Abstract: The present disclosure relates to the field of reactor engineering technologies, and particularly to a spherical element detecting and positioning device. The spherical element detecting and positioning device includes a pressure-bearing casing, an internal member and an execution part; the pressure-bearing casing includes a tank body, one sphere inlet adapter pipe and two sphere outlet adapter pipe respectively arranged on the tank body; the internal member is arranged in the rotor counter-bored hole and includes a lining ring and a limit ring; and the execution part includes a turntable and two support lugs.

Abstract: A high-temperature nuclear reactor, cooled by a liquid fluoride salt, is described. The reactor uses an annular fuel pebble comprised of an inert graphite center kernel, a TRISO fuel particles region, and a graphite outer shell, with an average pebble density lower than the density of the liquid salt so the pebbles float. The pebbles are introduced into a coolant entering the reactor and are carried into the bottom of the reactor core, where they form a pebble bed inside a plurality of vertical channels inside one or more replaceable Pebble Channel Assemblies (PCAs). Pebbles are removed through defueling chutes located at the top of each PCA. Each PCA also includes channels for insertion of neutron control and shutdown elements, and channels for insertion of core flux mapping and other instrumentation.

Abstract: This invention relates to a method of preparing nuclear fuel including the step of depositing at least two adjacent series of layers (16, 18) around a kernel (12) of fissile material, each series comprising a layer of pyrolytic carbon (16) contiguous with a layer of silicon carbide (18) and each layer (16, 18) having a thickness of at most (10) micrometers, such that alternate layers of (16, 18) of pyrolytic carbon and silicon carbide are deposited around the kernel (12). The invention extends to a nuclear fuel element (10).

Abstract: Disclosed is an advanced process that relates to the enhanced production of energy using the integration of multiple thermal cycles (Brayton and Rankine) that employ multiple fuels, multiple working fluids, turbines and equipment. The method includes providing a nuclear reactor, reactor working fluid, heat exchangers, compressors, and multiple turbines to drive compressors that pressurize a humidified working fluid that is combusted with fuel fired in at least one gas turbine. The turbine(s) provide for electrical energy, processes or other mechanical loads.

Abstract: The invention relates to a novel design and production of fuel element pebbles which satisfy the requirements of high temperature pebble bed nuclear reactors of the next generation. The invention uses a shell of the fuel element pebbles that is devoid of fuel and consists of silicon carbide (SiC) and/or zircon carbide (ZrC), in addition to natural graphite and graphitized petroleum coke, said shell having a maximum average nominal thickness of 5 mm and preferably only 3 mm.

Abstract: A liquid fluoride salt cooled, high temperature reactor having a reactor vessel with a pebble-bed reactor core. The reactor core comprises a pebble injection inlet located at a bottom end of the reactor core and a pebble defueling outlet located at a top end of the reactor core, an inner reflector, outer reflector, and an annular pebble-bed region disposed in between the inner reflector and outer reflector. The annular pebble-bed region comprises an annular channel configured for receiving pebble fuel at the pebble injection inlet, the pebble fuel comprising a combination of seed and blanket pebbles having a density lower than the coolant such that the pebbles have positive buoyancy and migrate upward in said annular pebble-bed region toward the defueling outlet. The annular pebble-bed region comprises alternating radial layers of seed pebbles and blanket pebbles.

Abstract: An improved nuclear fission reactor of the liquid metal cooled type including a core configuration allowing for only two operational states, “On” or “Off”, therefore bi-stable. The flow of the primary cooling fluid suspends the core in the “On” state, with sufficient flow to remove the heat to an intermediate heat exchanger during normal operation. This invention utilizes the force of gravity to shut down the reactor after any loss of coolant flow, either a controlled reactor shut down or a “LOCA” event, as the core is controlled via dispersion of fuel elements. Electromagnetic pumps incorporating automatic safety electrical cut-offs are employed to shutdown the primary cooling system to disassemble the core to the “Off” configuration in a situation of a loss of secondary coolant.

Abstract: A nuclear reactor includes a reflector and a flow path. The reflector reflects neutrons, contains graphite and a moderator having a smaller moderating power than the graphite, and is sectioned into plural parts along a direction of flow of fuel pebbles. The flow path is surrounded by the reflector, and the fuel pebbles flow through the flow path and undergo nuclear reaction to generate power. Volume ratio of the graphite to the moderator having a smaller moderating power than the graphite in each part of the reflector is determined based on a power distribution in the reactor core in the direction of flow of the fuel pebbles.

