Abstract: A method and an apparatus for testing, repairing or exchanging nozzles of the bottom of a reactor pressure vessel include inserting individual shielding containers into the reactor pressure vessel. Shafts pass through a shielding container and water-filled cartridges can be inserted into the shafts. Tubes for receiving probes of an in-core instrumentation are embedded into bottom plates of the remaining shielding containers and into bottoms of the cartridges. After removing a cartridge, a carrier for working tools can be introduced into the shaft. In this way the radioactive loading is considerably reduced by the probes inside or outside the reactor pressure vessel.

Abstract: The invention relates to a volume delimitation tank (1) for preventing or limiting contamination of the surrounding liquid medium when working with contaminated parts. The volume delimitation tank (1) comprises a sack or channel which constitutes at least the substantially vertical walls (1a-d) of the tank and is made of a material which is capable of being folded, which is radiation-resistant, and resistant to puncture. The walls (1a-d) can be provided with fold notches (27) to obtain a well-defined folding when, for example, lowering at least one wall portion (1a-d) for passing objects out of the tank (1). The walls (1a-d) of the tank (1) are arranged at a bottom part (9). Cleaning equipment (16) is arranged inside the tank (1) for continuous cleaning of the contained volume.

Abstract: Disclosed is a method for reducing embrittlement of certain materials of pressurized water reactor vessels caused by neutron flux. According to this method, "shadow shielding" is placed within the core support barrel in areas having a more benign flow environment than that of the downcomer area. This shadow shielding provides an increased neutron scattering cross section. In one example, the shadow shielding replaces segments of the core shroud plate in a manner which does not interfere with coolant flow in the vessel. The segments of the shroud plate which are replaced are those near critical regions of the vessel, typically welds. The size and shape of the shielding is determined according to plant specific requirements.

Abstract: In order to eliminate the need to weld, drill or otherwise machine a shroud structure which is used to surround a plurality of fuel assemblies in a nuclear reactor, a support ring which either seats on top of the upper edge of the shroud, or is formed in multiple segments and is clamped to the side wall of the shroud, have hangers which are rigid therewith on which support hooks can be detachably mounted. The hooks are arranged to be engagable with the inner peripheral wall of the RPV in a manner which prevents lateral movement of the shroud within the pressure vessel.

Abstract: A fast reactor comprises a core composed of nuclear fuel, a core barrel surrounding an outer periphery of the core, an annular reflector surrounding an outer periphery of the core barrel, a partition wall structure surrounding an outer periphery of the annular reflector and supporting the core barrel by a supporting structure arranged radially of the fast reactor, the partition wall structure constituting an inner wall of a coolant passage for a primary coolant, a neutron shield surrounding an outer periphery of the partition wall structure and disposed in the coolant passage, a reactor vessel surrounding an outer periphery of the neutron shield and having an inner wall constituting an outer wall of the coolant passage, and a guard vessel surrounding an outer periphery of the reactor vessel.

Abstract: A launderable lead blanket cover system for rehabilitating contaminated lead blankets and which provides a lead blanket launderable cover. Lead blankets which can be removed from a nuclear facility or which are manufactured directly, include an outer cover which is heat sealed around the periphery to the inner lead blanket. The heat sealed periphery can include a plurality of blanket supporting metal grommets having a uniform predetermined spacing. A contaminated lead blanket which cannot be removed from a nuclear facility, has the contaminated cover removed in the nuclear facility and securing strips are secured to the inner cover. The contaminated lead blanket then is rehabilitated by adding a replaceable cover open on one end and having a heat sealed periphery and metal grommets in the other three sides. The open end with the lead blanket inside is then folded over and sealed, such as with an adhesive and then metal grommets can be secured through the sealed periphery to complete the lead blanket.

