Abstract: An integrated head assembly (100) is disclosed for a nuclear reactor. The preferred integrated head assembly includes a lift assembly (150) that supports the reactor vessel closure head (90) and integrated head assembly for removal, a separate support structure (202) supported by a ring beam (151) that sits atop the reactor vessel closure head, a shroud assembly (200), a seismic support system (300), a baffle assembly (500), a missile shield (400), and a CRDM cooling system. The CRDM cooling system draws cooling air into the baffle assembly, downwardly past the CRDMs (96), outwardly to upright air ducts (600), upwardly to an upper plenum (680), and out of the assembly through the air fans (190).

Abstract: The present invention is used to reduce thermal load itself, being the cause to generate stress, which develops near liquid surface in a nuclear reactor wall and to contribute to further improvement of safety. A partition member (5) is arranged above a coolant liquid surface (9) in an annulus space (3) between a reactor vessel (1) and a guard vessel (2), a low-temperature gas is circulated through the annulus space above the partition member to cool down, the gas is circulated through the annulus space from under the coolant liquid surface to the partition member, and the high-temperature gas heated under the coolant liquid surface is used to raise the temperature above the coolant liquid surface.

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 reinforced concrete containment vessel in a nuclear reactor includes a cylindrical shell having a side wall. The side wall includes an opening and a plurality of reinforcing bars, at least one of which is interrupted at the side wall opening. A reinforcing plate having an opening is located in the cylindrical shell so that the reinforcing plate opening is aligned with the side wall opening and the interrupted reinforcing bars are connected to the reinforcing plate. Reinforcing bar terminators connect the reinforcing bars to the reinforcing plate.

Abstract: An integrated head assembly (100) is disclosed for a nuclear reactor. The preferred integrated head assembly includes a lift assembly (150) that supports the reactor vessel closure head (90) and integrated head assembly for removal, a separate support structure (202) supported by a ring beam (151) that sits atop the reactor vessel closure head, a shroud assembly (200), a seismic support system (300), a baffle assembly (500), a missile shield (400), and a CRDM cooling system. The CRDM cooling system draws cooling air into the baffle assembly, downwardly past the CRDMs (96), outwardly to upright air ducts (600), upwardly to an upper plenum (680), and out of the assembly through the air fans (190).

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: In a heat shield (1), in particular for combustion chambers and for thermal fluid flow machines, the heat shield consists of a feltlike material (3) composed of compressed and sintered intermetallic fibers. Advantageously, the intermetallic fibers consist of an iron based or nickel based intermetallic phase.

Abstract: When a radioactivated reactor pressure vessel is carried out from a nuclear reactor building of a nuclear power plant, a first opening portion for carrying out the reactor pressure vessel is provided in a roof of the nuclear reactor building, a radiation shield for covering the reactor pressure vessel and shielding radiations is carried into the reactor building through the first opening portion, and installed on a reactor shield wall, lowering a hanger through the first opening portion and a slit provided on an upper lid of the radiation shield, a part of a lid of the reactor pressure vessel and a part of the upper lid of the radiation shield are abutted by hanging up the reactor pressure vessel by the hanger, and the reactor pressure vessel and the radiation shield integrated therewith are raised and carried out of the reactor building, whereby the shield can be easily mounted on the large-sized apparatus in a short time and a dose of radiations exposed to a worker when the shield is mounted can be reduced.

Abstract: A forged upper shroud section which may be machined from a single piece rectangular cross-section ring forging and includes a circular flange and a cylindrical shell is described. Openings and slots are machined into the flange to align and support the shroud head. A groove is machined along an inside surface of the cylinder section, and the groove may be used to support top guide grid (not shown). An end of the cylinder section is machined with a weld prep for attachment to the core section of the shroud.