Abstract: A nuclear reactor includes a reflector and a flow path. The reflector reflects neutrons, contains graphite and a moderator having a smaller moderating power than the graphite, and is sectioned into plural parts along a direction of flow of fuel pebbles. The flow path is surrounded by the reflector, and the fuel pebbles flow through the flow path and undergo nuclear reaction to generate power. Volume ratio of the graphite to the moderator having a smaller moderating power than the graphite in each part of the reflector is determined based on a power distribution in the reactor core in the direction of flow of the fuel pebbles.

Abstract: The present invention provides a nuclear fuel comprising an actinide nitride such as 233U, 234U, 235U, 236U, 238U, 232Th, 239Pu, 240Pu, 241Pu, 242Pu, 244Pu, 239Np, 239Am, 240Am, 241Am, 242Am, 243Am, 244Am, 245Am, 240Cm, 241Cm, 242Cm, 243Cm, 244Cm, 245Cm, 246Cm, 247Cm, 248Cm, 249Cm, 259Cm, 245Bk, 246Bk, 247Bk, 248Bk, 249Bk, 250Bk, 248Cf, 249Cf, 250Cf, 251Cf, 252Cf, 253Cf, 254Cf, 255Cf, 249Es, 250Es, 251Es, 252Es, 253Es, 254Es, 255Es, 251Fm, 252Fm, 253Fm, 254Fm, 255Fm, 256Fm, 257Fm, 255Md, 256Md, 257Md, 258Md, 259Md, 260Md, 253No, 254No, 255No, 256No, 257No, 258No and 259No, and optionally fission products such as 97Tc, 98Tc and 99Tc, suitable for use in nuclear reactors, including those based substantially on thermal fission, such as light and heavy water reactors, gas-cooled nuclear reactors, liquid metal fast breeders or molten salt fast breeders. The fuel contains nitrogen which has been isotopically enriched to at least about 50% 15N, most preferably above 95%.

Abstract: An upper plenum structure of a cooled pressure vessel for a prismatic very high temperature reactor which secures a space for coolant to supply to a core and also supports an upper reflector located inside a graphite structure on top of the core. The upper plenum structure includes a cavity structure where the coolant goes down in the upper plenum structure, a plurality of upper reflector supports formed with the cavity and supporting the upper reflector located on top thereof, and a plurality of coolant distributing blocks. Each of the coolant distributing blocks is coupled with a bottom portion of a respective one of the upper reflector supports and is located on top of the core in order to distribute the coolant collected in a cavity, formed by the upper reflector support, to the core. The coolant distributing blocks cooperate with the upper reflector supports to define the cavity structure.

Abstract: In the method, a reference core design is generated based on a defined set of limits. The set of limits may include a target hot excess reactivity constraint to be satisfied over a given core energy cycle and a given desired control blade definition that is set for the cycle. A reference core design is generated based on the defined limits. A unique subset of fresh fuel bundles is subject to an iterative improvement process including replacing, at each fuel location, at least one of the current fresh fuel bundles with at least one of the selected fresh fuel bundles, and simulating reactor operation on the reference core design to obtain a plurality of outputs to be ranked based on the defined set of limits. The highest ranked output may represent an accepted core design with set control blade definition that satisfies the target hot excess reactivity constraint.

Abstract: An improved nuclear fission reactor of the continuous fueling type involves determining an asymptotic equilibrium state for the nuclear fission reactor and providing the reactor with a moderator-to-fuel ratio that is optimally moderated for the asymptotic equilibrium state of the nuclear fission reactor; the fuel-to-moderator ratio allowing the nuclear fission reactor to be substantially continuously operated in an optimally moderated state.

Abstract: In the method, a set of limits applicable to a core may be defined, and a test core loading pattern design, to be used for loading the core, may be determined based on the limits. Reactor operation on at least a subset of the core may be simulated to produce a plurality of simulated results. The simulated results may be compared against the limits, and data from the comparison may indicate whether any of the limits were violated by the core during the simulation. A designer or engineer may use the data to modify the test core loading pattern, creating one or more derivative core loading pattern design(s) for simulation and eventual perfection as an acceptable core loading pattern design for the core.

