Abstract: A modular radiation shielding system for use on the lower side of a nuclear steam generator tubesheet 14 to protect inspection and repair workers in the primary head 20 of the generator 10 from radiation of the tubesheet 14 and plurality of tubes 12 it secures. The modular assemblies each comprise a geometrically shaped lead panel 22 sheathed in a stainless steel box 30 with a transverse opening extending therethrough for alignment with a tube 12. A rapid installation tube gripper 40, which may have a lead nose for shielding, extends through the opening and into a tube 12 to hold the geometrically shaped modular assembly against the lower surface of the tubesheet 14.

Abstract: A sealoff device and method are disclosed for controlling the level of a fluid within first and second confined regions which are arranged in fluid communication with one another. In the preferred embodiment, the invention permits shielding of the tube bundle contained within the wrapper of a nuclear steam generator while controlling the level of the working fluid within the surrounding annular downcomer passage. A sealoff device constructed of a flexible hollow tube is provided in sealing engagement between the wrapper and outer shell forming the downcomer passage to provide a substantially fluid-tight seal thereat. The sealoff device permits the maintaining of a high water level inside the wrapper to shield the tube bundle which is emitting nuclear radiation while maintaining a low water level within the downcomer passage to permit greater accessibility for repair and maintenance of the steam generator in a dry environment and to permit greatly increased working time in a greatly reduced radiation field.

Abstract: A shielding device is disclosed for use in shielding the under-vessel area from radiation emanating above the lower terminus of a control rod drive of a power generating nuclear reactor of the boiling water type. The device may be comprised of a plurality of individually mountable shell-like housings which are joined in mating contiguous relation to surround the lower terminus of a control rod drive. In the preferred embodiment, each such device is provided with an integrated access door which will allow access to and removal of any connectors and cables such as those of a position indicating probe.

Abstract: A nuclear reactor with juxtaposed prismatic fuel assemblies cooled by the flow of a liquid in a cylindrical jacket. A partitioning of the core between the peripheral assemblies and the jacket is constituted by rods parallel to the assemblies, guided laterally by bracing plates fast to the jacket in which the rods are free to slide longitudinally.

Abstract: In a liquid metal cooled nuclear reactor with a nuclear fuel assembly in a coolant-containing primary vessel housed within a concrete containment vault, there is thermal insulation to protect the concrete, the insulation being disposed between vessel and concrete and being hung from metal structure secured to and projecting from the concrete, the insulation consisting of a plurality of adjoining units each unit incorporating a pack of thermal insulating material and defining a contained void co-extensive with said pack and situated between pack and concrete, the void of each unit being connected to the voids of adjoining units so as to form continuous ducting for a fluid coolant.

Abstract: Shielding for technicians working around a nuclear reactor during the refueling process is provided by permanently mounting a shield support around the reactor shroud and temporarily hanging shielding members such as lead panels from the support. The shield support includes a permanent rail encircling the shroud and swingout arms which are pivotably mounted to the permanent rail. During use the shielding members are positioned adjacent the swingout arms by a stud tensioner hoist, and the swingout arms are pivoted outward to receive the shielding members. When installed, the edges of the shielding members overlap.

Abstract: A method and apparatus for eliminating leakage spaces between the partitions (1) surrounding the core of a pressurized water nuclear reactor, after it is brought into operation. Operations are carried out under water, during shutdown of the reactor. The defective joins (12) between the partitions (1) are identified. For each join, the partitions (1) are pierced, the hole inside a partition (1) is screw-threaded, the swarf is recovered, a screw with diametrical expansion is introduced and screwed into the hole and the screw is expanded by displacement of a rod in the longitudinal direction of the screw. Moving location, the operations are repeated for each defective join (12). The apparatus comprises a case (25) containing a drum (36) bearing tools for boring (54-65), screw-threading, and screwing, a cleaning tube and a punch for locking the screw.

