Abstract: The method consists in removing the cooling fluid of the primary circuit, and, as a function of the cooling fluid concentration, in passing either all of the cooling fluid into at least one electrodialysis module, or only a part of the cooling fluid into the electrodialysis modules and the other part towards at least one reverse osmosis apparatus, in adding to the cooling fluid, when it leaves the primary circuit, an additive to promote dissociation of the boric acid, and in then returning the cooling fluid into the primary circuit.

Abstract: A nuclear fuel assembly with a debris filter. The lower end fitting of the fuel assembly has a stamped plate attached thereto that serves as a debris filter immediately upstream of the fuel rods. The stamped plate is provided with a plurality of flow holes in a size and pattern that provides filtration of debris damaging to the fuel rods while maintaining adequate coolant flow through the fuel assembly.

Abstract: A debris screen for a fuel assembly for a reactor to which coolant fluid is supplied comprises a substantially planar plate member having an array of coollant openings extending through the plate member dimensioned to trap at least a portion of debris particles carried by the coolant; and a skirt member enclosing the periphery of the plate member; each of the coolant flow openings having a coolant entry region at a lower surface, a coolant exit region at an upper surface and a coolant flow path extending between the entry and exit regions, the flow path including an intermediate segment laterally offset from the entry and exit regions to cause coolant to change direction of flow in the intermediate segment and thereby prevent at least a portion of the debris particles from passing through the plate members.

Abstract: Metal surfaces having an oxide coating containing radioactive substances, such as the primary system of a pressurized water reactor, are decontaminated by passage thereover of a decontamination solution containing a weak chelating agent, such as nitrilotriacetic acid, and a ferrous salt, such as ferrous glutonate. The weak chelating agent is present in an aqueous solution in an amount of 0.1 to 2.0 percent by weight and the ferrous salt in an amount to provide 50 to 500 parts per million iron based on the weight of the solution. The solution, after contact with the metal surfaces is regenerated by an ion exchange resin or, preferably, by electrolysis.

Abstract: A fuel assembly has a spring detent spacer grid of intersecting strips for capturing and retaining deleterious debris carried by reactor coolant before it enters the active region of a fuel assembly. A plurality of fuel end caps are peripherally grooved to receive springs projecting from the strips. The end caps are thus captured by springs and debris is wedged and trapped on opposite sides of the strip and against the end caps by pairs of adjacent integral leaves projecting from the stips intermediate and substantially symmetrically arranged about their intersections.

Abstract: A debris filter bottom nozzle of a nuclear fuel assembly is spaced below the lowermost grid, supports the guide thimbles, and is adapted to allow flow of liquid coolant into the fuel assembly. The debris filter bottom nozzle includes an enclosure defining a coolant flow chamber therethrough, and an upper transverse nozzle structure composed of a consolidated array of elongated cylindrical sections disposed across the chamber of the enclosure in side-by-side relation to one another, extending axially in the direction of coolant flow through the chamber, rigidly connected together and to the enclosure, and having tubular cross-sectional configurations defining passages for the coolant flow through the chamber.

Abstract: The device consists of a unit comprising a housing closure plug (13) extended by a cylindrical body (14), a maneuvering rod (20) mounted along the axis of an opening (18) passing axially through the plug (13) and the cylindrical body (14), a device (25, 26) for moving the maneuvering rod (20) axially, over a limited length, the head (30) for closing the filter (2) connected to one of the ends of the maneuvering rod (20) and a device for locking (38, 41) the head (30) onto the filter body (5). The device (12) makes it possible to carry out the replacement of the filter (2) packing without employing a handling module and special tooling for dismantling the filter head.

