Motivation for a commercial source of reactor-relevant molten salts.

Next generation reactors offer an opportunity to advance nuclear energy efficiency and safety. Molten salt reactors (MSRs) are one example, where high temperatures (>500°C), highly corrosive environments, the need to isolate systems within an inert atmosphere, and designs that rely on liquid fuel, can make it very difficult to apply traditional diagnostic technologies. Because of the growing government and commercial interest and MS reactor technology advancement, concurrent development of technologies to support effective MSR systems is essential.

High-temperature molten fluoride and chloride salts [1,2] are used as a nuclear reactor liquid fuel [3-6] medium and as a heat transfer fluid in several advanced reactor systems as well as heat storage and heat transfer fluids for concentrated solar power. The design, modeling for design, and operation of these reactor systems require extensive development of the chosen salt system components together with their realistic function in the presence of contaminants.

It is critical for molten salt reactor progress that a commercial source of customer-specified molten salts exist. Furthermore this source must be able to supply well documented salts of precise, but widely varied compositions. Given that molten salt corrosion is very sensitive to low levels of impurities, it is also necessary to supply salts with predetermined and accurately measured impurity concentrations. Potential corrosion is a particular concern in Sodium Cooled Fast Reactors as well as Molten Salt Reactors, two of the major Gen IV small modular reactor designs that are being researched. Standard nitrate based molten salts are readily available, but reactor salts such as FLiNaK, FLiBe, and many others are not practically available; fissile salts are even less available.

Properties of the supplied molten chloride and molten fluoride salts need to be measured at temperatures up to 800°C under strictly controlled conditions. Furthermore, salt purification procedures involve the use of hazardous materials that are best used by an experienced provider. Both of these characteristics make it impractical for researchers to make their own molten salts.

Thoughtventions’ molten salt fabrication and testing program is expected to provide a critical commercial source of precisely specified molten salt for researchers involved in the development of novel molten salt reactor systems.

References

1. Xue-Hui An, Jin-Hui Cheng, Tao Su, et al., “Determination of thermal physical properties of alkali fluoride/carbonate eutectic molten salt,” AIP Conference Proceedings 1850, 070001 (2017)

2. C. Agca, K.E. Johnson, J.W. McMurray, J.A. Yingling, and T.M. Besmann, “FY21 status report on the Molten Salt Thermal Properties Database (MSTDB) development,” ORNL/SPR-2021/2102 (2021)

3. G. Zhu, Y. Zou, R. Yan, et. al., “Low enriched uranium and thorium fuel utilization under once‐through and offline reprocessing scenarios in small modular molten salt reactor,” International Journal of Energy Research · July, pp. 5755-5587, (2019)

4. M.W. Rosenthal, P.R. Kasten, and R.B. Briggs, “Molten salt reactors-history, status, and potential,”. Nucl Appl Technol.;Vol. 8, No. 2, pp. 107‐117.(1970)

5. J. Serp, M. Allibert. O. Benes, et al., “The molten salt reactor (MSR) in generation IV: overview and perspectives,”. Prog. Nucl. Energy, Vol. 77, pp. 308‐319 (2014)

6. T. Abram, S. Ion, “Generation IV nuclear power: a review of the state of the science,” Energy Policy, Vol. 36, No. 12, pp. 4323‐4330, (2008).

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Last updated: May 2025