Abstract: In the method, a set of limits are defined and a reference core design is generated based on the limits, and includes an initial loading pattern of current fresh fuel bundles arranged in a plurality of fuel locations. A unique subset of fresh fuel bundles is selected for evaluation as the reference core design is subjected to an iterative improvement process. The iterative process includes replacing, at each fuel location, at least one of the current fresh fuel bundles with at least one of the selected fresh fuel bundles, and simulating reactor operation on the reference core design to obtain a plurality of outputs. The outputs may be ranked based on the defined set of limits, and the highest ranked output may be selected as an accepted core design for the nuclear reactor.

Abstract: In a nuclear power plant making use of a high temperature gas cooled reactor, it is necessary, prior to commencing power generation and connection of a generator to an electrical distribution grid, to condition the power generation circuit of the plant. This involves creating stable conditions within the power generation circuit. To this end, the plant includes a start-up blower system for circulating working fluid, typically helium, around the power generation circuit until the desired conditions are satisfied. The start-up blower system typically includes a normally open in-line valve, at least one blower connected in parallel with the in-line valve and a normally closed isolation valve connected in series with the blower. Conditioning the power generation circuit will typically include stabilizing the pressure in the circuit at between 10 bar and 50 bar.

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 reactor core cooling structure of the present invention comprises cooling gas flow-in slits for making a cooling gas flow in a circular reactor core, which slits are provided at an outer graphite cylinder for covering an outside of the circular reactor core; cooling gas flow-out slits for making the cooling gas flow in a circular reactor core, which slits are provided at an inner graphite cylinder for covering an inside of the circular reactor core; a circular cooling gas flow path that is provided at an outside of the outer graphite cylinder, and is connected to an inlet piping of the cooling gas at a foot of the outer graphite cylinder; and an inner cooling gas flow path that is provided at an inside of the inner graphite cylinder, and is connected to an outlet piping of the cooling gas at a foot of the inner graphite cylinder.

Abstract: A reactor core cooling structure of the present invention comprises cooling gas flow-in slits for making a cooling gas flow in a circular reactor core, which slits are provided at an outer graphite cylinder for covering an outside of the circular reactor core; cooling gas flow-out slits for making the cooling gas flow in a circular reactor core, which slits are provided at an inner graphite cylinder for covering an inside of the circular reactor core; a circular cooling gas flow path that is provided at an outside of the outer graphite cylinder, and is connected to an inlet piping of the cooling gas at a foot of the outer graphite cylinder; and an inner cooling gas flow path that is provided at an inside of the inner graphite cylinder, and is connected to an outlet piping of the cooling gas at a foot of the inner graphite cylinder.

Abstract: An automatically scramming nuclear reactor system. One embodiment comprises a core having a coolant inlet end and a coolant outlet end. A cooling system operatively associated with the core provides coolant to the coolant inlet end and removes heated coolant from the coolant outlet end, thus maintaining a pressure differential therebetween during a normal operating condition of the nuclear reactor system. A guide tube is positioned within the core with a first end of the guide tube in fluid communication with the coolant inlet end of the core, and a second end of the guide tube in fluid communication with the coolant outlet end of the core. A control element is positioned within the guide tube and is movable therein between upper and lower positions, and automatically falls under the action of gravity to the lower position when the pressure differential drops below a safe pressure differential.

Abstract: This invention relates to a nuclear power plant (10) having a nuclear reactor (11) of the pebble bed type, making use of spherical fuel and/or moderator elements, and an element handling system (20) having at least one sphere flow path (22) along which spheres are conveyed under the influence of a fluid stream. More particularly, the invention relates to a method of decelerating spheres before being discharged from a discharge end (24) the sphere flow path (22). The invention extends to an element handling system (20), to a decelerating assembly (26) for decelerating spherical elements before being discharged from a discharge end (24) of the sphere flow path (22) and to a decelerator fitting for use in decelerating spherical elements before being discharged from a discharge end (24) of the sphere flow path (22).

Abstract: A nuclear plant includes a closed loop power generation circuit which makes use of a Brayton cycle as a thermodynamic conversion cycle. The plant further includes a start-up blower system having an in-line valve and a blower connected in parallel with the in-line valve. Further a normally closed blower isolation valve is provided in series with the blower and a blower bypass arrangement in parallel with the blower. A method of starting the Brayton cycle includes bringing the power generation circuit into standby mode in which helium is circulated around the power generation circuit by the start-up blower system and increasing power generated in the power generation circuit until the helium is circulated around the power generation circuit by a compressor independently of the start-up blower system.

