Effect of excess Mg to control corrosion in molten MgCl2 and KCl eutectic salt mixture

Hanson, Kasey; Sankar, Krishna Moorthi; Weck, Philippe F.; Startt, Jacob; Dingreville, Remi Philippe Michel; Deo, Chaitanya; Sugar, Joshua D.; Singh, Preet M.

doi:10.1016/j.corsci.2021.109914

Cited by 25 publications

(5 citation statements)

References 40 publications

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“…It is well known that highly reactive metals like K, Li, Na, and Mg can promote a reducing environment and thus decrease corrosion in molten chloride salts. , However, metallic K and Na would be problematic in an MSR melt, and Li softens the neutron spectrum for typical chloride salt fast reactors. Thus, for our nominal salt composition, we examined the impact of trace magnesium additions as suggested by Hanson et al on the corrosion potential at 1000 K (Figure ). The equilibrium x CrCl 2 calculations are consistent with Hanson et al and Ding et al in that only a very small quantity of Mg is needed to greatly reduce the formation of CrCl 2 .…”

Section: Resultsmentioning

confidence: 99%

“…7,69 However, metallic K and Na would be problematic in an MSR melt, and Li softens the neutron spectrum for typical chloride salt fast reactors. Thus, for our nominal salt composition, we examined the impact of trace magnesium additions as suggested by Hanson et al 7 on the corrosion potential at 1000 K (Figure 23). The equilibrium x CrCld 2 calculations are consistent with Hanson et al 7 and Ding et al 69 in that only a very small quantity of Mg is needed to greatly reduce the formation of CrCl 2 .…”

Section: Nacl−kcl−crclmentioning

confidence: 99%

“…5 Previous thermodynamic assessments have described the Na−K−U(III) chloride system, 6 which is extended in this work to include CrCl 2 and UCl 4 at relatively low concentrations. The additional constituent MgCl 2 is included as it may be formed during redox control 7 from Mg metal and is seen in investigations of MSR salt compositions, thermodynamics, corrosion studies, and fast spectrum reactor analysis. The highest concentration base salt components for MSR systems are NaCl and KCl, with MgCl 2 and UCl 3 intermediates in content and UCl 4 and CrCl 2 as minor salt constituents.…”

Section: Introductionmentioning

confidence: 99%

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Thermodynamic Assessment of CrCl₂ with NaCl–KCl–MgCl₂–UCl₃–UCl₄ for Molten Chloride Reactor Corrosion Modeling

Yingling

Aziziha

Schorne-Pinto

et al. 2023

ACS Appl. Energy Mater.

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The formation of corrosion species in molten salt reactor systems is driven by the salt redox condition, which can be indicated by the uranium oxidation state ratio (U4+/U3+). In chloride salts, chromium is well known to have the highest tendency to deplete from alloy surfaces; however, no available thermodynamic database suitably represents the effect of trivalent and tetravalent uranium chloride on the corrosion potential. In this work, we extend the Molten Salt Thermal Properties Database–Thermochemical with Gibbs energy models suitable for application to alloy corrosion in chloride molten salt-fueled nuclear reactors. The work required the development of fully constrained thermodynamic models, utilizing the modified quasi-chemical model in the quadruplet approximation for the melt and a single sublattice model for the solid solution phases allowing accurate estimations of thermodynamic properties even in systems for which few thermodynamic data are available. The effort included differential scanning calorimetry (DSC) measurements to find the previously unreported phase equilibria of the CrCl2–UCl3 system and to confirm the equilibria of the MgCl2–UCl3 system. Elemental period correlations allowed the estimation of thermodynamic values for compounds in the NaCl–CrCl2 and KCl–CrCl2 systems allowing a well-informed description of CrCl2 behavior in the compositions of technical interest for the Na–K–Mg–U3+–U4+ chloride salt.

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Section: Resultsmentioning

confidence: 99%

Section: Nacl−kcl−crclmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Thermodynamic Assessment of CrCl₂ with NaCl–KCl–MgCl₂–UCl₃–UCl₄ for Molten Chloride Reactor Corrosion Modeling

Yingling

Aziziha

Schorne-Pinto

et al. 2023

ACS Appl. Energy Mater.

