Abstract: A nuclear reactor start-up method of starting up a boiling water reactor which is in the cold shut-down state. The method includessetting a subcooled temperature of a coolant in a reactor core inlet to a range smaller than a critical subcooled temperature which is determined by the condition whereby the coolant starts boiling in the reactor core and the condition whereby the instability due to a periodic variation of buoyancy begins,thereafter starting an increase of power of the reactor.

Abstract: A toroidal fusion device with an elongated axial cross section is described which is capable of ignition without auxiliary heating and with modest toroidal magnetic field. The device is based on the principle that for elongated toroids the toroidal current density in the plasma at ignition is subject to a limit which is proportional to the product of the elongation and the toroidal magnetic field. The elongation is made greater than about 4. The aspect ratio is preferably between about 3 and 10.

Abstract: A magnetically confined helical z-pinch plasma is formed as a helicoid having an approximately D-shaped cross section, thereby generating a large transform of magnetic field line pitch suitably distributed throughout the plasma volume to aid in the reversal of field lines in the axial direction and increase magnetic shear.

Abstract: A metal conduit assembly for interconnecting the discharge duct of the pump and the inlet coolant duct or reactor core in a pool-type nuclear reactor. The conduit assembly comprises an upper section for connection to the discharge of a reactor pump, a lower section for connection with the coolant inlet duct with reactor core and a third intermediate tubular section for interconnecting the other two sections. Joint means are provided for interconnecting one end of the intermediate section with an adjoining end at the upper section and an opposite end of the intermediate section with an adjoining end of the lower section. The joint means comprises a male portion having a ridge provided with a circumferential groove for receiving a seal means and an associated female portion having an inside diameter greater than that of the ridge for receiving said male portion and a seal means.

Abstract: A compensating valve arrangement is connected between a throttling direction control valve or proportioning valve which controls fluid flow from a pressure source to a load. The compensating valve is provided with a pressure reducing valve, check valves and throttling points between the pressure supply and the control piston of the compensating valve to compensate for surges, prevent sudden driving of the load and prevent leakage.

Abstract: A piston made of cast aluminum base alloy is provided with gudgeon pin bosses which are connected to the piston skirt by means of a frusto-conical strut which has recesses in the skirt and are specially dimensioned to leave large unsupported skirt areas to minimize risk of seizure in an engine cylinder; in particular the distance between the outer surfaces of the bosses is from 0.6 to 0.8 of the outer diameter of the piston and the distance between the inner surfaces of the bosses is 25 to 35 percent of the outer diameter of the piston, and the cone angle of the struts is from 60.degree. to 110.degree..

Abstract: A winch system comprising a cable drum coupled with a reversible hydromotor and a reversible hydropump arranged with the hydromotor in a closed circuit by means of two communication conduits, in which a safety circuit connecting the communication conduits with one another at the occurrence of pressure shocks therein is arranged and provided with one controllable relief pressure valve, whose inlet and outlet are connected with each one of the communication conduits through non-return valves allowing supply to and, respectively, drainage from the relief pressure valve.

Abstract: A roof reflector for a small, high temperature reactor with a hot gas collector space arranged above the roof reflector comprises a side reflector arranged under the roof reflector around a reactor core with a thermal side shield arranged around both the side reflector and the roof reflector. The roof reflector is composed of individual, mutually supporting, wedge-shaped graphite blocks and is supported on the thermal side shield by means of springingly elastic fastening elements in a radially expandable manner.

Abstract: A signal valve (38) is connected to a supply conduit (16) connecting a pump (11) with a control valve (14) for transmitting an artificial load signal to a load signal chamber (34) of a pressure compensated unloader valve (27) when the control valve is at an operating position and the pressure in the supply conduit (16) is below a preselected value. This moves a valve member (31) of the unloader valve (27) to a blocking position causing essentially full pump flow to be directed to the hydraulic jack for decreasing the response time in situations wherein the hydraulic jack has cavitated and no positive load pressure signal is present.

Abstract: Depolarization mechanisms arising from the recycling of the polarized fuel at the limiter and the first-wall of a fusion reactor are greater than those mechanisms in the plasma. Rapid depolarization of the plasma is prevented by providing a first-wall or first-wall coating formed of a low-Z, non-metallic material having a depolarization rate greater than 1 sec.sup.-1.

Abstract: A hydraulic cylinder usable as a shock-absorbing trim and tilt cylinder for adjusting the position of an outboard motor or outdrive unit of a boat, is provided with a piston including pilot-operated valve means which stepwise responds at a precisely setable pressure, to pressures resulting from impact of an outboard motor or outdrive unit upon an obstacle, the valve means then departing as a poppet-type relief valve to allow the outboard motor or outdrive unit to return to operative position following the impact. The hydraulic cylinder is provided with an integral conduit formed by milling a groove or slot from a point adjacent its mounting end to the point adjacent its rod end, and fastening a cover over the groove.

