In the United States, there is a resurgence of interest in molten salt nuclear reactor technology. One of the very promising players in this market is the startup Elysium Technologies, which develops designs for large-scale reactors with a capacity of 10 MW to 1200 MW.
It is important to note that now the entire Elysium project is more of a political, educational nature, rather than a commercial one. First, experts complain about the undeservedly forgotten concept of molten salt reactors that has been ousted from the industry. They draw an analogy with electric cars, which were invented before the internal combustion engine, but for a century dropped out of sight. Secondly, a small, even tiny, reactor model is better suited for registration with the US Nuclear Regulatory Commission, and the Elysium concept allows such systems to be built cheaply.
Among the advantages, it is indicated that it is a fast neutron reactor, thanks to which it can burn almost any radioactive fuel, including waste and reprocessed weapons-grade plutonium. Elysium burns 95% of the fuel, and its waste is dominated by elements with a complete decay period of 300 years, rather than 10, 000 years, as in other reactors. Working with fast neutrons requires special protection, but most of the processes take place at atmospheric pressure, and not at elevated pressure - the system is safe.
A unique feature of the Elysium reactor is called a "natural emergency valve". It is a section of a pipe with active cooling, which is why a plug of frozen salt is constantly present in it. If an accident occurs and overheating occurs, the contents of the reactor will flow down the pipe, melt the plug and safely pour into passively cooled containers. How it works in reality, engineers promise to show in the near future on a 10-megawatt model, if its construction is approved by the US government.