Using the Quasi-chemical formalism beyond the phase Diagram: Density and viscosity models for molten salt fuel systems

Flores, Jaén A. Ocádiz; Konings, R.J.M.; Smith, Anna

doi:10.1016/j.jnucmat.2022.153536

Cited by 10 publications

(3 citation statements)

References 49 publications

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“…Ocádiz-Flores et al used a modified quasichemical model of the computer coupling of phase diagrams and thermochemistry (CALPHAD) approach to calculate the NaCl–UCl 3 molten binary system based on Robelin et al Their calculations of the density of molten NaCl–UCl 3 result in good agreement with Desyatnik et al and Mochinaga et al at 1020 K and with our RK model parameters, which were calculated using experimental density data from Desyatnik et al , However, the agreement at higher and lower temperatures will need to be tested. Data from Mochinaga et al have significantly higher thermal expansion terms in their density data on the UCl 3 -rich side, as also shown by an experimental/semi-empirical study from Parker et al and an ab initio molecular dynamics study by Andersson et al Parker et al’s theoretical density plots between molten NaCl–UCl 3 indicate slight positive deviation from ideality, as opposed to negative deviation from RK model results in this study …”

Section: Resultsmentioning

confidence: 64%

Density Measurements of Various Molten Sodium, Magnesium, Potassium, and Uranium Chloride Salt Compositions Using Neutron Imaging

Moon

Andrews

Agca

et al. 2022

Ind. Eng. Chem. Res.

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With an increased interest in the use of molten salts for energy generation, obtaining thermophysical properties of salt mixtures becomes critical for the understanding of salt performance and behavior. Density is one of the significant thermophysical properties of salt systems. This work presents the density measurement of molten chloride salt mixtures using neutron imaging. This work was performed at the Oak Ridge National Laboratory High-Flux Isotope Reactor. Resulting densities as a function of temperature for different molten chloride salts from this work were compared with calculated values using Redlich–Kister modeling. Agreement between the calculated and measured values was within 1–10%, with the exception of the ternary UCl3–NaCl–KCl salt that showed a 32% discrepancy between several literature reports; however, the results did align well with another neutron radiography article. Analysis of the radiographs suggests that microbubbles in the ternary mixture might have biased the density measurements.

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Section: Resultsmentioning

confidence: 64%

Density Measurements of Various Molten Sodium, Magnesium, Potassium, and Uranium Chloride Salt Compositions Using Neutron Imaging

Moon

Andrews

Agca

et al. 2022

Ind. Eng. Chem. Res.

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“…Notably, nonideal mixing can be handled with a modified version of the Katti-Chaudhri rule, which involves determination of excess activation energy and falls within the quasichemical formalism. This mixing has been studied by Flores [12], but only the RK framework is considered in this work. Exact mathematical formalisms are planned to be be released in peer-reviewed journal articles in the future for the work described herein.…”

Section: Progress On Applying Redlich-kister To Viscositymentioning

confidence: 99%

An Overview of the Molten Salt Thermal Properties Database–Thermophysical, Version 2.1.1 (MSTDB-TP v.2.1.1)

Termini¹,

Birri²,

Henderson³

et al. 2023

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This report presents the current status of the Molten Salt Thermal Properties Database-Thermophysical (MSTDB-TP). Building off of MSTDB-TP and through the direction of the Roadmap for Thermal Property Measurement of Molten Salt Reactor Systems [1], MSTDB-TP v2.1.1 has now been released, containing a total 448 salt entries (data from 140+ independent studies), an increase compared with the original commit of 62 [2, 3], and containing thermophysical properties, including density, viscosity, thermal conductivity, and heat capacity. Along with the new database release, the further advancement of Saline, which is a C++ application programming interface, and a graphical user interface have facilitated increased user/developer interaction with the database. Furthermore, estimation techniques, first principles calculations (ab initio), and interpolation/extrapolation methods (Redlich-Kister/Muggianu) have shown great promise in the future of thermophysical property determination for filling out compositional spaces and investigating experimentally difficult salts (hazardous and/or expensive). This report describes the database composition, the development and advancement of database tools, and the strategy of advancing and implementing estimation data into future iterations of the database for MSTDB-TP.