Abstract: A neutron streaming shield comprising a plurality of wire mesh baskets, each basket located between two adjacent vessel nozzles, the total area of the nozzles and baskets being sufficient to intercept any streaming neutrons. The baskets are substantially filled with a multiplicity of randomly packed lumps of a neutron attenuating material, preferably a borated-hydrogenated-argillaceous media. Since the basket is somewhat flexible, it can be inserted in the annulus above the nozzles and then filled with the lumped material, forming a plurality of barriers to compliment the attenuating affect of the nozzles, such that any streaming neutrons will be stopped either by the nozzles or the lumped material in the baskets.

Abstract: A panel of neutron shielding material comprises outer sheathing layers of aluminum having therebetween alternate thin layers or plies of aluminum and metallurgically bonded uniform mixtures of aluminum particles and particles of a neutron absorbing material, preferably boron carbide (B.sub.4 C) in which the layers have their major dimensions extending substantially parallel to the outer aluminum layers. In a modified construction, the alternate layers or plies may extend perpendicular to the outer aluminum layers or plies. The assembly is hot rolled to a final thickness, usually about one quarter or one eighth inch, metallurgically bonding the aluminum sheets, strips, and/or particles and the aluminum and boron carbide particles into a continuous mass.

Abstract: A heat shield for high thermal loading and particularly pulse heat loading n fusion reactors e.g. as first wall, plasma physics installations, particle accelerators, etc. contains a cooled support plate carrying a large number of shielding or limiter members on its side facing a heat source, e.g. a hot plasma. The shielding or limiter members are detachably connected to the support plate by a good thermally conducting seat, e.g. a bevel, ball or flat seat. By suitably shaping and arranging the limiter members, it is possible to substantially cover the surfaces of practically any desired shape such as, e.g., the inner wall of a toroidal vacuum vessel. As a result of their limited size, the limiter members can be adapted in a optimum manner to locally differing requirements. The size and shape of the support member can be adapted to widely differing boundary conditions.

Abstract: A plenum separator system for separating the hot plenum from the cold plenum and from the reactor vessel wall in a pool-type nuclear reactor. One or more intermediate plena containing substantially stagnant and thermally stratified coolant provide axial separation of the hot and cold plena. A dual pass forced bypass flow through annuli at the upper portion of the reactor vessel wall, in conjunction with the intermediate plenum and an annular gas space adjacent the reactor vessel wall, provide radial separation of the hot plenum and the vessel wall.

Abstract: An inspection and repair system for a substantially enclosed radioactive work environment to protect and shield workers therein from radiation. The system decreases health hazards for workers and increases the safety margin within the environment. The method contemplates utilizing a tank coupled to the environment for entrance thereto. The environment and the tank are filled with a radiation attenuating fluid which protects workers entering the environment through the tank. The workers are supplied with air from an external source for respiratory protection and relieving the worker of cumbersome self contained breathing apparatus. The system can also utilize pumps for circulating the water therein and a filter for filtering out contaminants.

Abstract: A reactor cavity surrounding a reactor coolant inlet or outlet pipe is designed to reduce pressurization of the cavity in the event of a LOCA pipe break therein.

Abstract: The invention relates to a radiation-shielding closure arrangement wherein closure body closes off an opening in a wall between two mutually adjacent large-area cells of a nuclear facility. When the closure body is in the closed position, the cell adjacent the cell wherein radiation is present is shielded against the radiation. If one of the cells contains a cell crane and is at the same time a prohibited area because of radiation present therein, the adjacent cell is configured to be an access cell so that maintenance work on the cell crane can be conducted there. The opening in the partition wall between the two cells must be closed during the time that the maintenance work on the crane is performed. For this reason the closure body is mounted on a horizontal rail track for movement therealong. The outer profile of the closure body fits snugly in the inner profile of the wall opening or overlaps the wall opening completely.

Abstract: Slab for closing a fast neutron nuclear reactor, comprising a first central annular part (10) the diameter of which is substantially equal to the diameter of the reactor vessel (5) and a second peripheral annular part (11) connected to the first part (10) by its outer shell (14). Both parts of the slab are made in the form of steel caissons enclosing concrete. The central part (10) is strengthened by two frusto-conical shells (20, 21). The peripheral part (11) is strengthened by flat axial webs. The inner shell coincides with the outer shell (14) of the central part. The invention applies in particular to fast neutron nuclear reactors cooled with liquid sodium, of an integrated type.