Abstract: A nuclear power plant includes a containment for the retention of radioactivity having an overpressure safety outlet. A filter connected to the outlet includes a vessel for receiving a scrubbing liquid up to a given liquid level, a venturi scrubber disposed in the vessel having an outlet disposed above the given liquid level, an impact plate disposed at the outlet of the venturi scrubber for mist collection, a metal-fiber filter downstream of the venturi scrubber having at least first and second layers with a thickness of from 10 to 20 mm, the first layer being a moisture collector with a fiber thickness of from 8 to 20.mu. and the second layer being an aerosol collector with a fiber thickness of from 2 to 7.mu., and a mist collector downstream of the metal-fiber filter. The vessel has a top with a gas outlet downstream of the mist collector. A stack is connected to the gas outlet and leads to the atmosphere.

Abstract: For determining the content and the chemical composition of particulate compounds in a liquid flow (15), the particulate compounds are collected on a filter (20) in a container (19) of a material which is permeable to microwaves. When carrying out the determination, samples of a fixed size of the liquid in the flow are supplied batchwise to the container on one side of the filter via an openable and a closable connection (16, 17) between the liquid flow and the container. At the same time, liquid from each liquid sample supplied batchwise, which has passed through the filter, is discharged from the container via an openable and a closable outlet (30, 31) on the other side of the filter.

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 bottom nozzle plate for a fuel assembly in a nuclear reactor. The bottom nozzle plate is formed from a rigid substantially square plate having legs adapted to be positioned on the lower core plate of the reactor for supporting the fuel assembly above coolant inlet openings in the core plate. The rigid square plate has two types of coolant flow holes therethrough. The first flow holes are grouped in clusters of four to define a square pattern relative to the sides of the plate such that the width of the sections of the plate between the flow holes in each cluster is less than the width of the sections of the plate between the clusters of four holes. Each of the second flow holes is formed in an irregular pattern to define a substantially clover leaf shape. The second flow holes are positioned so as to be above the coolant inlet openings in the core plate when the bottom nozzle plate is installed in the reactor.

Abstract: A method of restraining a diffusion of tritium and an apparatus for same are disclosed. The method includes the step of disposing a hydrogen-absorbing metal in a tritium passage in a direction of diffusion of tritium so that the hydrogen-absorbing metal absorbs tritium to be diffused. The apparatus includes a hydrogen-absorbing metal surrounding a device of a fast breeder reactor. The tritium to be diffused can be readily captured. An arrangement of capturing the tritium permeating the device is simplified in the present invention.

Abstract: A nuclear fuel assembly having an array of longitudinally extending fuel rods and axially spaced transverse grids with cells receiving the fuel rods therethrough employs anti-fretting protective devices for protecting lower end portions of tubular claddings of the fuel rods from damage-inducing contact with debris entrained in upward flow of coolant through the fuel assembly. Each device is in the form of a hollow sleeve disposed about and extending coextensive with the lower end portion of one fuel rod cladding. The sleeve has an upper portion which extends through one grid cell between lower and upper ends thereof, and a lower portion which extends below the grid cell from the lower end thereof to a bottom end of the fuel rod cladding spaced below the grid cell lower end.

Abstract: A filter for a respirator for removal of tritiated water having a housing with fluid inlet and output ports. A filter chamber is interposed between and in communication with the inlet and outlet for containing the tritium filter medium. A tritium filter media is selected from a particulate activated carbon or a particulate silica gel in which the media has a moisture content of from about 25% to 40% by weight of the media and a particulate distribution size range of from 6.times.20 to 12.times.30.

Abstract: A fuel assembly (10) has a lower end fitting debris collector and end cap spacer grid (20) assembled in the form of a welded assembly of an "eggcrate" grid (21) and cast base (40) with hollow legs (42). Fastener seats (46) in hollow legs (42 ) permit guide tubes (14) with internally threaded ends to be joined to the upper surface of the lower end fitting debris collector (20) by means of slotted fasteners (50). End caps (22) rest on grid (21) at the intersection of slottedly interlocked bars (24 and 26). Thin strips (30) mounted in slots between bars (24) and bars (26) provide small debris catching openings in grid (21). Thick strips (30a) project upwardly between strips (30) to limit lateral movement of the end caps. Projections (70) on bars (24) prevent axial fuel rod movement by engagement of tab (70a) in circumferential groove (23) of end caps (22). Opposing capture force is provided by a wire (72) which is supported in openings in thick strips (30a) and which is received in groove (23).

