A method and system for generating and maintaining a solid structure is provided. The system includes a frame composed of an interconnected network of pipes configured for transporting liquid, the frame having a substantially spherical shape, a plurality of nozzles uniformly distributed along the pipes, wherein the plurality of nozzles are configured for dispensing liquid, a repository that holds a liquid composed of water and at least one additive, a refrigeration unit configured for refrigerating the liquid from the repository to at least a freezing temperature, and a pump for pumping the liquid from the refrigeration unit through the pipes and out of the nozzles, wherein the system is configured to dispense the liquid at said freezing temperature so as to freeze upon egress and create a solid structure surrounding the pipes. The system may also return melted liquid from the solid structure to the repository.

A nuclear reactor is positioned on a barge which floats on the water of a water tank. The water tank includes a bottom wall, first and second end walls and first and second side walls. The bottom wall includes a lower layer of concrete, an intermediate layer of water impervious material positioned on the lower layer of concrete, and an upper layer of concrete positioned on the intermediate layer of water impervious material. Each of the first and second end walls and the first and second side walls includes an outer layer of concrete, an intermediate layer of water impervious material positioned at the inner side of the outer layer of concrete, and an inner layer of concrete material positioned at the inner side of the intermediate layer of water impervious material.

A nuclear reactor is positioned on a barge which floats on the water of a water tank. The water tank includes a bottom wall, first and second end walls and first and second side walls. The bottom wall includes a lower layer of concrete, an intermediate layer of water impervious material positioned on the lower layer of concrete, and an upper layer of concrete positioned on the intermediate layer of water impervious material. Each of the first and second end walls and the first and second side walls includes an outer layer of concrete, an intermediate layer of water impervious material positioned at the inner side of the outer layer of concrete, and an inner layer of concrete material positioned at the inner side of the intermediate layer of water impervious material.

A migration prevention system for radioactive wastewater from an underground nuclear power plant. The underground nuclear power plant includes a nuclear island including an underground cavern group including a reactor cavity and auxiliary cavities. The migration prevention system includes a protective layer coating the reactor cavity and an impermeable layer surrounding the nuclear island. The protective layer includes an inner liner, a drainage layer, and a filling layer of rock fractures in that order. The inner liner is configured to prevent exosmosis of the radioactive wastewater of the reactor cavity. The drainage layer is configured to gather and drain seepage water. The impermeable layer is disposed in the periphery of the underground cavern group including the reactor cavity and the auxiliary cavities, and is configured to isolate the underground cavern group from natural underground water.

A migration prevention system for radioactive wastewater from an underground nuclear power plant. The underground nuclear power plant includes a nuclear island including an underground cavern group including a reactor cavity and auxiliary cavities. The migration prevention system includes a protective layer coating the reactor cavity and an impermeable layer surrounding the nuclear island. The protective layer includes an inner liner, a drainage layer, and a filling layer of rock fractures in that order. The inner liner is configured to prevent exosmosis of the radioactive wastewater of the reactor cavity. The drainage layer is configured to gather and drain seepage water. The impermeable layer is disposed in the periphery of the underground cavern group including the reactor cavity and the auxiliary cavities, and is configured to isolate the underground cavern group from natural underground water.

A method for manufacturing a core barrel according to the embodiment includes: welding one end part of a short ring to a lower core support plate; and machining the lower core support plate to which the short ring is welded. The machining of the lower core support plate includes forming a placement surface on which the fuel assembly is to be placed; and forming a fuel alignment pin hole, in which a fuel alignment pin for positioning the fuel assembly is to be inserted. After the machining of the lower core support plate, a main body barrel is welded to the other end part of the short ring, where the main body barrel covers the reactor core including the fuel assembly to be placed on the placement surface.

A method for manufacturing a core barrel according to the embodiment includes: welding one end part of a short ring to a lower core support plate; and machining the lower core support plate to which the short ring is welded. The machining of the lower core support plate includes forming a placement surface on which the fuel assembly is to be placed; and forming a fuel alignment pin hole, in which a fuel alignment pin for positioning the fuel assembly is to be inserted. After the machining of the lower core support plate, a main body barrel is welded to the other end part of the short ring, where the main body barrel covers the reactor core including the fuel assembly to be placed on the placement surface.

According to a first aspect, there is provided a nuclear fission reactor. The nuclear fission reactor comprises a core, a tank surrounding the core, and a cooling system located outside the tank. The cooling system comprises one or more structures configured to absorb thermal radiation emitted from an outer wall of the tank. The structures are not substantially thermally coupled to the tank except by radiation. The cooling system further comprises a cold air inlet and a hot air outlet, positioned such that air flows from the cold air inlet to the hot air outlet over, around and/or through the one or more structures.

Nuclear reactors have very few systems for significantly reduced failure possibilities. Nuclear reactors may be boiling water reactors with natural circulation-enabling heights and smaller, flexible energy outputs in the 0-350 megawatt-electric range. Reactors are fully surrounded by an impermeable, high-pressure containment. No coolant pools, heat sinks, active pumps, or other emergency fluid sources may be present inside containment; emergency cooling, like isolation condenser systems, are outside containment. Isolation valves integral with the reactor pressure vessel provide working and emergency fluid through containment to the reactor. Isolation valves are one-piece, welded, or otherwise integral with reactors and fluid conduits having ASME-compliance to eliminate risk of shear failure. Containment may be completely underground and seismically insulated to minimize footprint and above-ground target area.

Nuclear reactors have very few systems for significantly reduced failure possibilities. Nuclear reactors may be boiling water reactors with natural circulation-enabling heights and smaller, flexible energy outputs in the 0-350 megawatt-electric range. Reactors are fully surrounded by an impermeable, high-pressure containment. No coolant pools, heat sinks, active pumps, or other emergency fluid sources may be present inside containment; emergency cooling, like isolation condenser systems, are outside containment. Isolation valves integral with the reactor pressure vessel provide working and emergency fluid through containment to the reactor. Isolation valves are one-piece, welded, or otherwise integral with reactors and fluid conduits having ASME-compliance to eliminate risk of shear failure. Containment may be completely underground and seismically insulated to minimize footprint and above-ground target area.