Abstract: A heat removal system for the under reactor pressure vessel area of a boiling water nuclear reactor system that provides both protection of the containment boundary from attack by molten core debris and cools the molten core debris to prevent a breach of the containment boundary in the unlikely event of a severe accident where the molten core penetrates the lower head of the reactor vessel is described. The heat removal system includes a glass matrix slab positioned adjacent the floor of the containment and a plurality of heat tubes at least partially embedded in the glass matrix slab and extending into the area under the nuclear reactor pressure vessel. The cooling system also includes a passive containment cooling system, and fused vent pipes connecting the suppression pool with the drywell.

Abstract: A nuclear power plant includes at least two reactor vessels enclosed within a single containment building. In a first embodiment, the reactor vessels and steam generators operate separately from one another. In a second embodiment the reactor vessels jointly provide heat to a common header having a plurality of steam generators associated therewith. In a third embodiment, the reactor vessels are completely integrated with one another by means of a single control and coolant system.

Abstract: An enclosed cutting zone for use in a nuclear power plant. The cutting zone includes a cutting zone barrier and a transfer zone. The cutting zone includes a movable submergible upper rig, an upper inflatable ring supported by the submergible rig; a lower inflatable ring supported by the submergible rig; and a means for coupling the vertically extending edges of the submergible upper rig to form a cutting zone barrier having enclosed sidewalls. The transfer zone includes a movable, submergible upper rig; an upper inflatable ring supported by the submergible rig; and a lower inflatable ring supported by the submergible rig. The transfer zone is coupled to exterior surface of the cutting barrier so as to form a structure having enclosed sidewalls and an open top.

Abstract: A top guide to shroud head interface is described. In one embodiment, the interface includes a top guide that includes a flange that is configured to engage a corresponding flange of the shroud head. The top guide flange includes a plurality of frusto-conical shaped guide pins extending from the top surface of the flange. The shroud head flange includes a plurality of guide pin openings configured to align with the guide pins located on the top guide flange. Each guide pin opening includes a frusto-conical portion that extends through the flange from the bottom surface of the shroud head flange and has a slope equal to the slope of the frusto-conical pins. Each guide pin opening also includes a cylindrical portion that extends from the small base of the frusto-conical portion of the guide pin opening to the top surface of the shroud head flange.

Abstract: A gap forming structure for use with water cooled nuclear reactors is invented to prevent overheating and ultimately structurally failing of the lower head of a reactor vessel in a nuclear reactor core meltdown accident by virtue of a cooling effect in the gap structure for facilitating the retention of accumulated molten core debris. Single layer or multilayer gap structures can be installed either inside or outside the vessel lower head by joining, or fastening structures or secured to the instruments/control guide tubes within the vessel. The water cooling capacity inside the gap can prevent the vessel lower head from overheating and subsequently failing and thus defend against severe accidents by preventing the lower head of the reactor vessel from rupturing.

Abstract: A modular differential pressure measuring system for a boiling water nuclear reactor pressure vessel is described. The modular pressure differential system includes a plurality of pressure lines having a plurality of pressure line sections. The system also includes a shroud having at least one replaceable shroud section. Each shroud section includes at least one pressure line section which is configured to connect to and disconnect from corresponding pressure line sections in adjacent shroud sections without welding. Additionally, the system includes a reactor bottom head petal section having a shroud support flange and a plurality of bores defining pressure line sections wherein at least one pressure line section of said bottom head petal is configured to couple with a corresponding pressure line section of an adjacent shroud section. The modular pressure system does not require cutting of the pressure lines or pressure line supports for replacement of the replaceable shroud sections.

Abstract: The invention relates to a rotating electric machine including a coil of a wire having thereon an insulating coating comprising a polybenzimidazole. This rotating electric machine is stably maintained for a long time in dielectric strength even under a highly radioactive environment, due to the use of the special insulating coating. With this, the rotating electric machine can be driven stably for a long time. The invention further relates to another rotating electric machine including (a) a rotor having a rotating shaft; (b) a bearing for supporting the rotating shaft; and (c) a grease applied to the bearing. This grease contains (1) a polyphenyl ether having at least three aromatic rings in the molecule and (2) a urea. The rotor of this rotating electric machine is stably supported in the bearing for a long time even under a highly radioactive environment, due to the use of the special grease. Thus, this rotating electric machine can also be rotated stably for a long time.

