Thermophysical Properties of PuO2 and AmO2 Solid Solutions Simulated by Molecular Dynamics
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1043-T09-09
Thermophysical Properties of PuO2 and AmO2 Solid Solutions Simulated by Molecular Dynamics Tosawat Seetawan1, Thaweewat Khuangthip1, Vittaya Amornkitbamrung2, Ken Kurosaki3, Jun Adachi3, Masahito Katayama3, Anek Charoenphakdee3, and Shinsuke Yamanaka3 1 Program of Physics, Faculty of Science and Technology, Sakon Nakhon Rajabhat University, 680 Nittayo Road, Sakon Nakhon 4700, Thailand, Sakon Nakhon, 47000, Thailand 2 Integrated Nanotechnology Research Center and Departments of Physics, Khon Kaen, 123 Mittraparb Road, Muang District, Khon Kaen 40002, Thailand, Khon Kaen, 40002, Thailand 3 Division of Sustainable Energy and Environmental Engineering, Graduate School of, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan, Suita, 565-0871, Japan ABSTRACT PuO2 and AmO2 solid solutions: (Pu, Am)O2 are one of the candidates of fuels in a sub-critical acceleratordriven system (ADS). To understand the fuel performance, the thermophysical properties such as thermal conductivity and heat capacity are quite important. However, it is very hard to experimentally determine the physical properties of plutonium as well as americium compounds due to their handling-difficulties. Molecular dynamics (MD) would be a specific method to describe the physical properties of such materials. In the present study, we have investigated thermophysical properties of PuO2, AmO2, and their solid solutions in the temperature range from 300 to 2,500 K. The lattice parameter, compressibility, heat capacity, linear thermal expansion coefficient, and thermal conductivity were evaluated. A Morse-type potential function added to the Busing-Ida type potential was employed as the potential for interatomic interactions. The calculated lattice parameters of (Pu, Am)O2 obeyed Vegard’s law, and the values increased with temperature. The heat capacities of (Pu, Am)O2 were similar in any compositions. The thermal conductivities of (Pu, Am)O2 were lower than those of PuO2 and AmO2, indicating that a point-defect scattering effect of phonons could be realized in the MD calculations.
INTRODUCTION The plutonium (Pu)- and americium (Am)- containing oxide fuels are considered to be the transmutation of minor actinide (MA) oxide nuclear fuels [1]. In addition, the MA-containing mixed oxide (MOX) fuels are promising candidates for future fast breeder reactors [2, 3]. Although, the thermophysical properties of (Pu, Am)O2 fuels are very important to evaluate the fuel performance, there is limited information on these properties, due to the difficulties associated with the high radiation fields. Therefore, it is necessary to develop a new technique to evaluate the thermophysical properties of the (Pu, Am)O2 fuels. In this article, we present the results of the molecular dynamics (MD) calculation performed on Pu1xAmxO2 (x = 0, 0.1, 0.3, 0.5, 0.7, 0.9, 1.0). We evaluated the thermophysical properties such as the linear thermal expansion coefficient, heat capacity, and thermal conductivity in the temperature range from 300 to 2,500 K.
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