Abstract: A nuclear power plant spent fuel negative pressure unloading system comprises a fuel element transport pipe and a gas transport pipe. The fuel element transport pipe comprises a fuel element output pipe, a fuel element lifting pipe, and a fuel element unloading pipe connected in series. The fuel element unloading pipe is arranged obliquely downward in the direction of fuel element movement. The distal end of the fuel element unloading pipe is connected sequentially to fuel loading apparatus and a transfer apparatus. Two nozzles of the gas transport pipe are connected to set positions on the fuel element output pipe and the fuel element unloading pipe respectively. A gas driving mechanism is connected to the gas transport pipe. An inlet of the gas driving mechanism is arranged at one end in proximity to the fuel element unloading pipe.

Abstract: This invention relates to a nuclear plant including a main power system and a fuel handling and storage system. The system is connected to a sphere inlet and a sphere outlet of a multi-pass high temperature gas cooled pebble bed reactor. The system is configured such that gas flows from the system into the reactor through both the sphere inlet and the sphere outlet thereby inhibiting the ingress of high temperature gas from the reactor into the system. Restricting indexers permit the movement of spheres between the reactor and the system and dampen out the transmission of pressure fluctuations from the power system to the system.

Abstract: This invention relates to a nuclear plant including a main power system and a fuel handling and storage system. The system is connected to a sphere inlet and a sphere outlet of a multi-pass high temperature gas cooled pebble bed reactor. The system is configured such that gas flows from the system into the reactor through both the sphere inlet and the sphere outlet thereby inhibiting the ingress of high temperature gas from the reactor into the system. Restricting indexers permit the movement of spheres between the reactor and the system and dampen out the transmission of pressure fluctuations from the power system to the system.

Abstract: This invention relates to a nuclear plant including a main power system and a fuel handling and storage system. The system is connected to a sphere inlet and a sphere outlet of a multi-pass high temperature gas cooled pebble bed reactor. The system is configured such that gas flows from the system into the reactor through both the sphere inlet and the sphere outlet thereby inhibiting the ingress of high temperature gas from the reactor into the system. Restricting indexers permit the movement of spheres between the reactor and the system and dampen out the transmission of pressure fluctuations from the power system to the system.

Abstract: A device and method to move a fuel assembly of a nuclear reactor, wherein the device eliminates the potential for dropping the fuel assembly due to stress corrosion cracking of the upper guide thimble sleeves that attach the top nozzle to guide thimbles.

Abstract: A guide ring is positioned in the reactor core vessel of a pebble-bed nuclear reactor to segregate fuel pebbles and reflector pebbles fed into the vessel through respective conduits. The reflector pebbles pass through the guide ring and form a central reflector column, while the fuel pebbles pass outside the guide ring and form an annular fuel column surrounding the central reflector column. The guide ring controls the size and shape of the reflector column and controls mixing of the two types of pebbles.

Abstract: A vent tube (66) and housing nut (62) replace the original housing plug (52) on a pressurized water nuclear reactor. The vent tube engages the installed vent stem (38) cross-slot (48) with a cross-shaped projection (70). During operation, the vent tube (66) is pushed down to engage the vent stem (38) and rotated to allow vented air to travel through stem (38) and tube (66). After venting, the vent stem is rotated back and tightened. The invention provides visual indication of a leaking ball (32) since any leakage lifts vent tube (66). Time required for venting is reduced and no removal of installed ball seal (32,34), a proven primary seal, is required.

Abstract: A lightweight three sector reactor for use in space. The three sectors provide redundancy for safety and operation assurance. The reactor can be launched empty or fueled and can be fueled, emptied, and refueled while in space. The reactor can be used to power manned space platforms.

Abstract: A nuclear power plant that is of a walk-away type with an encapsulated reaction core in a glass matrix pool having a reactive Thorium/U.sup.233 composition in a containment structure that radiates thermal energy for use in a closed gas cycle with a split path having a common compressor with an output that divides into a first path communicating with the thermal source and a second path communicating with an intercooler, the two paths combining in a turbine with an expander that discharges to a common collector for return to the compressor.

Abstract: A multi-region reactor core pebble bed high temperature gas reactor comprises a pebble bed reactor core housed within a pressure vessel and charged with spherical fuel. The reactor core is surrounded by a reflector wall comprising a partition wall which partitions the reactor core into a plurality of reactor core sub-regions. The reflector wall comprises a plurality of layers of reflector blocks, adjacent blocks of a layer being secured against one another by removable tapered keys wedged therein between.

Abstract: A shutdown system for a high temperature nuclear reactor where absorber material elements in the form of balls pass from an elevated reservoir into a vertical channel formed by aligned vertical cavities in horizontal, nose-shaped projections from the side reflector. The balls are transported back to the reservoir by way of a conveyor device. It must be insured that even in the case of accidents the absorber balls arrive in the cavities and that a rapid return of the absorber balls into the reservoir takes place. For the purpose, the reservoir is provided with an automatically-actuated and controllable device for releasing an opening between the reservoir and the vertical channel feed line. Below the channel is a removal tube terminating in a housing and arranged to form a pile of the absorber balls which seals the removal tube. To return the absorber balls, a metering gas acts on the pile and brings the absorber balls to a carrier gas.

Abstract: A nuclear reactor installation with a simple configuration includes a transport container which may be placed on the cover of the cavity. The transport container bottom overlaps the cover access opening. A vertical displaceable pebble conveyor line extends from the pebble pile surface to the transport container interior. A blower is located between the transport container and the reactor. The blower suction line is connected to the transport container interior and the blower pressure line leads into the reactor vessel.