Abstract: A control system for a nuclear reactor is disclosed. A control rod strategy computer provides for dynamic control of core power distribution in both radial and axial directions and forms the basis for a partial trip capability. Several microprocessor-based computation centers are combined together in a data-sharing network which processors determine local power density, determine the instantaneous differential and integral reactivity worth of each group of control rods, determine and effectuate partial trip for immediate power reduction, determine and provide for uniform core burnup, and effectuate core reactivity changes by directing the movement of groups of four control rods from zero to one hundred percent of travel while minimizing power distribution factors throughout the core. The power control circuitry to move the groups of control rods are bus arranged such that the power circuitry is shared among the groups of control rods.

Abstract: A steam generator level measurement system of the type having a reference leg which is kept full of water by a condensation pot, has a separator pot in the connecting line between the condensation pot and the steam phase in the steam generator to remove excess liquid from the steam externally of the steam generator. The separator pot has an expansion chamber which slows down the velocity of the steam/liquid mixture to aid in separation, and a baffle, which directs steam introduced at the top of the chamber on one side of the baffle to flow downward and then upward for discharge on the other side of the baffle to avoid direct liquid penetration into the line connected to the condensate pot.

Abstract: A protection system such for a nuclear power plant shuts down the reactor in response to the detection of a negative flux rate characteristic of a dropped rod, but inhibits the trip if the specified negative flux rate is preceded within a selected time interval by a positive flux rate characteristic of a net load rejection when the moderation temperature coefficient is highly negative.

Abstract: A pressure tight seal is formed between the confronting planar sealing surfaces on the flanges of a nuclear reactor pressure vessel and its hemispherical head, by a toroidal, crushable tubular seal member which is locked into a flat annular spacer member by a resilient annular member, such as a circular coil spring seated in a V-shaped recess in the inner surface of the flat annular member. The thickness of the flat annular member and the resiliency of the circular coil spring control the deformation of the tubular seal member as the sealing surfaces are drawn toward each other by flange bolts. The flat annular member is provided with axial bores which register with the flange bolts to provide positive positioning of the tubular seal member without the necessity of providing grooves in the confronting planar sealing surfaces.

Abstract: A control device for a PWR includes a plurality of clusters arranged for insertion into and removal from the core and each having a plurality of rods connected to a common carrier vertically slidable in a stationary guide structure and connectable to a drive shaft. First clusters contain neutron absorbing material and are each individually associated with electromagnetic actuation means for adjusting the amount of insertion of the associated one of the first clusters. Second clusters contain a different material and are each individually associated with hydraulic actuation means controllable to cause upward and downward movement. A set of one first cluster and one second cluster is associated with some of said fuel assemblies, with the drive shafts of the two clusters in each set being arranged symmetrically with respect to the axis of a single stationary structure located above the associated fuel assembly and arranged for authorizing mutually independent movement of the first and second clusters.

Abstract: A fluid actuator characterized by a feedback mechanism for indicating actuator position. The feedback mechanism is driven by the actuator screw shaft, whereby the movements of the feedback mechanism are proportional to the rate and position of the actuator movements. The feedback mechanism and actuator movements may be synchronized so that the extreme end positions of the feedback mechanism will correspond to the fully retracted and extended positions of the actuator. A stroke limiting mechanism may also be provided for preventing the actuator from overstroking the feedback mechanism in the event that they are not properly synchronized.

Abstract: A control rod driveline and grapple is disclosed for placement between a control rod drive and a nuclear reactor control rod containing poison for parasitic neutron absorption required for reactor shutdown. The control rod is provided with an enlarged cylindrical handle which terminates in an upwardly extending rod to provide a grapple point for the driveline. The grapple mechanism includes a tension rod which receives the upwardly extending handle and is provided with a lower annular flange. A plurality of preferably six grapple segments surround and grip the control rod handle. Each grapple rod segment grips the flange on the tension rod at an interior upper annular indentation, bears against the enlarged cylindrical handle at an intermediate annulus and captures the upwardly flaring frustum shaped handle at a lower and complementary female segment. The tension rods and grapple segments are surrounded by and encased within a cylinder.

Abstract: Device for purifying liquid metal coolant for a fast neutron nuclear reactor, comprising a pump (6) for circulating the liquid metal, the metal then being purified and heated after purification, as well as a filter (24) of metallic fibers. It consists of an assembly of annular chambers with a vertical axis, closed at their lower part by a base plate (10) and defined and separated from each other by an assembly of coaxial cylindrical metallic shells. The device comprises, from the exterior inwards, a degassing chamber (12), a chamber enclosing an economizer-exchanger (14, 16), a thermal insulation wall (18), a cooling chamber (20) and a purifying chamber (22) in the central part of which is a filter cartridge (24). In the central part of the cartridge (24) is a channel (25) for collecting the purified liquid metal in communication with a basin (44) for collecting the purified liquid metal rising above the device.

Abstract: Methods and associated apparati for use of collisions of high energy atoms and ions of He, Ne or Ar with themselves or with high energy neutrons to produce short wavelength radiation (.lambda..apprxeq.840-1300 .ANG.) that may be utilized to produce cathode-anode currents or photovoltaic currents.