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.

Abstract: A method and apparatus for clearing thermal barrier regions of trapped ions in a tandem mirror fusion reactor apparatus utilizing a bend at each end of the cylindrical plasma chamber within which bend the thermal barrier is positioned. Ions trapped in said thermal barrier are caused by said bend to drift in a direction perpendicular to the incident magnetic field and the direction of centrifugal force, such that said ions are enabled to be collected in a divertor positioned along said ion drift path.

Abstract: A photovoltaic-electrolytic unit is provided to produce an electric current from solar energy and utilize the current to produce hydrogen by the electrolysis of water. The unit floats in an aqueous medium so that photoelectric cells are exposed to solar radiation, and electrodes submerged in the medium produce oxygen which is vented and hydrogen which is collected in the unit.

Abstract: A transition joint is disclosed for joining together tubular pieces formed respectively from a low alloy or carbon steel and a high temperature alloy composition including approximately 20% chromium, the transition joint including a plurality of tubular parts welded together and formed from standard code-approved materials of selected composition with a maximum variation in chromium content of approximately 2-5% between adjacent parts when the chromium content is below approximately 10% and a maximum chromium content variation of approximately 3-7% between adjacent transition parts when the chromium content of either part is above approximately 10% in either part, the transition parts being joined by friction welding and/or fusion welding and/or formed entirely by fusion welding deposition.

Abstract: A transition joint is disclosed for joining together tubular pieces formed respectively from a low alloy or carbon steel and a high temperature alloy composition having substantially different characteristics such as coefficient of thermal expansion, the transition joint including a plurality of tubular parts interconnected with each other by means of friction weld joints formed at an angle of 90.degree. to the axis of the transition joint, the tubular parts at opposite ends of the transition joint being selected to facilitate in situ welding to the low alloy or carbon steel and high temperature alloy respectively.

Abstract: Methods and apparatus for plasma generation, confinement and control such as Tokamak plasma systems are described having a two layer field shaping coil system comprising an inner coil layer close to the plasma and an outer coil layer to minimize the current in the inner coil layer.

Abstract: A reusable thermally actuated linkage arrangement includes a first link member having a longitudinal bore therein adapted to receive at least a portion of a second link member therein, the first and second members being sized to effect an interference fit preventing relative movement therebetween at a temperature below a predetermined temperature. The link members have different coefficients of thermal expansion so that when the linkage is selectively heated to a temperature above the predetermined temperature, relative longitudinal and/or rotational movement between the first and second link members is enabled. Two embodiments of a thermally activated linkage are disclosed which find particular application as actuators for a grapple head positioning arm in a nuclear reactor fuel handling mechanism to facilitate back-up safety retraction of the grapple head independently from the primary fuel handling mechanism drive system.

Abstract: Relatively dry hydrogen iodide can be recovered from a mixture of HI, I.sub.2 and H.sub.2 O. After the composition of the mixture is adjusted so that the amounts of H.sub.2 O and I.sub.2 do not exceed certain maximum limits, subjection of the mixture to superatmospheric pressure in an amount equal to about the vapor pressure of HI at the temperature in question causes distinct liquid phases to appear. One of the liquid phases contains HI and not more than about 1 weight percent water. Often the adjustment in the composition will include the step of vaporization, and the distinct layers appear following the increase in pressure of the vapor mixture. Adjustment in the composition may also include the addition of an extraction agent, such as H.sub.3 PO.sub.4, and even though the adjusted composition mixture contains a significant amount of such an agent, the creation of the distinct liquid phases is not adversely affected.

Abstract: Apparatus is disclosed for generating electrical pulses in response to rotation of a shaft. The apparatus incorporates an internal optical disc carried by a hub assembly attached to the operating shaft, with the hub assembly having a beveled bearing surface at one end thereof for engaging a similarly beveled surface of the apparatus housing, and biasing means for biasing the hub assembly toward said housing beveled surface to compensate for mechanical wear and to also minimize erratic movement of the optical disc. The combination of a light emitting diode and photo-transistor generate electrical signals in response to the blocking and transmitting of light through radially oriented opaque segments of the disc during rotation. The light emitting diodes and photo-transistors are retained by receptacles which snap fit within cooperating apertures of the housing.

Abstract: A two-stage process for the catalytic decomposition of H.sub.2 SO.sub.4 wherein H.sub.2 SO.sub.4 in vapor form is contacted in a first stage with a platinum group metal catalyst at temperatures between about 700.degree. K. and 970.degree. K. The platinum group metal catalyst is supported on a substrate of titania, barium sulfate, zirconia, silica, zirconium silicate or a mixture thereof, and at least about 40 percent of the H.sub.2 SO.sub.4 is decomposed to SO.sub.2. Vapors from the first stage enter a second stage where they contact a copper oxide and iron oxide catalyst at a temperature above 970.degree. K. The second stage catalyst is supported on a substrate of barium sulfate, zirconium oxide or titanium oxide.

