Hello, A yearly allocation for the LCRC cluster has been requested with the following updated information: Submitter/PI: Dieter Wolf Project Name: RadiationDamage Division: MSD Project title: Atomistically informed mesoscale simulation of irradiation damage Associated funding: BES Computational Materials and Chemical Sciences Network ANL LDRD Other Systems: None Science: The scientific challenge to accurately predict the behavior and lifetime of irradiated materials lies in informing the currently employed empirically-derived engineering-based continuum level models lower-scale models and input parameters. The latter include information on radiation-induced point-defect clustering, dislocation dynamics, void migration, fission-gas release, bubble formation, swelling, etc. Computationally, these extreme length scale methods can be bridged via mesoscale methods, such as, phase field and kinetic Monte Carlo, which are informed by lower-scale (atomistic and electronic-level) materials input parameters and microstructural mechanisms. In this project, we implement bottom-up approach, where we uncover key mechanisms of the radiation-induced atomic level phenomenon that can be systematically fed into mesoscale methods using molecular dynamics (MD) and density functional theory (DFT) calculations; these, in turn, can be used to inform contin uum models of materials performance. Specific objectives: One of our goals is to incorporate stress and temperature gradient effects into existing point defect models under irradiation. In particular, the project will elucidate: • thermo-migration of voids in BCC Mo and UO2 as model metallic and oxide fuel materials; • interaction of point defects with grain boundaries, voids and line dislocations. Project description: Computational methods: Molecular dynamics (MD) simulation Density functional theory (DFT) Phase-field methods Programming model: MD: using the HELL code developed at Argonne over the past 20 years. DFT: VASP Phase-field modeling: home-grown code Technical details: Our thoroughly performance-tested MD code has recently been used to perform extensive simulations of point-defect clustering in uranium dioxde and cerium dioxide, the goal being to determine the degree to which CeO2 and be used as a (non-radioactive) surrogate material for UO2. We will continue this work by determining the mechanism by which voids can be formed by the clustering of irradiation-induced pont-defects in UO2 (as an oxide model material) and Mo (as a model bcc metal). The insigths and related materials parameters extracted from these simulations provide the input needed for mesoscale simulations using our existing phase-field code. These simulations will determine the kinetics of void clustering and, ultimately, the formation of a superlattice of voids that has been observed experimentally in many materials during the past 30 years, but has never been captured by simulation. The simulations will be performed by a new post-doc that we are presently recruiting. Project URL: Current FY Hours Used: undetermined amount New FY Requested allocation: 50000 Q1: 5000 Q2: 15000 Q3: 15000 Q4: 15000 Justification: Thank You, The LCRC Accounts System