Calculation of neutron-induced radiation damage to gold and lutetium-aluminium microstructures using MCNP6.2

Abstract

Interaction of particles and photons with materials in extreme radiation environments like the nuclear reactor may lead to basic alterations in the microstructural properties of crystalline solids. These changes accumulate over time into defects on the macrostructure translating to changes in the material's physical and mechanical properties. Studying the level of damage in the materials requires a good prediction of damage using statistical approaches like Monte Carlo simulations. This study aims to calculate the level of damage to Gold (Au) and Lutetium-Aluminium (Lu-Al) due to neutron irradiation, owing to the applications of the materials in reactor technology and other extreme radiation environments. Neutron fluxes, displacement per atom (dpa) rates, and heat deposition expected during irradiation were calculated with Monte Carlo N-particle transport code, MCNP6.2, using the SAFARI-1 research reactor model. The total neutron flux incident on gold and Lutetium-Aluminium was $2.26\times {10}^{11}$ n cm⁻² s⁻¹ and $6.94\times {10}^{12}$ n cm⁻² s⁻¹ respectively, while the dpa rate in Au and Lu-Al was estimated to be $1.96\times {10}^{-7}$ s⁻¹ and $6.56\times {10}^{-5}$ s⁻¹. The calculated neutron dpa rates and fluence for the materials suggest an elevated level of damage to the microstructure of the materials.