Abstract: A spirally fluted metallic heat transfer tube is disclosed wherein the finished tube has improved heat transfer performance through the provision of a predetermined number range of multiple start continuous helical flutes formed along its longitudinal length, the flutes having specific helix angle relation and flute height to tube hydraulic diameter ratio so as to establish a ratio of thermal diffusivity to momentum diffusivity greater than 1.

Abstract: A nuclear reactor core assembly is described in which a plurality of fuel elements and a plurality of blanket elements are arranged in a core assembly. Conduit means direct fluid coolant through the fuel elements and through the blanket elements. The conduit means which direct the coolant through the blanket elements have flow restrictor means therein comprising a plurality of surface roughened elements for limiting the flow of coolant through the blanket elements. The flow restrictor means have a static configuration such that at shutdown, the percentage of coolant flow through the blanket elements compared with the total coolant flow is substantially greater than the percentage of coolant flow through the blanket elements during full power operation.

Abstract: A nuclear reactor system is described wherein a prestressed concrete reactor vessel is provided with a main cavity for the reactor core and at least one subsidiary cavity for a steam generator. At least two feedwater penetrations are provided in the reactor vessel communicating between the exterior of the reactor vessel and the subsidiary cylindrical cavity. A superheater penetration is provided aligned with the axis of the cavity with the feedwater penetrations and the superheater penetration having mutually parallel axes. Superheater outlet means are positioned in the superheater penetration and include a tubesheet positioned a substantial distance from both the subsidiary cylindrical cavity and the exterior of the reactor vessel.

Abstract: A toroidal plasma device has a toroidal confinement vessel defining a toroidal space and confining ionized gas therein. A solenoid which links the toroidal space induces a toroidal electric field therein to produce plasma current. A plurality of first windings are wound substantially helically around the vessel substantially equally spaced around its minor circumference. A plurality of second windings are wound substantially helically around the vessel substantially midway between successive first windings. Direct current is passed through the respective first and second windings in opposite directions with the current in the respective first and second windings equal or slightly unbalanced. The currents in the first and second windings produce a helical magnetic field.

Abstract: The cavity within a pressure vessel for a gas-cooled nuclear reactor is divided into chambers by an intermediate support floor, with the reactor core thereabove and heat-exchangers therebelow. Separate heat-exchange units are connected to separate circulators which discharge the repressurized primary gas coolant through an annular passageway along the inner surface of the pressure vessel cavity. The heat extraction system includes a separate secondary gas coolant circuit connected to each heat-exchange unit, which coolant may be heated to about 850.degree. C. at which it is suitable to provide process heat. Emergency cooling is effected by a heat dump which is connected into each secondary circuit to promptly provide low-temperature secondary gaseous coolant which then indirectly removes the reactor core heat.

Abstract: A vapor generator is described wherein cross-over loops joining two different tube bundles are positioned in a stagnant area out of the flow of the heating fluid, thus reducing the tube metal temperatures in a highly stressed area. Tube anchor devices are provided to reduce expansion movement and stresses while permitting some relative movement and providing support during seismic disturbances.

Abstract: An improved optical card reader is disclosed which is adapted for use with processing means for providing on-the-fly decoding of multibit data words from a card that is inserted therein. The card reader has two sets of light emitting means and two sets of light detecting means and the light detecting means are interconnected to provide a single set of outputs to comparators which measure the signal levels and provide distinct digital outputs. Selective energization of the light emitting means provides effective multiplexing of two multibit data words from a single set of outputs.

Abstract: In a heat exchanger such as a steam generator for a nuclear reactor, two or more bundles of helically coiled tubes are arranged in series with the tubes in each bundle integrally continuing through the tube bundles arranged in series therewith. Pitch values for the tubing in any pair of tube bundles, taken transverse to the path of the reactor coolant flow about the tubes, are selected as a ratio of two unequal integers to permit efficient operation of each tube bundle while maintaining the various tube bundles of the heat exchanger within a compact envelope. Preferably, the helix angle and tube pitch parallel to the path of coolant flow are constant for all tubes in a single bundle so that the tubes are of approximately the same length within each bundle.

Abstract: Methods and apparatus for plasma impurity control in toroidal plasma systems such as Tokamak plasma systems is disclosed which utilize an axisymmetrical plasma diffusion pump system.