Abstract: A method for chemically controlling cobalt decontaminating the water cooling system of a water cooled nuclear fission reactor to reduce the radiation hazard to personnel.

Abstract: A fuel assembly for a light-water nuclear reactor includes a plurality of vertical fuel rods (10, 42) which are arranged, in spaced relationship in a lateral direction, between a bottom tie plate (11, 44) and a top tie plate (12, 43), the bottom tie plate, defining through-going vertical channels (50) for conducting water through the bottom tie plate and into the spaces between the fuel rods. The bottom tie plate also defines horizontal channels (51, 52) which cross the vertical channels and which are preferably arranged, at edges (54) on the bottom tie plate, in open communication with the spaces between the fuel rods. Helical springs (61, 62) with horizontal symmetry axis are arranged in at least some of the horizontal channels where the horizontal channels cross the vertical channel so as to trap debris in the water passing upwardly through the through-going vertical channels.

Abstract: A filtered venting system located in association with a reactor containment vessel installed in a reactor building comprises a filter device disposed in the reactor building and including filter means, a first venting line disposed on an upstream side of the filter device and having one end connected to the reactor containment vessel and another end connected to the filter device, a stand-by gas treatment system including outlet fan means or pump means and connected to the first venting line at the downstream side of the fan or pump means, and a second venting line disposed at a downstream side of the filter device and another end connected to an outlet means/ The filter device being utilized for the stand-by gas treatment system for treating and removing a radioactive substance contained in an atmosphere delivered from the reactor containment vessel.

Abstract: The nozzle (8) comprises a transverse element consisting of a cross-braced structure (14) comprising wall elements (15) delimiting cells (16) of large dimensions. Ends of a plurality of mutually parallel leaves (18) are fixed to the inside walls of each of the cells (16) so that their faces are substantially parallel to the direction of circulation of the cooling water through the nozzle (8). The leaves (18) provide between them spaces of a width which is less than the size of the particles likely to be entrained in the cooling fluid and to lodge in the fuel assembly.

Abstract: The present invention is an apparatus and method of preparing and inspecting a submerged surface of a fluid reservoir. The apparatus includes a chassis sized and shaped to provide an optimally low center of gravity, a propulsion system comprising two independently controllable motor and track means, a scrubbing/vacuuming system disposed at the front of the chassis which includes a scrubbing system designed to mechanically break up sediment on the surface beneath the apparatus and a vacuuming system to remove sediment and sediment-containing fluid from beneath the apparatus, and an inspection system located immediately behind the scrubbing/vacuuming system with respect to the direction of apparatus travel and operative to inspect the freshly cleaned surface with either ultrasonics, optics, or a combination of both.

Abstract: A decontaminating apparatus for cleaning radioactive contaminated surfaces and recovering for disposal the contaminated material, including a first recovery unit comprising a vacuum creating source in association with a second recovery unit that filters and demists the vacuum recovered contaminated material, and a third recovery unit that initially vacuum recovers the contaminated material and separates the same into fluid and air borne contaminates. The second and third recovery units each having a critical mass control responsive to the volume of contaminated material vacuumed from the surface being decontaminated.

Abstract: The present invention presents a novel apparatus and a method of demolishing a biological shield wall of a nuclear reactor using a concrete cutter device working on a wire saw, said apparatus comprising a concrete cutter device consisting of a driving part for a wire saw and a concrete cutting part attached on the engaging receiver of the driving part, a core boring machine to be attached interchangeably on the receiver in the place of the cutting part and a carrier truck to carry the wire saw driving part of said cutter device, further the concrete cutting part having a pair of vertical rods supported on a table movable vertically and adjustable in a distance of the rods and, at the bottom end of the rods, supporting pulleys and guide rollers for disposing the wire saw are provided.

Abstract: A nuclear reactor having a chemical decontamination system is provided in which every piece of decontamination equipment which processes radioactive materials is located within a decontamination building. The decontamination system is designed to provide for adequate protection for personnel safety and also incorporates a modular design for equipment transportation and storage.

Abstract: The lower connector comprises an adaptor plate of square shape, traversed by water passage orifices, and a filtration plate pierced with holes of small dimensions and abutting against the adaptor plate. The water passage orifices of the adaptor plate are arranged completely symmetrically in relation to the medians and to the diagonals of the adaptor plate. The set of orifices in each of the zones of the adaptor plate limited by a diagonal and a median comprises orifices have an oblong cross-section and, if appropriate, water passage orifices of a different shape. The filtration plate comprises sets of holes of small dimensions arranged in the zones of the plate which come into alignment with the oblong orifices of the adaptor plate.

