Interaction of dislocations in UO2 during high burn-up structure formation

Баранов, В. Г.; Lunev, Artem; Tenishev, A. V.; Khlunov, A. V.

doi:10.1016/j.jnucmat.2013.09.042

Cited by 14 publications

(3 citation statements)

References 30 publications

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“…Uraninite is the most abundant uranium bearing mineral, and is an important economic source of uranium. Dislocations, a type of linear topological defect that act as carriers of plastic strain, are produced by interaction with radiation during burn-up [1,2] and are important for understanding the mechanical properties of UO 2 , especially at low temperatures.…”

Section: Introductionmentioning

confidence: 99%

Peierls-Nabarro modeling of dislocations in UO 2

Skelton

Walker

2017

Journal of Nuclear Materials

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Under conditions of high stress or low temperature, glide of dislocations plays an important role in the deformation of UO 2. In this paper, the Peierls-Nabarro model is used to calculate the core widths and Peierls stresses of ½<110> edge and screw dislocations gliding on {100}, {110}, and {111}. The energy of the inelastic displacement field in the dislocation core is parameterized using generalized stacking fault energies, which are calculated atomistically using interatomic potentials. We use seven different interatomic potential models, representing the variety of different models available for UO 2. The different models broadly agree on the relative order of the strengths of the different slip systems, with the 1/2<110>{100} edge dislocation predicted to be the weakest slip system and 1/2<110>{110} the strongest. However, the calculated Peierls stresses depend strongly on the interatomic potential used, with values ranging between 2.7-12.9 GPa for glide of 1/2<110>{100} edge dislocations, 16.4-32.3 GPa for 1/2<110>{110} edge dislocations, and 6.8-13.6 GPa for 1/2<110>{111} edge dislocations. The glide of 1/2<110> screw dislocations in UO 2 is also found to depend on the interatomic potential used, with some models predicting similar Peierls stresses for glide on {100} and {111}, while others predict a unique easy glide direction. Comparison with previous fully atomistic calculations show that the Peierls-Nabarro model can accurately predict dislocation properties in UO 2 .

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Section: Introductionmentioning

confidence: 99%

Peierls-Nabarro modeling of dislocations in UO 2

Skelton

Walker

2017

Journal of Nuclear Materials

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“…The values of and are not completely known, but Molecular Dynamics simulations obtain a value around 1.4 for the product of the two of them [34].…”

Section: Model Governing Equationsmentioning

confidence: 99%

Model for radiation damage-induced grain subdivision and its influence in U3Si2 fuel swelling

Marquez

Ougouag

Petrović

2020

Annals of Nuclear Energy

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The swelling mechanisms of U3Si2 from neutron irradiation under power reactor conditions are not unequivocally known. The limited experimental evidence that is available suggests that the main driver for swelling in this material would be fission gas accumulation at crystalline grain boundaries. The stages that lead to the accumulation of fission gases at these locations are multiple and complex. However the main mechanism is that, gradually, the gaseous fission products migrate by diffusion. Upon reaching a grain boundary, which acts as a trap, the gaseous fission products accumulate thus leading to formation of bubbles and hence to induced swelling. Therefore, a quantitative model of swelling requires a correct accounting for the presence of grain boundaries and for phenomena and changes that increase their numbers, thus creating sites for bubble formation and growth while concurrently decreasing grain sizes, thus decreasing the effective distance for gas species migration to gas accumulation sites.A model for the subdivision, or recrystallization, of crystal grains is presented. It is assumed that new grain boundary formation results from the conversion of stored energy from accumulated dislocations into energy for local matter rearrangements that create the new grain boundaries hence subdividing the initial grain. The model is applied to grain subdivision in U3Si2, albeit using highly uncertain parameters.. Then the implications of the model are assessed using a swelling modeling code to evaluate the total swelling of a fuel pellet during its lifetime in the I 2 S-LWR reactor, accounting for the influence of grain subdivision.The present model relaxes assumptions from previous models that limit their applicability in the case of the power levels and temperature conditions of the I 2 S-LWR concept. In particular, the new model assumes fully time-dependent conditions and does not postulate equilibrium or steady-state conditions for any population of radiation induced damage structures or the products of their evolution, such as vacancies, interstitials, and dislocations. Unlike others, the present model explicitly accounts for a population of diinterstitials. The model predicts that when a critical fission density is reached, the crystal grains subdivide and new, smaller grains are formed.It is shown that for some plausible, though uncertain, sets of physical parameters, a critical fission density can be reached at which recrystallization can occur in U3Si2, which can then result in the onset of breakaway swelling. It is found that the critical fission density depends strongly on the fission rate density and that it decreases with increases in the fission rate density. The critical fission density is found to display a minimum at intermediate temperatures, which suggest possible fuel performance advantages in operating the reactor in ways that imply higher fuel temperatures.

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“…Cheng and Shehadeh (2006) took the multiscale dislocation dynamics to analyse laser shock peening (LSP) in Si single crystals, and obtained the dislocation mechanism of hard brittle materials. Baranov et al (2014) investigate the distribution of dislocation in oxide nuclear fuel under irradiation using the values of dislocation density from experiments, and they consider the synergistic action of gliding and climbing. The dislocations dynamic can directly revealing the changes of mechanical properties.…”

Section: Introductionmentioning

confidence: 99%

Dislocation dynamic simulation of dislocation pattern evolution in the early fatigue stages of aluminium single crystal

Bai

et al. 2017

IJNM

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Abstract:The two-dimensional discrete dislocation dynamics simulations under fully periodic boundary conditions has been employed to study the dislocation pattern evolution in the early stages of fatigue in aluminium single crystal. Long-range force among of dislocations is solved by line elasticity model, and short-range force is obtained by constitutive equations of dislocation nucleation, slip, pileup and annihilate. Dislocation movement mechanisms of single-slip-oriented and multi-slip systems are simulated and the evolution process of fatigue pattern is revealed. The result shows that dislocation quantity and microstructure strongly depend on external load and internal configuration. The dislocation pattern of single-slip-oriented generate matrix wall, and positive dislocations are vertical alignment and negative dislocations are at the angel of 45° with slip oriented in the initial stage. For multi-slip system, maze structure of dislocations is produced during dislocation multiplication, which eventually transforms into persistent slip band. The result is consistent with the existing experiment.Keywords: the aluminium single crystal; single crystal aluminium; early fatigue stages; dislocation pattern; discrete dislocation dynamics.Reference to this paper should be made as follows: Bai, J., Bai, Q., He, X. and Zhang, Q. (2017) 'Dislocation dynamic simulation of dislocation pattern evolution in the early fatigue stages of aluminium single crystal', Int.

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Interaction of dislocations in UO2 during high burn-up structure formation

Cited by 14 publications

References 30 publications

Peierls-Nabarro modeling of dislocations in UO 2

Peierls-Nabarro modeling of dislocations in UO 2

Model for radiation damage-induced grain subdivision and its influence in U3Si2 fuel swelling

Dislocation dynamic simulation of dislocation pattern evolution in the early fatigue stages of aluminium single crystal

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