Abstract: A nuclear fuel rod assembly storage rack comprises a rigid structure delimiting vacant spaces of square, cross-section and neutron-absorbing units also having a square cross-section prearranged before introduction into all or part of the vacant spaces between the shroud tubes. Each neutron-absorbing unit is made up of four flat plates of neutron-absorbing material, surrounded by at least two support grids. The support grids may comprise two units assembled together, for example by welding.

Abstract: The invention relates to a rotating electric machine including (a) a rotor having a rotating shaft; (b) a bearing for supporting the rotating shaft; (c) a radiation resistant grease applied to the bearing; and (d) a shield layer for shielding the grease from radiation. The shield layer is made of lead and surrounds the bearing. The shield layer includes (1) a first cylindrical shield member that is positioned to cover the bearing, such that the bearing is shielded from a first radiation that is in a direction substantially perpendicular to an axis of the rotating shaft, and (2) second and third disk shield members that are positioned to interpose therebetween the bearing in a direction along the axis of the rotating shaft, such that the bearing is shielded from a second radiation that is in a direction substantially along the axis of the rotating shaft. Thus, the rotor of this rotating electric machine is stably supported in the bearing for a long time even under a highly radioactive environment.

Abstract: A shroud attachment assembly which provides both structural support for the shroud and a seal between the shroud and shroud support is described. In one specific embodiment, the shroud attachment assembly includes a shroud flange formed integral with the shroud, and a pump deck flange formed integral with the pump deck. The shroud flange extends over the pump deck flange, and a plurality of studs extend through aligned openings in the flanges. In addition, a plurality of wedges are secured to the shroud flange by studs, and the wedges extend between the shroud flange and the pump deck flange. Generally, the studs which extend through aligned openings in the shroud and pump deck flanges transfer vertical loads from the shroud to the pump deck, and the wedges transfer horizontal loads from the shroud to the pump deck.

Abstract: An apparatus for repairing the core shroud of a nuclear reactor having one or more cracked vertical seam welds. The repair involves machining two holes in the shroud on opposing sides of the cracked vertical seam weld and then attaching two flexible links on the inside and outside of the shroud wall by means of two shear bolts inserted in the machined holes. The flexible links bridge the cracked vertical weld seam. Multiple link assemblies can be placed along the length of a crack. The links are made of an alloy having a coefficient of thermal expansion less than the coefficient of thermal expansion of the shroud material. The links are installed while the reactor is shutdown. When the reactor returns to operation, the consequent temperature rise causes the shroud section being bridged by the links to expand more than the links expand. As a result the links exert a circumferential compressive load across the crack in the vertical seam weld.

Abstract: Spent nuclear fuel storage casks, particularly a protective and venting cover for such storage casks which are stored above ground. The protective and venting cover may be assembled from annular or doughnut-shaped cast concrete members stacked one upon the other and/or steel members extending the height of the storage cask. The annuli are axially indexed with respect to the storage cask, such that a venting annulus is formed about the storage cask and the annulus contributes to a defocusing geometry against armor piercing weapons, such an anti-tank "shaped charge" weaponry.

Abstract: An integrated head assembly for a nuclear reactor pressure vessel includes a closure head with CRDM assemblies extending upwardly from the head. A CRDM seismic support disposed above the closure head provides lateral support for the CRDM assemblies. The seismic support also has air flow holes which communicate with the interior of a shroud enclosing the CRDMs and extending upwardly from the closure head to the seismic support. The shroud has an air port in direct air flow communication with the surrounding atmosphere so that the closure head, shroud and seismic support define an air flow passageway directly communicating with the surrounding atmosphere via the air port and without the extensive ductwork and, therefore, with substantially less power. A missile shield disposed above and in air flow communication with the seismic support provides a lightweight, compact physical barrier for removing energy from dislocated objects such as CRDM drive rods.