Abstract: The invention provides a new high temperature isotopic exchange fuel processing loop for tritium recovery in which tritium is exchanged out of impurities such as tritiated ammonia, methane and water by swamping with H.sub.2 and isotopically equilibrating the mixture in a high temperature reactor. Downstream of the reactor is a Pd/Ag permeator for separation of the hydrogen from the impurities, the separated hydrogen being sent to an isotope separation system for tritium recovery and the residual impurities being recycled. The process eliminates the need for impurity oxidation and electrolysis of DTO and does not rely on complicated catalytic decomposition reactions.

Abstract: A foreign matter recovering apparatus includes a body for approaching a fuel assembly, a body fixing section for fixing the body to the fuel assembly for positioning, a moving mechanism section movable relative to the body, a recovering working unit adapted to be moved by the moving mechanism section to gain access to clearance of the fuel assembly to allow foreign matter to be recovered thereby, and a remote control section for remotely controlling the working unit on the basis of an image representing a working state of the working unit to operate it properly.

Abstract: A pump assembly which overcomes a shaft and cover cracking problem comprising a means for heating the seal purge water flowing along the shaft before it exits into an annulus (mixing region) thus reducing the temperature difference between the cooler seal purge water and the hotter product water prior to the mixing of the two waters.

Abstract: A unique resin processing system for providing and removing resin to large demineralizer vessels during chemical decontamination of nuclear reactor primary systems is disclosed. Resin is premeasured in a batching tank for accurate filling of demineralilzer resin bed while minimizing personnel radioactivity exposure. Sluice water transfers spent resin to a storage tank and, thereafter, is recycled for subsequent sluicing operations. Spent resin from the storage tank is periodically delivered to high integrity containers for ultimate disposal.

Abstract: The filtration plate (10), arranged in the lower part of the fuel assembly and ensuring the retention of particles contained in the cooling fluid of the reactor, has at least one active zone where it is pierced with holes (12) of a size determined according to the size of the particles to be retained. The active zones of the filtration plate come into alignment with a water-passage hole through the lower core plate of the reactor when the assembly is in operation. The water-passage orifices of the filtration plate (10) can consist of cutouts of square or triangular form or of stamped parts of the plate or be delimited by parallel lamellae constituting a grating.

Abstract: Measurement values of conductivity of pH of water in the primary cooling water system of a boiling water atomic power plant are input through on-line and the measurement values of conductivity and pH at times of measurement when water quality changes are compared with values at the time of normal operation. Tendencies to increase or decrease the conductivity and pH are combined to prepare one diagnosis data, and causes of anomaly in progress in component apparatus members are discriminated and diagnosed by the diagnosis data. By using a correlation between logarithm of conductivity and pH in preparing the diagnosis data from combinations of conductivity and pH, causes of anomaly can be diagnosed more accurated.

Abstract: A nuclear reactor having a chemical decontamination system is provided in which every piece of decontamination equipment which processes radioactive materials is located within the containment chamber of the nuclear reactor. This decontamination system therefore presents advantageous safety benefits over an outside of containment system in the unlikely event of a leak of radioactive materials from the decontamination system.

Abstract: The connector comprises an adaptor plate (6), supporting feet (7) and a flat element (10) constituting a filter for the retention of particles contained in the cooling fluid of the nuclear reactor. The flat element (10) is fastened to the lower part of the supporting feet (7) of the assembly, in order, during operation, to come to rest on the lower core plate (1) of the reactor. At least one zone of the flat element (10) constitutes a filtration grating located opposite a cooling-water passage (2) through the lower core plate (1).

Abstract: An apparatus for cleaning up reactor coolant includes a piping for taking out water in a reactor core, and this piping is provided separately from a primary loop recirculation piping and has its open end located at the bottom of a reactor pressure vessel. The taking-out piping extends upward from the open end within the reactor pressure vessel and extends through and outside of the side wall of the reactor pressure vessel. In a preferred form, the taking-out piping is provided near the highest position of its portion outside the reactor pressure vessel with a siphon brake valve.

Abstract: A primary coolant circuit for cooling a nuclear reactor has wetted mechanically stressed nickel base alloy components such as Alloy 600 tubes in steam generators having oxidized surfaces comprising 1-10 w/o zinc, which tubes are inhibited against primary water stress corrosion cracking. The crack initiation times may be delayed by a factor of two in pressurized water nuclear reactors.

Abstract: A reactor for use in the separation of tritium from tritiated water by the vapor phase catalytic exchange process comprises an evaporator section, a superheater section, a catalytic reactor section and a condenser section serially arranged within a common casing structure defining a unitary pressure vessel. In a multistage plant the reactors are interconnected to provide for countercurrent flow of the water and hydrogen gas from stage to stage, with co-current contact in the catalytic reactor section of each stage. By incorporating the components of each stage in a common casing structure, the external piping is minimized and the risk of leakage is reduced.