Abstract: This system is able to intervene on the inner pane (2) of a "high activity` cell whilst ensuring the biological and radiological protection of operators.It includes means able to extract the shielding window (5) of the orifice and a protective screen (7) mounted moving with respect to a fixed structure (20, 21) and intended to block up the orifice of the cell when the shielding window (5) is extracted. It includes handling means, such as pliers (32), for intervening on the pane (2) with equipment able to be passed through the shield (7) by means of a spring barrel (36).Application for cleaning of the sealing pane (2) on "high activity" screened cells.

Abstract: A boiling water reactor control rod drive housing support bars having wing assemblies to limit the travel of a control rod in the event that a control rod housing is ruptured. The wing assemblies are placed on support bars located in rows on opposing sides of the control rod drives. Each wing on the wing assemblies supports a quadrant of a control rod drive. The wing assemblies may be rotated from an operation position to a service position to allow replacement of the control rod drives.

Abstract: A boiling water reactor control rod drive housing support bars having radiation shields to limit the travel of a control rod in the event that a control rod housing is ruptured and protect persons working under the reactor vessel from radiation exposure. The radiation shield includes radiation shield cups for surrounding the bottom portion of a control rod drive. The radiation shield cups are placed on support bars located in rows on opposing sides of the control rod drives. The radiation shield may be easily raised and lowered automatically by the control rod drive installation/removal machine.

Abstract: This invention relates to a method for protecting the integrity of the reactor container base in nuclear power plants, and a device for implementing the method.The proposed method and device are applicable to all reactor types (PWR or pressurized water reactor, BWR or boiling water reactor, HWR or heavy water reactor, etc.) and to all types of containing system (large dry type, steam suppression type, condensation on ice type, subatmospheric type etc.), although for simplicity the present text will describe only their application to a PWR with a steam suppression and large dry containing system.

Abstract: The invention relates to a glove holder unit for a confinement enclosure.The aim of the invention is to produce a unit making it possible to easily change a protective glove for the hand.This aim is achieved with the aid of a glove holder unit having a sleeve (11), for protecting the arm and the forearm, assembled to a working glove (15), protecting the hand, and placed in an enclosure. The glove holder unit comprises means (49) for locking an assembly means (17) of the glove (15) and the protective sleeve (11). The locking means (49) being mobile between a locked position, in which they maintain the assembly means (17) and the glove (15) outside the enclosure (1) and an unlocked position in which they allow the passage of the glove (15) and its assembly means (17) between the interior and the exterior of the enclosure.

Abstract: An improved lower end fitting 10 (L.E.F.) having a bell mouth multistage type of flow jet diffuser 30 with stages 31, 31' decreases pressure drop 15-20% over a single stage bell mouth diffuser and more evenly distributes flow and adds strength. It includes neutron thimble flux impingement shield 50 of instrument and/or cable. Each diffuser stage 31, 31' is S.S., of circular cross-sect. and parabolic to optimize diffusion. The multistage shape is based on lower core plate 20 flow hole 24 geometry, L.E.F. design and reactor flow rate. Thinner L.E.F. legs 36, smaller L.E.F. gussets 38 and thinner L.E.F. flow plates 22 are possible.

Abstract: A shielded access door for a nuclear steam generator manway port having a beam of radiation streaming therethrough, the port being surrounded by a manway flange. The door comprises a bracket adapted to be removably connected to the flange. A plurality of swing arms have the first end portion thereof pivotally connected to the bracket. A first shield member is connected to the second end portions of the arms and is disposed parallel and adjacent to the port for shielding against the beam of radiation. The first shield member and the port define a gap therebetween for allowing access to the steam generator interiorly of the port while simultaneously shielding against the beam of radiation. The first shield member has a ventilation hole therethrough in communication with the port for ventilating the port, so that air-borne radioactive particles present interiorly of the steam generator are exhausted from the steam generator.

Abstract: A shield apparatus is arranged for ease of mounting in assembled configuration particularly for use in shielding various radiations, such as relative to nuclear plants. The shielding structure is arranged for use in emergency as well as in a permanent relationship relative to such radiation emitting structure.