Abstract: A passage through a reinforced concrete pressure vessel is provided, wherein the tolerance ranges required for the fastening of the components in the passage may be produced safely and without excessive expenditures. This is achieved by an arrangement including a lining having a first, outer tube resting against the concrete and a second tube arranged within the first tube.

Abstract: A nuclear reactor is provided with novel composite assemblies at selected locations at the periphery of the reactor core in order to reduce the rate of radiation exposure to a critical pressure vessel weld. The composite assemblies include a shield zone at a selected location close to the weld and a fuel zone incorporating fissile material. This approach reduces the rate of radiation exposure at at the weld while also contributing to production of power by the core.

Abstract: A nuclear reactor having a remotely removeable and replaceable thermal and/or radiation insulating shield for the head. This shield is formed of interlocked integrated shielding units of thermal insulating material. Each unit has a vertical member and a horizontal member. Each unit has a lifting-and-lowering rod on its top and it may be raised vertically by a remotely operable clamp engaging the head. The interlocking surfaces of adjacent units are so formed that when any unit is raised or lowered vertically its interlocking surface readily slides along the interlocking surfaces of the units adjacent to it with which it is interlocked.

Abstract: A self-supporting modular radiation attenuation system formed from a plurality of modules stacked on one another in any desired alignment to protect workers from radiation exposure. The modules include a skin assembled with a radiation attenuation medium therein and shaped to mate with one another when assembled. The medium can be lead particles or compressed lead wool. The outer module skin is sufficiently dimensionally stable to support stacking; however, flexible enough to allow the modules to conform to irregular surfaces. The modules can include a particle binder and the system can include framing to support the modules.

Abstract: An improved modular reactor head shielding system is provided that includes a frame which is removably assembled on a reactor head such that no structural or mechanical alteration of the head is required.The shielding system also includes hanging assemblies to mount flexible shielding pads on trolleys which can be moved along the frame. The assemblies allow individual pivoting movement of the pads. The pivoting movement along with the movement allowed by the trolleys provides ease of access to any point on the reactor head. The assemblies also facilitate safe and efficient mounting of the pads directly to and from storage containers such that workers have additional shielding throughout virtually the entire installation and removal process.The flexible shielding pads are designed to interleave with one another when assembled around the reactor head for substantially improved containment of radiation leakage.

Abstract: Heat retarding closure system for partitions having pressure relief openings formed therein especially in nuclear reactor buildings where main coolant nozzles of a reactor pressure vessel penetrate a biological shield, including lightweight construction closure elements having a side facing the reactor and anchors for holding the closure elements, the closure elements being pushable out of the anchors by an overpressure in a given pressure difference direction on the reactor side, and an outer sealing blowout skin, the closure elements being in the form of heat-retarding cassette inserts having a front surface with a peripheral shearing edge formed thereon resting against the blowout skin, and the blowout skin having a given thickness in the given pressure difference direction enabling the cassette insert to shear off the blowout skin and be pushed out of the anchors when a given pressure difference is at least reached.

Abstract: The present invention relates to an upper neutron protection device for a nuclear reactor assembly.This device comprises at least one container partly filled with a neutron-absorbing product and maintained within a wall located in the upper part of the assembly by at least one spacing plate.Application to fast neutron reactors.

Abstract: An improved passive cooling arrangement is disclosed for maintaining adjacent or related components of a nuclear reactor within specified temperature differences. Specifically, heat pipes are operatively interposed between the components, with the vaporizing section of the heat pipe proximate the hot component operable to cool it and the primary condensing section of the heat pipe proximate the other and cooler component operable to heat it. Each heat pipe further has a secondary condensing section that is located outwardly beyond the reactor confinement and in a secondary heat sink, such as air ambient the containment, that is cooler than the other reactor component. Means such as shrouding normally isolated the secondary condensing section from effective heat transfer with the heat sink, but a sensor responds to overheat conditions of the reactor to open the shrouding, which thereby increases the cooling capacity of the heat pipe.

