How we are building our molten salt reactor
Laser induced breakdown spectroscopy
Copenhagen Atomics is developing a LIBS interface for measuring flowing molten salt, enabling real time updates of the isotopic composition of the salt with ppm precision.
LIBS is considered a non-destructive technique – less than one billionth of a gram of material is effected during a typical measurement. Laser pulses generate a high temperature micro-plasma at the lasers focal point. After this excitation, light that is characteristic of the isotopic composition of the material is emitted and analyzed within the spectrometer.
The laser is very powerful and is focused to a microscopic point on the sample and causes virtually no sample heating around the tiny test area. No sample preparation is needed before the measurement can be executed. Furthermore, the method does not require direct physical contact with the sample making it a true remote sensing technique.
Extraction of fission products
Vacuum spraying, developed by Copenhagen Atomics, is an advancement of the traditional helium bubbling method, which allows for a much larger fraction of the fission products to be extracted from the fuel salt than is possible with helium bubbling. Both methods relies on evaporation of noble gases and boiling of volatile fission product compounds for the extraction of fission products.
While far from all fission products are neither noble gasses nor volatile at the operating temperature and pressure of the primary salt in molten salt reactors, a majority of the fission products decay through multiple elements that are. Thus, most fission products can technically be extracted through short lived intermediate states along their decay chain.
The enhanced fission product extraction of vacuum spraying is achieved by increasing the surface to volume ratio and hence increasing the evaporation rate of noble gasses and volatile compounds, and decreasing the ambient pressure to a fraction of atmospheric pressure here by increasing the volatility the majority of the fission products. It's this combination of spraying tiny droplets into a low pressure region, promptly upon leaving the reactor core, that allows for vacuum spraying technology to theoretically extract up to half of the fission products without the need for any online wet chemical reprocessing.
Many of the technologies being developed by Copenhagen Atomics requires testing with flowing molten salts, thus Copenhagen Atomics design and build molten salt loops in-house. Their purpose is to test and validate the designs and technologies that is being pursued by Copenhagen Atomics, such as LIBS salt composition measurements, nozzle spraying for online removal of fission products, and heavy water moderated cores.
Our loops are not built for corrosion testing but rather for rapid prototyping and as such is made from inexpensive stainless steel off-the-shelf parts. Our most recent loop is fitted with a pump and valves that are also designed, built, and tested in-house.
The loops is designed to handle temperatures up to 800 degrees Celsius and has been tested with FLiNaK salt.
Through designing, building, and testing our own loops we gained a lot of experience, experience that we've realized is outside the timeframe of most PhD's and other research projects. Thus, Copenhagen Atomics have just recently decided to make our loops commercially available in the hope that we can help to accelerate the research within the molten salt reactor community and foster new research partnerships.