Greatly Enhanced Thermal Conductivity of Fully Inert Matrix Dispersion Pellet (IMDP) Produced by Spark Plasma Sintering (SPS) Technique

In order to improve nuclear reactor’s performance and safety, a new-type fuel, Inert Matrix Dispersion Pellet (IMDP) with greatly enhanced thermal conductivity was studied. In this paper, the pellet was developed by Spark Plasma Sintering Technique (SPS), which brings an improved thermal conductivity compared with normal method and exhibits fully dense SiC matrix with a higher TRISO volume in kernel of pellet. Thermal-physical properties of the IMDP from room temperature to 1400 °C were investigated. The thermal conductivity improved 1100% at room temperature and 974% under 1000°C when TRISO volume is 40%, which behave much better than traditional UO₂ fuel. The thermal diffusivity reduced and heat capacity increased at different TRISO volumes, linearly implied stable geometry at high temperature. From CT test we can see an intact structure of uniform TRISO granules. For comparison, modeling thermal conductivity is analyzed by FEM, which shows lower than measured data, indicating an optimized technology of this new method. Advantages of SPS will be discussed as well.