DFT+ U Study of the Thermal Conductivity and Noble Gas Impurities in Uranium Dioxide

2019 ◽  
Author(s):  
E. Torres ◽  
T. P. Kaloni
Keyword(s):  
Thermal Conductivity ◽  
Uranium Dioxide ◽  
Noble Gas

Sintering behavior and thermal conductivity of graphite flakes/uranium dioxide composites

2021 ◽  
pp. 153106
Author(s):  
Yi Zhong ◽  
Zhenliang Yang ◽  
Qiqi Huang ◽  
Zhiyi Wang ◽  
Yun Wang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Uranium Dioxide ◽  
Sintering Behavior

scholarly journals Impact of Noble-Gas Filler Atoms on the Lattice Thermal Conductivity of CoSb3 Skutterudites: First-Principles Modelling

2020 ◽  
Author(s):  
Jianqin Tang ◽  
Jonathan Skelton
Keyword(s):  
Thermal Conductivity ◽  
First Principles ◽  
Thermal Transport ◽  
Noble Gas ◽  
Detailed Balance ◽  
Resonant Scattering ◽  
Acoustic Mode ◽  
Cage Compounds ◽  
Mode Dispersion ◽  
Group Velocities

We present a systematic first-principles modelling study of the structural dynamics and thermal transport in the CoSb<sub>3</sub> skutterudites with a series of noble-gas filler atoms. A range of analysis techniques are proposed to estimate the filler rattling frequencies, to quantify the separate impacts of filling on the phonon group velocities and lifetimes, and to show how changes to the phonon spectra and interaction strengths lead to suppressed lifetimes. The fillers are found to reduce the thermal conductivity of the CoSb<sub>3</sub> framework by up to 15 % primarily by suppressing the group velocities of low-lying optic modes. Calculations show that the filler rattling frequencies are determined by a detailed balance of increasing atomic mass and stronger interactions with the framework, and are a good predictor of their impact on the heat transport. Lowering the rattling frequency below ~1.5 THz by selecting heavy fillers that interact weakly with the framework is predicted to produce a much larger suppression of the thermal transport, by inducing avoided crossings in the acoustic-mode dispersion and facilitating resonant scattering with a consequent large reduction in the lifetimes. Approximate rattling frequencies determined from the harmonic force constants may therefore provide a useful metric for selecting filler atoms to optimise the thermal transport in skutterudites and other cage compounds such as clathrates.

The effect of density on the thermal conductivity of uranium dioxide

1969 ◽  
Vol 29 (1) ◽  
pp. 67-81 ◽  
Author(s):  
R.B. Asamoto ◽  
F.L. Anselin ◽  
A.E. Conti
Keyword(s):  
Thermal Conductivity ◽  
Uranium Dioxide

Utilization of Thorium in LWR Fuels Aiming at Thermal Conductivity Improvements

2016 ◽  
Author(s):  
Jan Kubáň ◽  
Radek Škoda
Keyword(s):  
Thermal Conductivity ◽  
Uranium Dioxide ◽  
Nuclear Power ◽  
Fuel Pellet ◽  
Thorium Dioxide ◽  
Heterogeneous Distribution ◽  
Thermal Output ◽  
Homogenous Distribution ◽  
Limiting Parameters ◽  
Almost All

One of the main drawbacks of uranium dioxide, which is used in almost all nuclear power reactors, is its low thermal conductivity. As a consequence, temperature at the center of fuel pellet is relatively high, because heat is poorly conducted away. To reach a higher level of safety, maximal temperature in any fuel pellet is one of the main limiting parameters, which restrict the fuel thermal output. This paper deals with the use of thorium in LWR fuels with the objective of fuel pellet maximal temperature reduction. Research investigating homogenous distribution of thorium dioxide (thoria) in uranium dioxide fuel has already been done and did not lead to considerable thermal conductivity improvements. The aim of this study is to investigate heterogeneous distribution of thorium in commonly used uranium dioxide fuel in the form of uranium and thorium pellets placed together.

