Title:	Early stages of radiation damage in metallic alloys
DNr:	NAISS 2023/5-55
Project Type:	NAISS Medium Compute
Principal Investigator:	Mattias Klintenberg <mattias@physics.uu.se>
Affiliation:	Uppsala universitet
Duration:	2023-03-28 – 2024-04-01
Classification:	10304
Keywords:

Abstract

Computational modelling enables to study materials response in extreme environments, such as nuclear reactor, safely and, also, reduce the costs associated with carrying out multiple experimental studies to map out wide operational conditions. Therefore, we can effectively use these methods to gain new insights into processes happening at the atomic level and determine the most important ones affecting for example the degradation of the material under irradiation conditions. Due to the large lengthscales, necessary to contain a collision cascade, classical molecular dynamics has to be used to study radiation damage events. These methods often neglect the role of electronic stopping which can contribute to about 20% energy loss by the energetic particles. We have developed a novel model that is able to capture the energy losses to electrons in collision cascade simulations and are going to employ the method in this proposal. Austenitic steels is one of the main types of materials used in nuclear reactors. The electronic losses have often been neglected in the computational research studying the radiation damage in these materials. Moreover, our previous work, among others, has shown that the inclusion of electrons can significantly affect the defect production in the material due to irradiation damage. This work will be part of the ANITA project funded by Energimyndiheten, industry and Uppsala university where small modular reactor (SMR) concepts are studied. Our project aims at studying the radiation damage in FeCrNi austenitic steel as a model system and expanded to FeCrAl steel. We will employ the state-of-the-art models to include all the necessary physics taking place in the extreme events. We have developed the parameterisation for the electron-ion interaction and will be using available interatomic potentials for FeCrNi compound. We will carry out the simulations using LAMMPS software and our electron-ion interaction model. In the project we will carry out simulations at multiple damage energies (10-100 keV). For each energy we will gather statistical averages by running many simulations with different initial conditions and will gather information on the surviving defects which can be compared to available experimental data. Furthermore, we will study the electronic effects in FeCrAl steel by first running time-dependent density functional theory calculations to map the energy transfer from energetic ions to electrons from first principles. This data will be used in the development of the electron-ion coupling model that can be used in classical MD simulations. After, the parameterisation of the model we will carry out similar radiation damage simulations as for FeCrNi compound.