New model of equiaxed grain growth in irradiated UO2

Khoruzhii, O. V.; Kourtchatov, S.Yu.; Likhanskiǐ, V. V.

doi:10.1016/s0022-3115(98)00632-1

Cited by 16 publications

(7 citation statements)

References 14 publications

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“…With N p constant, the pinning model predicts the unimpeded GB velocity for r p = 1 nm, and it decreases linearly with r p , since P g is now a linear function of r p , as shown in Eq. (49). The effective mobility predicts a velocity higher than the pinning model for very small pore radii, but its velocity decreases quickly with increasing pore radius and drops below the pinning model.…”

Section: Mpmentioning

confidence: 84%

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Mesoscale modeling to inform Bison models of accident tolerant fuel concepts

Aagesen

Andersson

Beeler

et al. 2020

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U 3 Si 2 and doped UO 2 have been under investigation in recent years as potential accidenttolerant fuel concepts. In this report, lower-length scale studies of these fuel concepts carried out during Fiscal Year 2020 are detailed.U 3 Si 2 is a potential accident-tolerant fuel that shows promise due to its high thermal conductivity and higher uranium density relative to UO 2 . However, its swelling and fission gas release behavior in light water reactor (LWR) conditions is relatively unknown. To provide mechanistic insight and determine parameters for engineering-scale fuel performance modeling of pellet-form U 3 Si 2 , phase-field simulations of the growth, interconnection, and venting of intergranular fission gas bubbles were performed. The fractional coverage of the grain boundary and the fraction of bubble area that is vented were calculated as a function of time. From the simulation data, the fractional grain boundary coverage at saturation, an important parameter needed in engineering-scale modeling of swelling and fission gas release, was determined. Multiple simulations were run to determine the uncertainty in the calculated value. The effect of model assumptions and input parameters that are not well known was evaluated. Simulation results are compared to related theoretical and computational work. Based on the simulation results, a value of 0.60 for the fractional grain boundary coverage at saturation is recommended for U 3 Si 2 fuel.Chromium-doped UO 2 is a widely-studied near-term deployable accident-tolerant fuel concept because it results in a dense, large-grain structure that increases the fuel resistance to densification, swelling, and fission gas release. Densification occurs during reactor operation as pores remaining in the fuel from manufacturing shrink and are gradually eliminated. However, grain growth also occurs concurrently with densification and the resulting grain size change affects the densification process. Thus, it is necessary to have a mechanistic, quantitatively accurate model for grain growth as a basis for a densification model. In this report, the development a mechanistic model of grain growth in undoped UO 2 fuel during reactor operation. The model development builds on published experimental data on UO 2 grain growth, as well as atomistic and mesoscale simulation results. We begin by developing new fits with temperature T (in K) for the average grain boundary (GB) energy and mobility in UO 2 using literature data, where the GB energy γ = (1.56 − 5.87 × 10 −4 T ) ± 0.3 J/m 2 and the GB mobility M = (2.14 ± 0.15 × 10 −7 ) exp(−(290 ± 22 kJ/mol)/RT ) m 4 /(Js). We then discuss the pinning of grain boundaries by porosity, including porosity left over after sintering and fission gas bubbles that form during operation. We present our mechanistic model and validate it using existing grain growth data. Finally, we implement the model in the BISON fuel performance code and quantify its impact for constant and transient power cases. Our model produces similar results to an empirical m...

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Section: Mpmentioning

confidence: 84%

“…These depend on the initial grain size and the temperature but are independent of the porosity. Only a few semi-empirical models have been developed for in-reactor grain growth [7,49], and the oldest is still the most commonly used [7]. The predicted grain growth in this model is a function of initial grain size, temperature, and burnup.…”

Section: Introductionmentioning

confidence: 99%

Mesoscale modeling to inform Bison models of accident tolerant fuel concepts

Aagesen

Andersson

Beeler

et al. 2020

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“…frontiersin.org assumed to be the average grain diameter, which is obtained by solving the equation given in the literature (Khoruzhii et al, 1999)…”

