This lecture covers the design and operation of Molten Salt Reactors (MSRs), including the primary, secondary, and ternary circuits, as well as key parameters of the Fuji MSR project and the Molten Salt Fast Reactor (MSFR). It also discusses radiotoxicity in final repositories, fissile nuclides for the Th-U3 cycle startup, and safety aspects related to reactor safety and proliferation resistance. The instructor presents the Aircraft Reactor Experiment (ARE) and the National Centre for Scientific Research proposal for the MSFR. The lecture concludes with an exam schedule and details on the physics of nuclear reactors, including general questions on neutron lifecycle, diffusion theory, reactor kinetics, and reactor design.