Atomistic Simulation of Nuclear Fuels
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Atomistic Simulation of Nuclear Fuels Matthias Krack Laboratory for Reactor Physics and Systems Behaviour, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
ABSTRACT The experimental investigation of actinide materials like nuclear fuels is difficult and usually very costly. Therefore a reliable multi-scale modeling of these often hazardous materials starting at the atomistic level is inevitable to gain further insight into this type of materials. The development of new, more advanced simulation methods accompanied by the rapid growth of the available computational resources provided by high-performance computing facilities, allows the modeling of such materials at a new quality level. Also the recent development of the CP2K program package (http://www.cp2k.org) has been partially focused on enabling state-of-the-art simulations of actinide materials using classical potential as well as electronic structure methods. The long-term goal is to perform reliable molecular dynamics simulations for actinide materials including advanced simulation techniques like nudged elastic band or metadynamics simulations. In this work, the CP2K program package and its application to the simulation of defect migration in uranium dioxide (UO2) using the nudged elastic band method is presented.
INTRODUCTION Actinide materials play an important role as nuclear fuels for the energy production as well as a crucial component for the design of novel materials due to their special physical properties. For instance, the coordinative bonding in actinide complexes differs from transition metals or lanthanides and thus enables the design of new catalysts [1]. Uranium dioxide (UO2) is one of the most prominent actinide materials, because it is the main nuclear fuel operated world wide in today's light water reactors. A tremendous experience base has been accumulated over the years allowing for efficient fuel exploitation up to high levels of burn-up. Irradiation programs are still a key element in developing the necessary experience base. Unfortunately, irradiation programs require very significant resources and time. Moreover, in spite of the numerous experimental and theoretical studies, a fundamental understanding of the structural processes occurring at the atomic scale in UO2 under irradiation or self-irradiation is not yet achieved. However, this knowledge is crucial for the design and the safety of nuclear plants and storage repositories. Thus a basic understanding of the physical processes at the atomic level occurring in actinide materials is highly desired. Atomistic simulation methods in computational materials science have matured in the recent years. Concurrently, the available computational resources have increased significantly, which will allow for more realistic simulations by using advanced techniques. As an example, the simulation of defect migration in UO2 using the CP2K program package [2] is presented in this work.
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COMPUTATIONAL METHODS The CP2K program package [2] is employed for all simulations in this work. CP
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