Abstract: A nuclear reactor such as a pressurized water reactor has an integrated head package providing structural support and increasing shielding leading toward the vessel head. A reactor vessel head engages the reactor vessel, and a control rod guide mechanism over the vessel head raises and lowers control rods in certain of the thimble tubes, traversing penetrations in the reactor vessel head, and being coupled to the control rods. An instrumentation tube structure includes instrumentation tubes with sensors movable into certain thimble tubes disposed in the fuel assemblies. Couplings for the sensors also traverse penetrations in the reactor vessel head. A shroud is attached over the reactor vessel head and encloses the control rod guide mechanism and at least a portion of the instrumentation tubes when retracted.

Abstract: The heat shield according to the invention makes it possible to protect a structure from a very high thermal flux. It is mainly constituted by tiles (2) fixed to a support structure (4) by means of a spring (8) fixed in translation with respect to a tile (2) and on which bears a locking arm (10). The latter can be fixed to the support structure (4) by means of locking screws (30), which are accessible from the outside through locking orifices (12) in the tile (2). The compression of the spring (8) allows locking to take place and also a satisfactory heat exchange from the tile (2) to the support structure (4), which can be cooled by cooling medium flow ducts (14).

Abstract: Method and apparatus for maintaining a water level which immerses heat exchanger tubes, containing radioactive emitting material, within an inner shell of a steam generator while permitting space between the inner shell and a coaxial outer shell to be free of water during operations performed by workmen in such space after the apparatus is installed thereby reducing exposure of the workmen to harmful radiation. Seal support segments are installed around the inner shell at the lower end of the space and in engagement with the inner and outer shells. A pair of inflatable tubes are placed end-to-end on the support segments so as to encircle the inner shell. Seal retention segments which, together, form a ring around the inner shell are placed on the inflatable tubes and the latter tubes are inflated to form a water tight seal between the shells.

Abstract: A liquid metal cooled nuclear reactor having a passive cooling system for removing residual heat resulting for fuel decay during reactor shutdown, or heat produced during a mishap. The reactor system is enhanced with sealing means for excluding external air from contact with the liquid metal coolant leaking from the reactor vessel during an accident. The invention also includes a silo structure which resists attack by leaking liquid metal coolant, and an added unique cooling means.

Abstract: In the field of commercial nuclear reactors, there is an increasing demand for long-life control blades in order to meet the requirements of higher economy and reduction in the disposal of radioactive wastes. A control blade proposed by the invention stands a long use by virtue of the use of a long-life neutron absorber which is typically made of hafnium. Despite the use of hafnium which has a large specific weight (13.3 g/cm.sup.3), the size, shape and weight of the control blade are substantially the same as those of conventional control blades which employ boron carbides B.sub.4 C as the neutron absorber, so that the control blade can be back-fitted in existing boiling water reactors without difficulty.

Abstract: An improved lower end fitting (L.E.F.) having a bell mouth type of flow jet diffuser decrease pressure drop 10-15%, more evenly distributes flow and adds strength. It includes neutron thimble flux impingement shield of instrument and/or cable. Diffusers are stainless steel of circular cross-sect. and parabolic to optimize diffusion. Shape is based on lower core plate flow hole geometry, L.E.F. design and reactor flow rate. Thinner L.E.F. legs, smaller L.E.F. gussets and thinner L.E.F. flow plates possible.

Abstract: A frame 10 with downwardly projecting members 52 mounts by means of a pair of hoists 36 and lifting bracket 42 downwardly into upwardly open recesses of complementary mounting members 54 secured to reactor head lifting legs 30. Frame 10 is mounted on the head either with lead wool shielding blankets 40 hanging from it or without. In the latter case, hangers 60 with blankets 40 hanging therefrom and horizontally gravity biased hooks 64 mounted on a curved beam 62, are lowered by hoist 36 until hooks 64 grapple, pivot and hang hanger 60 and the shielding on frame 10 at a location radially inwardly of the head bolt locations 22. The hook of hoist 36 is lowered until it is disengaged from the radially outwardly biased bail 70 of hanger 60.

