12 results about "Fissile material" patented technology

Nuclear fuel pellet incorporating thermally conductive inserts in the form of rods distributed at different azimuths and altitudes, fuel rod and associated nuclear fuel assembly. The invention consists of a nuclear fuel pellet (6), comprising: - a straight cylinder (60) of fissile material with a central axis (X) whose length and diameter respectively define the length (H) and diameter (Ø) of the pellet; - a plurality of inserts (8; 80, 81, 82) of thermally conductive material, the inserts being solid rods, distributed at different azimuth and altitude positions within the straight cylinder, and spaced apart from each other. Figure for the abstract: Fig. 4

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.

This invention provides a method for evaluating the properties of fuel debris containing a mixture of nuclear fuels with varying burnup levels. [Solution] The evaluation method includes the step of calculating the fissile material ratio indicating the properties of the fuel debris based on the evaluated values ​​of the Cm-244 count rate and the amount of fissile material of the fuel debris, data showing the correlation between the ratio of the Cm-244 count rate and the amount of fissile material and the fissile material ratio, and / or the evaluated values ​​of the Eu-154 count rate and the amount of fissile material of the fuel debris, data showing the correlation between the ratio of the Eu-154 count rate and the amount of fissile material and the fissile material ratio.

A variable diameter fuel rod of a nuclear reactor assembly is disclosed. The variable diameter fuel rod includes an elongated cladding tube configured to house a plurality of fuel pellets including a fissile material arranged in a fuel stack orientation. The elongated cladding tube includes first and second axial reflector regions and a middle axial region therebetween. The middle axial region comprises an outer diameter defined as d1. The first and second axial reflector regions comprise an outer cladding diameter defined as d2 and d3, respectively. The variable diameter fuel rod further includes a transitional region between the diameter d1 of the middle axial region and the diameter d2 of the axial reflector region. The diameter d2 of the axial reflector region is greater than the diameter d1 of the middle axial region.

A nuclear power plant has a nuclear reactor including a reactor pressure vessel containing a plurality of fuel rods containing fissile material. The nuclear power plant also has means for submerging the reactor pressure vessel in water to thereby water cool the reactor pressure vessel in the event of an emergency requiring cooling of the nuclear reactor. The nuclear power plant also has a primary core catcher located outside the reactor pressure vessel, the primary core catcher being made of a material adapted to retain molten core material in the event that the core material escapes the reactor pressure vessel. The nuclear power plant also has a secondary core catcher outside the primary core catcher, the secondary core catcher being lined with a tank that is filled with water in normal use of the nuclear power plant to submerge the primary core catcher and thereby water cool the primary core catcher. The secondary core catcher is also made of a material adapted to retain molten material in the event that the molten material escapes the first core catcher.

A nuclear fuel pellet incorporating a thermally conductive insert in the form of branching limbs extending from a hollow inner cylinder to the outside of the pellet. The invention essentially consists of a nuclear fuel pellet that incorporates, within a straight cylindrical ring of fissile material, a thermal conductor, particularly metallic, in the form of main branching limbs extending from the inside of the ring outwards, advantageously distributed homogeneously within the ring. The insert formed by its limbs and branches at the macrostructural scale reduces the maximum fuel temperature by several hundred degrees Celsius, depending on its dimensions, constituent material, and the distribution of its limbs within the straight cylindrical fuel ring. Figure for the abstract: Fig. 4

This application provides a hybrid nuclear energy system, including a fusion core adapted to radiate fusion products; a blanket device surrounding the fusion core to receive fusion products, the blanket device being adapted to contain blanket material, including fissile material; a fuel loop connected to the blanket device, the blanket material being adapted to circulate within the blanket device and the fuel loop; a heat exchange module adapted to contain heat exchange material, at least a portion of the fuel loop being located within the heat exchange module or the heat exchange module being at least partially located within the blanket device; and a cooling loop connected to the heat exchange module, the heat exchange material circulating within the heat exchange module and the cooling loop and exchanging heat with the blanket material. This application provides a hybrid nuclear energy system that can improve the system's energy gain factor and has stronger reliability and safety.

[Problem] To provide: a high-temperature gas-cooled reactor fuel capable of immobilizing radioactive cesium, which is produced by nuclear fission in fuel kernels of a high-temperature gas-cooled reactor and released from coated fuel particles, within the high-temperature gas-cooled reactor fuel in a temperature range of room temperature to 1600°C; and a raw material powder to be used for the high-temperature gas-cooled reactor fuel. [Solution] A high-temperature gas-cooled reactor fuel having the function of chemically trapping radioactive cesium comprises: coated fuel particles 6 each including at least a fuel kernel 1 containing a fissile material, a low-density pyrolytic carbon layer 2 coating the fuel kernel 1, and an outer high-density pyrolytic carbon layer 5 coating the low-density pyrolytic carbon layer 2; and a matrix material 7 configured to retain the coated fuel particles 6 and composed of carbon or silicon carbide. Aluminum silicate is added to a raw material powder of the matrix material 7 and / or to a surface of the matrix base material 7.

A nuclear fuel, moderator, and absorber (FMA) assembly provides a mechanism to tailor the fissile material density, moderating power, and neutron absorbing functions at each lateral and axial location within the core; maintains the geometry of the materials required for these functions; retains gaseous fission products, solid fission products, and gaseous phases such as hydrogen as necessary. The FMA concept may be used in many different types of reactors to optimize reactor fuel utilization and safety performance. Advanced methods such as genetic algorithms or other methods that are currently available or become available and the use of artificial intelligence may be used to specify the components, materials, or features of each individual FMA for optimization of reactor core loading that results in superior reactor safety and economic performance. The Fuel Moderator and Absorber (FMA) assembly may be configured to enhance the retention of fission products, allowing siting of nuclear reactors with a minimal Emergency Planning Zone.

A method for producing a fuel kernel is provided. The method comprises producing a dry fissile material comprising enriched uranium, forming a particle from the dry fissile material, the particle having a diameter of 1 millimeter or less; and thermally processing the particle to produce the fuel kernel. A press system for dry fissile material is also provided.

A nuclear fuel pellet incorporating at least one cavity, free of fissile material, with a cross-section in the form of at least one portion of a spiral not opening to the outside of the pellet. Associated manufacturing methods. The invention essentially consists of a fuel pellet (6), comprising: - a straight cylinder (60) of fissile material with central axis (X); - at least one cavity (61; 61.1 to 61.10), free of fissile material, extending over at least part of the length of the pellet, the cavity being shaped and oriented such that its cross-section, right-angled by a transverse plane perpendicular to the central axis X, has the form of at least one portion of at least one spiral, the cavity(ies) being axisymmetric with respect to the central axis X and not opening to the outside of the pellet. Figure for the abstract: Fig. 4

A nuclear fuel pellet incorporating at least one cavity, free of fissile material, with a cross-section in the form of at least one portion of a spiral not opening to the outside of the pellet, and associated manufacturing methods. The invention essentially consists of a fuel pellet (6), comprising: - a straight cylinder (60) of fissile material with central axis (X); - at least one cavity (61; 61.1 to 61.10), free of fissile material, extending over at least part of the length of the pellet, the cavity being shaped and oriented such that its cross-section, right-angled by a transverse plane perpendicular to the central axis X, has the form of at least one portion of at least one spiral, the cavity(ies) being axisymmetric with respect to the central axis X and not opening to the outside of the pellet. Figure for the abstract: Fig. 4