Analysis of Double Heterogeneous Effect Under Double Dispersion of Fuel and Burnable Poison Particles

Dispersed particle fuel is an advanced form of fuel. Due to the need for reactivity control, burnable poison particles and fuel particles are often dispersed in the matrix together. In order to prove the double dispersion mechanism of fuel and burnable poison particles with high calculation accuracy, a random dispersion model of burnable poison particles is constructed in this paper under the conditions of fuel homogenization and random dispersion of fuel particles. Compared with the random dispersion model, direct homogenization of fuel or burnable poison can cause large deviation in the calculation of system eigenvalues according to the MCX calculation. Under the same fuel phase volume, fuel enrichment and burnable poison loading, the maximum deviation can reach 1494pcm. The deviation increases with the increase of the loading mass of the burnable poison in the system, subject to fuel particle diameter of the order ∼100 μm. At a relatively high content of the burnable poison, the deviation decreases with the change of the content of the burnable poison. The calculation results show that the double heterogeneity effect of the system composed of fuel and burnable poison particles cannot be ignored, and the traditional homogenization calculation method must be corrected according to the actual situation. This paper is of valuable reference for the calculation and correction of dispersion fuel homogenization under the condition of strong absorber, and the program development and verification of using a new method to deal with the double heterogeneity effect.