The Advanced High-Temperature Reactor (AHTR) is a 3400-MW(thermal) fluoride salt-cooled high-temperature reactor that uses coated particle fuel compacted into slabs rather than spherical or cylindrical fuel compacts. Simplified methods are required for parametric design studies to perform burnup analysis on the entire feasible design space. These simplifications include fuel homogenization techniques to increase the speed of neutron transport calculations and equilibrium depletion analysis methods to analyze systems with multibatch fuel management schemes.

This paper presents three elements of significant novelty. First, the reactivity-equivalent physical transformation (RPT) methodology usually applied in systems with cylindrical and spherical geometries has been extended to slab geometries. Second, implementing this RPT homogenization, a Monte Carlo-based depletion methodology was developed to search for the maximum discharge burnup in a multibatch system by iteratively estimating the beginning of equilibrium cycle composition and sampling different discharge burnups. This iterative equilibrium depletion search method fully defines an equilibrium fuel cycle (keff, power, flux, and composition evolutions) but is computationally demanding. Therefore, an analytical method, the nonlinear reactivity model, was developed so that single-batch depletion results could be extrapolated to estimate the maximum discharge burnup in systems with multibatch fuel management schemes.