The heart of ThorCon is a sealed Can. Each Can contains a 557 MWt reactor, which we call the Pot, a primary loop heat exchanger (PHX), and a primary loop pump (PLP). The pump takes liquid fuelsalt — a mixture of sodium, beryllium, uranium and thorium fluorides called nabe — from the Pot at 704C, and pushes the fuelsalt over to the PHX at a rate of just under 3000 kg/s. Flowing downward through the PHX, the fuelsalt transfers heat to a secondary salt, and is cooled to 564C in the process. The fuelsalt then flows over to the bottom of the Pot, and rises through the reactor core, which is mostly filled with graphite slabs, called a moderator. This moderator slows the neutrons produced by the fissile uranium, allowing a portion of the uranium in the fuelsalt to fission as it rises through the Pot, heating the salt to 704C, and (indirectly) converting a portion of the thorium to fissile uranium. It’s that simple; and that magical.
This sketch shows some of the Can numbers. The Pot pressure is less than 2 bar gauge. The outlet temperature of 704C results in an overall plant efficiency of 45%, and a net electrical output per Can of 250 MW. Each Can consumes 112 kg of fissile uranium per full-power year, about half as much as a light water reactor with the same electrical output. The Can is a cylinder 11.6 m high and 7.3 m in diameter. It weighs about 400 tons. The Can has only one major moving part, the pump rotor.