Abstract: A reaction chamber (20) is charged with a reactant metal (18) which is heated to a molten state by a suitable heating arrangement (21). A field generating arrangement (17) generates a unidirectional electromagnetic field through the molten reactant metal (18) and through at least one target area preferably within the molten reactant metal. The electromagnetic field directs beta particles toward the first target area. A radiation absorbing module (15, 16) is positioned in the first target area and includes at least one radiation absorbing material (75, 76). The radiation absorbing material (75, 76) in the modules (15, 16) absorb the beta radiation which has been directed to the target area by the electromagnetic field.

Abstract: A nuclear reactor plant includes a reactor pressure vessel having a core barrel supported on a cylindrical holding structure fixed in the reactor pressure vessel. The core barrel has a lower part with at least one elastically resilient segment. A projection disposed on the segment engages under the holding structure in such a way that a wedge-like gap is formed between a lower surface of the holding structure and the projection. A wedge is braced in the gap. A method is also provided for mounting the core barrel.

Abstract: A mid-shroud joint which improves the replaceability of the shroud is described. In one embodiment, the shroud includes a core shroud and a lower shroud. A core plate support flange is clamped between the core shroud and the lower shroud, and the core plate support flange supports a core plate. The mid-shroud joint is formed by a flange of the core shroud and a flange of the lower shroud. The core plate support flange is positioned between core shroud and lower shroud flanges, and openings in these flanges align so that bolts can be inserted through such aligned openings.

Abstract: A shroud including an integral track for mounting inspection and cleaning tooling is described. In one embodiment, the shroud includes substantially cylindrical first and second shroud sections having a main body with a first end and a second end. One shroud first end has a weld prepared surface. Each shroud section includes a ledge in an exterior surface adjacent the first end. A weld is formed between the weld prepared surface and the first end of the second shroud section. At the weld, the shroud is substantially geometrically balanced with equal material on both sides of the weld. A geometrically balanced weld provides the same heat sink characteristics on both sides of the weld, and allows for a more uniform distribution of weld residual stresses.

Abstract: An integrated head assembly for a nuclear reactor pressure vessel includes a closure head with CRDM assemblies extending upwardly from the head. A CRDM seismic support disposed above the closure head provides lateral support for the CRDM assemblies. The seismic support also has air flow holes which communicate with the interior of a shroud enclosing the CRDMs and extending upwardly from the closure head to the seismic support. The shroud has an air port in direct air flow communication with the surrounding atmosphere so that the closure head, shroud and seismic support define an air flow passageway directly communicating with the surrounding atmosphere via the air port and without the extensive ductwork and, therefore, with substantially less power. A missile shield disposed above and in air flow communication with the seismic support provides a lightweight, compact physical barrier for removing energy from dislocated objects such as CRDM drive rods.

Abstract: There is provided an Al base alloy containing boron which is superior in mechanical properties such as strength, ductility or workability and the like and has a neutron absorbing capacity and an ability to recycle. This is an Al base alloy containing boron with Mg: 2 to 8% (massed %, similarly applied hereinafter) and B: 0.5 to 1.5% and satisfying a relation of .sup.10 B/(.sup.10 B+.sup.11 B).gtoreq.95%, and a rate of AlB.sub.2 in all boron compounds is 80% or more by a volumetric rate.

Abstract: Spent nuclear fuel storage casks, particularly a protective and venting cover for such storage casks which are stored above-ground. The protective and venting cover may be assembled from annular or doughnut-shaped cast concrete members stacked one upon the other. The annuli are axially indexed with respect to the storage cask, such that a venting annulus is formed about the storage cask and the annulus contributes to a defocusing geometry against armor piercing weapons, such as anti-tank "shaped charge" weaponry.