Abstract: A low capacity nuclear reactor with spherical fuel elements laid out in an underground configuration and characterized by a compact structure and the far-reaching elimination of active operating installations, such as a charging apparatus, gas purification installations and control systems. The reactor is particularly suitable for generation of heat for heating purposes. The graphite reflector surrounding the pile of fuel elements on all sides includes layers of spherical graphite elements with a diameter equal to that of the fuel elements. The poured part of the graphite reflector and the pile of fuel elements are located in a metal core vessel made of lattice work or perforated sheet metal and capable of supporting the entire weight of the graphite and fuel elements. The mesh or the holes of cage-like core vessel are smaller than the diameter of the spherical elements.

Abstract: The invention relates to a gas cooled high temperature reactor located in the cavity of a pressure vessel, with spherical fuel elements, and removal apparatus for fuel elements. The latter is made of at least one ceramic pebble outlet tube extending through the graphite structural parts of the nuclear reactor (bottom reflector, bottom layers) and a number of metal pebble outlet tubes installed through the bottom of the pressure vessel. They are arranged coaxially in the liner of the passage through the vessel. To be able to dismantle the metal pebble outlet tubes, they are constructed of several releasably interconnected tube segments. Between the uppermost tube segment and the corresponding ceramic pebble outlet tube a compensating tube is provided and connected with the tube segment by means of a sliding joint. The other end of the compensating tube is fastened to the thermal bottom shield.

Abstract: A gas cooled high temperature reactor with spherical fuel elements surrounded by a reflector utilizes at least one ceramic tube and at least one metal tube for removal of pebbles from the core of the reactor. Each cermaic tube is surrounded directly by a ring of graphite columns wherein a plurality of recesses house a number of rod-shaped boron bodies. Additional plate-shaped boron bodies may advantageously be located in the bottom layes of the reflector.

Abstract: A ball-bed (pebble-bed) nuclear reactor, instead of having fuel elements e or less continuously withdrawn and new or reconstituted fuel elements more or less continuously reintroducted, is initially partly filled with fuel balls of which two-thirds have a fissionable material content 12% below and the upper third 24% higher than the average content. This filling meets the requirements of criticality in order to begin operation. Thereafter, fuel balls are added slowly, a few hundred per day, having 150 to 250% of the average fissionable material content of the initial loading, thus preserving the criticality requirments, while keeping the temperature within safe limits until the reactor cavern is filled. Thereafter, the reactor is shut down, cooled off, pressure relieved and emptied, the last step typically from above. An ordered array of the fuel balls in regular layers avoids excess pressure loads on the reflector over the life time of the filling.

Abstract: A medium power, high temperature pebble bed nuclear reactor, which includes a means for introduction and withdrawal of operating elements. The installation is provided in such a way that it can be more economically built and operated. The installation includes several input stations above a prestressed concrete pressure vessel, and charging hatch blocks positioned on top of the prestressed concrete pressure vessel. The blocks include selectors through which the pebble-shaped operating elements, after traversing helical and meandering charging conduits, reach into the reactor core. The selectors and charging conduits are installed within armored ducts which penetrate the prestressed concrete pressure vessel. Similar armored ducts are provided for exit ducts for withdrawal of pebbles from the core, and a first common exit hatch block is connected to the exit ducts. The block is arranged within foundation walls which support the prestressed concrete pressure vessel.

Abstract: A high-temperature nuclear reactor having spherical fuel elements which are rranged approximately ring-shaped about a graphite core, and in particular, a massed-sphere nuclear reactor providing for inherent passive stabilization in the event of damage. The inventive high-temperature reactor of the above-mentioned type distinguishes itself in that the graphite core is formed by a pile or mass of graphite spheres. Through the intermediary of such an axial graphite sphere region, the maximum temperature of the fuel elements of the core can be limited in the event of encountered damage in a manner similar to that as would be the case for a compact graphite column.

Abstract: A system and method for the loading of spherical nuclear fuel in vertical fuel rods. The system includes a fuel rod support, a glovebox, a weighing station system, a means for feeding spherical fuel to the fuel rod and transportation means for moving the fuel between parts of the system.

Abstract: A feeding apparatus for the loading of the spherical nuclear fuel into a fuel rod. The apparatus feeds fuel of three different diameters into a fuel rod so that the three different sized spheres are appropriately packed to achieve sufficient density of fuel to be used in a nuclear reactor.

Abstract: Disclosed is a process for reloading the contaminated empty reactor cavity of a nuclear reactor with spherical operating elements forming the core of a high temperature reactor comprising supplying the operating elements to the reactor cavity first through a central loading tube in the roof reflector of the nuclear reactor to a predetermined load level, the loading tube being extended at the onset of the loading process toward the floor reflector and being adjusted upwardly during continued loading with the rising load level and after reaching the predetermined load level, supplying further operating elements through a plurality of auxiliary loading tubes in the roof reflector of the nuclear reactor in concentric circles about the central loading tube with the loading sequence proceeding circle after circle beginning with the circle closest to the central loading tube.

Abstract: Grill gates respectively formed by oppositely moving, interfitting rod combs with gaps between the rods which are smaller than the particle diameter are so arranged so that each comb may be individually moved to the open position and shut again without allowing any of the even sized particles of the bulk material to pass through the other comb while testing the readiness of the comb operating system. Grooves of circular arc cross-section fitting the size of the spheres of a high-temperature reactor are provided in the upstream sides of the wall produced by the interfitting combs to enable close packing of the spheres against the closure wall in an ordered arrangement that allows either comb to be withdrawn and reinserted without breakage of the spherical elements. The grooves are oriented in the length dimension of the comb rods, and one set of comb rods provides the groove bottoms and the adjoining rods of the other set the cooperating groove flanks.