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 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.

Fission reactor has a shell encompassing a reactor space within which are a central longitudinal channel, a plurality of axially extending rings with adjacent rings defining an annular cylindrical space in which a first plurality of primary axial tubes are circumferential located. Circumferentially adjacent primary axial tubes are separated by one of the plurality of secondary channels and a plurality of webbings connects at least a portion of the plurality of primary axial tubes to adjacent structure. A fissionable nuclear fuel composition is located in at least some of the plurality of secondary channels and a primary coolant passes thorough at least some of the primary axial tubes. Additive and/or subtractive manufacturing techniques produce an integral and unitary structure for the fuel loaded reactor space. During manufacturing and as-built, the reactor design can be analyzed using a computational platform that integrates and analyzes data from in-situ monitoring during manufacturing.

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.

Fission reactor has a cladding encasing a heat generating source including a fissionable nuclear fuel composition. The heat generating source is offset from the surface of the cladding and molten metal is located within the void space formed by the offset. As a liquid, the molten metal will flow and occupy any contiguous network of void space within the fuel cavity and provides thermal transfer contact between the heat generating source and the cladding. The cladding separates the heat generating source and the molten metal from the primary coolant volume.

Fission reactor has a cladding encasing a heat generating source including a fissionable nuclear fuel composition. The heat generating source is offset from the surface of the cladding and molten metal is located within the void space formed by the offset. As a liquid, the molten metal will flow and occupy any contiguous network of void space within the fuel cavity and provides thermal transfer contact between the heat generating source and the cladding. The cladding separates the heat generating source and the molten metal from the primary coolant volume.

A method for depositing divalent metal compounds on the surface of a nuclear power plant component, the component being a nickel-based or austenitic stainless steel alloy includes: providing within the component an aqueous treatment solution containing at least one soluble metal-containing compound such as a zinc salt and at least one source of oxygen; allowing the treatment solution to remain in the component until the compound is deposited on the wetted surface of the component; and, removing the aqueous solution after exposure. The treatment may be applied more than once, using more than one divalent metal compound, and the surface may further be exposed to a solution containing a noble metal species and a reducing agent. The treatment temperature is preferably below 100? C.

A method for depositing divalent metal compounds on the surface of a nuclear power plant component, the component being a nickel-based or austenitic stainless steel alloy includes: providing within the component an aqueous treatment solution containing at least one soluble metal-containing compound such as a zinc salt and at least one source of oxygen; allowing the treatment solution to remain in the component until the compound is deposited on the wetted surface of the component; and, removing the aqueous solution after exposure. The treatment may be applied more than once, using more than one divalent metal compound, and the surface may further be exposed to a solution containing a noble metal species and a reducing agent. The treatment temperature is preferably below 100? C.

A nuclear reactor is designed to couple the load path of control elements with the reactor core, thus reducing opportunity for differential movement between the control elements and the reactor core. A core barrel can be fabricated in a manufacturing facility to include the reactor core, control element supports, and control element drive system. The core barrel can be mounted to a reactor vessel head. Movement, such as through seismic forces, transmits an equal direction and magnitude to the control elements and the reactor core, thus inhibiting the opportunity for differential movement.