scholarly journals In-pile thermal conductivity of uranium dioxide at low burnup

2020 ◽  
Vol 538 ◽  
pp. 152210
Author(s):  
M.N. Cinbiz ◽  
W. Wiesenack ◽  
S. Yagnik ◽  
K.A. Terrani
Keyword(s):  
Thermal Conductivity ◽  
Uranium Dioxide

scholarly journals Noble-gas-infused neoprene closed-cell foams achieving ultra-low thermal conductivity fabrics

RSC Advances ◽  
2018 ◽  
Vol 8 (38) ◽  
pp. 21389-21398 ◽  
Author(s):  
Jeffrey L. Moran ◽  
Anton L. Cottrill ◽  
Jesse D. Benck ◽  
Pingwei Liu ◽  
Zhe Yuan ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Molecular Weight ◽  
High Molecular Weight ◽  
Noble Gases ◽  
Noble Gas ◽  
Low Thermal Conductivity ◽  
Closed Cell

Herein, we develop, demonstrate, and model a repeatable process for synthesizing ultra-low-thermal-conductivity closed-cell neoprene garments by infusing high-molecular-weight noble gases.

Thermal Transport in Defective Actinide Oxides

2018 ◽  
Author(s):  
Alex Resnick ◽  
Katherine Mitchell ◽  
Jungkyu Park ◽  
Hannah Maier ◽  
Eduardo B. Farfán ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Oxygen Vacancy ◽  
Uranium Dioxide ◽  
Thermal Transport ◽  
Dynamics Simulation ◽  
Nuclear Fuels ◽  
Plutonium Dioxide ◽  
Vacancy Defects ◽  
Actinide Oxides ◽  
Substitutional Defects

The present study employs a molecular dynamics simulation to explore thermal transport in various oxide nuclear fuels with defects such as uranium oxide and plutonium oxide. In particular, the effect of vacancy and substitutional defects on the thermal transport in actinide oxides are investigated. It is found that the thermal conductivities of these oxide nuclear fuels are significantly reduced by the presence of vacancy defects. In spite of their small size, oxygen vacancy is shown to alter the thermal conductivity of oxide fuels greatly; 0.1% oxygen vacancy reduces the thermal conductivity of plutonium dioxide by more than 10% when the number of unit cell in length is 100. It was shown that the missing of larger atoms alters the thermal conductivity of actinide oxides more significantly. For the case of uranium dioxide, 0.1% uranium vacancies decrease the thermal conductivity by 24.6% while the same concentration of oxygen vacancies decreases the thermal conductivity of uranium dioxide by 19.4%. However, the uranium substitutional defects are shown to have a minimal effect on the thermal conductivity of plutonium dioxide because of the small change in the atomic mass.

MODELING THERMOPHYSICAL PROPERTIES OF NOBLE GAS INVOLVED MIXTURES

2011 ◽  
Vol 08 (01) ◽  
pp. 19-39 ◽  
Author(s):  
MOHAMMAD MEHDI PAPARI ◽  
JALIL MOGHADASI ◽  
SOUDABEH NIKMANESH ◽  
ELHAM HOSSEINI ◽  
ALI BOUSHEHRI
Keyword(s):  
Thermal Conductivity ◽  
Potential Energy ◽  
Thermophysical Properties ◽  
Noble Gas ◽  
Pair Potential ◽  
Virial Coefficients ◽  
Model Potential ◽  
Intermolecular Potential ◽  
Inversion Method ◽  
Second Virial Coefficients

The present work involves in determining isotropic and effective pair potential energy of binary gas mixtures of Kr–Xe , Kr–C2H6 , Xe–C2H6 , Kr–C3H8 , and Xe–C3H8 from thermophysical properties consisting of viscosity and second virial coefficients through inversion method. Typically, the calculated intermolecular potential energy of Kr–Xe system has compared with HFD model potential reported in literature. A desirable harmony between our model potential and HFD model has been obtained. In order to assess the potential energies obtained, transport properties including viscosity, diffusion, thermal diffusion factor, and thermal conductivity of aforementioned mixtures were predicted using the calculated models potential. The deviation percentage of the calculated viscosity and thermal conductivity of above-mentioned mixtures from the literature values are, respectively, within ±2%, ±3%.

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