An improved xenon equation of state for nanobubbles in UO2

Li, Yang; Wirth, Brian D.

doi:10.1016/j.jnucmat.2022.154089

Cited by 8 publications

(4 citation statements)

References 53 publications

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“…In this section, we derive an EOS for He bubbles in W. We follow a similar approach that was successfully employed in the derivation of an EOS for xenon bubbles in uranium dioxide 43 . Firstly, we derive an EOS for a free He gas.…”

Section: Resultsmentioning

confidence: 99%

Equation of state for He bubbles in W and model of He bubble growth and bursting near W{100} surfaces derived from molecular dynamics simulations

Dasgupta

Blondel

Nandipati

et al. 2023

Sci Rep

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Molecular dynamics (MD) simulations are performed to derive an equation of state (EOS) for helium (He) bubbles in tungsten (W) and to study the growth of He bubbles under a W(100) surface until they burst. We study the growth as a function of the initial nucleation depth of the bubbles. During growth, successive loop-punching events are observed, accompanied by shifts in the depth of the bubble towards the surface. Subsequently, the MD data are used to derive models that describe the conditions that cause the loop punching and bursting events. Simulations have been performed at 500, 933, 1500, 2000, and 2500 K to fit the parameters in the models. To compute the pressure in the bubble at the loop punching and bursting events from the models, we derive an EOS for He bubbles in tungsten with an accompanying volume model to compute the bubble volume for a given number of vacancies ($$N_\text {V}$$ N V ), He atoms ($$N_\text {He}$$ N He ), and temperature (T). To derive the bubble EOS, we firstly derive the EOS for a free He gas. The derived free-gas EOS can accurately predict all MD data included in the analysis (which span up to 54 GPa at 2500 K). Subsequently, the bubble EOS is derived based on the free-gas EOS by correcting the gas density to account for the interaction between He and W atoms. The EOS for the bubbles is fitted to data from MD simulations of He bubbles in bulk W that span a wide range of gas density and sizes up to about 3 nm in diameter. The pressure of subsurface bubbles at the loop punching events as calculated using the bubble-EOS and the volume model agrees well with the pressure obtained directly from the MD simulations. In the loop punching model, for bubbles consisting of $$N_\text {V}$$ N V vacancies and $$N_\text {He}$$ N He helium atoms, the $$N_\text {He}/N_\text {V}$$ N He / N V ratio that causes the event, the resulting increase in $$N_\text {V}$$ N V , and the associated shift of the bubble depth are formulated as a function of $$N_\text {V}$$ N V and T. In the bursting model, a bubble must simultaneously reach a certain depth and $$N_\text {He}/N_\text {V}$$ N He / N V ratio in order to burst. The burst depth and $$N_\text {He}/N_\text {V}$$ N He / N V are also modeled as a function of $$N_\text {V}$$ N V and T. The majority of the loop punching events occur at bubble pressures between 20 and 60 GPa, depending on the bubble size and temperature. The larger the bubble and the higher the temperature, the lower the bubble pressure. Furthermore, our results indicate that at a higher temperature, a bubble can burst from a deeper region.

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Section: Resultsmentioning

confidence: 99%

Equation of state for He bubbles in W and model of He bubble growth and bursting near W{100} surfaces derived from molecular dynamics simulations

Dasgupta

Blondel

Nandipati

et al. 2023

Sci Rep

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“…As summarized in the previous reports [8,12], the number of xenon atoms required to produce a measured number of Xe L-series counts is straightforward to calculate; the volume of the bubble can be estimated to produce an estimated volume, and then the atoms per unit volume is found. From the xenon equation of state [13] and the estimated temperature, the pressure in each bubble can be estimated.…”

Section: Bubble Pressuresmentioning

confidence: 99%

Advanced Multiscale Microscopy Characterization of High Burnup LWR UO<sub>2</sub> Before and After LOCA Testing

McKinney,

Parish,

Werden

et al. 2023

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“…While 4th order optimizations both including and excluding the 3rd order term were pursued, as has recently been performed by Yang and Wirth, (2022) for Xe in UO 2 , the accuracy of the fit to the MD data was not improved. A comparison to the Kaplun…”

Section: Xe Bubble Equation Of State In U-momentioning

confidence: 99%

The reconciliation and validation of a combined interatomic potential for the description of Xe in γU-Mo

Beeler

Zhang

2023

Front. Nucl. Eng.

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A U-Mo alloy has been selected as the fuel design for the conversion of high-performance research reactors in the United States. Efforts are ongoing to describe the fuel evolution as a function of time, for a variety of different reactor conditions. The accurate prediction of fuel evolution under irradiation requires the implementation of correct thermodynamic properties into mesoscale and continuum-level fuel performance modeling codes. Molecular dynamics has proven to be a valuable tool to parameterize or inform these higher-length scale models. However, there are currently inaccuracies in the only available U-Mo-Xe potential, which limits the predictive capabilities of molecular dynamics to inform critical phenomena in these fuel systems such as fission gas swelling. This work provides an updated U-Mo-Xe ternary interatomic potential which combines existing potentials in a reconciled format. The validation of the interatomic potential is performed by analyzing the phase stability and vacancy formation energies. Subsequently, Xe solution energies and an equation of state to describe Xe bubbles in U-Mo are calculated, providing 1) evidence of the significant differences between the prior ternary potential and the currently presented potential, and 2) updated data/tools for implementation into mesoscale simulation methodologies to study fission gas bubble evolution.

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An improved xenon equation of state for nanobubbles in UO2

Cited by 8 publications

References 53 publications

Equation of state for He bubbles in W and model of He bubble growth and bursting near W{100} surfaces derived from molecular dynamics simulations

Equation of state for He bubbles in W and model of He bubble growth and bursting near W{100} surfaces derived from molecular dynamics simulations

Advanced Multiscale Microscopy Characterization of High Burnup LWR UO<sub>2</sub> Before and After LOCA Testing

The reconciliation and validation of a combined interatomic potential for the description of Xe in γU-Mo

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