scholarly journals An analysis of the impact of having uranium dioxide mixed in with plutonium dioxide

10.2172/9433 ◽  
1998 ◽  
Author(s):  
R.M. MARUSICH
Keyword(s):  
Uranium Dioxide ◽  
Plutonium Dioxide ◽  
The Impact

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.

Molecular Dynamics Simulation of the Impact of Fission Fragment Energy Deposition on Ion Tracks in Uranium Dioxide

2015 ◽  
Vol 1743 ◽  
Author(s):  
Jonathan L. Wormald ◽  
Ayman I. Hawari
Keyword(s):  
Molecular Dynamics ◽  
Uranium Dioxide ◽  
Energy Deposition ◽  
Md Simulations ◽  
Dynamics Simulation ◽  
Atomic Lattice ◽  
Ion Tracks ◽  
Fission Fragments ◽  
Enhanced Mobility ◽  
The Impact

ABSTRACTIn fission based nuclear reactors, uranium dioxide fuel is subject to an intense neutron environment that drives the fission chain reaction. In this process, fission fragments will be produced with an energy reaching 1 MeV/amu. These fragments will initially lose energy through inelastic interactions resulting in excitations of the electronic structure. The excitations subsequently transfer energy to the atomic lattice through electron-phonon (e-p) coupling resulting in a thermal spike which may enhance mobility of fuel atoms. Consequently, the enhanced mobility resulting from fission energy deposition is expected to promote annealing of lattice defects such as ion tracks. Classical molecular dynamics (MD) simulations of uranium dioxide were performed using the LAMMPS code to investigate the effects of fission enhanced mobility on ion tracks formed in the fuel. The MD model was composed of 10×60×60 unit cells, 432000 atoms, and used a Buckingham potential to describe interatomic interactions. A two-temperature model was used to capture the process of fission energy deposition in the electronic subsystem and its transfer to the atomic lattice through e-p coupling. Previous MD simulations demonstrated that fission-enhanced diffusion became more pronounced as the electronic system behavior was varied from metal-like to insulator-like, i.e., increasing the e-p coupling strength. In the present MD simulations, the annealing of an existing ion track (radius nearly 3.0 nm) due to the interaction with 18 keV/nm and 22 keV/nm fission fragments was observed. For a metal-like system (weak e-p coupling), it was found that the track persisted with a radius of nearly 3.0 nm. For an insulator-like system (strong e-p coupling), it was found that the track can be reduced significantly in size approaching a radius of 1.4 nm.

Pyrochemical reduction of uranium dioxide and plutonium dioxide by lithium metal

2002 ◽  
Vol 300 (1) ◽  
pp. 15-26 ◽  
Author(s):  
T Usami ◽  
M Kurata ◽  
T Inoue ◽  
H.E Sims ◽  
S.A Beetham ◽  
...  
Keyword(s):  
Uranium Dioxide ◽  
Lithium Metal ◽  
Plutonium Dioxide
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