Abstract: A method and an apparatus for producing microspherical ceramic particles such as particulate ceramic fuels for use in nuclear reactors. To produce gel particles by performing microwave heating on the small droplets of a stock solution or sol that contains uranium and other elements for nuclear reactor fuels, the small droplets are allowed to fall down through a cavity resonator using microwaves having an engineering frequency of 2.45 GHz and a quartz rod is inserted into or withdrawn out of the resonator to adjust the resonant frequency so that it will lie within the spectrum width of the microwave frequency.

Abstract: A method for mitigating crack initiation and propagation on the surface of metal components in a water-cooled nuclear reactor. An electrically insulating coating is applied on the surfaces of IGSCC-susceptible reactor components. The preferred electrically insulating material is yttria-stabilized zirconia. The presence of an electrically insulating coating on the surface of the metal components shifts the corrosion potential in the negative direction without the addition of hydrogen and in the absence of noble metal catalyst. Corrosion potentials .ltoreq.-0.5 V.sub.she can be achieved even at high oxidant concentrations and in the absence of hydrogen.

Abstract: A nuclear propulsion reactor. A pressure vessel is provided with a reactor core that is surrounded by a radial reflector. Nuclear fuel elements in the core are formed from a hexagonal housing made from a high performance moderator and having a plurality of axial bores that extend the full length of the housing. A stack of nuclear fuel compacts having axial bores for coolant flow is received in the central axial bore of the housing. Hollow lithium hydride slugs are received in the bores at the corners of the housing. A rocket nozzle is attached to one end of the pressure vessel. Coolant/propellant flows into a passageway around the rocket nozzle for cooling thereof, upward through bores in the reflector and through the hexagonal housings of the fuel elements, downward through the bores in the nuclear fuel compacts and then out the rocket nozzle where propulsive thrust is produced.

Abstract: A hydrogenous moderated thermionic nuclear reactor operating in the thermal neutron energy region. Thermionic fuel elements are formed from multiple concentric cylinders. The center cylinder is a combination heat pipe and thermionic converter collector. The second cylinder is the converter emitter. The third cylinder is the nuclear fuel. The outer cylinder is the physical barrier between the fuel element and moderator. Between the outer radius of the fuel and outer cylinder is a gap containing multi-foil insulation. The insulation acts as a thermal barrier between the fuel and the outer cylinder and accommodates fuel expansion. This also causes heat flow to be radially inward from the fuel to the center converter/heat pipe.

Abstract: A core of a light-water reactor comprises a plurality of fuel assemblies each including a number of fuel rods. The fuel rod is provided with at least one area interposed between fuel areas in a clad of the fuel rod. The interposed area contains extremely reduced or substantially no fissile nuclide. At least two areas or layers with high enrichment of the fissile nuclide are formed in the axial direction of the reactor by the location of the interposed areas throughout the whole fuel assemblies arranged in the light-water reactor core.

Abstract: A wear resistant coating (50) for fuel rod cladding (20) comprises a ceramic material (52) which is premixed with a glass (54). The cladding tube is heated and the ceramic/glass mixture is flame sprayed onto the cladding tube. The coating is applied to lower portions of the fuel rods (10) in the area of the first support grid (12) where debris tends to fret the fuel rod.

Abstract: A wear resistant coating (50) for fuel rod cladding (20) comprises a ceramic material (52) which is premixed with a glass (54). The cladding tube is heated and the ceramic/glass mixture is flame sprayed onto the cladding tube. The coating is applied to lower portions of the fuel rods (10) in the area of the first support grid (12) where debris tends to fret the fuel rod.

Abstract: An array of rods is assembled to form a fuel element for a pressurized water reactor, the rods comprising zirconium alloy sheathed nuclear fuel pellets and containing helium.The helium gas pressure is selected for each rod so that it differs substantially from the helium gas pressure in its closest neighbors. In a preferred arrangement the rods are arranged in a square lattice and the helium gas pressure alternates between a relatively high value and a relatively low value so that each rod has as its closest neighbors up to four rods containing helium gas at the other pressure value.