Abstract: Iodine and organic iodine compounds which may be radioactive and which may be found in waste gases or vapors from nuclear reactors can be removed from such gases or vapors by passing the iodine or organic iodine compound-containing gases or vapors through a layer of binder-free silver-exchanged molecular sieve granulates of the faujasite type.

Abstract: A debris filter bottom nozzle in a fuel assembly has support structure in the form of four legs adapted to rest on a lower core plate of the nuclear reactor and a nozzle plate fixed one side of the four legs facing toward a lowermost grid of the fuel assembly. The nozzle plate has defined therethrough only a plurality of flow holes individually smaller in size than the maximum dimension of unoccupied spaces through the lowermost grid which allow flow of liquid coolant through the nozzle plate. Therefore, any debris being carried by the liquid coolant flowing through the bottom nozzle from the lower core plate to the fuel assembly which is small enough in size to pass through the flow holes will also pass through the unoccupied grid spaces, whereas any debris which is large enough to not pass through the unoccupied grid spaces and collect in the grid will not pass through the aperture plate flow holes.

Abstract: A high-temperature reactor with a reactor core containing fuel elements crossed by a cooling gas circuit comprises a malfunction filter for filtering metal fission products discharged from the fuel elements in the event of core overheating. The filter is mounted in the cooling gas circuit outside the reactor core and consists of a carbon which is incompletely graphitized, or is not graphitized at all.

Abstract: A process and an apparatus for cleaning nuclear reactor cooling water with cation exchange resin whose ion-exchanging groups have a bonding energy of not more than 300 KJ/mole are disclosed, whereby the radiation exposure of operators in an atomic power plant can be considerably reduced, and the waste ion exchange resin can be readily disposed.

Abstract: A method and apparatus for pressure relief of a nuclear power plant includes the feeding of fluid from an outlet opening of a containment through a filter to a stack. The filter is operated with sliding pressure regulated as a function of the pressure in the containment.

Abstract: A pressurized gas discharge system for the safety containment of a nuclear reactor includes a conduit structure connected to the containment and consisting of a plurality of modular conduit units which are flanged together end-to-end, each having flanged side openings with filter frame members including stainless steel fiber filter packs flanged thereto in end-to-end relationship. The filter packs extend fully across the frame members and have their circumferential edges clamped between the flanges of adjacent frame members so that in the clamped areas the filter packs are reduced in thickness to a fraction of their original thickness, the flanges having U-shaped members disposed on their faces such that the legs of the U-shaped member project toward the adjacent flange and provide two seal strips with the edges of the filter packs compressed therebetween.

Abstract: A nuclear power plant includes a containment for containing activity carriers. An outlet in the form of an excess pressure safety device leads out of the containment. A filter connects the outlet to the atmosphere. The filter includes a container, a washing fluid disposed in the container, a Venturi scrubber being integrated in the container and connected to the outlet, the container having an upper region with a gas outlet, and a stack connected to the gas outlet.

Abstract: An apparatus for storing nuclear reactor fuel assemblies in a water pit, includes means for holding an end of a fuel assembly and for transporting the fuel assembly through the water pit, a vessel disposed in the water pit having a closed bottom and an open top in communication with a water space in the water pit forming a vertically elongated well in the vessel for at least partly receiving a fuel assembly, a suction connection in communicaton with the well through the closed bottom of the vessel, a suction pump connected to the suction connection, a shielding container, and a filter disposed in the shielding container and connected to the pump for collecting deposits suctioned from the well.

