Understanding fission gas bubble distribution, lanthanide transportation, and thermal conductivity degradation in neutron-irradiated α-U using machine learning

2021 ◽  
pp. 111657
Author(s):  
Lu Cai ◽  
Fei Xu ◽  
Fidelma Dilemma ◽  
Jeffrey J. Giglio ◽  
Michael Benson ◽  
...  
Keyword(s):  
Machine Learning ◽  
Thermal Conductivity ◽  
Gas Bubble ◽  
Bubble Distribution ◽  
Fission Gas

scholarly journals Phonon Scattering and Thermal Conductivity of Actinide Oxides with Defects

2020 ◽  
Vol 10 (5) ◽  
pp. 1860 ◽  
Author(s):  
Katherine Mitchell ◽  
Jungkyu Park ◽  
Alex Resnick ◽  
Hunter Horner ◽  
Eduardo B. Farfan
Keyword(s):  
Thermal Conductivity ◽  
Thermal Transport ◽  
Phonon Dispersion ◽  
Temperature Drop ◽  
Gas Bubbles ◽  
Interfacial Thermal Resistance ◽  
Large Temperature ◽  
Gas Bubble ◽  
Fission Gas ◽  
Actinide Oxides

In the present study, we examine the effect of point defects and fission gases on thermal transport in representative actinide oxides used in modern reactors. In particular, oxygen interstitials and Kr/Xe fission gas bubbles are of primary focus. Reverse non-equilibrium molecular dynamics is employed to investigate thermal transport in UO2 and PuO2 with oxygen interstitials at the defect concentrations of 0.1%, 1%, and 5%. The results show that any alteration to the lattice structures of these fuels reduce their thermal conductivities significantly. For the largest UO2 structure simulated in the present study, for example, 0.1% oxygen interstitials decreased the thermal conductivity by 18.6%. For the case of the effect of fission gas bubbles, serious modification to phonon dispersion in oxide fuels is caused by the presence of a single fission gas bubble, resulting in a large temperature drop in their temperature profiles. The average interfacial thermal resistance across a fission gas bubble (comprised of 30 Kr and/or Xe atoms) is estimated to be 2.1 × 10−9 Km2/W.

Modelling Fission Gas Bubble Distribution in UO2

2012 ◽  
Vol 323-325 ◽  
pp. 209-214 ◽  
Author(s):  
Richard Skorek ◽  
Serge Maillard ◽  
Amélie Michel ◽  
Gaëlle Carlot ◽  
Eric Gilabert ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Thermal Desorption Spectroscopy ◽  
Release Mechanism ◽  
Gas Bubble ◽  
Release Process ◽  
Second Stage ◽  
Bubble Distribution ◽  
Fission Gas ◽  
Simulation Results ◽  
Dynamics Method

The Cluster Dynamics method is assessed for the investigation of fission gas behaviour in a krypton-implanted and annealed UO2sample. The simulation results are then compared to Thermal Desorption Spectroscopy (TDS) data. A release mechanism is proposed: the initial burst is related to krypton migration via an interstitial mechanism, while the second stage of the release process can be accounted for by the diffusion of krypton in a substitutional position. This latter mechanism is compatible with a diffusion coefficient of 4.10-21m²/s.

Atomistic Level Molecular Dynamics Analysis and its Integrity in the Interim of Irradiation

2021 ◽  
Vol 318 ◽  
pp. 39-47
Author(s):  
Ahli K.D. Willie ◽  
Hong Tao Zhao ◽  
M. Annor-Nyarko
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Mixed Oxide ◽  
Md Simulation ◽  
Lattice Thermal Conductivity ◽  
Gas Diffusion ◽  
Mixed Oxide Fuel ◽  
Fission Gas ◽  
Increasing Temperature ◽  
End Members

In this work, molecular dynamics (MD) simulation was utilized in relation to access the thermal conductivity of UO2, PuO2 and (U, Pu)O2 in temperature range of 500–3000 K. Diffusion study on mixed oxide (MOX) was also performed to assess the effect of radiation damage by heavy ions at burnup temperatures. Analysis of the lattice thermal conductivity of irradiated MOX to its microstructure was carried out to enhance the irradiation defects with how high burnup hinders fuel properties and its pellet-cladding interaction. Fission gas diffusion as determined was mainly modelled by main diffusion coefficient. Degradation of diffusivity is predicted in MOX as composition deviate from the pure end members. The concentration of residual anion defects is considerably higher than that of cations in all oxides. Depending on the diffusion behavior of the fuel lattice, there was decrease in the ratio of anion to cation defects with increasing temperature. Besides, the modern mixed oxide fuel releases fission gas compared to that of UO2 fuel at moderate burnups.

Recrystallization and fission-gas-bubble swelling of U–Mo fuel

2013 ◽  
Vol 436 (1-3) ◽  
pp. 14-22 ◽  
Author(s):  
Yeon Soo Kim ◽  
G.L. Hofman ◽  
J.S. Cheon
Keyword(s):  
Gas Bubble ◽  
Fission Gas
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