The photo is sourced from: Flibe Energy
A distinctive feature of the reactor is the use of molten salts as fuel or coolant. The first and so far the only molten-salt reactor was designed at the Oak Ridge National Laboratory founded back in the Manhattan Project days, the United States, in the 1960s. The fuel for the 7.4 megawatt (MW) reactor was uranium fluoride dissolved in salts of lithium, beryllium (a light gray alkaline earth metal), and zirconium (a silver gray metal). Research at the reactor was conducted over five years, but then it was closed because of its low commercial potential.
However, in recent years, the industry’s interest in molten-salt reactors has been growing again. One of the main reasons is their industrial and environmental safety.
Unlike uranium, thorium, does not have a self-sustaining ability to fission. Therefore, in an emergency situation, to stop a thorium reactor, it is enough to stop proton accelerator required for production of high-intensity neutrons, but in case of a conventional uranium reactor, this requires complete unloading of fuel. Molten-salt reactors are also safe: on the one hand, a mixture of molten salts is located in the reactor core under low pressure, which eliminates explosion possibility; on the other, any increase in the operating temperature leads to an increase in the salt mixture density, which, in its turn, results in a slowdown in the reaction and a temperature drop.
The project developed by Flibe Energy involves one more protection mechanism, which is a frozen salt plug installed at the bottom of the reactor vessel: when power is turned off, the plug melts quickly, the melted fuel salt flows into a storage tank, and stops the fission process. This should prevent the risk of a reactor core meltdown.
Another project advantage will be a relatively high level of environmental safety: according to Flibe Energy, thorium and lithium fluoride reactors will generate a thousand times less nuclear waste than light water reactors using ordinary water as a coolant.
Flibe Energy is implementing its project almost simultaneously with the Swiss startup Transmutex, which is going to create a full-fledged commercial analogue of a thorium reactor by the early 2030s. The startup was based on the ideas of Italian scientist Carlo Rubbia, a Nobel laureate and a Global Energy Prize winner, who back in the 1980s proposed to use a proton accelerator for creation of a high-intensity neutron source.