Highly purified FLiNaK, FLiBe and other salts

Test salts like FLiNaK and FLiBe, fuel salts like UF4 and ThF4, and enriched lithium delivered as LiF

Copenhagen Atomics is a leading manufacturer of highly purified salts for molten salt reactors, fusion, academic and similar applications.
Salts are provided in purity as low as 20 ppm oxides. Using these purified salts it is possible to significantly eliminate corrosion.
We are providing a number of clean, dry, and pre-melted salts. These salts are:

Highly purified salts

FLiNaK and FLiBe

Fuel salts

Uranium fuel salt (UF4) and Thorium fuel salt (ThF4)

Enriched Lithium

Li-6 salt and Li-7 salt

Molten salt

Highlights

Ships in two
grades, Lab and
Loop grade

Ships is volumes
of 1 kg, 50 kg
and ton scale

Pre-mixed and
pre-melted
pellets or tanks

Less impurity
from moisture,
oxides and
metal traces

10 times less
moisture uptake
compared
to powder

Significantly
less corrosion

The molten salts

Introduction

Copenhagen Atomics has developed purification processes which enables control of the amount of metallic and oxygen containing impurities in our salts, because impurity-driven corrosion is one of the main material degradation mechaninsms in any molten salt system.

Traditionally commercially available FLiNaK salt comes in powder form and needs to be mixed to the eutectic composition, while often containing a large and variable amount of moisture, oxide and metal contaminants.

Therefore, Copenhagen Atomics has de- veloped two high purity grades of FLiNaK salt commercially available. The control of these impurities and pre-mixed product  enable research groups and companies using molten salt to obtain more reliable and consistent data and less corrosion in processes employing molten salts.

Laboratory grade

The highest grade of FLiNaK, suitable for experiments where impurities need to be at a minimum, it has been processed under labour intensive purifying steps to ensure the highest purity by minimising oxides and metal impurities. 

Loop grade

FLiNaK undergoes a time consuming purification process to drive out moisture and oxygen from the salt. Loop Grade is available in large quantities, intended for large testing requirements or molten salt processes in operation.

THE DETAILS

Corrosion and Impurities

Copenhagen Atomics has significantly increased the accuracy of measuring  impurity in FLiNaK salt, by 10% or more.

Metal impurity is measured through ICP OES and oxide impurity through electrochemical techniques.

See the oxide and metal contaminant level in different grade salts in the figure on the right

Increased accuracy of impurity measurement, leads to increased accuracy of measuring corrosion, as corrosion scales with increased moisture, oxide and metal content.

Corrosion rate decreases substantially with FLiNaK salt produced by Copenhagen Atomics.

  • Corrosion rate induced by Copenhagen Atomics’ Loop grade is less than 0.01 mm/y*.
  • Corrosion rate induced by Copenhagen Atomics’ Lab grade is less than 0.005 mm/y*.
  • Corrosion rate induced by commercially available FLiNaK powder is more than 1 mm/year*.
TABLE OF TYPICAL IMPURITIES
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WHY US?

Advantages

of using our salts

Copenhagen Atomics purified salts ships in ingots and canisters.

There is around 10 times the amount of moisture uptake in the powdered salt compared to the ingot at each time interval, when exposing the FLiNaK salt to air measuring the increase in the mass.

It is challenging to ship and handle salts in powder form without introducing moisture. The handling alone will introduce a large amount of moisture that will potentially result in 5 - 10 times more corrosion of steel.

As the use of Copenhagen Atomics’ Loop and Lab grade salts will result in signicantly less corrosion if handled correctly*.

It would be more cost effective to use purified salts from Copenhagen Atomics and stainless steel 316 instead of powder-based salts and more expensive steels, such as Hastelloy N.

*Copenhagen Atomics will provide guidelines on how to handle the salt in order to minimize the oxygen content in your system during loading and operation.

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FAQ

There are many different applications for molten salt. We are building a molten salt reactor and we need a lot of highly purified salt for this. More than 10 tonnes this year alone. Other applications include concentrated solar power, thermal storage, fusion projects and general scientific research on flow, corrosion and more. So we see a growing interest to use this technology and we are happy to make our salts available for the market.

You have to go through a very time consuming and labor intensive process in order to mix the unrefined salt into the eutectic composition. In addition, molten salts that contain a large amount of moisture, oxide and metal contaminants are highly corrosive. We have created a special production method to reduce oxides in the salt to below 20 ppm and from extensive testing we see that this has a great impact on corrosion. Our goal is to supply the highest purified salt for others to focus on their technological development rather than battling corrosion.

No. We supply a great number of salts such as, but not limited to, FLiBe and Chloride Salts.

The salts are offered in three forms. Lab grade for less than 1 kg quantity, 50-100 kg. Canisters and ton scale for industrial use. The containers and the salt-loader, which allows you to load the molten salt in liquid state, are returned after the salt is loaded into your own system. The salt-loader melts the salt and ensures it is kept free from moisture and oxygen during the melting and transfer process. This data is logged digitally and a purity measurement certificate of each canister from the production day will be provided. The transfer happens by pushing the liquid salt from the caister into your tanks by use of pressure through an insulated 6 mm stainless steel pipe. Similar procedures apply to industrial scale deliveries.

Salt from Copenhagen Atomics is highly purified compared to other salts available, especially due to the fact that other commercially available salts are provided in powder form. Not only is it difficult to handle, it also needs to be mixed into the eutectic composition, which is very time and labor consuming, and often contains a large and variable amount of moisture, oxide and metal contaminants. Moreover, there is around 10 times the amount of moisture uptake in the powdered salt compared to this salt due to a lower surface area.

It is possible to use SS316L with these salts and get very low corrosion rates, if the salt is handled in a way where they do not get contaminated and cover gas in the system is also very pure, e.g. less than 50 ppm oxygen in the cover gas. We find that very expensive materials like Hasteloy do not perform much better than SS 316 in such a clean environment. Both the heat exchangers and the pump used in Copenhagen Atomics are also made from SS316L.

Samples received from Copenhagen Atomics are always vacuum packed in special containers to minimize the moisture uptake during transport. It is important to always unpack these inside a glovebox with 100 ppm oxygen and moisture. We can provide sensors which can help monitor this. We provide the salt in bars or in tanks, because this minimizes the moisture uptake per minute by a factor of 10 compared to powder. When you purchase salt from Copenhagen Atomics, we provide instructions on how to handle it to minimize oxygen and moisture exposure while you load the salt, in order to avoid corrosion in your own system.