Benchmarking Serpent 2 and Rattlesnake Static Calculations Using a Molten Salt Reactor Experiment Model

Abstract

Canadian Nuclear Laboratories is evaluating reactor physics codes to perform transient simulations for advanced small modular reactors (SMR), based on ongoing interest in and developments of SMR technologies. Two candidate tools are Serpent 2 (a Monte Carlo, continuous energy, neutron transport code), and Rattlesnake (a finite element neutron diffusion and transport code). In this study a 3D full core model of the Molten Salt Reactor Experiment (MSRE), excluding fuel flow, was implemented in Serpent 2 and Rattlesnake. In addition to calculating k-effective and flux distribution, Serpent 2 was used to generate homogenized group constants for input into Rattlesnake static k-effective calculations, and the calculated k-effectives were compared to evaluate the fidelity of the Rattlesnake outputs to those of Serpent 2. This study shows that this methodology achieved good agreement between the Serpent 2 and Rattlesnake calculations, with differences in k-effective of less than 5 mk for various control rod positions using seven energy groups.