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: The invention relates to a nuclear plant (8) having a reactor (10) containing a core comprising a plurality of moderator elements in a central region and a plurality of spherical fuel elements located in an annular region around the central region. The plant (8) further includes a fuel and moderator handling system (40) for circulating fuel and moderator elements around the plant (8). It further relates to a method of loading the core with moderator and fuel elements.

Abstract: The invention provides a method of handling fuel spheres in a nuclear reactor which includes scanning the spheres using a tomography scanner to permit identification of the fuel spheres. The invention extends to a nuclear plant having scanners at different positions to identify and control the movement of the fuel spheres. The invention further extends to a fuel element which incorporates particles intended specifically to facilitate identification of the fuel element.

Abstract: The invention relates to a pebble bed reactor comprising a core cavity filled with spherical fuel elements and bounded by reflector material. Spherical fuel elements pass through the core cavity under the effect of gravity. Coolant gas flows through the core cavity in a descending or ascending stream. The coolant-gas lines provided for the purpose discharge laterally above the base of the cavity bottom. In the reactor according to the invention, coolant gas can be conveyed through the pile of fuel elements without problems over long operating times.

Abstract: A method for producing energy from a nuclear fuel material contained in an enclosure, through a process of breeding of a fissile element from a fertile element of the fuel material via a .beta.-precursor of the fissile element and fission of the fissile element. A high energy particle beam is directed into the enclosure for interacting with heavy nuclei contained in the enclosure so as to produce high energy spallation neutrons. The neutrons thereby produced are multiplied in steady sub-critical conditions by the breeding and fission process. The breeding and fission process is carried out inside the enclosure.

Abstract: A bimodal nuclear power and propulsion system for space is disclosed. Closed cycle heat engines are in operative association with each sector of a sectored reactor core. Heat exchangers employing waste heat, electric power and reactor heat are used to heat propellant to increase Isp. Non-nuclear ground testing of the system is also disclosed.

Abstract: A throttle valve having defined characteristics controls flow of gas from a gas heater to a turbine in a closed cycle gas turbine system. The gas heater may be a nuclear reactor fueled by fission material preferably having a negative temperature coefficient of reactivity whereby the reactor automatically ceases heat production upon closing of the throttle valve.

Abstract: A nuclear propulsion reactor. A reactor vessel is provided with an annular first core and a cylindrical second core that is radially encompassed by the first core. Nuclear fuel elements in the first core provide first stage heating of propellant as they direct the propellant axially through the first core. The second core, which contains fissionable material in a highly refractory form, is in fluid communication with the first core for receiving the heated propellant. Fission reactions in the second core driven by leakage neutrons from the first core provide second stage heating of the propellant as it passes therethrough. The second core directs the coolant to a propellant nozzle for providing propulsive thrust.

Abstract: If an emergency arises in gas-cooled nuclear reactor plants having a heat exchanger for removing afterheat due to failure of a blower, the afterheat can be only inadequately removed because of the many deflections and restrictions in a primary circulation loop. In order to achieve adequate removal of afterheat solely on the basis of natural draught, a heat exchanger is located above a top reflector and reaches across a part of coolant gas bores in the top reflector. During normal operation of the nuclear reactor plant, there is a flow of cold gas through the heat exchanger in the direction toward the reactor core and in the event of an emergency, there is a flow of hot gas in a direction out of the center of the core of the reactor. A natural draught coolant circulation is established with the return of the cooled gas through the coolant gas bores in the top reflector.

Abstract: The combustion chamber and associated fuel injection and ignition equipment of a turbine engine is removed and replaced with a particle bed reactor. The reactor has central fuel elements removed to receive a shaft therein. The shaft is connected between a turbo compressor and drive turbine. Air compressed by the compressor turbine is heated by the reactor and the heated gas passes across rotor vanes of the drive turbine, the latter powering the interconnecting shaft. Exhaust gases from the drive turbine furnish resultant thrust.

Abstract: A multiplicity of pebble-bed cores are housed within separate concrete cavities of a multi-cavity prestressed concrete pressure vessel. Primary cooling systems, one for each pebble-bed core, are supported within another cavity which is coaxial with the longitudinal axis of the prestressed concrete pressure vessel. Tunnel ducts formed within the walls of the concrete vessel communicate between the cavities which house the pebble-bed cores and the cavity which houses the primary cooling systems. Pipes connecting the cores to the primary cooling systems pass through these ducts.

