<p style="text-align: justify">With today’s concerns about worldwide energy security and environmental impact, nuclear energy is presented as a real option. This generation technology is hugely expensive to build but very cheap to run and meets more than 20% of the world’s demand for electricity through the 447 nuclear reactors operating in the world as of January 2020. In nuclear reactors, heat conduction takes place by both phonons and free electrons, and the heat is conducted away by the cladding materials from the fuel interior. One of the most important tasks in reactor core and assembly design is predicting how the properties of the core will change over its lifetime. However, the underline challenge of low thermal conductivity which is responsible for high centerline temperature in Uranium-dioxide nuclear plant fuel type associated with the current generation of commercial reactors remain a huge concern to the Nuclear Power industry.&nbsp; The accident at the Fukushima Daiichi Nuclear Power Plant (FDNPP) in Japan on March 11, 2011 clearly illustrates the risks involved in the continuous usage of the nuclear fuel type. Until now, the only fuel other than that has been burned in&nbsp;commercial nuclear reactors is the mixed oxide. Hence, the standard uranium dioxide fuel which is highly compatible with water, continues to dominate the nuclear energy scene. Although, researchers in the nuclear industry have proposed uranium mononitride (UN) as a promising candidate for accident tolerant fuel and Generation-IV nuclear reactor fuels, unfortunately, there is still a lack of clear understanding of the point and surface defects influence on the thermal conductivity of UN. Many computational codes have been used to study advanced fuels to help enhance our understanding of the thermal properties in particular thermal conductivity of UN. Researchers’ findings on the way some of these defects affect the performance of advanced fuels. While the addition of UN to Uranium-dioxide was found to increase both the thermal conductivity and uranium density. Therefore, there still a need to carry out meaningful performance calculations and simulation through multi scale computer. In this paper, non-equilibrium molecular dynamics simulation method is used to study the thermal conductivity of UN. Among the various options of the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) to measure the thermal conductivity, the reverse non-equilibrium technique is used. Experimental and simulation relevant literatures were reviewed in this work to analyze the influence of point and surface defects on the thermal conductivity of UN. Calculated thermal conductivities for UN will be compared with similar thermal conductivity calculations using equilibrium molecular dynamics, reported in the open literature. Results from this research would help with the understanding and application of UN in nuclear engineering to ensure the performance, safe, and economical operation of fuels.</p>

Molecular Dynamics Simulation of Thermal Conductivity of Uranium Mononitride

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

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