Abstract: An expansion gap radiation shield is formed from a flexible container housing a radiation shielding fluid, that is located within a variable gap in permanent shielding. The invention reduces radiation dose rates outside the gap when the radiation sources are located on the opposite side of the gap. The device accommodates varying gap sizes with no loss of shielding capability.

Abstract: Passive emergency cooling in response to a loss of coolant accident (LOCA) in a PWR, having an integral reactor pressure vessel incorporating the steam generators and housed in a small high pressure containment vessel, is provided by circulating cooling water through the steam generators and heat exchangers in an external tank to cool the reactor vessel at a rate sufficient to lower the pressure in the reactor vessel below that in containment to reverse mass flow out of the reactor vessel and keep the reactor core covered without the addition of makeup water. Suppression tanks inside the small high pressure containment structure limit peak blowdown pressure in containment and provide flood-up water and gravity fed makeup water to cool the core. Diverse cooling is provided by natural circulation of air, and if needed, water, over the spherical containment structure.

Abstract: The present invention, in one form, is a natural circulation reactor having, in one embodiment, a layer of high aluminate cement concrete disposed between an uninsulated steel liner and a prestressed concrete reactor vessel. The prestressed concrete reactor vessel includes a concrete shell having a cavity therein. The steel liner is positioned in the cavity and spaced from the concrete shell so that an insulating chamber is formed between the steel liner and the concrete shell. The insulating chamber is filled with high aluminate cement concrete which is configured to substantially insulate the concrete shell from the steel liner and to transfer loads such as pressure from the liner to the concrete shell.

Abstract: A nuclear reactor containment cooling system includes a containment vessel having a drywell and a wetwell, a cooling condenser submerged in a cooling pool of water located outside the containment vessel, a vent line extending from the condenser to a suppression pool disposed in the wetwell, and at least one drain line extending from the condenser to a condensate drain tank located in the drywell. An end of the drain line is vertically submerged below the surface of a pool of water in the drain tank. To enhance flow, a blower can be located in the drain line. The containment cooling system can include a drywell gas recirculation subsystem coupled to the vent line, and including a suction pipe coupled to the vent line, at least one valve located in the suction pipe, at least one blower coupled to the suction line, and a discharge pipe in flow communication with the drywell.

Abstract: A nuclear steam supply containment system employing prefabricated component supports that are surrounded by steel concrete forms and anchored to the floor liner of a nuclear containment. The prefabricated component supports extend through the concrete forms and a reinforce concrete slab cap to a support elevation for the component. A second inner steel concrete form can be employed to form an annular concrete channel through which the supports extend. The center of the inner form can be filled with a sand-like substance, radiation absorber material or concrete grout.

Abstract: A liquid metal nuclear reactor is described. The reactor includes a concrete reactor silo, and at least one primary vessel located in the reactor silo and coupled to a reactor shield deck. Each primary vessel is substantially surrounded by a containment vessel in a spaced apart relationship. The reactor also includes a heat removal system which includes a guard vessel substantially surrounding each containment vessel in a spaced apart relationship, at least one inlet conduit in fluid communication with the ambient atmosphere outside the nuclear reactor, and at least one outlet conduit in fluid communication with the ambient atmosphere outside the nuclear reactor. A fluid flow heat transferring flowpath is formed by the inlet conduits, the space intermediate the guard vessel of each primary vessel and the containment vessel of each primary vessel and the outlet conduits.

Abstract: A joint for interfacing a steel head closure and a steel-lined prestressed concrete reactor vessel (PCRV). The steel head closure is bolted to a thick steel annular plate and a thermal barrier is arranged in a volume bounded by the head ring, the liner and the concrete of the PCRV wall. The thermal barrier is made of zirconia sand or other material having a low thermal conductivity, a high bulk modulus equal to that of concrete, and a low shear modulus. Differential thermal expansion of the vessel head closure and PCRV is accommodated by a flexible connection of the PCRV liner to the inner periphery of the head ring. In the alternative, the steel head closure is interfaced to the top of the PCRV via a sliding joint or a thermal stress relief ring. In accordance with a further alternative, thermal stresses in the steel vessel head closure are mitigated by reducing the temperature of the head closure by installing thermal insulation on all internal surfaces thereof.

Abstract: A nuclear reactor having a pressure vessel which is open at the top. The open top of the pressure vessel is closed by a steel dome. A containment, which is open at the top, extends upward from and is joined to the top of the pressure vessel and has an open containment head at the top thereof. The open top of the containment is closed by a steel dome, thereby forming a containment well bounded laterally by the containment, on the bottom by the vessel closure and on the top by the containment closure. The pressure vessel can be a steel-lined prestressed concrete vessel, while the containment is formed by an extension of the prestressed concrete vessel. Alternatively, the pressure vessel and the containment are parts of a unitary steel vessel. Isolation valves are installed on each penetration pipeline to isolate the system in the event of a loss-of-coolant accident.