Abstract: A mixing apparatus for a plurality of turbulently flowing fluid flows varying in temperature and/or composition includes a mixing chamber having a non-circular or predetermined cross section and a straight or curved center line. A plurality of single-conduit and parallel or radial deflector elements are disposed beside the mixing chamber and staggered in the direction of the center line. The deflector elements receive a fluid flow being oriented at an angle relative to the center line and staggered laterally. The deflector elements deflect the fluid flow tangentially into the mixing chamber. The mixing chamber has an outlet opening for the exit of a mixed fluid flow. In a gas-cooled, high-temperature nuclear reactor with a circular outline, the mixing apparatus has a horizontal, annular mixing chamber with a plurality of sectors. Horizontal annular conduits receive at least one fluid flow.

Abstract: A high temperature reactor has a downflow type nuclear reactor provided at the top portion thereof with a gas inlet and a plurality of steam generators provided around the nuclear reactor. The steam generator has a heat insulation tube provided vertically from the bottom portion of the nuclear reactor to a level higher than the top gas inlet of the reactor, a heat exchanger provided in a descending gas flow path formed around the heat insulation tube, and a gas circulator provided at the bottom portion thereof for feeding a gas coolant to the gas inlet of the nuclear reactor, whereby said gas coolant, after being used for cooling the reactor core, delivered from the bottom portion of the reactor, flows into the heat insulation tube, flows upward to the top portion of the tube, is reversed in direction at the top end of the tube, then flows downward through the descending gas flow where the heat exchanger is provided, and is then recycled to the gas inlet flow path of the reactor by the gas circulator.

Abstract: A ball-bed (pebble-bed) nuclear reactor, instead of having fuel elements more or less continuously withdrawn and new or reconstituted fuel elements more or less continuously reintroduced, 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 requirements, 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 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 process is provided for the long term shutdown of a high temperature nuclear reactor comprised of a pile of spherical fuel elements in a core by means of a neutron absorbing absorber material wherein the absorber material consisting of spherical absorber elements is introduced in the core of spherical fuel elements in the form of a column, but wherein the intermixing of the absorber material with the fuel elements is prevented. An apparatus for practicing the process is also provided comprised of a graphite side reflector concentrically surrounding a circular cylindrical core filled with a pile of spherical fuel elements of a high temperature nuclear reactor, into which at least two nose shaped projections distributed uniformly about the circumference radially project, with each of the projections comprising a vertical cavity to contain the absorber material. The vertical cavity is located in the vicinity of the core in the area of the frontal side facing the core of each projection.

Abstract: A safety system controlling extremely unlikely disturbances in high temperature reactors in addition to and independent of the normal reactor protection systems. Accident instrumentation located in the high temperature reactor monitors certain characteristic process parameters (hot gas temperature, cold gas temperature, cooling gas pressure), for values of which clearly exceed limiting values of the reactor pressure system. The measured data is evaluated electronically and power supply to the cooling gas blowers, feed water pumps and absorber rod holding devices is interrupted if predetermined limiting values are exceeded. The power supply interruption is further actuated by temperature and pressure sensitive devices located in the nuclear reactor. A manually operated emergency switch is provided to turn off the aforementioned sensibilities.

Abstract: A gas cooled nuclear reactor may have a stationary pile of spherical operating elements. The reactor may be controlled and shut down by absorber rods displaceable in channels of the side reflector. The neutron sources required for the safe start-up of such pellet pile reactors, which in the case of higher capacity pile reactors are installed in bores of the side reflector, are arranged in the stationary pile, where they are more effective and do not occupy positions in the side reflector. They may be located in one or more graphite elements having the same diameter as the operating elements. These elements may be introduced and removed into and from the core together with the operating elements and remain stationary in operation.

Abstract: An energy producing system employing nuclear fission of fuel in pellets disposed in a boiling liquid to produce superheated vapors.

Abstract: A roof reflector comprising at least three individual layers of tapered layer elements combined in the form of vertical columns. Each column rests on a block column of the lateral reflector. Individual elements are secured by wedges and dowels to permit vertical column movements without constraint. The top and bottom layers comprise gas collector spaces communicating with each other by passage openings in the middle layer. In the top and bottom layers are also slot-shaped passage openings leading to an from the collector spaces. Preferably, they are radially offset relative to the passage openings in the middle layer to obtain good gas mixing as it rises through the reflector.Such a roof reflector is useful for avoiding roof reflector element damage if one element is vertically displaced relative to an adjacent element. The roof elements are carefully designed to achieve this end and maintain cover utility.

