Exploration of Viability of Spark Plasma Sintering for Commercial Fabrication of Nuclear Fuel Pellets

The viability of spark plasma sintering (SPS) for fabrication of industrial-grade nuclear fuel pellets is explored by utilizing die designs for single- and multiple-pellet manufacturing. Traditional UO₂ pellets were also manufactured by systematically varying processing temperature and pressure as needed for single- and multiple-pellet fabrication. The pellets were then qualified against commercial fuel specifications for density, shape, microstructure, and surface flaws. Pellets produced one at a time met all commercial specifications except for grain size. Pellets produced in batches of two, four, and eight pellets showed suboptimal density indicating that further changes to sintering conditions are warranted. Additionally, commonly used graphite tooling for pellet fabrication was shown to be ineffective in producing large numbers of fuel pellets, as the die and punches were shown to undergo severe wear in each run thus decreasing the reliability of the tooling for production of pellets as per the specification. Finally, additional discussion is provided for identifying the avenues for scale-up of SPS to meet the current commercial demand of 400 million pellets/year. These studies are viewed as first step toward assessing the ability of SPS technology to meet the quality specifications and quantity demands of nuclear fuel pellets.