Abstract: A method of replacing a boiling water reactor core shroud includes the steps of removing at least a portion of the existing core shroud from supporting structure in the reactor vessel, lowering a replacement shroud into the reactor vessel, positioning the replacement shroud on the supporting structure such that a bottom portion of the replacement shroud mates cooperatively with the supporting structure to limit lateral movement of the replacement shroud relative to the reactor vessel, and holding the replacement shroud assembly in place by applying axially compressive forces to the shroud in the direction of the supporting structure. If the existing core shroud is secured by welds, a parting cut is made to remove the shroud and the replacement shroud is held in place by securing a plurality of tie rods between sites on the replacement shroud and the supporting structure at a respective plurality of angularly spaced locations about the shroud periphery.

Abstract: In a pressure vessel of a nuclear reactor containing a core assembly enclosed within a core shroud, the core shroud spaced radially inwardly of a pressure vessel wall, with an annular shroud support plate fixed to the pressure vessel wall, wherein a lower end of the shroud is seated on an upper edge of the support plate to create a joint interface further wherein, and a plurality of brackets are secured between the shroud and the shroud support plate, spanning the joint interface.

Abstract: The device (15) for joining together a first plate (7) and a second plate (8)of the baffle assembly, which are located substantially at right angles, includes a screw (16) engaged in a housing consisting of an opening (18) passing through the first plate (7), and of a tapped blind opening (20) in the second plate (8). At least one opening (21) places an annular space (18b) around the shank (16b) of the screw in communication with the entry part (18a) of the opening (18) passing through the first plate (7), in order to deconfine the screw (16). The opening (21) may be a radial opening passing through a cup (17) against which the screw head (16a) comes to bear or an opening machined in the first plate (7) against a shoulder (18c) of the screw housing and the part (18b) of the opening for passing through the first plate (7) in which the shank (16b) of the screw (16) is engaged.

Abstract: A ceramic composition for absorbing electromagnetic waves and a method for manufacturing the same are disclosed. The composition comprises a raw powder comprising by weight between about 60% and about 80% Fe.sub.2 O.sub.3, between about 3% and about 8% NiO, between about 15% and about 25% ZnO, and between about 3% and about 8% CuO, and a mixture around the raw powder comprising by weight between about 30% and about 50% water, between about 0.2% and about 0.6% a dispersing agent, between about 0.5% and about 1.0% a plasticizer, and between about 0.1% and about 0.4% a lubricant. The method comprises the steps of grinding the powder, converting the grounded powder into granulates, forming the granulates into a shaped body, sintering the shaped body in a furnace, and cooling the sintered body gradually. The ceramic composition can absorb much of the electromagnetic waves generated from electric devices such as cellular phones, beepers, computers, wireless telephones, etc.

Abstract: An integrated head assembly for a nuclear reactor pressure vessel includes a closure head with CRDM assemblies extending upwardly from the head. A CRDM seismic support disposed above the closure head provides lateral support for the CRDM assemblies. The seismic support also has air flow holes which communicate with the interior of a shroud enclosing the CRDMs and extending upwardly from the closure head to the seismic support. The shroud has an air port in direct air flow communication with the surrounding atmosphere so that the closure head, shroud and seismic support define an air flow passageway directly communicating with the surrounding atmosphere via the air port and without the extensive ductwork and, therefore, with substantially less power.

Abstract: A shroud for a nuclear reactor is described. In one embodiment, the shroud includes first and second shroud sections, and each shroud section includes a substantially cylindrical main body having a first end and a second end. With respect to each shroud section, a flange is located at the main body first end, and the flange has a plurality of bolt openings therein and a plurality of scalloped regions. The first shroud section is welded to the second shroud section, and at least some of the bolt openings in the first shroud section flange align with respective bolt openings in the second shroud section flange. In the event that the onset of inter-granular stress corrosion cracking is ever detected in the weld between the shroud section, bolts are inserted through bolt openings in the first shroud section flange and through aligned bolt openings the second shroud section flange. Each bolt, in one embodiment, has a shank section and first and second threaded end sections.

