Reactor buildings and vessel systems are disclosed. A nuclear power system includes: a building structure that comprises at least two exterior side walls and two end walls, at least one of the exterior walls angled non-orthogonally relative to a floor of the building structure, the at least two exterior walls and two end walls defining an interior volume of the building structure; one or more nuclear reactor systems mounted at least partially in the interior volume of the building structure; and one or more heat exchanger systems mounted at least partially to at least one of the exterior walls. A nuclear reactor vessel system includes: a nuclear fission reactor; an inner vessel that defines an inner volume sized to at least partially enclose the nuclear fission reactor; and an outer vessel sized to wholly or substantially enclose the inner vessel, the inner vessel being removable from the outer vessel.

The reactor core includes at least one module, a solid neutron moderator, and a liquid neutron moderators. Each module contains a casing, at least one heat pipe, one fuel element and thermal insulation. The heat pipe comprises a casing, a wick, and a coolant. The fuel element is made of nuclear fuel, arranged along an evaporation area of the heat pipe, around the heat pipe casing, in thermal contact with the heat pipe casing, and enclosed in a can. Liquid metals are used as the coolant of the heat pipe. Thermal insulation is arranged between the can and the module casing. At least one hole is made in the solid neutron moderator. Each module is arranged within a respective hole of the solid neutron moderator. The space between the module casing and the solid neutron moderator is filled with a liquid neutron moderator.

The reactor core includes at least one module, a solid neutron moderator, and a liquid neutron moderators. Each module contains a casing, at least one heat pipe, one fuel element and thermal insulation. The heat pipe comprises a casing, a wick, and a coolant. The fuel element is made of nuclear fuel, arranged along an evaporation area of the heat pipe, around the heat pipe casing, in thermal contact with the heat pipe casing, and enclosed in a can. Liquid metals are used as the coolant of the heat pipe. Thermal insulation is arranged between the can and the module casing. At least one hole is made in the solid neutron moderator. Each module is arranged within a respective hole of the solid neutron moderator. The space between the module casing and the solid neutron moderator is filled with a liquid neutron moderator.

Methods of fabricating structures, such as parts for use in nuclear power generation systems, are described herein. A representative method of fabricating a part for a nuclear reactor system includes coating a plurality of particles of a powder of a first material with a second material, and then pressing and/or heating the coated powder into a monolithic structure. The second material can be substantially solidly insoluble with the first material such that, after pressing and/or heating, the particles of the first material define grains of the monolithic structure and the second material substantially encapsulates the grains in the monolithic structure. The first material can be susceptible to corrosion by a select process, and the second material can be resistant to corrosion by the select process such that the bulk first material of the monolithic structure is resistant to corrosion by the select process.

Heat can be stably extracted with easy criticality control. A nuclear reactor includes: a fuel portion being a reactor core having a nuclear fuel body; a shielding portion covering all over outer sides of the fuel portion to shield against radiations generated from the reactor core; and a thermal conduction part that conducts heat generated in the reactor core to exterior of the shield part. The nuclear fuel body contains a fissile material with an enrichment not less than 5% by weight throughout an operation period.

A nuclear reactor core includes at least one module, a solid neutron moderator, and liquid neutron moderator. Each module comprises a housing, at least one heat pipe, at least one fuel element, casing, and thermal insulation. The heat pipe comprises a housing, wick, and evaporating coolant. The fuel element includes a shell and nuclear fuel. An evaporation zone of the heat pipe and the fuel elements are enclosed by the casing. The casing is filled with a liquid coolant. Liquid metal, for example, lithium, calcium, lead, and/or silver, is used as the heat pipe coolant and the liquid coolant. The thermal insulation is arranged in a space between the casing and module housing. The solid neutron moderator has at least one hole, wherein at least one module is located. A space between the solid neutron moderator and module is filled with the liquid neutron moderator.

A nuclear reactor core includes at least one module, a solid neutron moderator, and liquid neutron moderator. Each module comprises a housing, at least one heat pipe, at least one fuel element, casing, and thermal insulation. The heat pipe comprises a housing, wick, and evaporating coolant. The fuel element includes a shell and nuclear fuel. An evaporation zone of the heat pipe and the fuel elements are enclosed by the casing. The casing is filled with a liquid coolant. Liquid metal, for example, lithium, calcium, lead, and/or silver, is used as the heat pipe coolant and the liquid coolant. The thermal insulation is arranged in a space between the casing and module housing. The solid neutron moderator has at least one hole, wherein at least one module is located. A space between the solid neutron moderator and module is filled with the liquid neutron moderator.

A wick assembly for use with a heat pipe is disclosed. The wick assembly includes an end plug including a wick receiving area, a wick, and a crimp. A portion of the wick is positioned about the wick receiving area. The crimp is positioned about the portion of the wick and the wick receiving area. The end plug, the portion of the wick, and the crimp are diffusion bonded.

A wick assembly for use with a heat pipe is disclosed. The wick assembly includes an end plug including a wick receiving area, a wick, and a crimp. A portion of the wick is positioned about the wick receiving area. The crimp is positioned about the portion of the wick and the wick receiving area. The end plug, the portion of the wick, and the crimp are diffusion bonded.

A reactor core block is disclosed including a fuel channel, a heat pipe, a primary moderator matrix configured to encompass the fuel channel and the heat pipe, and a secondary moderator channel configured to at least partially surround the fuel channel, the heat pipe, and the primary moderator matrix. The secondary moderator channel is comprised of metal hydride.