Abstract: Methods for making nuclear fuel compacts containing precise amounts of nuclear fuel material which exhibit low heavy metal contamination and fewer defective coatings following compact fabrication using a hardenable binder including petroleum pitch or the like. Nuclear fuel particles having a multiple layer fission-product-retentive barrier, with a dense outer layer thereof being surrounded by a protective overcoating, e.g., pyrocarbon having a density between about 1 and 1.2 g/cm.sup.3, that is encapsulated within a thin shell of pyrocarbon from about 1.7 to about 2 g/cm.sup.3 in density, can be precisely metered to create charges containing very precise amounts of nuclear fuel material that can be pre-compacted in molds under relatively high pressures and then combined with the fluid binder which is ultimately carbonized to produce carbonaceous compacts containing very precise nuclear fuel loadings.

Abstract: A microwave traveling-wave production element produces diamond using a chemical vapor deposition (CVD) process. The production element includes a waveguide of a specified length and cross section designed to operate in a specified microwave transmission mode. A microwave oscillator mounted at one end of the waveguide provides microwave energy to the waveguide at a specified frequency for operating in the desired transmission mode. A matched termination load mounted at the other end of the waveguide absorbs the microwave energy that travels through the waveguide and prevents standing waves from being developed within the waveguide. One or more substrate plates are positioned within the waveguide so as to follow a contour of approximately constant tranverse electric field strength. A gaseous mixture, having a composition that promotes the deposition of diamond on the substrate plates, is maintained proximate the substrate plates at a specified pressure.

Abstract: An apparatus to acoustically fluidize a bed of fine particles comprises a generally box-shaped hollow chamber. An acoustic source is located at the bottom of the chamber and a convection inhibiting heater is located at the top of the chamber. An acoustic wave is directed from the source into the chamber to levitate and suspend fine particles within the chamber at determinable distances from the acoustic source according to the intensity and frequency of the acoustic wave.

Abstract: A superconducting transmission line system for transferring electrical power over long distances. The system includes a superconducting transmission line extending from a first location where power is supplied to the line to a second location where electrical power is taken from the line. The line includes an inner tube, and a superconducting core positioned inside the tube and spaced from the inner surface of the tube. The core and the inner tube define a passageway for a cryogenic liquid, the boiling temperature of which is above the superconducting transition temperature of the core. The transmission line system also includes a number of spaced supports holding the transmission line with the portion of the transmission line extending between a pair of adjacent supports being lower than the parts of the line held by the pair of adjacent supports. A regenerator for the cryogenic liquid is mounted on each of the pair of supports.

Abstract: A magnetic field control apparatus for establishing a uniform field of flux for use in magnetic resonance imaging comprises a pair of opposed magnetic poles mounted on end plates of variable thickness. A pair of substantially flat parallel pole faces are attached to the facing surfaces of the magnetic poles. The end plates are supported by connecting members. In addition, there is included a plurality of segments movably mounted to the periphery of the pole face for adjusting the density of the magnetic field. The top and bottom end plates may have substantially identical concave portions on the opposite outside surfaces thereof. The magnetic poles and pole faces are preferably in the shape of thin, flat, circular plates. In one embodiment, there is included one or more inner concentric rings for further adjustably controlling the homogeneity of the uniform magnetic flux in the air gap between the opposing pole faces into which a patient can be inserted for magnetic resonance imaging.

Abstract: A cyclotron autoresonance maser includes an evacuated drift tube with a first end, a second end and an axis. An electron gun introduces a beam of relativistic electrons to the drift tube first end and, for example, a wiggler magnet causes the electrons to gyrate with the gyrations having relatively small radii. A magnetic field generator is provided which forces the beam of relativistic, gyrating electrons to spiral about the axis of the drift tube. The radii of the spirals is large relative to the radii of the gyrations so that the effective interaction length of the electron beam and a maser beam, having an axis substantially coincidental with the axis of the electron beam, is substantially greater than that of a relativistic electron beam and a maser beam which simply cross. A method of generating coherent radiation is also disclosed.

Abstract: A method for making a prestressed concrete article including a cylindrical body surrounded by a cylindrical jacket by joining end walls to the jacket overlying the ends of the article and placing gasket rings between the article and the end walls. A hardenable medium is injected between the jacket and the concrete article and generates a sufficient pressure so as to outwardly bulge the jacket, drawing the end walls together thereby compressing the gaskets.