Abstract: An apparatus for repairing the core shroud of a nuclear reactor having one or more cracked vertical seam welds. The repair involves installation of a ring around the circumference of the shroud while the reactor is shutdown. The ring is tensioned with a mechanical preload and then vertically supported with shear bolts or struts. The ring is made of an alloy having a coefficient of thermal expansion less than the coefficient of thermal expansion of the shroud material. When the reactor returns to operation, the consequent temperature rise causes the shroud to expand more than the ring expands. As a result the ring exerts a circumferential compressive load across any cracks in the vertical seam welds intersected by the ring.

Abstract: Core shrouds are conventionally welded together from cylindrical parts and annular flanges, wherein cracks have recently occurred in the region of weld seams in reactors of the boiling-water type. A core shroud, in particular for cladding a reactor core in a boiling-water nuclear reactor and a method for repairing a core shroud, include recesses disposed transversely relative to the circumferentially extending weld seams. The recesses have a middle part which passes through a region that is thermally influenced during welding as well as transverse grooves or widenings located in front of ends of the middle part and lying outside the thermally influenced region. A clamp which is fitted into the recess is disposed approximately flush with a shroud surface and is wedged in one of the transverse grooves.

Abstract: In order to reduce the number of lifts which are required to remove the various equipment normally disposed above the reactor pressure vessel and to make way for refuelling or regular maintenance, the control rod element drive mechanisms are completely enclosed within a cylindrical enclosure which is attached to the head of the pressure vessel. The top of the cylindrical enclosure is closed with a cap-like member which acts as both a missile shield and a head area cable tray. The missile shield, the cylindrical enclosure, the control rod drive mechanisms and the pressure vessel head, are connected to form an integral unit which can be removed in a single lift. Cable trays are pivotally supported on a wall of a building to establish a bridge between the building and the head area cable array and to establish a connection with the control element drive mechanism cables. During lifting, the control element drive mechanism cables are disconnected and the pivotal bridge trays are swung out of the way.

Abstract: A method of replacing a boiling water reactor core shroud includes the steps of removing at least a portion of the existing core shroud from supporting structure in the reactor vessel, lowering a replacement shroud into the reactor vessel, positioning the replacement shroud on the supporting structure such that a bottom portion of the replacement shroud mates cooperatively with the supporting structure to limit lateral movement of the replacement shroud relative to the reactor vessel, and holding the replacement shroud assembly in place by applying axially compressive forces to the shroud in the direction of the supporting structure. If the existing core shroud is secured by welds, a parting cut is made to remove the shroud and the replacement shroud is held in place by securing a plurality of tie rods between sites on the replacement shroud and the supporting structure at a respective plurality of angularly spaced locations about the shroud periphery.

Abstract: In a pressure vessel of a nuclear reactor containing a core assembly enclosed within a core shroud, the core shroud spaced radially inwardly of a side wall of the pressure vessel with an annular pump deck located in an annular radial space between the core shroud and the side wall of the pressure vessel, the improvement wherein the shroud is removably secured to an annular support leg extending upwardly from the bottom of the pressure vessel; and further wherein the annular pump deck is provided in the form of a plurality of removable segments.

Abstract: A storage tank for radioactive fissile material solutions. The tank comprises at least one cell containing a radioactive solution and a solid neutron-absorbing material while preventing any risk of criticality. A network of substantially vertical tubes is arranged within said cell and metal walls completely separate the radioactive solution from the solid neutron absorbing material. Said tubes contain the neutron absorbing material and are located in compartments defined by the metal walls throughout the radioactive solution. Said tank occupies a reduced floor space.

Abstract: A neutron absorbing apparatus which includes two adjacent neutron absorbing plates and a mounting assembly with latching means configured to be easily secured to fuel assemblies while the fuel assemblies remain under water in a fuel storage rack, thereby eliminating the need to remove the fuel assemblies or the fuel storage rack for installation. The two neutron absorbing plates are positioned orthogonally to form a chevron cross section which can be placed about the fuel assemblies by insertion in the existing space between the fuel assemblies and the cell walls of a fuel storage rack. A prescribed orientation of the chevron configured neutron absorbing plate in the cells of the fuel storage rack together with the selected use of a single neutron absorbing plate economically provides sufficient neutron absorption in all radial directions about the fuel assemblies to maintain safe storage condition sin closely packed fuel storage racks.

