FLiNaK is the name of the ternary eutectic alkaline metal

fluoride Fluoride (). According to this source, is a possible pronunciation in British English. is an inorganic, monatomic anion of fluorine, with the chemical formula (also written ), whose salts are typically white or colorless. Fluoride salts ty ...

salt Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. Salt is present in vast quant ...

mixture LiF- NaF- KF (46.5-11.5-42 mol %). It has a melting point of 454 °C and a boiling point of 1570 °C. It is used as

electrolyte An electrolyte is a medium containing ions that is electrically conducting through the movement of those ions, but not conducting electrons. This includes most soluble salts, acids, and bases dissolved in a polar solvent, such as water. Upon ...

for the

electroplating Electroplating, also known as electrochemical deposition or electrodeposition, is a process for producing a metal coating on a solid substrate through the reduction of cations of that metal by means of a direct electric current. The part to be ...

refractory metals Refractory metals are a class of metals that are extraordinarily resistant to heat and wear. The expression is mostly used in the context of materials science, metallurgy and engineering. The definition of which elements belong to this group d ...

and compounds like

titanium Titanium is a chemical element with the symbol Ti and atomic number 22. Found in nature only as an oxide, it can be reduced to produce a lustrous transition metal with a silver color, low density, and high strength, resistant to corrosion i ...

tantalum Tantalum is a chemical element with the symbol Ta and atomic number 73. Previously known as ''tantalium'', it is named after Tantalus, a villain in Greek mythology. Tantalum is a very hard, ductile, lustrous, blue-gray transition metal that ...

hafnium Hafnium is a chemical element with the symbol Hf and atomic number 72. A lustrous, silvery gray, tetravalent transition metal, hafnium chemically resembles zirconium and is found in many zirconium minerals. Its existence was predicted by Dmitri M ...

zirconium Zirconium is a chemical element with the symbol Zr and atomic number 40. The name ''zirconium'' is taken from the name of the mineral zircon, the most important source of zirconium. The word is related to Persian '' zargun'' (zircon; ''zar-gun'' ...

and their

boride A boride is a compound between boron and a less electronegative element, for example silicon boride (SiB3 and SiB6). The borides are a very large group of compounds that are generally high melting and are covalent more than ionic in nature. Some bo ...

s. FLiNaK also could see potential use as a coolant in the

very high temperature reactor A high-temperature gas-cooled reactor (HTGR), is a nuclear reactor that uses a graphite moderator with a once-through uranium fuel cycle. The HTGR is a type of high-temperature reactor (HTR) that can conceptually have an outlet temperature of ...

, a type of nuclear reactor.

Coolant

FLiNaK salt was researched heavily during the late 1950s by

Oak Ridge National Laboratory Oak Ridge National Laboratory (ORNL) is a U.S. multiprogram science and technology national laboratory sponsored by the U.S. Department of Energy (DOE) and administered, managed, and operated by UT–Battelle as a federally funded research an ...

as potential candidate for a coolant in the

molten salt reactor A molten salt reactor (MSR) is a class of nuclear fission reactor in which the primary nuclear reactor coolant and/or the fuel is a molten salt mixture. Only two MSRs have ever operated, both research reactors in the United States. The 1950's ...

because of its low melting point, its high heat capacity, and its chemical stability at high temperatures. Ultimately, its sister salt,

FLiBe FLiBe is a molten salt made from a mixture of lithium fluoride (LiF) and beryllium fluoride (BeF2). It is both a nuclear reactor coolant and solvent for fertile or fissile material. It served both purposes in the Molten-Salt Reactor Experim ...

, was chosen as the solvent salt for the molten salt reactor due to a more desirable nuclear cross section. FLiNaK still gathers interest as an intermediate coolant for a high-temperature molten salt reactor where it could transfer heat without being in the presence of the fuel.Williams, D. F. (2006)
Assessment of candidate molten salt coolants for the NGNP/NHI Heat-Transfer Loop
/ref> Molten Flinak Salt

Chemistry

Fluoride salts, like all

salts In chemistry, a salt is a chemical compound consisting of an ionic assembly of positively charged cations and negatively charged anions, which results in a compound with no net electric charge. A common example is table salt, with positively c ...

, cause corrosion in most metals and alloys. FliNak is different from FLiBe in the sense that is a basic melt—or it has an excess of fluorine ions. As FLiNak melts, all three components are alkali fluorides and therefore disassociate into positive and negative ions. The concentration of molten fluorine ions are able to corrode any metallic structures if it is energetically favorable. This is in contrast to FLiBe, which in a 66-34 mol% mixture will be a chemically neutral mix, as fluorine ions from LiF are donated to BeF₂ to create the tetrafluoroberyllate ion BeF₄²⁻.

References

{{DEFAULTSORT:Flinak Nuclear materials Electrochemistry Nuclear chemistry Nuclear reactor coolants Fluorides Metal halides Lithium compounds Sodium compounds Potassium compounds Alkali metal fluorides

Coolant

Chemistry

See also

References