Load-following nuclear reactor system using thermal expansion-based neutron reflector movement and fuel assembly interval adjustment mechanisms and liquid metal primary coolant

A reduced size nuclear power generation system comprising:

• a reactor core including a plurality of fuel assemblies, wherein
• each fuel assembly is formed from a plurality of fuel rods each prepared by enclosing a metallic fuel into a cladding tube, the metallic fuel containing one or both of
• uranium (U)-235 and U-238, and
• plutonium (Pu)-239;
• a nuclear reactor vessel housing the reactor core;
• a primary coolant including any one of metallic sodium (Na), lead (Pb), tin (Sn), and lead-bismuth (Pb—Bi), the primary coolant being put in the nuclear reactor vessel and heated by the reactor core;
• a reduced size nuclear reactor including
• a neutron reflector arranged around the reactor core in a surrounding fashion, and at least one of a neutron reflector movement mechanism and a fuel assembly interval adjustment mechanism, which are provided in order to control a nuclear reaction in the reactor core, wherein
• the neutron reflector has neutron reflection efficiency which establishes a critical state in the core reactor while maintaining an effective multiplication factor of neutrons radiated from the reactor core equal to or above unity,
• each of the neutron reflector movement mechanism and the fuel assembly interval adjustment mechanism includes a mechanism containing any of a liquid and a gas, which has a larger thermal expansion rate than that of the neutron reflector, and being configured to convert an amount of volume thermal expansion of any of the liquid and the gas into an amount of linear thermal expansion of any of the liquid and the gas,
• the reflector movement mechanism is joined to the neutron reflector and configured to change an interval between the neutron reflector and the reactor core by a displacement attributed to the volume thermal expansion converted into the amount of linear thermal expansion corresponding to a temperature in the nuclear reactor vessel and thereby to change the neutron reflection efficiency,
• the fuel assembly interval adjustment mechanism is joined to a member to set an interval between the plurality of fuel assemblies in the reactor core and configured to change the interval between the plurality of fuel assemblies by the displacement attributed to the volume thermal expansion converted into the amount of linear thermal expansion corresponding to the temperature in the nuclear reactor vessel and to change a neutron effective multiplication factor by using the changed interval, and
• a load-following control depending on the temperature is enabled by at least one of the neutron reflector movement mechanism and the fuel assembly interval adjustment mechanism;
• a secondary coolant;
• a heat exchanger configured to perform heat exchange of heat of the primary coolant heated in the reactor core with the secondary coolant;
• and
• a turbine power generation system configured to convert heat of the secondary coolant into electric power.