Claimed embodiments of the integral nuclear reactor relate to nuclear technology and can be used in reactors with different types of heat transfer fluids with a high boiling point, such as, for example, liquid metals, molten salts, etc. Design features of the invention embodiments claimed which have a coil heat exchanger sectioned along the secondary heat carrier circuit provides for an improvement in technical and economic features due to a decrease in metal consumption of the reactor; efficient use of the internal volume of the reactor; improved safety in case of the heat exchanger tube leaks; enabling the removal of residual heat during the time after removal of the protective plug before fuel discharge operations.

Passive safety systems cool reactors using surrounding ground as a heat sink. A coolant flow channel may loop around the reactor and then pass outside, potentially through a containment building, into surrounding ground. No active components need be used in example embodiment safety systems, which may be driven entirely by gravity-based natural circulation. The coolant loop may be air-tight and seismically-hardened and filled with any coolant such as water, air, nitrogen, a noble gas, a refrigerant, etc. The ground may include a soil of grey limestone, soft grey fine sandy clay, grey slightly silty sandy gravel, etc. or any other fill with desired heat-transfer characteristics. Coolant fins and/or jackets with secondary coolants may be used on the coolant loop. The coolant loop may be buried at any constant or variable depth, and the reactor and containment may also be buried in the ground.

A method for the manufacture of Actinium-225 from a Radium-226 containing material. Radium-226 containing starting target material is shielded with a thermal neutron absorption shield and is subjected to neutron irradiation from a moderated nuclear reactor. Radium-226 is thereby converted into Radium-225 to provide a Radium-225-containing material. The Radium-225 in the Radium-225 containing material is allowed to decay into Actinium-225, and the Actinium-225 is isolated from the Radium-225 containing material. The neutron absorption shield shields the starting target material from neutrons having an energy in the range of 20 eV to 1000 eV.

A panel that uses the gamma radiation emitted by fission to produce electrical power. The panel includes layers of a metal with a relatively high atomic number (Z), that form an emitter, a high temperature electrical resistor, and an electrical conductor with a relatively low Z value, that forms a collector. The gamma radiation emitted during the fission process produces Compton and photoelectrical electrons in the layer of the Emitter located between the reactor Baffle and the fuel assemblies. The electrons that have sufficient energy to penetrate the resistor layer between the emitter layer and the collector layer will be stopped in the collector. This creates a substantial voltage difference between the emitter and the collector. This voltage difference may be used to produce significant electric power both during reactor operations and with the reactor shutdown to meaningfully augment the electricity produced by the turbine generators.

Method for the manufacture of Radium-225-containing material from Radium-226-containing materials by subjecting a starting material containing Radium-226 to neutron irradiation from a nuclear reactor to convert .sup.226Ra into Radium-225 to provide a Radium-225-containing material, characterised in that the neutron irradiation of Radium-226-containing starting material is performed in a moderated nuclear reactor; and the Radium-226-containing starting material is shielded with a thermal neutron absorption shield.

In a panel that uses the gamma radiation emitted by fission to produce electrical power, a source of an electrical current is connected to a layer of the panel made of a metal with a relatively high atomic number (Z) that forms an electron emitter. The emitter layer is surrounded by an insulation layer which in turn is surrounded by a relatively low Z value layer for collecting electrons from the emitter. Another layer of insulation and an outer sheath surround the collector. The improved panel may be used for reactor power level and power distribution measurements, and for initiating, maintaining or returning molten salt or metal coolants in the liquid state.

An internal interface structure of a nuclear thermal propulsion nuclear reactor including a reactor vessel and a reactor head, including a substantially cylindrical body having a top end, a bottom end, an inner surface, and an outer surface, and an annular flange extending radially-outwardly from the outer surface of the body, wherein the annular flange of the interface structure is mounted between an upper flange of the reactor vessel and a bottom flange of the reactor head.

An internal interface structure of a nuclear thermal propulsion nuclear reactor including a reactor vessel and a reactor head, including a substantially cylindrical body having a top end, a bottom end, an inner surface, and an outer surface, and an annular flange extending radially-outwardly from the outer surface of the body, wherein the annular flange of the interface structure is mounted between an upper flange of the reactor vessel and a bottom flange of the reactor head.

Passive safety systems cool reactors using surrounding ground as a heat sink. A coolant flow channel may loop around the reactor and then pass outside, potentially through a containment building, into surrounding ground. No active components need be used in example embodiment safety systems, which may be driven entirely by gravity-based natural circulation. The coolant loop may be air-tight and seismically-hardened and filled with any coolant such as water, air, nitrogen, a noble gas, a refrigerant, etc. The ground may include a soil of grey limestone, soft grey fine sandy clay, grey slightly silty sandy gravel, etc. or any other fill with desired heat-transfer characteristics. Coolant fins and/or jackets with secondary coolants may be used on the coolant loop. The coolant loop may be buried at any constant or variable depth, and the reactor and containment may also be buried in the ground.

A panel that uses the gamma radiation emitted by fission to produce electrical power. The panel includes layers of a metal with a relatively high atomic number (Z), that form an emitter, a high temperature electrical resistor, and an electrical conductor with a relatively low Z value, that forms a collector. The gamma radiation emitted during the fission process produces Compton and photoelectrical electrons in the layer of the Emitter located between the reactor Baffle and the fuel assemblies. The electrons that have sufficient energy to penetrate the resistor layer between the emitter layer and the collector layer will be stopped in the collector. This creates a substantial voltage difference between the emitter and the collector. This voltage difference may be used to produce significant electric power both during reactor operations and with the reactor shutdown to meaningfully augment the electricity produced by the turbine generators.