Nuclear Technology / Volume 167 / Number 3 / September 2009 / Pages 348-361
Technical Paper / Fuel Cycle and Management
Technological feasibility of a simplified mixed-oxide (MOX) pellet fabrication process, the short process, was studied. About 300 g of microwave heating denitrated (MH)-MOX powder with adjusted plutonium content to 30% could be successfully processed by a tumbling granulator for subsequent pelletizing and sintering processes. The granulated 30%PuO2-MOX powder could be pressed into green annular pellets directly and smoothly when using a die wall lubrication method. The pellet tensile strengths were compared for a granulated molybdenum powder that has similar characteristics to those of granulated 30%PuO2-MOX powder, and they were higher for pellets obtained when using the die wall lubrication method than when using the conventional powder mixing method. The amount of additives in the green pellets could be controlled at a low value of 0.06 wt% in this process. It is, therefore, possible to carry out dewaxing and sintering of green pellets in the same furnace. By controlling the average particle sizes of granulated 30%PuO2-MOX powders, pellets with more than 95% theoretical density could be obtained after sintering at 1700°C for 2 h.
As a result, it can be concluded that the short process is technologically feasible to fabricate MOX annular pellets.