special roll compactor. The operating parameters (hydraulic pressure, roll speed, feeding rate, roll gap) of the roll compactor were evaluated, and the volume reduction factor of each waste powder and the strength of the pellet were estimated.