Neutronics Design Optimization of a Sodium Cooled Micro Modular Fast Reactor Using OpenMC

Abstract

Very small modular nuclear reactors (vSMR), or micro-reactors, are identified as a potential means to provide reliable and cost-effective power between 1 and 10 MWe for remote installations. This paper presents a neutronic optimization study of a sodium heatpipe-cooled Micro Modular Reactor (MMR) design that has been simulated using the Monte Carlo method. As a high-fidelity open-source Monte Carlo code, OpenMC has been used to simulate the neutron flux distribution, power and burnup of the reactor core using the ENDF-B/VII.1 data library.

This Micro Modular Reactor is a 5MWe power reactor with a 20-year lifetime without refuelling, designed to operate in a fast spectrum with TRISO fuel. TRISO particles are the leading-edge nuclear fuel form that is structurally more resistant to neutron irradiation, corrosion, oxidation and high temperature than traditional reactor fuel. TRISO fuels comprise thousands of micro-encapsulated uranium-bearing fuel kernels and are individually coated with multiple layers of pyrolytic carbon and silicon carbide that act as containment for the fuel and fission products. This paper shows the study of a hexagonal unit cell with a sodium-cooled heat pipe in the center surrounded by the TRISO particles embedded in a beryllium matrix and the effect of different absorbing materials on the full core.