Abstract: Handling pool for nuclear fuel, located above the vessel of a pressurized water-nuclear reactor, characterized in that it has, around the vessel cover and the mechanisms surmounting it, a bulkhead, which is generally cylindrical of revolution and is tightly and detachably fixed to the pool bottom. This arrangement makes it possible to keep the pool filled with water outside the bulkhead during reactor operation, so that within the safety enclosure there is a large water reserve on the core, which facilitates its reflooding if there is a fracture to the primary circuit. The still full pool can be used for storing spent fuel.

Abstract: A gas cooled high temperature reactor with a core of preferably spherical fuel elements enclosed by a graphite roof and a side and bottom reflector. In order to minimize environmental contamination by fission products, even upon (hypothetical) core overheating accidents, the upper part of the roof reflector incorporates volatile iodine and cesium iodide, suitable metal atoms or molecules of the compounds of these metals bonded into the cracked binder material of the graphite. The dilution of the doping material must be high enough (from 1:100 to 1:10,000), so that the substances (for example alkaline earth metals or rare earths) are present as individual atoms or molecules. The iodine is chemically bound to the doping atoms, and iodide formed in this matter is retained in the cracked binder material. Molecules of high temperature oxides may also be incorporated.

Abstract: A first plurality of water filled shielding tanks is introduced through a nuclear reactor containment building hatch and placed between the stored core internals and the reactor vessel. A support structure for this vertical wall is previously shipped, disassembled, introduced into containment and erected between the reactor vessel and the stored internals. A second plurality of water filled shielding tanks is placed on the containment building operating floor level to cover the stored internals. Once in place, the tanks allow manned activity in the reactor vessel area, such as preparations for annealing.

Abstract: An improved emergency cooling system is provided for an organic cooled and moderated nuclear reactor. The cooling system permits an inherently safe reactor design to be achieved having a number of other novel and significant advantages. Most importantly, the reactor can be designed to survive a largest credible accident which involves the loss of the entire primary coolant inventory, while continuing to provide core cooling in a passive mode for a period of one or more days post-accident.

Abstract: Shielding and exhaust covers are disclosed herein which are mountable on the primary manways of a nuclear steam generator for protecting maintenance personnel from potentially harmful radiation during maintenance operations. Each of these doors includes mounting flanges which are detachably mountable to the manway flange. These mounting flanges include brackets for mounting a jewel rail track assembly which in turn slidably mounts two opposing quarter circle panels which, when slid together, form a semicircular shielding cover. The shielding and exhaust covers of the invention may be easily mounted over their respective manways by a single person, and may be opened or closed by a single person standing to the side of the manway and hence out of the radiation shine eminating therefrom. Finally, the shielding material contained in each of the covers is hermetically sealed within stainless sheet metal, which renders it mechanically strong and easily decontaminated.

Abstract: A new design for nuclear reactor internals resulting in reduced fast neutron leakage to the reactor vessel. The first step of the two-stage process reflects high energy or fast neutrons back into the core, by placement of a reflector made of tungsten, stainless steel, or zirconium oxide in the baffle barrel region. The second stage involves reducing the energy of any fast neutrons that may pass through the reflector by the use of a neutron energy reducer, composed of an hydrogenous material such as titanium hydride, surrounding the core barrel in the areas of high neutron flux. In addition to protecting the reactor vessel wall and increasing the operating life of a nuclear reactor, the neutron economy in the core, and hence the operating efficiency of a nuclear power plant, are significantly increased.

Abstract: A radiation reducing door assembly comprises a mounting bracket having hinge means affixed thereto, said hinge means defining different axes of rotation for doors of at least two types, the doors being sized and shaped to overlie at least a portion of the opening with which the assembly is associated. The door assembly also includes means for rotatably coupling the removable doors to the hinge means whereby the mounted door is supported from said bracket and may be pivoted between open and closed positions.

