Effect of thorium addition on the thermophysical properties of uranium dioxide: Atomistic simulations

Xiao, Hongxing; Long, Chongsheng; Tian, Xiaofeng; Chen, Hongsheng

doi:10.1016/j.matdes.2016.02.019

Cited by 12 publications

(4 citation statements)

References 63 publications

(89 reference statements)

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“…The MD simulation provides a convenient and economic way to study and estimate the thermal conductivity of materials. Previous research [ 24 , 25 ] has demonstrated that the simulated result by the MD method is in qualitative agreement with the measured data. Thus, the MD method was adopted here to investigate the thermal conductivity of each phase in cement paste.…”

Section: Model Parameterssupporting

confidence: 68%

Multiphase Model for Predicting the Thermal Conductivity of Cement Paste and Its Applications

2021

Materials

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Thermal conductivity plays a significant role in controlling thermal cracking of cement-based materials. In this study, the thermal conductivity of cement paste at an early age was measured by the hot plate method. The test results showed that the thermal conductivity of cement paste decreased with the increase of water/cement ratio and curing age. Meanwhile, a multiphase model for the thermal conductivity of cement paste was proposed and used to study the influence of saturation and curing temperature on the thermal conductivity of cement paste. To determine the parameters involved in this model, the thermal conductivity of each phase in cement paste was calculated by the molecular dynamic simulation method, and the hydration of cement was simulated by the Virtual Cement and Concrete Testing Laboratory. The inversion results showed that the relative error between experimental and simulation results lay between 1.1% and 6.5%. The thermal conductivity of paste in the saturated condition was 14.9–32.3% higher than that in the dry state. With the curing temperature increasing from 10 °C to 60 °C, the thermal conductivity of cement paste decreased by 3.9–4.9% depending on the water/cement ratio.

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Section: Model Parameterssupporting

confidence: 68%

Multiphase Model for Predicting the Thermal Conductivity of Cement Paste and Its Applications

2021

Materials

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“…Superheating and supercooling phenomena are common in MD simulations of solid-liquid phase transformation [56][57][58].…”

Section: From Our MD Calculated H(t)-h(300) Versus Temperature Data mentioning

confidence: 99%

Melting behavior of (Th,U)O2 and (Th,Pu)O2 mixed oxides

Ghosh

Kuganathan

Galvin

et al. 2016

Journal of Nuclear Materials

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The melting behaviors of pure ThO2, UO2 and PuO2 as well as (Th,U)O2 and (Th,Pu)O2 mixed oxides (MOX) have been studied using molecular dynamics (MD) simulations. The MD calculated melting temperatures (MT) of ThO2, UO2 and PuO2 using two-phase simulations, lie between 3650-3675 K, 3050-3075 K and 2800-2825 K, respectively, which match well with experiments. Variation of enthalpy increments and density with temperature, for solid and liquid phases of ThO2, PuO2 as well as the ThO2 rich part of (Th,U)O2 and (Th,Pu)O2 MOX are also reported. The MD calculated MT of (Th,U)O2 and (Th,Pu)O2 MOX show good agreement with the ideal solidus line in the high thoria section of the phase diagram, and evidence for a minima is identified around 5 atom% of ThO2 in the phase diagram of (Th,Pu)O2 MOX.

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“…Furthermore, the experimental work on the microstructures can be closely interfaced with first-principles computational approaches to establish validated models for new insights and predictive understanding of the chemical and physical properties of Th-based MOX under extreme environments as well as their ability to accommodate fission products and highly radioactive wastes. The local structure of Th is closely related to the physicochemical properties of Th-MOX involved in the thorium-based nuclear fuel cycle. , Therefore, it is important to study the microstructural responses of ThO 2 to actinide doping or mixing.…”

Section: Introductionmentioning

confidence: 99%

“…The local structure of Th is closely related to the physicochemical properties of Th-MOX involved in the thorium-based nuclear fuel cycle. 5,6 Therefore, it is important to study the microstructural responses of ThO 2 to actinide doping or mixing.…”

Section: Introductionmentioning

confidence: 99%

Uranium-Induced Changes in Crystal-Field and Covalency Effects of Th⁴⁺ in Th_1–xU_xO₂ Mixed Oxides Probed by High-Resolution X-ray Absorption Spectroscopy

et al. 2018

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Knowledge of the local Th structure is a prerequisite for a better understanding of the physicochemical properties of the thorium-based mixed oxides (Th-MOX) involved in the Th-based nuclear fuel cycle. The crystalline electric field (CEF) splitting of the 6d shell in ThU O ( x = 0.25, 0.5, 0.75) solid solution was probed by the Th L edge high-energy-resolution fluorescence-detected (HERFD) X-ray absorption near-edge spectroscopy (XANES) collected at the L emission line, which cannot be obtained by conventional X-ray absorption methods. The detected CEF split between the 6d e and t orbitals in ThO consisting of ordered Th-O cubes with cubic symmetry is ∼3.5 eV for the Th ion. Because the split peaks of the white line corresponding to the crystal-field splitting of the unoccupied 6d states were resolved in the HERFD-XANES spectra, the analysis of these split peaks combined with first-principles calculations revealed that an increase of the U content involves the distortion of the Th-O cubes in the ThU O mixed oxides. The lower symmetry of the Th-O cube induced by the incorporated U tends to reduce the local crystal-field around Th as well as the hybridization of Th 6t-O 2p which is mainly responsible for the covalent property of the Th-O bond. The phenomenon is noticeable in ThUO, whose CEF splitting is decreased by approximately 10%, and covalent mixing between Th 6d t and O 2p orbitals is substantially reduced compared to that of pure ThO.

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Effect of thorium addition on the thermophysical properties of uranium dioxide: Atomistic simulations

Cited by 12 publications

References 63 publications

Multiphase Model for Predicting the Thermal Conductivity of Cement Paste and Its Applications

Multiphase Model for Predicting the Thermal Conductivity of Cement Paste and Its Applications

Melting behavior of (Th,U)O2 and (Th,Pu)O2 mixed oxides

Uranium-Induced Changes in Crystal-Field and Covalency Effects of Th⁴⁺ in Th_1–xU_xO₂ Mixed Oxides Probed by High-Resolution X-ray Absorption Spectroscopy

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Effect of thorium addition on the thermophysical properties of uranium dioxide: Atomistic simulations

Cited by 12 publications

References 63 publications

Multiphase Model for Predicting the Thermal Conductivity of Cement Paste and Its Applications

Multiphase Model for Predicting the Thermal Conductivity of Cement Paste and Its Applications

Melting behavior of (Th,U)O2 and (Th,Pu)O2 mixed oxides

Uranium-Induced Changes in Crystal-Field and Covalency Effects of Th4+ in Th1–xUxO2 Mixed Oxides Probed by High-Resolution X-ray Absorption Spectroscopy

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Uranium-Induced Changes in Crystal-Field and Covalency Effects of Th⁴⁺ in Th_1–xU_xO₂ Mixed Oxides Probed by High-Resolution X-ray Absorption Spectroscopy