18 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.

A fuel design for high burnup in water-cooled reactors is disclosed. A nuclear fuel rod comprising an outer zone of annular fuel pellets composed of actinides and fissile material and an interior comprising a low density, high open porosity ceramic foam of zirconia or magnesia is used. Use of annular pellets lowers fuel temperature, reduces fission gas release and fuel swelling. Foam with low crushing strength is used to accommodate fuel swelling. Fresh fuel reactivity is controlled by burnable absorbers such as gadolinia, incorporated as sintered bodies within the foam or as part of the fuel composition or both. The placement of burnable absorber in the foam reduces the contact area with surrounding media, mitigating diffusional transport and preserving its self-shielding characteristic. A novel two-piece foam holder is proposed to insert the ceramic foam.

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.

Nuclear fuel pellet with radially variable enrichment The nuclear fuel pellet is of rotationally symmetrical shape about a central axis (B) and contains a fissile material, the pellet having concentric layers including a proximal layer (20), an intermediate layer (22) and a distal layer (24), in which the enrichment in fissile material within the pellet varies radially, the intermediate layer (22) comprising a high enrichment zone in which the enrichment is strictly greater than the enrichment in the proximal layer (20) and / or the enrichment in the distal layer (24). Figure for abstract: Figure 3

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.

The invention is suitable for the technical field of nuclear detection and embedded systems, and provides an embedded fission chamber assembly and a method for monitoring delayed neutrons thereof.The embedded fission chamber assembly comprises an outer cylinder, the outer cylinder serves as a shell structure of the assembly, a fission chamber body is arranged in the outer cylinder and fixedly installed in the outer cylinder, and the fission chamber body is arranged in the outer cylinder; and the fission chamber main body forms a basic framework of the detection core chamber. The fission chamber main body is internally provided with a gas filling chamber, and the gas filling chamber is used for filling working gas; a collecting electrode and a high-voltage electrode penetrating through the head and the tail are assembled on the collecting electrode in the gas filling chamber, the high-voltage electrode serves as an electric field applying end, and the collecting electrode serves as a signal output end; the outer wall of the collecting electrode and the inner wall of the high-voltage electrode are plated with high-concentration uranium 235 layers; the uranium plating layer serves as a fission material coating and directly participates in nuclear fission reaction caused by neutrons, a large number of fission fragments are generated, and ionization signals are remarkably enhanced. The design of the uranium plating layer can reduce the covering effect of the gamma-ray background on the neutron signal and improve the signal-to-noise ratio of the signal. Double electromagnetic shielding is achieved through the staggered design of the inner shielding layer and the outer shielding layer, external radiation interference and electromagnetic noise are restrained, and the signal distortion rate is reduced.

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.

The method for producing a nuclear fuel is implemented using nuclear elements (2) comprising a fissile material (4) contained within cladding (6), inside a capsule (8) or in a composite material (10) formed by the fissile material dispersed in a matrix (12). The processing method comprises cutting the nuclear elements into fragments (36), reducing the fragments to a powder in order to obtain a powder, and using the powder to manufacture nuclear fuel.

The invention relates to a nuclear fuel pellet having a rotationally symmetrical shape about a central axis (B) and comprising a fission material, the pellet having concentric layers comprising a proximal layer (20), an intermediate layer (22) and a distal layer (24) wherein the degree of enrichment of the fission material within the pellet varies radially, the intermediate layer (22) comprising a region of high degree of enrichment, and the distal layer (24) comprising a region of high degree of enrichment. The degree of enrichment in the high-degree-of-enrichment region is strictly greater than the degree of enrichment in the proximal layer (20) and / or the degree of enrichment in the distal layer (24).

[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

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 include 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.