Abstract: Apparatus for partitioning off the core of a nuclear reactor constituted by a set of boxes (8, 9, 10, 11) each comprising at least two plates (12-13, 14-15, 27-29, 28-30) rigidly assembled at right angles and disposed in the longitudinal direction of the assemblies, and a plurality of transverse plates (32) perpendicular to the longitudinal plates. The boxes are removably disposed side by side inside the core casing (1), and bearing thereon. The faces of the longitudinal plates directed towards the reactor core serve as bearing faces for the assemblies. Each of the boxes is fixed to at least one of the upper or lower plates of the core by a flexible coupling allowing longitudinal displacement.

Abstract: A process to produce energy with the fusion of hydrogen and carbon in a thermonuclear fusion reaction with an extension, wherein carbon targets are bombarded with a beam of fast protons at temperatures of 457 kev. The thermonuclear fusion reaction produces two helium atoms and two neutron particles.The neutrons are captured by a blanket of lithium 7 which cools the walls and carries the heat to a turbulent heat exchanger, then to a generator and turbine complex which generates energy, giving tritium as a sub-product.The helium atoms plus alpha particles and protons are extracted to the reactor's extension where, combined with the tritium emitted in the first cycle of the thermonuclear fusion reactor, they go to generate more energy.This process becomes self-maintaining once the thermonuclear fusion reactor is put into operation.

Abstract: A modular reactor head shielding system formed from a plurality of flexible pads shaped to interleave with the edges of each adjacent pad around the reactor head. The shielding system is assembled to protect workers from radiation exposure in working in the area around the reactor head or when working on the reactor head during refueling of the reactor. The pads are formed by inserting a pair of blankets secured to one another inside a pair of outer covers which are secured to one another in offset relation to form an interleave or tongue and groove configuration to eliminate radiation paths between pads. The blankets are formed by quilting lead wool within the blanket covers. Each pad has a hanging plate secured to one end which can be hung from a frame around a reactor head or from the reactor head itself. The pads are secured to one another such as with straps to insure elimination of radiation paths therebetween.

Abstract: A core shroud including flexible panels sealingly attached to the inner surface of the shroud at an elevation opposite the fuel assembly grids nearest the core midplane. Each panel forms the outer wall of a deformable chamber which is pressurized through a conduit carried by the shroud. One end of the conduit is in fluid communication with the reactor coolant at a high pressure location remote from the panels, producing a pressure differential across the panel which urges the panel against the adjacent grid to prevent core bowing.

Abstract: An after-heat removal system for a nuclear reactor, especially a gas-cooled uclear reactor in which the core is formed by a pile of spherical nuclear fuel elements, comprises an outlet in the side reflector of the reactor core which is connected to an after-heat removal system and draws the hot gases from a location within the pile, the return line from the after-heat removal system opening into the main cooling gas inlet.

Abstract: A nuclear reactor including a vertically extending reactor vessel containing a number of reactor components and located within a cavity defined by a vertically extending, circumferential cavity wall assembly is disclosed herein. The reactor also includes a particularly designed guard vessel arrangement including a guard vessel located around and spaced from the reactor vessel between the latter and the cavity wall assembly. The guard vessel is supported by means in the shape of an inverted frustum which not only serves as a support but which also acts as a means to provide a uniform temperature gradient between the guard vessel and cavity wall assembly and provides for ready access into the space between the two vessels by suitable equipment for providing in-service inspection of the vessel walls defining this space.

Abstract: A head equipment support structure system (HESS) (10) particularly adapted to be cooperatively associated with a nuclear reactor vessel (12) for purposes of effecting a separation of the electrical cables (30) that are utilized in the head area of such a vessel (12), as well as for purposes of providing support for these cables (30). The subject HESS (10) which is in the form of an integral structure that is removably supported relative to the vessel (12) combines the features of cable support structure, missile shield, and cooling ductwork support structure. The HESS (10) embodies horizontally disposed multiple decks (14) to which the cables (30) are vertically routed from the reactor vessel head. The decks (14), which are located in vertically spaced relation directly above the reactor vessel head, support and separate the cables (30).