Section: Frontiers In Energy Researchmentioning

confidence: 99%

Multiphysics thermo-mechanical behavior modeling for annular uranium-plutonium mixed oxide fuels in a lead-cooled fast reactor

et al. 2022

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Understanding and predicting nuclear fuel behavior is the cornerstone for fuel design and optimization, and the safe and economic operation of nuclear reactors. Due to the excellent neutronic economy and safe operational characteristics of lead/lead-bismuth-based liquid metal coolant, lead-cooled fast reactor (LFR) has received much attention and has been regarded as one of the top candidate reactors for Generation IV nuclear power plants. Mixed oxide (MOX) fuel is beneficial to improve fuel cycle utilization and consume weapons-grade plutonium, among which hollow MOX fuel has excellent heat transfer advantages, which can further improve fuel economy and safety, and has good development prospects. In this work, an annular uranium-plutonium mixed oxide (MOX) fuel operating in a liquid lead/lead-bismuth cooled fast reactor is modeled and simulated to predict its behavior under transient and steady-state operation. This model has several modules working in a fully coupled approach based on COMSOL Multiphysics, such as heat transfer, fuel burnup, oxygen redistribution, plutonium redistribution, porosity evolution, fission gas release, JOG growth, and grain size evolution. The modeling results were benchmarked with the existing codes and experimental data, and the results were in satisfactory agreement. The parameters analysis was carried out in this work. Consistent with the solid MOX fuel, the O/M ratio (or deviation from the stoichiometry of oxygen) significantly affects temperature evolution, fission gas migration and release behavior, and plutonium redistribution. Linear power also has a significant influence on fuel performance.

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“…One of the microstructural features that has an obvious effect on fuel properties and has been extensively studied is the grain size. It is found that grain size has a major influence on fission gas release and fuel swelling rates [3]. At the interfaces of distinct grains, open channels exist, where the diffusion coefficients of fission products drastically change from that in the bulk of the grain, resulting in increased transport and release rates.…”

Section: Introductionmentioning

confidence: 99%

“…Thus, increasing the grain size both increases the diffusion distance from interior-to-boundary and decreases the overall interfacial area, reducing release rates at grain boundaries. This makes fuel microstructure consisting of large grains preferable [3][4][5].…”

Section: Introductionmentioning

confidence: 99%

Non-Destructive Characterization of UO_2+x Nuclear Fuels

Pokharel¹,

Brown²,

Clausen³

et al. 2017

Micros. Today

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This article describes the effect of fabrication conditions on as-sintered microstructures of various stoichiometric ratios of uranium dioxide, UO 2 + x , with the aim of enhancing the understanding of the fabrication process and developing and validating a predictive microstructure-based model for fuel performance. We demonstrate the ability of novel, non-destructive methods such as near-field highenergy X-ray diffraction microscopy (nf-HEDM) and micro-computed tomography (μ-CT) to probe bulk samples of high-Z materials by non-destructively characterizing three samples: UO 2.00 , UO 2.11 , and UO 2.16 , which were sintered at 1450°C for 4 hours. The measured 3D microstructures revealed that grain size and porosity were influenced by deviation from stoichiometry.

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New model of equiaxed grain growth in irradiated UO2

Cited by 16 publications

References 14 publications

Mesoscale modeling to inform Bison models of accident tolerant fuel concepts

Mesoscale modeling to inform Bison models of accident tolerant fuel concepts

Multiphysics thermo-mechanical behavior modeling for annular uranium-plutonium mixed oxide fuels in a lead-cooled fast reactor

Non-Destructive Characterization of UO_2+x Nuclear Fuels

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New model of equiaxed grain growth in irradiated UO2

Cited by 16 publications

References 14 publications

Mesoscale modeling to inform Bison models of accident tolerant fuel concepts

Mesoscale modeling to inform Bison models of accident tolerant fuel concepts

Multiphysics thermo-mechanical behavior modeling for annular uranium-plutonium mixed oxide fuels in a lead-cooled fast reactor

Non-Destructive Characterization of UO2+x Nuclear Fuels

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Non-Destructive Characterization of UO_2+x Nuclear Fuels