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“…Degradation may occur due to moisture impurities in the salts that drive oxidation. Alloying elements, such as chromium in stainless steel, may be selectively dissolved as it is more thermodynamically favorable to produce stable halide compounds [24]. This causes dealloying and subsequent degradation over time.…”

Section: Limitations Imposed When Measuring Molten Saltsmentioning

confidence: 99%

Use of a Needle Probe to Measure the Thermal Conductivity of Electrically Conductive Liquids at High Temperatures

Ruth,

Merritt,

Munro

2024

Preprint

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This paper considers the necessary conditions for using a derivative of a transient hot wire (termed a needle probe) approach to measure electrically conducting fluids at high temperatures, especially molten halide salts. The focus is on the development of a new theory based on a multi-layer system necessary to ensure electrical isolation of electrical wires from the surrounding fluid. This includes the use of a thin annulus of fluid to minimize convective heat transfer modes within the fluid of interest, which was inspired by the concentric cylinder method. Good measurements require the following considerations: concentricity of the probe and surrounding crucible to ensure a consistent fluid gap, accounting for corrections for deviation of the model at early times, and modeling radiation heat transfer through transparent fluids. Uncertainties are larger than transient hot wire methods because of the deviations from experimental conditions that can easily match an analytical approximation. An appropriate estimation of the measurement uncertainty can be obtained through careful design of the instrumentation, thorough uncertainty analysis, and limiting the measurements to only the applicable thermal property ranges of the approach. The 1D model used to interpret measured temperature data has been shown to be reliable for thermal conductivity measurements ranging from at least 0.39 W/mK to 0.92 W/mK and for temperatures from 293-1023 K. The approach is used to present thermal conductivity data of the molten salts NaCl-KCl (51-49 mol%) and LiCl-NaCl (28-72 mol%).

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“…A vast body of literature exists on corrosion of alloys in molten chloride under various conditions and concentrations of MgOHCl. [27][28][29][30][31][32][33][34][35][36][37] An acceptable threshold of corrosion (⩽20 μm year −1 ) can be obtained when MgOHCl concentration is 1000 ppm or less. 28,37 At these concentrations, corrosion was limited to ∼10 μm year −1 and enabled the use of stainless steel instead of costly Ni super alloys.…”

mentioning

confidence: 99%

Continuous Purification of Molten Chloride Salt: Electrochemical Behavior of MgOHCl Reduction

Witteman

Rippy

2023

J. Electrochem. Soc.

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We present a study on the electrochemical behavior of magnesium hydroxide (MgOH+) reduction on a tungsten (W) cathode in molten chloride salt (MgCl2-KCl-NaCl) across the temperature range of 475-525℃. MgOH+, which forms within the salt upon exposure to moisture, is a leading cause of corrosion. Corrosion is a major barrier to deployment of chloride salts across a number of applications, including concentrating solar power plants and nuclear power plants. While pre-purification protocols have been developed to ensure MgOH+ is removed from molten chloride salts prior to deployment, MgOH+ forms in-situ during operation of chloride-salt based plants. Thus, methods for continuous purification during plant operation are needed. Continuous electrochemical purification via electrolysis using a Mg anode and W cathode has been proposed, but little has been done to assess scalability. Here, we assess fundamental properties of electrochemical removal of MgOH+ to enable future scale up of this method.

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Effect of excess Mg to control corrosion in molten MgCl2 and KCl eutectic salt mixture

Cited by 25 publications

References 40 publications

Thermodynamic Assessment of CrCl₂ with NaCl–KCl–MgCl₂–UCl₃–UCl₄ for Molten Chloride Reactor Corrosion Modeling

Thermodynamic Assessment of CrCl₂ with NaCl–KCl–MgCl₂–UCl₃–UCl₄ for Molten Chloride Reactor Corrosion Modeling

Use of a Needle Probe to Measure the Thermal Conductivity of Electrically Conductive Liquids at High Temperatures

Continuous Purification of Molten Chloride Salt: Electrochemical Behavior of MgOHCl Reduction

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Effect of excess Mg to control corrosion in molten MgCl2 and KCl eutectic salt mixture

Cited by 25 publications

References 40 publications

Thermodynamic Assessment of CrCl2 with NaCl–KCl–MgCl2–UCl3–UCl4 for Molten Chloride Reactor Corrosion Modeling

Thermodynamic Assessment of CrCl2 with NaCl–KCl–MgCl2–UCl3–UCl4 for Molten Chloride Reactor Corrosion Modeling

Use of a Needle Probe to Measure the Thermal Conductivity of Electrically Conductive Liquids at High Temperatures

Continuous Purification of Molten Chloride Salt: Electrochemical Behavior of MgOHCl Reduction

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Thermodynamic Assessment of CrCl₂ with NaCl–KCl–MgCl₂–UCl₃–UCl₄ for Molten Chloride Reactor Corrosion Modeling

Thermodynamic Assessment of CrCl₂ with NaCl–KCl–MgCl₂–UCl₃–UCl₄ for Molten Chloride Reactor Corrosion Modeling