Abstract: An annular seal ring between a reactor pressure vessel and a containment wall is disposed in an annular expansion gap therebetween, having a support ring and inner and outer upwardly extending cylindrical sections. The inner cylindrical section is disposed below a flange on the reactor and has a flexible seal therebetween, while the outer cylindrical section terminates substantially parallel and spaced from a shelf in the containment wall with a flexible seal therebetween. The annular seal ring is supported by radial support beams, while support rods depending from the support ring position neutron shielding material in the annular expansion gap. Manways and ports provide access to the gap and thermal insulation is provided below the neutron shielding material to direct cooling air from the annular gap up through opened manway and port.

Abstract: A nuclear reactor containment arrangement has a permanent cavity ring seal extending across an annular expansion gap between a reactor pressure vessel and a containment wall to provide a water tight seal therebetween. The annular ring seal has a support ring with an inner downwardly extending cylindrical section resting on the reactor flange and an outer downwardly extending cylindrical section resting on a shelf in the containment wall. A vertically extending, L-shaped, seal extends between an inner end of the support ring while a vertically extending, L-shaped, seal extends between the outer cylindrical section and the containment wall shelf. Neutron shielding material is suspended, by support rods, within the annular expansion gap while thermal insulation is provided therebelow. Manways and ports in the support ring are sealed by hatches and provide access to the annular expansion gap and, while open, provide for flow of cooling air from the annular expansion gap through the support ring.

Abstract: Apparatus for shielding an otherwise exposed upper portion of a radioactive reactor component disposed in a refueling pool of water having a depth less than the height of the component. A vessel with a top end wall, a side wall larger than the transverse size of the component is disposed over the exposed upper portion until the lower rim thereof is immersed in the pool and the top end wall and the side wall are in spaced relation to the upper portion of the component. Fluid, mainly air, is evacuated from the vessel to cause water from the pool to enter the vessel and provide a water level therein which is above the water level in the pool and between the component and the walls of the vessel. The vessel is reinforced to withstand the pressures caused by removal of fluid therefrom and is suspended by beams and legs, the latter being engageable with the pool walls.

Abstract: A wear-reduction-shield (40) for use between the core plate (24) and lower end fitting (26) of a pressurized water reactor (10) to reduce excessive wear of in-core-instrumentation thimbles (30) due to flow induced vibrations and resist fuel assembly tipping has a cylindrical body portion 42with core plate engaging lower end surface (44). At the opposite and upper end, a tapered internal end wall (46) assists upward threading of the monitor and cable. On the outside of the upper end symmetrical leg portions (52) and central land (54) surround a thimble (30) receiving opening (48). Smoothly tapering outer surface (56) minimizes turbulence in and beyond opening (34) in lower end fitting (26). Internal dimensions of shield (40) avoid structure such as sleeve (50) which may be present.

Abstract: Nuclear residues with a Co60 specific activity of 1 to 100 Bq/g, such as concrete or metal parts of a nuclear reactor installation, are used as raw materials for the production of radiation shielding structures for such nuclear installation. The concrete reisdues can be broken up to form an aggregate for concrete which is cast to form such structures and metal objects can be added for the casting of transport and storage vessels for radioactive wastes.

Abstract: Method and apparatus for shielding an otherwise exposed upper portion of a radioactive reactor component disposed in a refueling pool of water having a depth less than the height of the component. A vessel with a top end wall, a side wall larger than the transverse size of the component is disposed over the exposed upper portion until the lower rim thereof is immersed in the pool and the top end wall and the side wall are in spaced relation to the upper portion of the component. Fluid, mainly air, is evacuated from the vessel to cause water from the pool to enter the vessel and provide a water level therein which is above the water level in the pool and between the component and the walls of the vessel. The vessel is reinforced to withstand the pressures caused by removal of fluid therefrom and is suspended by beams and legs, the latter being engageable with the pool walls.