Abstract: A particle bed fuel element designed to accommodate expansion and contraction within the particle fuel bed. Porous inner and outer frits connected together by an end cap at a first end and radially guided by a shoulder at a second end receive fuel particles in the annulus formed therebetween. Compressive devices at each end of the frits and within the fuel bed maintain packing force to prevent looseness during contraction and allow expansion without excessive pressure being placed on the fuel particles. Pairs of beleville springs, wave springs, and pressurized thin-walled metal donuts may be used as the compressive devices.

Abstract: In a high-temperature gas-cooled nuclear reactor system, which is suitable for modular utilization in combination with one or more other similar nuclear reactor systems, an arrangement which comprises passive heat sink means for absorbing decay heat energy generated at a reactor core included within said reactor system; and means for removing heat energy from said heat sink means at a rate sufficient to maintain the capacity of the heat sink means for absorption of decay heat energy such that release of fission products resulting from loss of forced circulation of gas coolant, or such loss in combination with coolant depressurization, when the reactor is critical and at power is prevented, thereby to provide safety means independent of human or automatic activation; and method embodiments corresponding to same.

Abstract: A gas-cooled high temperature reactor having a core filled with spherical fuel elements is provided comprising a graphite side reflector including at least one nose-like projection comprised of a plurality of graphite nose stones stacked one upon the other, said nose stones each including at least one vertically disposed continuous cavity aligned with at least one vertically disposed continuous cavity in adjacent nose stones, said cavity adapted to receive discrete absorber material elements introduced into the reactor core, said nose stones further including at least one vertically aligned continuous gap which extends into said nose stones from a front portion thereof and is aligned with a corresponding continuous gap in adjacent nose stones, communication between said continuous gap and said cavity being prevented, said nose stones also comprising in top and bottom surfaces thereof sealing means which enable adjacent nose stones to be stacked in a manner sufficient to seal said at least one cavity in a gas-

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: A high temperature reactor having a reactor core filled with spherical fuel elements is provided comprising a graphite side reflector including at least one nose-like projection protruding radially into the reactor core from said graphite said reflector, said at least one nose-like projection including a vertically disposed cavity adapted to receive discrete absorber material elements introduced into said reactor core as well as a vertically disposed continuous opening which permits communication between said cavity and the core of the reactor, and sealing means positioned in said continuous opening and cooperatively engaged with the portion of said nose-like projections defining said vertically disposed continuous opening, said sealing means being so configured and so cooperatively engaged so as to permit gaseous communication between said cavity and said core while preventing passage of said discrete absorber material elements through said continuous passage.

Abstract: A gas-cooled, high-temperature nuclear reactor includes a metallic core barrel, a graphite or carbon block lining disposed in the core barrel, a hot gas line including an outer pressure-confining metallic pipe and a ceramic flow guidance pipe, insulation separating the metallic pipe from the ceramic pipe, a stub concentric with the hot gas line, a device for detachably connecting the stub to the core barrel, the metallic pipe being tightly disposed in the stub, a device for detachably fastening the metallic pipe to the stub, a sleeve, a device for detachably fastening the sleeve to the lining, a bellows compensator being disposed in the stub and having one end tightly fastened to the stub and another end, and a device for connecting the other end to the sleeve.

Abstract: A gas-cooled high temperature reactor is provided having a core filled with spherical fuel elements, in combination with a graphite side reflector including at least one nose-like projection protruding radially into the reactor core from said graphite said reflector, the at least one nose-like projection including at least one vertically disposed cavity adapted to receive discrete absorber material elements introduced into said reactor core as well as a vertically disposed continuous opening which permits communication between said cavity and the core of the reactor, said opening having a maximum width adjacent said cavity which is less than the minimum dimension of said discrete absorber material elements in order to prevent passage of said elements into said continuous opening from said cavity.

Abstract: In a nuclear reactor installation with a small high temperature reactor (26) all of the components of the primary loop, together with the control and shutdown installations (82, 92, 114, 116; 194, 198, 200) are located inside a steel pressure vessel (16) and may be installed and dismantled from above. This makes an economical subterranean construction possible.