High-Accuracy Method for Measuring the Specific Heat Capacity of Molten Salts: Application to the FLiNaK and NaCl-MgCl2 Eutectics

High-Accuracy Method for Measuring the Specific Heat Capacity of Molten Salts: Application to the FLiNaK and NaCl-MgCl2 Eutectics | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article High-Accuracy Method for Measuring the Specific Heat Capacity of Molten Salts: Application to the FLiNaK and NaCl-MgCl2 Eutectics Juliano Schorne-Pinto, Aiswarya Padinhare Manissery, Ronald E. Booth, and 5 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9431226/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 6 You are reading this latest preprint version Abstract Specific heat values for molten salts are essential for thermal-hydraulic analysis, reactor physics calculations, and thermochemical modeling of molten salt reactors. However, achieving reduced measurement uncertainty requires rigorous control of experimental conditions, high-precision calorimetric instrumentation, and a maximized sample-to-crucible mass ratio. This study presents a procedure for high-accuracy measurement of the specific heat (c P ) of air-sensitive molten salts using a Calvet-type DSC with a small temperature step method and custom laser-welded lightweight hermetic nickel crucibles. Instrument reproducibility of 1.54% (k = 2) was achieved and validated through independent triplicate measurements of a NIST SRM720 sapphire standard. Using this methodology, the c P of molten 46.5LiF-11.5NaF-42KF mol% (FLiNaK) and 58NaCl-42MgCl2 mol% (NaCl-MgCl2) eutectics was determined with expanded uncertainties (k = 2) of 1.74% and 1.93%, respectively, for high-purity samples, incorporating regression contributions. These results confirm previously reported positive excess heat capacities in both eutectics, with an improved description of the temperature dependence. The measured data provide reference values for the Molten Salt Database - Thermochemical, and the protocol is readily transferable to other molten salts, including actinide-bearing fuel salts. Heat capacity molten salts eutectic FLiNaK NaCl-MgCl2 DSC Calvet calorimetry crucible design Full Text Additional Declarations No competing interests reported. Supplementary Files MethodforMeasuringtheSpecificHeatCapacityofMoltenSaltsSI.docx Cite Share Download PDF Status: Under Review Version 1 posted Reviewers agreed at journal 04 May, 2026 Reviewers agreed at journal 02 May, 2026 Reviewers invited by journal 16 Apr, 2026 Editor assigned by journal 16 Apr, 2026 Submission checks completed at journal 16 Apr, 2026 First submitted to journal 15 Apr, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9431226","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":624516878,"identity":"536c3db6-c150-42fb-b75f-f0baf783f57c","order_by":0,"name":"Juliano Schorne-Pinto","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA9klEQVRIiWNgGAWjYBACxgbmhgMgBj8QH3jYABNnw6eFEaJFEqj6QCIxWkCawJQBSCNRWphnJDYe+LnDxt742uGHBxJ32CQ28B9+wPCh7DBuO2YkNhzsPZOWuO12msGBxDNpxgwSaQaMM87h13KAt+1wgtntBKCWtsNyDBI8DMxAEfy2/G07bG88O/0DSAsPA/8ZBua/BLQcBprJuEE6B2oLQw4DMyM+LT0PGw7LtqUlzridUwD2CxvQLwd7zqXj1GLYnnz449s2G3v+2embP3wEhlg//+GHD36UWePW0oAuAoqRAzjVA4E8PslRMApGwSgYBWAAALY3X6s/rsY0AAAAAElFTkSuQmCC","orcid":"","institution":"University of South Carolina","correspondingAuthor":true,"prefix":"","firstName":"Juliano","middleName":"","lastName":"Schorne-Pinto","suffix":""},{"id":624516883,"identity":"20fc66ea-8d00-4ab7-aee4-b4420eefbd79","order_by":1,"name":"Aiswarya Padinhare Manissery","email":"","orcid":"","institution":"University of South Carolina","correspondingAuthor":false,"prefix":"","firstName":"Aiswarya","middleName":"Padinhare","lastName":"Manissery","suffix":""},{"id":624516884,"identity":"1bd41a69-cdd9-4e95-993f-8b2f3f3fef06","order_by":2,"name":"Ronald E. 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However, achieving reduced measurement uncertainty requires rigorous control of experimental conditions, high-precision calorimetric instrumentation, and a maximized sample-to-crucible mass ratio. This study presents a procedure for high-accuracy measurement of the specific heat (c\u003csub\u003eP\u003c/sub\u003e) of air-sensitive molten salts using a Calvet-type DSC with a small temperature step method and custom laser-welded lightweight hermetic nickel crucibles. Instrument reproducibility of 1.54% (k = 2) was achieved and validated through independent triplicate measurements of a NIST SRM720 sapphire standard. Using this methodology, the c\u003csub\u003eP\u003c/sub\u003e of molten 46.5LiF-11.5NaF-42KF mol% (FLiNaK) and 58NaCl-42MgCl2 mol% (NaCl-MgCl2) eutectics was determined with expanded uncertainties (k = 2) of 1.74% and 1.93%, respectively, for high-purity samples, incorporating regression contributions. 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