Abstract: A method for limiting movement of a thermal shield of a nuclear reactor, and a thermal shield displacement limiter therefor, is provided where at least four and preferably six or more key-way inserts are positioned in pockets machined in the upper portion of a thermal shield, and bolted and doweled to the thermal shield. Each key-way insert is engaged by a limiter key that is bolted and doweled to the core barrel to tangentially restrain movement of the thermal shield relative to the core barrel, while allowing radial and axial movement to the thermal shield relative to the core barrel. Preferably, lock pins extend diametrically through the bolts and dial pins and engage the key-way insert and limiter key, respectively, to lock the bolts and dowels in position, and the engaging surfaces between the key-way inserts and the limiter keys are wear hardened.

Abstract: A reactor cavity seal and shielding system for a PWR that protects personnel from radiation during full power operation and shutdown conditions, and allows the refueling canal to be flooded while allowing access to the lower portions of the reactor well. An integral annular seal and shield is sealed to the pressure vessel and to the primary shield. The seal preferably extends horizontally from a flange on the reactor pressure vessel to an inwardly extending ledge on the primary shield, and carries a generally coextensive body of solid neutron-absorbing material. The seal may be fabricated from stainless steel, and preferably incorporates a bellows seal to accommodate thermal expansion. The shield may be silicone rubber, refractory concrete, or any solid neutron absorber.

Abstract: An integrated head package for a nuclear reactor has a pressure vessel closure head with control rod drive mechanisms thereon enclosed in a shroud, and a plurality of vertical lift rods secured to the vessel head with a missile shield plate extrending between the lift rods and vertically slidably retained between spaced stop members adjacent the upper ends of the lift rods. A lift rig is secured to the missile shield plate, preferably through attachment to support blocks secured to the upper surface of the plate. Impact forces of a missile against the lower surface of the missile shield plate are transferred to a lifting force and are not transferred to the lifting rods, head lugs, closure studs and pressure vessel supports.

Abstract: A radiation shield (10) is comprised of three, equiangularly extending, arcuate sections (14) which are secured to the nuclear reactor pressure vessel closure head (12) so as to annularly surround the nuclear reactor control rod drive mechanisms (26) and thereby prevent radiation emanating from the mechanisms (26) from reaching maintenance personnel who may be operatively working within the peripheral section (20) of the closure head. The shield sections (14) are bolted together by fasterners (18) and are secured to closure head lift lugs (30) by means of mounting brackets (38) and transversely extending pins (36). Clevis assemblies (34) are also pinned to the mounting brackets (38) and lift lugs (30), and lift rods (32) are threadedly engaged with the clevis assemblies (34). In this manner, when the closure head (12) is lifted from its associated pressure vessel, the radiation shield (10) remains with the closure head (12).

Abstract: A radiation-reducing door assembly which may be configured as either an entry port or a ventilation port. The door assembly includes a split ring flange-type mounting bracket which can be quickly and easily installed on a manway flange regardless of the state of the manway cover mounting studs. A pair of radiation shielding doors or a ventilation port door may be quickly and easily coupled to the split ring mounting bracket.

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

Abstract: Nuclear residues, such as concrete or metal parts of a nuclear reactor installation, are used as raw materials for the production of radiation shielding structures for such nuclear installation. The concrete residues can be broken up to form an aggregate for concrete which is cast to form such structures and metal objects can be added for the casting of transport and storage vessels for radioactive wastes.

Abstract: An array of connected plates mounted on the inside wall of the vacuum vessel of a magnetic confinement reactor in order to provide a protective surface for energy deposition inside the vessel. All fasteners are concealed and protected beneath the plates, while the plates themselves share common mounting points. The entire array is installed with torqued nuts on threaded studs; provision also exists for thermal expansion by mounting each plate with two of its four mounts captured in an oversize grooved spool. A spool-washer mounting hardware allows one edge of a protective plate to be torqued while the other side remains loose, by simply inverting the spool-washer hardware.

