Thorium

Thorium is fertile but not fissile meaning thorium cannot maintain a chain reaction by itself. If a small amount of uranium 233 is introduced it will activate the thorium which will convert the thorium into more U 233 and this is fissile allowing the reaction to continue. As the thorium is used up more is added to keep the reaction going. If the thorium is stopped the reaction stops. Because of the power involved in nuclear fission one pound of thorium can produce the same energy as 5,000 tons of coal and it does so without producing any carbon dioxide. The reactor uses liquid salt. Salts are made from combining metals with non-metals. The best known salt is sodium chloride which is common table salt. Sodium a very active element combines with chlorine a deadly gas to form sodium chloride which is very safe. The salt used in thorium reactors is lithium fluoride. This salt is heated to a liquid and thorium dioxide another salt is added. This liquid salt mixture is circulated in a loop around the reactor and the fission process keeps the liquid salt very hot about 700 degrees C. Adjacent to this loop is another loop that contains lithium fluoride without the thorium dioxide. The heat is transferred from the first loop to the second loop and that loop is used to heat an inactive gas like helium. This heated gas under pressure is used to run the generator to produce electricity. The reactor works under normal pressure so if the power goes off the supply of thorium is shut off and the whole plant shuts down. There can be no melt down like uranium plants. Helium gas is used because if it escapes it poses no problem plus it has a very high specific heat meaning it conducts heat very well making for efficiency in the heat ex-changers.