Small scale engineering experiments on tumbling granulation method using water for MOX pellet production

Kato, Yoshiyuki ; Takahashi, Naoki ; Morita, Minoru; Yoshimoto, Katsunobu; Furuya, Hirotaka

In the fabrication process of oxide fuels for LWRs and FBRs, organic powder is usually mixed as a binder to granulate in prior to pellet pressing. This powder is removed during preliminary heating, however the residue and its decomposed material contaminates inside of the furnace and causes frequent cleaning which results in higher operational cost. If water is used instead of the organic powder, the preliminary heating process is skipped and the new process is free from the residue. This is one of the key benefits of the simplified pelletizing method to where we are advancing. Uranium oxide and uranium plutonium mixed oxide were prepared by the microwave heating method. Tests were carried out using a stirring blade which compresses moderately the powder and mixes the powder and water uniformly. In conclusion, the granule 120 to 140 micron in major diameter and 73 to 77 in flow ability was obtained with water addition rate of 13 wt%, despite the narrow range of operating conditions.