Abstract: A process for removing organic compounds from a nuclear waste slurry comprising reacting a mixture of radioactive waste precipitate slurry and an acid in the presence of a catalytically effective amount of a copper (II) catalyst whereby the organic compounds in the precipitate slurry are hydrolyzed to form volatile organic compounds which are separated from the reacting mixture. The resulting waste slurry, containing less than 10 percent of the orginal organic compounds, is subsequently blended with high level radioactive sludge and transferred to a virtrification facility for processing into borosilicate glass for long-term storage.

Abstract: A fuel assembly (10) has a lower end fitting debris collector (40) assembled in the form of a welded assembly of an "eggcrate" grid (21) and cast base (40) with hollow legs (42). Fastener seats (46) in hollow legs (42) permit guide tubes (14) with internally threaded ends to be joined to the upper surface of the lower end fitting debris collector (40) by means of slotted fasteners (50). Bevels (62) and notches (64) in the grid bars (26 and 24a, respectively), provide an embodiment with contoured seats for fuel rod end caps (22). Otherwise, end caps (22) rest on grid (21) at the intersection of slottedly interlocked bars (24 and 26). Thin strips (30) mounted in slots between bars (24) and bars (26) provide small debris catching openings in grid (21).

Abstract: A getter trap to remove hydrogen and oxygen from a liquid metal, such as liquid sodium, includes an elongated, closed housing having an inlet at one end thereof and an outlet at the other end. A getter material is randomly diposed within the housing comprising a zirconium-containing substrate of hollow, tubular sections having a coating thereon of a gettering alloy of zirconium, vanadium and iron. As a liquid metal flows through the inlet into the housing and through the getter material, and is discharged from the housing through the outlet, hydrogen and oxygen impurities are removed from the liquid metal. The getter trap is particularly useful in an improved liquid metal cooled nuclear reactor system.

Abstract: A debris resistant bottom nozzle in a fuel assembly has a support structure in the form of four legs adapted to rest on a lower core plate of a nuclear reactor and a top flat plate fixed on one side of the four legs facing upwardly toward a lowermost grid of the fuel assembly. The flat plate is of a substantially solid configuration with a plurality of spaced cut-out regions defined therethrough in alignment with and directly above a plurality of inlet liquid coolant flow holes in the lower core plate. A plurality of open separate criss-cross structures are provided, each being fixed to the plate and extending across one of the cut-out regions therein within the plane of the plate.

Abstract: A debris catching strainer grid for capturing and retaining deleterious debris carried by reactor coolant before it enters the active region of a fuel assembly and creates fuel rod cladding damage has a plurality of fuel end cap compartments defined by pairs of first and second intersecting and slottedly interlocked grid-forming strips attached to a perimeter member and to each other. The end cap compartments defined by strips including vertical rows of integral leaves on opposite sides of the strip or by pairs of adjacent integral leaves intermediate their intersections. In the latter case, each leaf of the pair of leaves is the mirror image of the other leaf of the pair with an asymmetric shape with the greatest distance of projection out of the plane of the strip remote from the midpoint of the strips between their intersections.

Abstract: A hollow fiber filter device has a plurality of fiber filter modules suspended therein, the filter module being improved in rigidity and arranged to be easily handled while minimizing the risk of being damaged by securing the opposite ends of hollow fibers of the hollow fiber bundle to two bundle plates and by extending a central pipe from one of the bundle plates through the other of the bundle plates, the module being encased within a protecting hollow cylinder with perforated walls.

Abstract: In operation of a boiling water-type, atomic power plant, rated operation is conducted while adjusting the pH of core water in the nuclear reactor to 7.0 to 8.5 by adding an alkali thereto, thereby controlling dissolution of radioactive corrosion products attached to fuel rods into the core water. An increase in the radioactive corrosion products in the core water and in the dose rate can be prevented.