Abstract: A method and apparatus is disclosed for reducing the exposure of pressure vessel welds to fast neutron fluxes. Localized peripheral core areas are provided with rod assemblies which may be made up of nuclear absorbing materials, nuclear reflecting materials, or any combination thereof, and of any desired length so as to reduce the exposure of the welds to such fast neutron fluxes. The rod assemblies are precisely tailored consistent with nuclear calculations to provide the desired effect without substantially reducing core ratings or adversely affecting reactor shutdown margins.

Abstract: For safety in storage and transport of nuclear fuel elements outside a nuclear reactor core, they are provided with a coating of a neutron-absorbing substance from a liquid phase, e.g. by immersion, spraying or pouring, utilizing a melt, a solution or immersion so that the possibility of critical mass attainment is eliminated or minimized.

Abstract: For safety in storage and transport of nuclear fuel elements outside a nuclear reactor core, they are provided with a coating of a neutron-absorbing substance from a liquid phase, e.g. by immersion, spraying or pouring, utilizing a melt, a solution or immersion so that the possibility of critical mass attainment is eliminated or minimized.

Abstract: A neutron absorbing panel has improved resistance to loss of efficiency resulting from bending about an axis located at a designated side of the panel. The panel comprises a core of substantially uniform thickness formed of a sintered mixture of particles of neutron absorbing material such as boron carbide (B.sub.4 C) and metal such as aluminum. Metal cladding sheets are provided at both sides of the core, and aluminum is the preferred metal for both the metal core particles, and cladding. The sintered core lacks the ductility of the outer cladding sheets, and to improve bendability, the thickness of one cladding sheet is materially greater than the other. Bending of the improved panel about an axis spaced outwardly from the side thereof having the thinner cladding sheet leaves the outer surface of the panel at the bend smoother than when the cladding sheets are of uniform thickness, and substantially uniform neutron absorbing ability is retained.

Abstract: A shield panel for use in a nuclear reactor including a reactor vessel susceptible to embrittlement when bombarded with high energy neutrons and a nuclear reactor core mounted within the reactor vessel, the reactor vessel having a longitudinal axis and an inner surface surrounding the longitudinal axis, and the nuclear core emitting high energy neutrons which impinge on the inner surface of the reactor vessel. The shield panel includes a canister which contains a completely enclosed interior space and which is mountable between the inner surface of the reactor vessel and the nuclear core in a region wherein the reactor vessel is susceptible to a higher rate of embrittlement than the remaining portion of the vessel when bombarded with high energy neutrons emitted from the nuclear core, and a substance consisting essentially of a heavy metal and hydrogen filling the interior space of the canister.

Abstract: In order to seal an opening formed in a vertical wall, a removable partition is formed, which is constituted by at least two dry-stacked brick layers. Each layer is formed from several rows of bricks, each constituted by bricks which, in cross-section, are shaped like a parallelogram, arranged in opposite directions on either side of a central locking brick which, in cross-section, is shaped like an isosceles trapezium. Each row of bricks behaves like a fictitious funicular arc when exposed to a horizontal force normal to the partition. Thus, the earthquake resistance is ensured without adding a reinforcing framework to the two faces of the partition.

Abstract: An internal radiation attenuation 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 frame which is formed from a plurality of interlocking segments which are quickly and easily assembled and disassembled. A plurality of radiation attenuation panels are slidably engaged upon the upper portion of the frame and a second plurality of radiation attenuation pads can be engaged to hang from the sides of the frame to substantially enclose a worker therein.

Abstract: Metallic reflector units supported solely by the core barrel substantially fill the annular spaces between the vertically spaced former plates which traverse the irregular space between the fuel assembly array and the core barrel in a pressurized water reactor. The support for each reflector unit comprises a pin extending radially outward along an extended line passing through the center of the metallic mass to support the vertical loads, and four elongated bolts in a rectangular pattern centered on the pin to resist overturning moments induced by seismic loads. The elongated bolts engage the core barrel and the bottoms of bores in the reflector units so that the bolts are free to bend to accommodate for thermal expansion of the reflector unit in all directions from the pin.