Project Title

PuO2 and UO2 Thermal Conductivity Sensitivity to Various Defect Types and Concentrations

Presenters

Academic department under which the project should be listed

SPCEET - Mechanical Engineering

Faculty Sponsor Name

Jungkyu Park

Additional Faculty

Eduardo Farfan, Mechanical Engineering, efarfan1@kennesaw.edu

There is no need.

Abstract (300 words maximum)

Plutonium is considered to provide more than one third of the reactor’s energy output. Pu-239 is most commonly formed by neutron capture from U-238. Thorium is an easily exploitable resource in many countries and is three times more abundant in nature than uranium. It is often found as fertile Th-232 with the potential for creating U-233 isotope within nuclear reactors. The conversion to Th-232 can also be achieved by the incineration of weapons grade plutonium. Recently, the growing demands for improving the safety margin and efficiency during nuclear power cycles push researchers to investigate how to improve the thermal conductivities of these actinide oxides. In this research study, the detailed thermal transport in PuO2 is explored by using reserve non-equilibrium molecular dynamics, and is then compared to ThO2 thermal transport from a previous study. Thermal conductivities are evaluated for different defect concentrations, i.e. 0.1%, 0.5%, 1%, 2%, and 5% concentrations of oxygen, plutonium, thorium vacancies. Finally, the thermal conductivities of PuO2 and ThO2 are compared when uranium substitution is introduced into the fuel structure. The results show that larger vacancy sites degrade the thermal conductivity of the actinide oxides more, and the size effect becomes bigger when the sample length becomes larger. Furthermore, the main element vacancies degrade the thermal conductivity most, followed by oxygen vacancy and then uranium substitution with the least effect on thermal conductivity.

Project Type

Oral Presentation (15-min time slots)

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PuO2 and UO2 Thermal Conductivity Sensitivity to Various Defect Types and Concentrations

Plutonium is considered to provide more than one third of the reactor’s energy output. Pu-239 is most commonly formed by neutron capture from U-238. Thorium is an easily exploitable resource in many countries and is three times more abundant in nature than uranium. It is often found as fertile Th-232 with the potential for creating U-233 isotope within nuclear reactors. The conversion to Th-232 can also be achieved by the incineration of weapons grade plutonium. Recently, the growing demands for improving the safety margin and efficiency during nuclear power cycles push researchers to investigate how to improve the thermal conductivities of these actinide oxides. In this research study, the detailed thermal transport in PuO2 is explored by using reserve non-equilibrium molecular dynamics, and is then compared to ThO2 thermal transport from a previous study. Thermal conductivities are evaluated for different defect concentrations, i.e. 0.1%, 0.5%, 1%, 2%, and 5% concentrations of oxygen, plutonium, thorium vacancies. Finally, the thermal conductivities of PuO2 and ThO2 are compared when uranium substitution is introduced into the fuel structure. The results show that larger vacancy sites degrade the thermal conductivity of the actinide oxides more, and the size effect becomes bigger when the sample length becomes larger. Furthermore, the main element vacancies degrade the thermal conductivity most, followed by oxygen vacancy and then uranium substitution with the least effect on thermal conductivity.