A transportable nuclear power generator assembly includes a first modular nuclear power generator unit and a second nuclear power generator unit. The first modular nuclear power generator unit includes a first transport container, a first nuclear power module positioned inside the first transport container, and a first supporting mechanism movably supports the first nuclear power module inside the first transport container. The second modular nuclear power generator unit includes a second transport container, a second nuclear power module positioned inside the second transport container, and a second supporting mechanism configured to support the second nuclear power module inside the second transport container. At least one of the first supporting mechanism and the second supporting mechanism is configured to move at least one of the first nuclear power module and the second nuclear power module relative to one another to result in an at least critical state or a subcritical state.

A nuclear fuel powder production plant comprises a conversion installation (2) for the conversion of uranium hexafluoride (UF.sub.6) into uranium dioxide (UO.sub.2) having a hydrolysis reactor (4) for the conversion of UF.sub.6 into uranium oxyfluoride powder (UO.sub.2F.sub.2) and a pyrohydrolysis furnace (6) for converting the UO.sub.2F.sub.2 powder into UO.sub.2 powder. The nuclear fuel powder production plant also includes a packaging unit (20) for the UO.sub.2 powder comprising a filling station (22) having a chamber (26) for receiving a container (24) to be filled, a filling duct (28) supplied from the furnace (6) and a suction system (32) comprising a suction ring (34) disposed at the outlet (30) of the filling duct (28) for sucking an annular air flow (A) around a stream (P) of UO.sub.2 powder falling from the outlet (30) from the filling duct (28) into the container (24).

A nuclear fuel powder production plant comprises a conversion installation (2) for the conversion of uranium hexafluoride (UF.sub.6) into uranium dioxide (UO.sub.2) having a hydrolysis reactor (4) for the conversion of UF.sub.6 into uranium oxyfluoride powder (UO.sub.2F.sub.2) and a pyrohydrolysis furnace (6) for converting the UO.sub.2F.sub.2 powder into UO.sub.2 powder. The nuclear fuel powder production plant also includes a packaging unit (20) for the UO.sub.2 powder comprising a filling station (22) having a chamber (26) for receiving a container (24) to be filled, a filling duct (28) supplied from the furnace (6) and a suction system (32) comprising a suction ring (34) disposed at the outlet (30) of the filling duct (28) for sucking an annular air flow (A) around a stream (P) of UO.sub.2 powder falling from the outlet (30) from the filling duct (28) into the container (24).

An installation for the conversion of uranium hexafluoride (UF.sub.6) to uranium dioxide (UO.sub.2) comprises a hydrolysis reactor (4) for the conversion of UF.sub.6 into uranium oxyfluoride powder (UO.sub.2F.sub.2), a pyrohydrolysis furnace (6) for converting the UO.sub.2F.sub.2 powder supplied by the reactor (4) into UO.sub.2 powder, a supply device (8) comprising reagent injection ducts (10) for the injection of UF.sub.6, water vapor or H.sub.2, and a control system (16) designed to control the supply device (8) so as to supply at least one of the reagent injection ducts (10) with a neutral gas during a shut-down or start-up phase of the conversion installation.

A process is described that includes forming a metal alloy component having a pre-specified three dimensional geometry for use in a nuclear reactor by an additive manufacturing process followed by annealing the formed component at a first annealing temperature within the alpha temperature range of the phase diagram for the metal alloy. A second annealing step at a second annealing temperature lower than the first annealing temperature may be added. Alternatively, annealing may be at an annealing temperature in the alpha+beta temperature range of a phase diagram for the metal alloy, followed by a second anneal in the alpha temperature range of the phase diagram for the metal alloy.

The present disclosure relates to a pellet containing an oxide additive to improve a nuclear-fission-gas-adsorption ability of a uranium-dioxide pellet used as nuclear fuel and increase the grain size thereof, and to a method of manufacturing the same. A La.sub.2O.sub.3—Al.sub.2O.sub.3—SiO.sub.2 sintering additive is added to uranium dioxide so that mass movement is accelerated due to the liquid phase generated during sintering of the uranium-dioxide pellet, which promotes the growth of grains thereof. Further, since less volatilization occurs during sintering due to the low vapor pressure of the liquid phase, efficient additive performance is exhibited, so the liquid phase surrounding the grain boundary effectively adsorbs cesium, which is a nuclear fission gas.

Device for holes and trepans cutting containing a movable platform, a mechanism of rotation and feeding of the cutting tool installed on the platform, a box-shaped repair cabin with a through hole in a vertical wall thereof and, accommodating a positioning sleeve with an inner flange facing the inside of the repair cabin and an outer flange fixed outside the repair cabin. A mounting fixture secured on the inner flange of the positioning sleeve comprises a mounting plate fixed on the inner flange of the positioning sleeve. A rotating positioning plate is pivotally installed on the mounting plate. The mounting plate and the rotating positioning plate are provided with a mechanism for fixing in the closed position. The movable platform is provided with height-adjustable rotatable wheel supports. A catcher is fixed on the outer flange of the positioning sleeve for primary storage of cut trepans and collection of chips.

Device for holes and trepans cutting containing a movable platform, a mechanism of rotation and feeding of the cutting tool installed on the platform, a box-shaped repair cabin with a through hole in a vertical wall thereof and, accommodating a positioning sleeve with an inner flange facing the inside of the repair cabin and an outer flange fixed outside the repair cabin. A mounting fixture secured on the inner flange of the positioning sleeve comprises a mounting plate fixed on the inner flange of the positioning sleeve. A rotating positioning plate is pivotally installed on the mounting plate. The mounting plate and the rotating positioning plate are provided with a mechanism for fixing in the closed position. The movable platform is provided with height-adjustable rotatable wheel supports. A catcher is fixed on the outer flange of the positioning sleeve for primary storage of cut trepans and collection of chips.

A composite moderator medium for nuclear reactor systems and a method of fabricating a composite moderator block formed of the composite moderator medium. The composite moderator medium includes two or more moderators, such as a low moderating material and a high moderating material. The high moderating material has a higher neutron slowing down power compared to the low moderating material. The low moderating material includes a moderating matrix of silicon carbide or magnesium oxide. The high moderating material is dispersed within the moderating matrix and includes beryllium, boron, or a compound thereof. The high moderating material is encapsulated within the low moderating material such that the high moderating material is not exposed outside of the low moderating material. The method can include selecting a sintering aid and a weight percent of the sintering aid in a composite moderator mixture based on the low moderating material and spark plasma sintering.

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.