Dual fluid reactor
The Dual Fluid Reactor (DFR) is the project of a private German research institute, the Institute for Solid-State Nuclear Physics, combining the advantages of the molten salt reactor with the ones of the liquid metal cooled reactor: The fuel is in a liquid metal or molten chloride salt solution, while the cooling is provided by liquid lead. As a fast breeder reactor, the DFR can burn both natural uranium and thorium, as well as recycle nuclear waste. Due to the high thermal conductivity of the molten metal, the DFR is an inherently safe reactor (the decay heat can be removed passively).
The reactor design won the vote in the German GreenTec Awards of 2013 but the award committee presiding over the awards changed the rules to exclude all nuclear designs before announcing the winner, the DFR participants successfully sued in response to this.
A conceptual predecessor of the DFR was the UK 1970s lead-cooled fast spectrum MSR (MSFR), which was undergoing a design path inclusive of the fissile fuel likewise dissolved in a molten chloride salt, with experimental work undertaken over 1968-73. Funding ceased in 1974.