Abstract: A pressure vessel apparatus for containing fluid under high pressure and temperature including pressure surges caused by in-vessel explosions includes a vessel main body, a vessel top body and a vessel head. Elongated tendons interconnect the vessel main body to the vessel top body and elongated tendons with removable anchors also connect the vessel head to the vessel top body. The tendons with insulated protecting sleeves connecting the vessel main body to the vessel top body are chosen to allow the vessel top body to temporarily separate from the vessel main body before the vessel head separates from the vessel top body. These tendons may be mounted directly, on springs, or on dampers in order to provide optimum (minimum) response to the postulated load cases.

Abstract: A method of constructing the top slab of a nuclear reactor container in which a flange for mounting the top head of the container is prepared separately from the sleeve of the container. When the outside diameter of the flange is greater than the inside diameter of a doughnut-shaped steel; reinforcement structure assembled on the container, the steel reinforcement structure is situated in place and then the flange is welded to the sleeve, thus shortening the construction period. Disclosed also is a nuclear reactor container constructed by this method.

Abstract: A nuclear reactor system pressure vessel comprises a steel inner liner part, an intermediate insulative layer part and an outer pre-stressed concrete part encasing these parts. Use of the pre-stressed construction allows for construction of pressure vessels of larger size than heretofore, and this coupled with utilization of squatter reactor cores allows natural convective circulation in the reactor vessel of the heated water pool in the higher capacity systems currently being introduced. The reactor pressure vessel because of its suitability allows enhanced natural steam separation in the vessel and eliminates need for use of centrifugal steam separators. The outer vessel part can be a cast single piece structure or it can be an integrated concrete segment assembled structure embodying pre-stressing tendons arranged in various orientations to effect pre-stressing.

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 nuclear power plant with a high temperature reactor located eccentrically in a prestressed concrete pressure vessel with spherical fuel elements for a capacity of 100-300 MWth intended primarily for power generation. The plant is inherently safe even in extreme accidents due to special devices for removal of decay heat. It is provided that upon a failure of the operational decay heat removal devices, decay heat is removed through a liner cooling system of the prestressed concrete pressure vessel. The liner cooling system is connected to a water-filled elevated reservoir by an external circulation loop. The elevated reservoir is connected to a further heat sink through a recooling circulation loop. It is possible to feed water into the elevated reservoir.

Abstract: Nuclear reactor confinement enclosure foundation comprising a skirt and a dome, the foundation comprising a footing in contact with the ground and which bears members and rods arranged annularly and supported on the confinement enclosure floor. The space between the footing and the floor can be used in different ways.

Abstract: A concrete reactor pressure vessel for a low capacity, gas cooled nuclear reactor is provided. To assure the safe containment of the cooling gas in an economical manner and to remove the heat generated in the reactor core, the pressure vessel is equipped with reinforcing or prestressing elements. Cooling gas transfers its heat to a heat exchanger means consisting of the liner of the pressure vessel and cooling pipes mounted on the concrete side of the liner with water flowing through the cooling pipes. The heat exchanger comprises on the secondary side at least two mutually independent systems, each provided with collector pipe means located outside the reactor pressrue vessel for the forerunnings and afterrunnings of the cooling water. Each cooling pipe is connected by means of an inlet and a drain line with the corressponding collector pipe means.

Abstract: The invention relates to a nuclear power station for a gas cooled high temperature pebble bed nuclear reactor. The nuclear power station is characterized by a combination of features, whereby the system inherent properties of a high temperature reactor are utilized to make possible the economical operation of a nuclear power station of medium capacity (300-600 MW.sub.el) while maintaining a high standard of safety. The characteristics comprise a reactor protection building equipped with pressure relief means in combination with filters, several auxiliary cooling systems separate from the operating cooling systems for the removal of decay heat in the case of accidents, and the utilization of a liner cooling system for the prestressed concrete reactor pressure vessel to assure the removal of the decay heat in case of a failure of the auxiliary cooling systems.

Abstract: A nuclear reactor installation with a high temperture, gas cooled nuclear reactor supported in a cavity on a segmented bottom plate held by a centered point of fixation. The first heat exchangers of the primary circulation loop are arranged in the cavity around the nuclear reactor, with the associated first blowers being supported in first passages of the pressure vessel roof. The second heat exchanger for the removal of the decay heat are arranged similarly, with the associated second blowers located in passages of the pressure vessel bottom. The blowers are equipped with contactless magnetic bearings for the rotors. The drives of the core rods and the reflector rods are designed for a banking operation. Simultaneously, the side reflector is supported by means of radial supports on the thermal side shield elastically and secured against rotation. The measures described provide a simplified configuration without affecting safety.

Abstract: A pressure vessel and a method for distributing the stresses in a thick-walled high-pressure vessel, so that they lie within allowable limits, by constructing the wall in a series of generally concentric layers, at least one intermediate layer of which is to be constructed before the other layers. The intermediate layer is constructed above a base, resting on it through a sliding joint. Then it is placed under an external prestressing pressure. Thereafter, that layer is secured to the base by a rigid concrete connection. The remaining layers of the wall are then constructed and are subjected to an external prestressing pressure. Preferably, stress-relieving slots are applied to the innermost layer, during its construction.