Abstract: An apparatus, which reinforces a shroud that is contained within a reactor vessel, is operable for reinforcement of the shroud in the event of cracking in the shroud. The apparatus comprises a reactor wall positioned surrounding the shroud. A beam is attached to and extends generally axially on the shroud for absorbing the forces generated by the cracking in the shroud, and a radial support is positioned between the beam and the wall of the reactor vessel for transmitting any forces absorbed by the beam to the wall.

Abstract: In a pressure vessel of a nuclear reactor containing a core assembly enclosed within a core shroud, the shroud spaced radially inwardly of a side wall of the pressure vessel, and an annular pump deck welded in a place in an annular radial space between the core shroud and the side wall of the pressure vessel. The shroud provided with a radially outwardly extending flange seated on and removably secured to the pump deck. Wedge elements are interposed between flange portions and the side wall.

Abstract: A function ally gradient composite material containing copper and carbon as main components and having a predetermined shape, in which the composition ratio of the copper to the carbon in the material continuously varies in at least one predetermined direction. The material is manufactured, for example, by impregnating carbon felt with a resin and thermo-compressively molding the impregnated felt (step S101), carbonizing the resin by baking (step S102) to provide a preformed carbon material (step S104). Pyrolytic carbon is thereafter deposited in the preformed carbon material by the CVI method (step S105) to provide a carbon material having the bulk density varying in a predetermined direction (step S107). After the wettability of the carbon material against copper is improved by siliconization (step S108), pores of the carbon material are impregnated with copper (step S109) to obtain a functionally gradient composite material of copper and carbon.

Abstract: A boiling water reactor control rod drive support system having radiation shields to protect persons working under the reactor vessel from radiation exposure and to limit the travel of a control rod in the event that a control rod housing is ruptured. The radiation shields include radiation shield rings for surrounding the control rod drive housing and radiation shield cups for surrounding the bottom portion of the control rod drive. The radiation shield rings can be used with support systems having radiation shield cups placed on rows of support bars or with existing support systems.

Abstract: A radiation shielding element especially for use in the temporary shielding of ancillary equipment or apparatus in nuclear-powered steam raising installations, said element comprising a flexible radiation-shielding sheet laminate comprising a flexible inner layer of plastic material, preferably silicone, filled with particles of radiation shielding material such as lead, said layer being interposed between two flexible skins of silicone elastomer.

Abstract: In a pressure vessel of a nuclear reactor containing a core assembly enclosed within a core shroud, the core shroud spaced radially inwardly of a side wall of the pressure vessel with an annular pump deck located in an annular radial space between the core shroud and the side wall of the pressure vessel, the improvement wherein the shroud is removably secured to an annular support leg extending upwardly from the bottom of the pressure vessel; and further wherein the annular pump deck is provided in the form of a plurality of removable segments.

Abstract: A method of removing radioactivity from the interior of a building by transporting radioactive material within a slurry, precipitating out or otherwise filtering out the then contaminated material outside the building, thus removing it in a continuous fluid recirculation system, and storing the precipitated out material while providing shielding of radiation, thereby to provide radiation protection without requiring conventional large mass to block the radioactivity. A toxic waste storage facility includes a building having a portion located below ground level, walls for bounding an interior space in the building, and recirculating fluid for removing thermal energy from the building and for providing radioactive shielding and absorption at least at part of the roof of the building.

Abstract: A nuclear reactor having a chemical decontamination clean-up system is provided in which every component of the chemical decontamination clean-up equipment which processes radioactive fluids is located within a shielded room of an existing on-site support building. Those components of the clean-up system not in direct contact with radioactive fluids are housed in portable trailers. The decontamination clean-up system is designed to provide for adequate shielding to minimize personnel exposure and also incorporates a modular design for component transportation and storage.