Abstract: A cleaning apparatus for atomic reactor control rod driving means (CRD) comprises a water tub for washing a CRD, rails laid within the water tub, a truck for loading the CRD installed on the rails, a CRD clamp unit mounted on the truck having means for rotating the CRD in the circumferential direction as well as for clamping the CRD, a CRD disassembling and assembling grapple unit installed within the water tub to clamp the CRD and move the same sideways, an outer-surface washing nozzle for washing an outer tube surface and strainer of the CRD, a lance installed within the water tub, which is insertable into the tubes of the CRD and which is equipped with a nozzle assembly to spray the washing water onto the inner surface of the tubes, a filter washing nozzle unit installed within the water tub to spray the washing water onto a cylindrical filter of the CRD, a washing-water circulating pipe connected to the water tub, and a filter unit provided on a portion of the pipe, to filter the washing water.

Abstract: Synthetic Crandallites of the general composition MeAl.sub.3 (PO.sub.4) (OH).sub.5.H.sub.2 O (Me=alkaline earth metal) are used for the separation of cations, especially alkaline earth metals, lanthanides and actinides, at a pH greater than 6 and temperature above 40.degree. C.

Abstract: Modular ultrafiltration device for the cooling liquid of a nuclear reactor, comprising a radiation absorbing containment (1), an ultrafilter (15) arranged in the containment (1), a heat exchanger (32) placed in the containment (1), and connection pieces intended for the various parts of the ultrafilter (15) and heat exchanger (32) and passing through the wall of the containment (1) in a leak-proof manner. A heat-insulating material (41) fills the inner volume of the containment (1). The modular device can easily be connected to an auxiliary circuit of the nuclear reactor. The ultrafiltration wall can be replaced without any difficulty.

Abstract: A method and an apparatus for loading containers with individual fuel rods or fuel-rod sections of irradiated nuclear reactor fuel elements are disclosed. In order to ensure maximum safety, cleanliness and close packing when loading the containers, the fuel rods or fuel-rod sections are horizontally front-loaded into the container which is horizontally positioned. The loading aperture is located as closely as possible to the upper inner periphery of the container. Following their insertion, the fuel rods or fuel-rod sections will drop onto the inner wall surface of the container or onto the already existing pile of previously loaded fuel rods or fuel-rod sections. The container for loading with such a method has a loading aperture in the end wall thereof arranged close to the inner periphery thereof for insertion of the fuel rods or fuel-rod sectons.

Abstract: An apparatus for filtering waste water containing radioactive solid particles or produced in a nuclear reactor power plant and wherein the water is filtered with a plurality of U-shaped hollow fibers each having a sponge like mesh structure containing numerous pores for trapping radioactive substances, the hollow fibers being made of flexible polyethylene and each pore having a diameter of about 0.1 micron. An air pipe is provided beneath the U-shaped hollow fibers for bubbling air into water to be filtered surrounding the fibers, thereby removing solid particles trapped in the pores.

Abstract: A cartridge for the permanent storage and disposal of radioactive particulate waste composed of a liquid impervious casing enclosing a waste storage region provided with a ferromagnetic matrix made of steel wool, together with inlet and outlet conduits suitably associated with the waste storage region to enable a liquid containing such waste material to be conducted through the matrix while the particulate waste is adhered thereto under the influence of a magnetic field and the remaining liquid filtrate is expelled from the cartridge, and to then permit an encapsulating material, such as a resin-catalyst mixture, to be introduced into the waste storage region to completely fill that region.

Abstract: A method of applying a descaling reagent comprising a one-electron reducing agent which is a low oxidation state transition metal ion in combination with a complexing agent to a surface to be treated to descale the surface which method comprises:(i) maintaining a low oxidation state transition metal ion either in solution under an inert atmosphere in a container made of or lined with an inert material or as a solid salt under an inert atmosphere;(ii) preparing a solution of the complexing agent and removing oxygen therefrom; and(iii) mixing the ingredients from steps (i) and (ii) either in situ in contact with the surface to be treated, or mixing the ingredients from steps (i) and (ii) prior to application to the surface to be treated under conditions whereby no substantial decomposition of the so-formed reagent occurs.

