Molten salt coolant for nuclear reactor

A nuclear fission reactor comprising:

• a reactor core, the reactor core comprising one or more containment units containing fissile fuel;
• a primary coolant system comprising a primary coolant, configured such that the primary coolant is in contact with the containment units and removes heat from the reactor core;
• wherein:
• the primary coolant is a molten salt comprising aluminium trifluoride and sodium fluoride;
• the nuclear fission reactor comprises graphite arranged such that the graphite is in contact with the primary coolant during operation of the reactor;
• and
• the nuclear fission reactor comprises a system for providing contact between aluminium metal and the molten salt during operation of the reactor.

A nuclear fission reactor, the reactor comprising:

• a heat exchanger;
• a fuel salt system comprising a reactor core and a fuel salt, and configured such that the fuel salt flows between the reactor core and the heat exchanger;
• wherein:
• the fuel salt is a molten salt comprising aluminium trifluoride, sodium fluoride, and a chloride or fluoride of an element having a fissile isotope;
• the nuclear fission reactor comprises graphite arranged such that the graphite is in contact with the primary coolant during operation of the reactor;
• and
• the nuclear fission reactor comprises a system for providing contact between aluminium metal and the molten salt during operation of the reactor.