Abstract: A magnetic resonance imaging magnet has a solenoidal superconducting winding producing a magnetic field and defining an examination region within a bore thereof. The examination region receives a body to be examined. The solenoidal superconducting winding generates a quasi-static magnetic field for aligning atomic nuclei in the body being examined. A two-fold or minimally symmetric ferromagnetic shield has a pair of magnetic flux return paths positioned on opposite sides of the solenoidal superconducting winding for reducing the magnetic field intensity in a region proximate to and outside of the solenoidal superconducting winding. A magnetic field inhomogeneity compensating system reduces magnetic field inhomogeneities introduced into the magnetic field within the examination region by the minimally symmetric ferromagnetic shield to provide a highly uniform quasi-static magnetic field within the examination region.

Abstract: Composites comprising high-temperature fibers reinforcing a carbonous matrix are protected from oxidation by a B.sub.2 O.sub.3 -based glass which includes a refractory oxide to stabilize the viscosity of the glass. Precursors of B.sub.2 O.sub.3 and the refractory oxide are dispersed into a carbon char-yielding material; the material is used to impregnate sheets of fibers; the sheets are laid up as plies; and the laid-up plies are carbonized and graphitized using heat and pressure to form a composite structure. The composite structure is then coated with an additional mix of char-yielding material and precursors, and the coated structure is heated to carbonize the material and leave a seal coat on the structure. Then, an outer coating of a refractory material is deposited on the structure. Oxygen which seeps through the seal coat is initially scavenged at high temperatures by the RO and B.sub.2 O.sub.3 precursors, converting the same to a B.sub.2 O.sub.

Abstract: A nuclear power system comprises a plurality of modules disposed in below-grade pits to provide a compact, self-contained nuclear power supply. The modules are preferably individually transportable so that they may be substantially preassembled prior to installation. The system operates at relatively low temperatures and pressures, and includes various safety features which would prevent radioactive contamination of the surrounding environment in the event of a disturbance causing rupture of one or more of the odules or the pipes interconnecting the modules. The system also provides a low resistance flow path for vapor discharged from the turbine to improve efficiency.

Abstract: A magnet system, having permanently installed power leads, for providing a magnetic field. The system includes a vacuum vessel and a cryogenic containment vessel supported within the vacuum vessel. The containment vessel holds a main coil formed of superconductive wire, along with a quantity of liquid helium to maintain the wire below its critical temperature. The power leads, which supply energy to the coil from a power supply outside the vacuum vessel, also take energy from the coil to a load resistor outside the vacuum vessel when the coil is discharged, each include an elongate metallic tube. The magnet system also includes a solenoid controlled valve which is responsive to the passage of electric current through the tubes of the power leads to cause helium gas resulting from the boiling of liquid helium in the containment vessel to be vented to atmosphere through the tube thereby cooling them.

Abstract: Disclosed is a prestressed tube and a method of its manufacture. The tube includes inner and outer walls with an intermediate nonadhering lamina layer. A pressure medium is fluidically injected through one of the walls to the interface between the nonadhering lamina layer and at least one of the walls so as to form a cavity therebetween for receiving the pressure medium. The medium is thereafter hardened to provide a prestress force to the tube. The method includes the step of fluidically injecting pressure medium between the walls to the intermediate lamina layer and the interface between that layer and at least one of the walls, so as to form a gap therebetween for receiving the pressure medium. During the step, one or both of the walls may be expanded so as to form an enlarged cavity for receiving the pressure medium. The method thereafter includes the step of hardening the pressure medium so as to provide a permanent leak-proof prestress force to the tube.

Abstract: A method and apparatus for separating at least one superconductive phase from a multiphase material which may contain multiple superconductive phases and a normal phase by the use of diamagnetic force. A material containing multiple phases is pulverized into granules approximately the grain size of a selected superconductive phase and is then subjected to a force to cause movement of the particles in a particular direction. The selected superconductive phase is made superconducting by cooling the material below its transition temperature. Diamagnetic force is then generated by an applied magnetic field which deflects and separates the superconducting granules but has substantially no effect on the nonsuperconducting granules. Conversely, the selected superconductive phase has a magnetic field applied to it and then is made superconducting to cause a separation.