Abstract: A low capacity nuclear reactor with spherical fuel elements in a subterranean configuration. The reactor is characterized by a compact construction and extensive elimination of active operating devices, such as charging installation, gas purification devices, regulating systems and safety systems. It is particularly suitable for the generation of thermal energy for heating purposes. A core vessel contains a pile of fuel elements also contains a portion of the graphite bottom and side reflector. Channels are provided in the part of the side reflector located inside the core vessel. Trim and shutdown rods are contained in the channels. The roof reflector rests on the stationary pile of fuel elements. The entire core vessel together with the components contained therein is removed following burnoff of the fuel elements. The heat generated in the core is transferred to a cooling system mounted on the inside of a pressure vessel enclosing the nuclear reactor by a cooling gas which flows from top to bottom.

Abstract: Disclosed is a prestressed concrete pressure vessel having a vessel opening which is closed by a concrete cover. Two separate gaskets are disposed between the cover and the pressure vessel, and bordering on an annular channel. The annular channel is connected with a gas detector by means of a connecting channel. At the same time, the inner area of the cover rises from the pressure vessel at a slight angle. The vertical prestress by which the cover is pressed down is larger than the force acting against it (the internal pressure). Additionally, the horizontal annular prestress of the cover is larger in its upper region than in the lower region. In this manner, a constant seal is combined with means for monitoring the seal.

Abstract: A cost-effective configuration of a metal liner for a reinforced concrete pressure vessel is disclosed wherein only stud shear connectors and cooling tubes of the liner cooling system are used to anchor the liner and the passages provided in the liner and the wall of the vessel. In the areas of the introduction of forces, stud connectors of different stud rigidities are used. In the anchoring of loads which is again effected by stud connectors only, further transmission is obtained by means of reinforcing rods.

Abstract: Process for the construction of a nuclear reactor having a reinforced concrete pressure vessel, comprising utilization of a corset frame to support the cavity liner, closing off the reactor cavity and installing the reactor components under "clean conditions", simultaneous to the layer-by-layer pouring of the walls and top of the reinforced concrete pressure vessel. The erection of the supporting corset substantially reduces the overall assembly time of the nuclear power station without involving additional expense.

Abstract: Nuclear power plant with a reactor building, a fuel building, buildings for the ancillary nuclear, electrical and safety equipment, and a building for turbo-electric machines.The group of buildings is in the general shape of a T, with the fuel and ancillary equipment buildings (2) and (3) in line at both sides of the reactor building, and the engine building (6) facing the reactor building (1) and perpendicular to the latter. The vault of the protective enclosure is connected to the foundation of the reactor building and is in the shape of a cylinder with horizontal generatrices.The invention is applicable to light water nuclear power stations.

Abstract: Annular slab for closing the vessel of a fast nuclear reactor, comprising at least one downwardly divergent frusto-conical sleeve coaxial with the inner and outer sleeves delimiting the slab, dividing the slab envelope into upper and lower parts respectively filled with concrete incorporating metal reinforcements and with concrete for radiation protection.

Abstract: A concrete pressure vessel (1) for a nuclear reactor is formed with an arch (6) arranged above the cover (4) of the pressure vessel, said arch having a horizontally directed opening permitting horizontal transport of the cover. The cover (4) is retained by a plurality of compressive force transmitting elements (11) arranged between the cover and the arch (6).

Abstract: A pressure vessel for a nuclear reactor comprises a reinforced concrete vessel with at least one open area located in the wall of the concrete vessel, a lining means anchored on the inside surface of the concrete vessel and the opea area for protection of the surfaces and at least one expansion space in the concrete vessel immediately adjacent the lining means to permit movement of the lining means and distribution of the stresses in the lining means under various reactor conditions.

Abstract: Nuclear power plant with a reactor building, a fuel building, buildings for the ancillary nuclear, electrical and safety equipment, and a building for turbo-electric machines. The group of buildings is in the general shape of a T, with the fuel and ancillary equipment buildings (2) and (3) in line at both sides of the reactor building, and the engine building (6) facing the reactor building (1) and perpendicular to the latter. The vault of the protective enclosure is connected to the foundation of the reactor building and is in the shape of a cylinder with horizontal generatrices. The invention is applicable to light water nuclear power stations.

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: Disclosed is a pressure vessel of a nuclear power plant comprising a generally cylindrical shaped first partial section, a cavity for housing a high temperature reactor within the first partial section, a second partial section forming the lower part of the pressure vessel, a horizontal tunnel for housing a gas turbine assembly within the second partial section and a plurality of recesses for housing components of a heat exchanger apparatus, wherein the cavity for housing the high temperature reactor is eccentrically arranged in the first partial section of the pressure vessel with respect to the cylindrical shape.

Abstract: The present invention relates to an improved attachment assembly for clamping a nuclear reactor foot ring into engagement with a surrounding support wall while allowing for thermal expansion of the foot ring.