Abstract: Device for cleaning the instrumentation guide tubes (5) of a pressurized-water nuclear reactor, comprising a pump (18) for injecting demineralized water under pressure into the tubes (5) and an assembly (15, 20, 21, 22) for recovering the radioactive waste. The assembly (15) can take up a position above each of the passages (7) located in the vessel bottom (2) and through which the guide tubes (5) open into the vessel (1). The assembly is put in place at the end of each of the passages (7) in succession, without the need to remove the lower internal equipment (9, 40) of the reactor. All operations are controlled from the platform (17) of the reactor fuelling machine. The invention is used for the maintenance of pressurized-water nuclear reactors during refuelling .

Abstract: A material is, herein disclosed for collecting radionuclides and heavy metals that comprises an acrylic fiber element having MnO.sub.2 and/or ferrocyanide compound of the formula K.sub.2 M.sup.II [Fe(CN).sub.6 ] (wherein M.sup.II is a divalent metal such as cobalt, zirconium, zinc or nickel) supported thereon. The material of the present invention is used in collecting and concentrating radionuclides present in liquid radioactive wastes discharged from nuclear power plants and other facilities using radioisotopes such as hospitals and non-destructive testing laboratories. The material is also used in collecting and concentrating radionuclides and heavy metals present in the seawater, rivers and industrial waste-water.

Abstract: An upwardly convex resilient annular strainer, fixed to the secondary core support base plate in a PWR, bends to remain in contact with the lower hemispherical head section of the pressure vessel as the gap between the internals and the lower hemispherical head section varies in size with reactor temperature to prevent debris from lodging in the gap where it could lead to reactor damage.

Abstract: Disclosed is a method of reducing the volume of a material containing addition polymerizable bonds by contacting the material with sufficient butyrolactone to dissolve the soluble organic material therein and form a slurry. About 0.1 to about 2% by weight, based on the slurry weight, of an addition polymerizable catalyst is added to polymerize and solidify the slurry. About 10 to about 50% by weight, based on total slurry weight, of an ethylenically unsaturated monomer, such as styrene, can be added to aid in the polymerization process. The process is especially suited to filter elements containing radioactive contaminants.

Abstract: Device for purifying liquid metal coolant for a fast neutron nuclear reactor, comprising a pump (6) for circulating the liquid metal, the metal then being purified and heated after purification, as well as a filter (24) of metallic fibers. It consists of an assembly of annular chambers with a vertical axis, closed at their lower part by a base plate (10) and defined and separated from each other by an assembly of coaxial cylindrical metallic shells. The device comprises, from the exterior inwards, a degassing chamber (12), a chamber enclosing an economizer-exchanger (14, 16), a thermal insulation wall (18), a cooling chamber (20) and a purifying chamber (22) in the central part of which is a filter cartridge (24). In the central part of the cartridge (24) is a channel (25) for collecting the purified liquid metal in communication with a basin (44) for collecting the purified liquid metal rising above the device.

Abstract: Ability of ion adsorption apparatus such as a desalting unit, etc. as used in an atomic power plant is continuously monitored, and any deterioration in the ability is detected in advance by a method and an apparatus for monitoring a break in an ion adsorption apparatus by detecting a break point of the ion adsorption apparatus using ion exchange resin, thereby determining a timing for regenerating or exchanging the resin, which comprises making an ion species having a weaker selective adsortability to the ion exchange resin as a sampling ion species than that of a target ion species to be adsorbed and present in water to be treated, and detecting leakage of the sampling ion species at the downstream side of the adsorption apparatus, thereby determining the break point of the ion exchange resin.