Abstract: A combined wheel/brake apparatus employing an electro-rheological fluid. The apparatus includes a wheel rotatably mounted on an axle and a first array of spaced, electrically conductive vanes extending in a first direction with the vanes non-rotatably held by the axle. The apparatus also includes a second array of spaced, electrically and thermally conductive vanes extending in a direction opposite the first direction, with the second and first arrays interdigitated but not contacting. An electro-rheological fluid is in the spaces between the vanes. At least some of the second vanes have a coolant passageway and the apparatus further includes a secondary coolant supply for these passageways. The coolant passageways are isolated from the electro-rheological fluid so that application of an electrical potential across the two array vanes causes an increase in the viscosity of the electro-rheological fluid to develop a braking force, with heat occasioned by the braking being transmitted to the secondary coolant.

Abstract: Apparatus for effecting mass transfer between liquid and gas phases includes a chamber having a tube bundle therein comprised of a plurality of spiral fluted tubes maintained in upstanding relation by transverse tube sheets. Relatively short tubular inserts cooperate with the opposite ends of the spiral fluted tubes in a manner to facilitate passage of liquid downwardly through each tube in the form of a liquid film on the interior spirally fluted tube surfaces, and enable passage of gas upwardly through each tube such that the gas directly contacts the liquid film and effects mass transfer therebetween. Inlet and outlet coolant passages enable coolant to be introduced into the chamber for removing heat of absorption from the external surfaces of the tubes.

Abstract: An improvement in cooling apparatus in a magnet system for providing a localized, substantially homogeneous magnetic field for use in magnetic resonance imaging. The magnet system includes a vacuum vessel, a cryogenic containment vessel inside the vacuum vessel and having a coil of superconductive wire along with a quantity of liquid helium to maintain the wire below its critical temperature. The system also includes an inner thermal radiation shield between the containment vessel and the vacuum vessel and an outer thermal radiation shield between the inner shield and the vacuum vessel. A cryogenic refrigerator is supported by the vacuum vessel and extends inside. This refrigerator has a first-stage heat station cooling the outer shield and second-stage heat station for cooling the inner shield. The improvement includes the provision of a tank holding a quantity of liquid nitrogen.

Abstract: Methods for forming prestressed concrete members wherein a pressure-containing casing is disposed around the outside surface of the concrete member and is spaced therefrom so that a cavity is formed between the casing and the outside surface of the concrete member. A pressurized medium is injected into the cavity between the casing and concrete member at a pressure sufficient to apply the required prestressed compressive force to the outside surface of the concrete member. The pressurized medium changes form by hardening or solidifying after injection. Examples of solid pressurized mediums include cement-like grouts and plastic, and epoxy resin materials. When the concrete member is cast within the casing so as to be in intimate contact with the casing the cavity is then formed by peeling the concrete member and casing away from each other as the pressurized medium is injected therebetween.

Abstract: A magnet system for use in magnetic resonance imaging. The system includes a vacuum vessel having a first wall assembly defining a bore for receiving the subject of the imaging and a pair of spaced metallic end plates welded to the ends of the first wall assembly. The system further includes a cryogenic containment vessel supported within the vacuum vessel and a coil disposed within the containment vessel for providing the magnetic field. The first wall assembly includes a weldable metallic cylindrical shell positioned intermediate the end plates and having a thickness insufficient without reinforcement to provide structural integrity during operation of the vacuum vessel.

Abstract: Methods and apparatus are provided for minimizing heat introduced by electrical leads into the cryogenic liquid in which a superconducting magnet is immersed. The electrical leads have normal portions extending from exterior of the cryogenic liquid containment vessel and thereinto and superconducting portions extending vertically downward therefrom and connected to the magnet. Means are provided to lower and raise the level of cryogenic liquid around the superconducting portions of the leads to fully immerse the supercoducting portions during periods of magnet energization and expose selected segments thereof when the magnet is de-energized. When exposed, the non-immersed segments provide a thermal resistance between the normal metal portions and the cryogenic liquid.

Abstract: A closure hold-down system for a prestressed concrete reactor vessel is disclosed which employs a concrete plug having an annular liner thereon and adapted to be received within the upper open end of a cavity in the reactor vessel. A prestressed concrete retaining ring is mounted on the reactor vessel concentric to the plug through a plurality of circumferentially spaced prestressed tendons anchored directly to the reactor vessel, and engages the concrete plug so that pressure forces acting on the plug from within the cavity are transmitted directly from the plug to the prestressed retaining ring through a contact surface therebetween. An omega seal is disposed between the closure plug and a cavity liner to prevent escape of fluid pressure from the cavity.