x-MeRA: Computationally efficient adaptive mesh refinement of Monte Carlo mesh based tallies

The reactor physics community is always focused on reducing the computational time and memory required for simulations. x-MeRA, which stands for flux-based-(x)-Mesh tally Refinement Adaptively, was built to reduce the computational time and memory required to solve the neutronics side of a multiphysics problem when compared to traditional methods for mesh based tallies in Monte Carlo (MC) simulations. x-MeRA couples a MC code with an adaptive mesh refinement (AMR) algorithm to take advantage of the accuracy of a MC code and the efficiency of an AMR algorithm. Also developed within x-MeRA was a set of metrics to assess the effects of the refinement on various parameters in the simulation space. For a plutonium sphere, x-MeRA shows a reduction in memory usage and computation time when compared to a fully refined mesh by a factor of 14.7 and 6.7, respectively. When compared to an unstructured mesh, improvement of 1.3 and 4.8 was achieved for memory usage and computation time. The development of x-MeRA helps solve the neutronics side of a multiphysics problem in a faster, more computationally efficient manner than traditional methods, and the final mesh created contains accurate results that can be passed onto the next physics code.