Patent Number: 
Section: claims

1. A reactor core, the reactor core comprising:a solid neutron moderator comprising at least one hole;a liquid neutron moderator; andat least one module, each module of the at least one module comprising:a module casing;thermal insulation positioned within the module casing;one heat pipe having an evaporation area, the one heat pipe comprising a heat pipe casing and a wick and containing a heat pipe coolant; andat least one fuel element comprising nuclear fuel and a can;each module of the at least one module being arranged within a respective hole of the at least one hole of the solid neutron moderator;the one heat pipe being located inside the module casing;the at least one fuel element being located along the evaporation area of the one heat pipe, around the heat pipe casing, in heat contact with the heat pipe casing, and enclosed in the can;the thermal insulation being arranged between the can and the module casing; andthe space between the module casing and the solid neutron moderator being filled with the liquid neutron moderator. 2. The reactor core according to claim 1, characterized in that each module of the at least one module comprises a vacuum located in the module casing. 3. The reactor core according to claim 1, characterized in that the reactor core comprises an inert gas and the module casing of each module of the at least one module is filled with the inert gas. 4. The reactor core according to claim 1, characterized in that the heat pipe coolant is at least one liquid metal. 5. The reactor core according to claim 1, characterized in that the liquid neutron moderator is water. 6. The reactor core according to claim 1, characterized in that the liquid neutron moderator is at least one non-freezing liquid at minus 40° C. 7. The reactor core according to claim 6 characterized in that the nonfreezing liquid is an aqueous alcohol solution. 8. The reactor core according to claim 3 characterized in that the inert gas is xenon. 9. The reactor core according to claim 4 characterized in that the at least one liquid metal is selected from the group consisting of lithium, calcium, lead, and silver. 10. The reactor core according to claim 4 characterized in that the at least one liquid metal comprises a plurality of liquid metals. 11. The reactor core according to claim 10 characterized in that the plurality of liquid metals comprises metals selected from the group consisting of lithium, calcium, lead, and silver. 12. The reactor core according to claim 1 characterized in that the at least one module comprises a plurality of modules and the at least one hole comprises a plurality of holes, each module of the plurality of modules being positioned within a respective hole of the plurality of holes. 13. The reactor core according to claim 12 characterized in that the at least one fuel element of each module of the at least one module is one fuel element. 14. The reactor core according to claim 13 characterized in that the one fuel element comprises a cavity for gaseous fission products of the respective nuclear fuel of the fuel element.