Double heterogeneity effect analysis for plate fuel with dispersed particles

In order to identify the strong double heterogeneity (DH) effect of dispersed particle fuel with plate type, a suit of problems with 63 cases have been defined and analyzed by using the Monte Carlo code NECP-MCX. Numerical results indicate the following findings. (1) For cases with only fuel particles, the DH effect is within 50 pcm when the diameters are below 300 mu m. (2) For cases with both fuel and burnable poison particles, eigenvalue deviation between the random dispersion case and the homogenized case can reach up to the maximum of 905 pcm. Even if, the diameter of burnable poison particles is very small (20 mu m), the deviation is more than 150 pcm, making the homogenization approach no longer applicable. This work provides a data basis for correcting neutronic calculations and can be used as reference for verifying the calculation program based on the new method.