Kinetic Monte Carlo (KMC) simulation of fission product silver transport through TRISO fuel particle

Bellefon, G. Méric de; Wirth, Brian D.

doi:10.1016/j.jnucmat.2011.04.010

Cited by 24 publications

(9 citation statements)

References 21 publications

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“…Again, ferritic alloys have been the primary object of these studies in neutron irradiation environments, both involving OKMC [187][188][189][190][191][192][193][194] and LKMC [195][196][197], as well as SiC [198][199][200]. Not directly related to fusion but also of interest for irradiated materials is similar work performed on nuclear fuels [201][202][203]. Next, we present results of cascade ageing in tungsten using KMC simulations seeded with defect distributions obtained from cascade simulations as discussed in the previous section.…”

Section: Kmc Simulationsmentioning

confidence: 99%

Recent advances in modeling and simulation of the exposure and response of tungsten to fusion energy conditions

Marian

Becquart

Domain³

et al. 2017

Nucl. Fusion

127

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Under the anticipated operating conditions for demonstration magnetic fusion reactors beyond ITER, structural and plasma facing materials will be exposed to unprecedented conditions of irradiation, heat flux, and temperature. While such extreme environments remain inaccessible experimentally, computational modeling and simulation can provide qualitative and quantitative insights into materials response and complement the available experimental measurements with carefully validated predictions. For plasma facing components such as the first wall and the divertor, tungsten (W) has been selected as the leading candidate material due to its superior hightemperature and irradiation properties, as well as for its low retention of implanted tritium. In this paper we provide a review of recent efforts in computational modeling of W both as a plasmafacing material exposed to He deposition as well as a bulk material subjected to fast neutron irradiation. We use a multiscale modeling approach-commonly used as the materials modeling paradigm-to define the outline of the paper and highlight recent advances using several classes of techniques and their interconnection. We highlight several of the most salient findings obtained via computational modeling and point out a number of remaining challenges and future research directions.

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Section: Kmc Simulationsmentioning

confidence: 99%

Recent advances in modeling and simulation of the exposure and response of tungsten to fusion energy conditions

Marian

Becquart

Domain³

et al. 2017

Nucl. Fusion

127

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“…It is important to note that the Ag diffusion through a pc-SiC may depend not only on the diffusivity in a given GB but also on the microstructure topology, particularly how the GB types are connected to form a network. In this work we focus on estimating D in HEGBs, a specific type of GB, and no model of mesoscale diffusion through a GB network is considered (please see Refs [29,30] for mesoscale transport models). However, since the HEGBs form a percolating network, if they are found to a fast diffusion path we expect these mesoscale effects on the overall measured diffusion coefficient and its activation energy to be relatively minor [29].…”

Section: Introductionmentioning

confidence: 99%

Ag diffusion in SiC high-energy grain boundaries: Kinetic Monte Carlo study with first-principle calculations

Deng

Szlufarska

et al. 2016

Computational Materials Science

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The diffusion of silver (Ag) impurities in high energy grain boundaries (HEGBs) of cubic (3C) silicon carbide (SiC) is studied using an ab initio based kinetic Monte Carlo (kMC) model. This study assesses the hypothesis that the HEGB diffusion is responsible for Ag release in TristructuralIsotropic (TRISO) fuel particles, and provides a specific example to increase understanding of impurity diffusion in highly disordered grain boundaries. The HEGB environment was modeled by an amorphous SiC (a-SiC), which approximately represents the local environments of HEGBs. The structure and stability of Ag defects were calculated using ab initio methods based on Density Functional Theory (DFT). The defect energetics suggested that the fastest diffusion takes place via an interstitial mechanism in a-SiC and that is what is modeled. Interstitial sites were identified by a gridded search and transition states were computed using the climbing image nudged elastic band method. The formation energy of Ag interstitials (relative to bulk Ag) and the Kinetic Resolved Activation (EKRA) energies between them were well approximated with Gaussian distributions that were then sampled in the kMC. The diffusion of Ag was simulated with the effective medium model using kMC. Ag diffusion coefficients were estimated for the temperature range of 1200-1600°C. Ag in a HEGB is predicted to exhibit an Arrhenius type diffusion and with a diffusion prefactor and effective activation energy of (2.73 ± 1.09) × 10 −10 m 2 s −1 and 2.79 ± 0.18 eV, respectively. The comparison between HEGB results to other theoretical studies suggested not only that GB diffusion is predominant over bulk diffusion, but also that the HEGB is one of fastest grain boundary paths for Ag diffusion in SiC. The Ag diffusion coefficient in the HEGB shows a good agreement with ionimplantation measurements, but is 2-3 orders of magnitude lower than the reported diffusion coefficient values extracted from integral release measurements on in-and out-of-pile samples. The discrepancy between GB diffusion and integral release measurements suggests that other contributions are responsible for fast release of Ag in some experiments and we propose that these contributions may arise from radiation enhanced diffusion.

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“…Out-of-reactor experiments used experimental conditions or materials that are very different from real TRISO-coated particles [14][15][16][17] . In simulations, the simulated materials and conditions are significantly different from the real ones [18][19][20][21][22] . For reactor experiments, the concentrations of FPs are usually low and the sizes of FP precipitates can be extremely small, imposing significant challenges on experimental characterization [23,24] .…”

Section: Introductionmentioning

confidence: 93%

Distribution of fission products palladium, silver, cerium and cesium in the un-corroded areas of the locally corroded SiC layer of a neutron irradiated TRISO fuel particle

Wen

Rooyen

2017

Journal of the European Ceramic Society

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Detailed electron microscopy studies were performed to investigate distribution and composition of fission products in the SiC layer of a tristructural-isotropic-coated particle exhibiting localized corrosion. Previous studies on this particle indicated that pure carbon areas in the SiC layer, resulting from localized corrosion of SiC by Pd, provide pathways for Ag, Cd, and Cs migration. This study reveals the presence of Ag-and/or Cd-containing precipitates in uncorroded SiC areas. Ag and Cd may exist by themselves or coexist with Pd. Ag and Cd mainly transport along SiC grain boundaries. An Ag-Pd-Cd precipitate was identified at a stacking fault inside a SiC grain, suggesting that intragranular transport of Ag and Cd is possible. Ce is present with Pd or Pd-U in some precipitates. U and Ce frequently coexist, whereas Ag and Cd usually do not coexist with U or Ce. No Cs was detected in any precipitates in the areas examined.

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Kinetic Monte Carlo (KMC) simulation of fission product silver transport through TRISO fuel particle

Cited by 24 publications

References 21 publications

Recent advances in modeling and simulation of the exposure and response of tungsten to fusion energy conditions

Recent advances in modeling and simulation of the exposure and response of tungsten to fusion energy conditions

Ag diffusion in SiC high-energy grain boundaries: Kinetic Monte Carlo study with first-principle calculations

Distribution of fission products palladium, silver, cerium and cesium in the un-corroded areas of the locally corroded SiC layer of a neutron irradiated TRISO fuel particle

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