NUMERICAL CALCULATIONS OF THE EFFECTIVE THERMAL CONDUCTIVITY OF THE DISPERSION FUEL SPHERE WITH THE INTERNAL HEAT SOURCES

The effective thermal conductivity of dispersion fuel sphere is an important parameter for its' temperature prediction. Whether the existing effective thermal conductivity models which does not consider the impact of inner heat source can predict the average temperature of heat generating dispersion fuel sphere is unknown. This study established the three-dimensional heat conduction model to calculate the temperature distribution of dispersion fuel sphere with inner heat source, then the effective thermal conductivity for average temperature prediction was calculated by conduction differential equation. The fuel particles are set to be uniformed with uniform inner heat source, fuel particles are defined uniformly distributed in probability in the fuel sphere. Through the analyses, the existing models overestimate the effective thermal conductivity of dispersion fuel sphere with inner heat source, and then underpredict the average temperature of dispersion fuel sphere. The distribution of inner heat source will affect the effective thermal conductivity. The values of inner heat source will not affect the effective thermal conductivity. This paper revealed the importance of inner heat source on effective thermal conductivity, and lay the foundation for further study.

Automated summary

This study established a three-dimensional heat conduction model considering the impact of inner heat source on dispersion fuel spheres, and found that existing models tend to overestimate the effective thermal conductivity and subsequently underestimate the average temperature. The distribution of inner heat source was revealed to affect the effective thermal conductivity, while the values of inner heat source did not impact the effective thermal conductivity.