A sparger includes a main pipe connecting inside and outside of a water tank having a storage space therein for storing cooling water, so as to define a flow path through which steam and air containing radioactive materials generated outside the water tank are discharged into the cooling water, a header part connected to one end portion of the main pipe located in the storage space, and having a storage chamber in which the steam and air transferred through the main pipe are collected, and a plurality of discharge nozzles disposed in a spacing manner, each having inlet and outlet formed on one end located in the storage chamber and another end located in the storage space, respectively, to discharge the steam and air from the storage chamber to the storage space, and at least some of the plurality of discharge nozzles protruding from the header part by different lengths.

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 nuclear power plant has a nuclear reactor including a reactor pressure vessel which houses plural fuel rods containing fissile material. The nuclear power plant further has means for submerging the reactor pressure vessel in water and thereby water-cooling the reactor pressure vessel in the event of an emergency requiring cooling of the nuclear reactor. The nuclear power plant further has a primary core catcher outwardly of the reactor pressure vessel, the primary core catcher being formed of a material suitable for retaining molten corium in the event corium escapes the reactor pressure vessel The nuclear power plant further has secondary core catcher outwardly of the primary core catcher, the secondary core catcher lining a tank which is water-filled in normal use of the plant to submerge and thereby water-cool the primary core catcher. The secondary core catcher is also is formed of a material suitable for retaining molten corium in the event corium escapes the primary core catcher.

An integrated passive cooling containment structure for a nuclear reactor includes a concentric arrangement of an inner steel cylindrical shell and an outer steel cylindrical shell that define both a lateral boundary of a containment environment of the nuclear reactor that is configured to accommodate a nuclear reactor and an annular gap space between the inner and outer steel cylindrical shells, a concrete donut structure at a bottom of the annular gap space, and a plurality of concrete columns spaced apart azimuthally around a circumference of the annular gap and extending in parallel from a top surface of the concrete donut structure to a top of the annular gap space. The outer and inner steel cylindrical shells and the concrete donut structure at least partially define one or more coolant channels extending through the annular gap space.

An integrated passive cooling containment structure for a nuclear reactor includes a concentric arrangement of an inner steel cylindrical shell and an outer steel cylindrical shell that define both a lateral boundary of a containment environment of the nuclear reactor that is configured to accommodate a nuclear reactor and an annular gap space between the inner and outer steel cylindrical shells, a concrete donut structure at a bottom of the annular gap space, and a plurality of concrete columns spaced apart azimuthally around a circumference of the annular gap and extending in parallel from a top surface of the concrete donut structure to a top of the annular gap space. The outer and inner steel cylindrical shells and the concrete donut structure at least partially define one or more coolant channels extending through the annular gap space.

A nuclear fuel assembly is constructed with fuel assembly components that are wire wrapped and positioned in hexagonal rings within a fuel assembly duct. The fuel assembly components positioned in an outermost ring of the fuel assembly are wire wrapped with a pitch that is shorter than fuel assembly components positioned at an interior ring of the fuel assembly. The shorter pitch at the outer ring of the fuel assembly increases pressure drop of a coolant fluid at the edge and corner subchannels and thereby reduces the temperature gradient across the fuel assembly, which provides a higher output temperature of the nuclear reactor without substantially increasing peak temperature of the fuel cladding.

A nuclear fuel assembly is constructed with fuel assembly components that are wire wrapped and positioned in hexagonal rings within a fuel assembly duct. The fuel assembly components positioned in an outermost ring of the fuel assembly are wire wrapped with a pitch that is shorter than fuel assembly components positioned at an interior ring of the fuel assembly. The shorter pitch at the outer ring of the fuel assembly increases pressure drop of a coolant fluid at the edge and corner subchannels and thereby reduces the temperature gradient across the fuel assembly, which provides a higher output temperature of the nuclear reactor without substantially increasing peak temperature of the fuel cladding.

An integrated passive cooling containment structure for a nuclear reactor includes a concentric arrangement of an inner steel cylindrical shell and an outer steel cylindrical shell that define both a lateral boundary of a containment environment of the nuclear reactor that is configured to accommodate a nuclear reactor and an annular gap space between the inner and outer steel cylindrical shells, a concrete donut structure at a bottom of the annular gap space, and a plurality of concrete columns spaced apart azimuthally around a circumference of the annular gap and extending in parallel from a top surface of the concrete donut structure to a top of the annular gap space. The outer and inner steel cylindrical shells and the concrete donut structure at least partially define one or more coolant channels extending through the annular gap space.

An integrated passive cooling containment structure for a nuclear reactor includes a concentric arrangement of an inner steel cylindrical shell and an outer steel cylindrical shell that define both a lateral boundary of a containment environment of the nuclear reactor that is configured to accommodate a nuclear reactor and an annular gap space between the inner and outer steel cylindrical shells, a concrete donut structure at a bottom of the annular gap space, and a plurality of concrete columns spaced apart azimuthally around a circumference of the annular gap and extending in parallel from a top surface of the concrete donut structure to a top of the annular gap space. The outer and inner steel cylindrical shells and the concrete donut structure at least partially define one or more coolant channels extending through the annular gap space.