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“…Therefore, experimental efforts across the national laboratory complex and university research laboratories represent only one current strategy to fill gaps in molten salt thermophysical data. First-principles modeling techniques such as ab initio [40,26,33,41,32,31,30,20,12,11,10,39] and semi-empirical approaches such as modified quasi-chemical [38,17] and Redlich-Kister [1,6] methods have been developed and demonstrated to fill some of the gaps as well. If an MSR developer were to utilize such models to hone in on a particular salt mixture and composition of interest, further experimental validation of the models for that particular composition would likely be required for NRC licensing.…”

Section: Introductionmentioning

confidence: 99%

FY23 Progress Report on Viscosity and Thermal Conductivity Measurements of Molten Salts

Birri,

Termini,

Garland

et al. 2023

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As presented in this report, thermal conductivity and viscosity measurements were performed on key chloride pseudo-binary molten salt systems of relevance to molten salt reactor developers. Thermal conductivity measurements were conducted with a variable gap technique, in which a known heat flux is driven across a molten salt specimen and the temperature difference is measured, allowing calculation of the thermal conductivity. This is achieved by establishing a small gap between the bottom of a cylindrical inner containment, which houses electrical heating elements, and an outer containment, which houses cooling channels; the gap size can be varied by compression of a formed bellows. A new calibration scheme was developed herein, involving a correction factor to the heat flux based on He measurements at various temperatures. Furthermore, the data processing methodology was improved to minimize the impact of radiative heat transfer in the calculation of salt specimen thermal conductivity from the temperature difference measurements. Viscosity measurements were conducted with a rolling ball viscometer, in which a ball rolls some known distance in an angled tubular crucible, and the terminal velocity can be used to calculate the viscosity of the salt. The measurement can be performed in a quartz crucible, with which a standard camera can be used to track the ball, or in a metal crucible, with which x-ray radiography is required to track the ball. A new custom x-ray system was made and dedicated to the rolling ball viscometer to enable high throughput automated measurements with salts which require containment with metal. Both systems have been integrated with a ventilation stack which allows for off-gassing of radioactive material, enabling future measurements with U-bearing salts.The thermal conductivity measurements performed herein were with NaCl-KCl (44 mol% NaCl). This salt system was measured in the previous fiscal year, however the thermal conductivity values obtained were comparatively low, and so the system was remeasured with the aforementioned calibration scheme and improved post-processing techniques. The newly obtained thermal conductivity values for NaCl-KCl (44 mol% NaCl) indicate good agreement with kinetic theory and ab-initio models (within 5-10 %). The viscosity measurements performed herein were with three different compositions of NaCl-KCl: 75, 50, and 25 mol% NaCl; a new calibration scheme was applied to account for variable flow effects in the laminar regime. The results show reasonable agreement with literature (5-20 %, depending on the temperature, composition, and study); however, literature values are likely higher than true values based on pure end-member measurements performed in the comparative studies. The measurements conducted herein do show a trend such that viscosity increases with increasing NaCl concentration, which agrees well with one of two comparative studies. In general, the measurements conducted herein gives confidence in the capability to use these systems to accurately m...

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Using the Quasi-chemical formalism beyond the phase Diagram: Density and viscosity models for molten salt fuel systems

Cited by 10 publications

References 49 publications

Density Measurements of Various Molten Sodium, Magnesium, Potassium, and Uranium Chloride Salt Compositions Using Neutron Imaging

Density Measurements of Various Molten Sodium, Magnesium, Potassium, and Uranium Chloride Salt Compositions Using Neutron Imaging

An Overview of the Molten Salt Thermal Properties Database–Thermophysical, Version 2.1.1 (MSTDB-TP v.2.1.1)

FY23 Progress Report on Viscosity and Thermal Conductivity Measurements of Molten Salts

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