Study of a fine-mesh 1:1 Computational Fluid Dynamics – Monte Carlo neutron transport coupling method with discretization uncertainty estimation

Investigation of discretization uncertainty in Monte Carlo neutron transport simulations of the Molten Salt Fast Reactor (MSFR)

“…It must be noted that GCI method suited well the calculations of discretization uncertainty for keff, which was expected because of the literature results [4]. After the initial criticality calculations, an iterative process was carried and the steady state composition was found.…”

“…However, as the complexity of the geometry rises, built-in capabilities of MCNT codes for geometry generation become unpractical, leading to other geometric approaches, such as meshed geometries. GCI method was extrapolated for mesh based Monte Carlo simulations previously, leading to promising results [4]. Therefore, this work presents an application of the GCI utilization for MCNT mesh based calculations using MSFR.…”

“…MCNT codes are stochastic, which implies that the result, will fluctuate around a value, being the magnitude of this fluctuation dependent of the sample size. Generally, MCNT codes are developed to work with Constructive Solid Geometry (CSG) [4].…”

“…In order to perform the evaluation, the results from MSFR Neutronic Benchmark [3] is compared with the calculated data in the present work. The numerical uncertainty given by the mesh utilization is evaluated using an extended version of the Grid Convergence Index (GCI) [4]. At first, calculations with CSG model is conducted to serve as baseline for the developed mesh based models.…”