Abstract: A process for the controlled discharge from a reactor containment structure of a gas cooled nuclear power plant and the installation for achieving this process include parallel discharge circuits from a reactor containment structure to a discharge stack. The flow of discharge from the reactor containment structure normally flows in a primary discharge circuit and may be directed wholly or partially to the parallel secondary discharge circuit. The secondary discharge circuit contains means for reduction of the temperature of the discharge, means for deposition of particulate fission products and they also contain means for recombination of combustible gases and means for filtration of the discharge. Nuclear power plant installations and processes for controlling the discharge from a reactor containment structure in this fashion permit safe discharge of naturally occurring leakage for gas cooled nuclear reactors, as well as leakage occurring in the event of reactor failure.

Abstract: A compound for chemically impregnating an activated charcoal bed for efficiently removing radioactive iodine from air flow from an area through a chemically impregnated carbon filter in a nuclear air cleaning system in which the compound is selected from Quinuclidine.CH.sub.3 I; Triethylenediamine.2CH.sub.3 I; and Hexamethylenetetramine.CH.sub.3 I.

Abstract: Process and apparatus for ultrafiltration of the cooling water of a pressurized water nuclear reactor, during operation of the reactor. A fraction of the flow of pressurized water is withdrawn continuously in at least one cold branch (8) of the primary circuit (2). This withdrawn water is circulated, while it is still at the temperature and pressure of the primary circuit (2), in contact with the entry face of an ultrafiltration wall (40). The filtrate is withdrawn at a pressure which is less than 15 bars lower than the primary water pressure. The concentrate is kept in circulation with the entry face of the wall (40). The wall (40) can consist of an assembly of tubes maintained between two tube plates. The invention applies to pressurized water nuclear reactors whatever the number of primary circuit loops.

Abstract: An improved bottom nozzle of a fuel assembly includes a housing and a modified adapter plate formed by a network of ligaments which extend across the housing and are connected to the side walls of the housing a short distance below its upper peripheral edge so as to define an open region therein. The improved bottom nozzle also includes a debris trap having a structure disposed within the open region of the housing upon the adapter plate and adapted to capture and retain debris carried by collant flowing from openings in the lower core plate of the nuclear reactor to the fuel assembly. The trap structure is composed of a plurality of straps aligned with one another in a crisscross arrangement and defining a plurality of interconnected wall portions which form a multiplicity of small cells each having open opposite ends and a central channel for collant flow through the trap.

Abstract: A debris trap is mounted within a bottom nozzle of a fuel assembly so as to capture and retain debris carried by coolant flowing from the lower core plate openings of the nuclear reactor to the fuel assembly. The trap includes a structure disposed below the adapter plate of the bottom nozzle and between the corner legs of the nozzle. The structure is composed of a plurality of straps aligned with one another in a crisscross arrangement and defining a plurality of interconnected wall portions which form a multiplicity of small cells each having open opposite ends and a central channel for coolant flow through the trap. A plurality of spring-like fingers are punched out of the wall portions and bent to extend into the cell channels toward the downstream end of the trap structure to provide means to capture and retain pieces of debris carried through the channels by flowing coolant.

Abstract: A debris trap is mounted within a bottom nozzle of a fuel assembly so as to capture and retain debris carried by coolant flowing from the lower core plate openings of the nuclear reactor to the fuel assembly. The trap includes a hollow enclosure disposed below the bottom nozzle adapter plate and between the corner legs thereof. The enclosure is composed of upper and lower walls and inwardly inclined side walls which space apart the upper and lower walls and interconnect their peripheries so as to form a debris capturing and retaining chamber within the hollow enclosure. The walls are composed of a material, such as wire mesh screen and/or perforated plate, which is permeable to liquid coolant but impermeable to debris. Openings are defined in the bottom wall of the enclosure aligned with the flow openings of the core plate. Two embodiments of features are provided for capturing debris and diffusing coolant flow within and through the trap.

Abstract: Method for removal of radioactive cesium from a hot vapor, such as high temperature steam, including the steps of passing input hot vapor containing radioactive cesium into a bed of silicate glass particles and chemically incorporating radioactive cesium in the silicate glass particles at a temperature of at least about 700.degree. F.