Molecular-dynamics study of diffusional creep in uranium mononitride

AbdulHameed, Mohamed [North Carolina State University, Raleigh, NC (United States)] (ORCID:0009000958823345); Beeler, Benjamin [North Carolina State University, Raleigh, NC (United States); Idaho National Laboratory (INL), Idaho Falls, ID (United States)] (ORCID:0000000319641177); Galvin, Conor Oscar T. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)] (ORCID:0000000226090417); Cooper, Michael William Donald [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)] (ORCID:0000000182707947); Elamrawy, Nermeen [North Carolina State University, Raleigh, NC (United States)] (ORCID:0009000158815590); Claisse, Antoine [Westinghouse Electric Sweden, Västerås (Sweden)]

doi:10.1016/j.jnucmat.2025.156153

DOE OSTI · 2588838

Molecular-dynamics study of diffusional creep in uranium mononitride

AbdulHameed, Mohamed [North Carolina State University, Raleigh, NC (United States)] (ORCID:0009000958823345)·Beeler, Benjamin [North Carolina State University, Raleigh, NC (United States); Idaho National Laboratory (INL), Idaho Falls, ID (United States)] (ORCID:0000000319641177)·Galvin, Conor Oscar T. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)] (ORCID:0000000226090417)·Cooper, Michael William Donald [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)] (ORCID:0000000182707947)·Elamrawy, Nermeen [North Carolina State University, Raleigh, NC (United States)] (ORCID:0009000158815590)·Claisse, Antoine [Westinghouse Electric Sweden, Västerås (Sweden)]

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Abstract

Uranium mononitride (UN) is a promising advanced nuclear fuel due to its high thermal conductivity and high fissile density. Yet, many aspects of its mechanical behavior and microstructural features are currently unknown. In this paper, molecular dynamics (MD) simulations are used to study UN's diffusional creep. Nanometer-sized polycrystals are used to simulate diffusional creep and to calculate an effective GB width. It is found that Nabarro-Herring creep is not dominant in the temperature range of 1700–2000 K and that the dominant diffusional creep mechanism is Coble creep with an activation energy of 2.28 ± 0.09 eV. A method is proposed to calculate the diffusional GB width and its temperature dependence in polycrystals. The effective GB width of UN is calculated as 2.69 ± 0.08 nm. This value fits very well with the prefactor of the phenomenological Coble creep formula. It is demonstrated that the most comprehensive thermal creep model for UN can be represented as the combination of our Coble creep model and the dislocation creep model proposed by Hayes et al.

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11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS 36 MATERIALS SCIENCE Coble creep Grain-boundary diffusion Grain-boundary width Molecular dynamics Nabarro-Herring creep Uranium nitride

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AbdulHameed, Mohamed [North Carolina State University, Raleigh, NC (United States)] (ORCID:0009000958823345), Beeler, Benjamin [North Carolina State University, Raleigh, NC (United States); Idaho National Laboratory (INL), Idaho Falls, ID (United States)] (ORCID:0000000319641177), Galvin, Conor Oscar T. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)] (ORCID:0000000226090417), Cooper, Michael William Donald [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)] (ORCID:0000000182707947), Elamrawy, Nermeen [North Carolina State University, Raleigh, NC (United States)] (ORCID:0009000158815590), Claisse, Antoine [Westinghouse Electric Sweden, Västerås (Sweden)]. 2025-09-12. Molecular-dynamics study of diffusional creep in uranium mononitride. https://doi.org/10.1016/j.jnucmat.2025.156153

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