Abstract: System for inspecting the interior of tube plugs, particularly tube plugs of the type having expander elements disposed therein. The system includes a probe assembly connectable to the tube plug, the probe assembly having a rotatable and translatable probe carrier housing for housing a sensor probe capable of inspecting the tube plug. The probe assembly also includes a leaf spring extending through the probe carrier housing and attached to the sensor probe for radially outwardly biasing the sensor probe into sensing contact with the interior of the tube plug, particularly the interior of the tube plug located between the top of the tube plug and the expander element. A tangle-free flexible hose is connected at one end thereof to the probe carrier housing for transversely rotating and longitudinally translating the probe carrier housing. The flexible hose is also connected at the other end thereof to a probe driver assembly that rotates the flexible hose which in turn rotates the probe carrier housing.

Abstract: In this decontamination process, the surfaces contaminated with radioactive substances, in particular on components of cooling circuits in nuclear reactors, are treated in a first treatment step with an aqueous decontamination solution, containing chromic acid and permanganic acid, at a temperature in the range from 270 to 350 K, in particular at usual room temperature. The contaminated surface layers are thus oxidized by means of the permanganic acid, while the effect of the chromic acid is that the modified surface layers do not adhere firmly. In a second treatment step, the surface layers thus modified are removed by a chemical treatment in the same temperature range, as a result of dissolution, or/and removed by mechanical or hydraulic action. Aqueous solutions of organic acids are suitable for the chemical treatment in the second treatment step, it also being advantageously possible to add reducing agents and complexing agents and/or corrosion inhibitors.

Abstract: Process for the radioactive decontamination of metal surfaces, particularly portions of the primary circuits of water-cooled nuclear reactors, characterized in that it comprises subjecting said surfaces to the successive stages of an oxidizing pretreatment with the aid of a solution of potassium permanganate KMnO.sub.4 and nitric acid, rinsing with demineralized water and then reducing treatment in a basic medium with the aid of a solution of alkali metal gluconate of formula HOH.sub.2 C--CHOH--CHOH--CHOH--CHOH--COOM, in which M is an alkali metal chosen from among Na and K, as well as soda NaOH.

Abstract: The device comprises an elongate transmission member (30) which can be moved inside the steam generator tube by pulling and pushing. The elongate member (30) comprises a central metal cable (31), a flexible peripheral sheath (32) and a plurality of annular members (33) which are not connected together and are threaded in sequence onto the flexible sheath (32). A clearance (34) corresponding to the difference in length between the sheath (32) and the total length of the members (33) when they are placed end to end allows the member (30) to be moved inside the tube by pushing without the application of great force. In particular, the device enables heating elements to be inserted and positioned in the curved parts of the tbes of the bundle of a steam generator of a pressurized-water nuclear reactor.

Abstract: A unique clean-up sub-system for chemical decontamination of nuclear reactor primary systems is disclosed. Chemically-processed fluids containing suspended and dissolved solids are directed through a back-flushable filter and, thereafter, through one or more cartridge filters. After this initial filtering of suspended solids, the process fluid is directed to one or more demineralizer banks for removal of dissolved solids, followed by additional cartridge filtering to remove any resin fines carried out of the demineralizer banks. After final filtering, the process fluids are returned to the primary system, with or without chemical injection.

Abstract: A unique and optimum nuclear steam supply system operating configuration for integration of a chemical decontamination system is disclosed. The chemical decontamination system is connected to, and returns to, the residual heat removal system downstream of a residual heat removal heat exchanger, thereby utilizing the residual heat removal system to control the temperature of process fluids entering the decontamination system. A reactor coolant pump or pumps generates heat for the chemical processes as needed and a nitrogen blanket within the primary system pressurizer is utilized for system pressure control.

Abstract: The device comprises a pipe for aspiration and delivery of water from a well, a column suspended from a traveling crane located above the well and an aspiration head fixed at the end of the column opposite to the crane. The aspiration head is composed of two hollow walls assembled to one another, between which there is a filtration wall separating the internal volume of the head into a first part having an aspiration opening and a second part connected via a conduit to the aspiration pipe.

Abstract: An auxiliary flexible vacuum seal for preparing a reactor coolant pump for vacuum degasification of the reactor coolant system employs a flexible boot member having a pair of longitudinally-displaced opposite open end portions and a pair of side-by-side longitudinally-extending side portions in the form of flanges defining a split in the boot member along a side thereof and extending between the open end portions for allowing flexing of the boot member between open and closed side configurations to permit its installation and removal on and from the pump. The seal also employs clamping brackets and fasteners for releasably and sealably clamping together the flanges of the boot member at the split to retain the boot member in its closed configuration.

Abstract: A device for cleaning and servicing a weld site about the periphery of a extending control rod drive mechanism and adapter tube including a housing adapted to be positioned adjacent to and rotated about the periphery of the control rod drive mechanism and a carriage assembly including an inner and outer portion reciprocably received within the housing is provided. Mounted within the housing is a first drive motor for driving a threaded lead screw rotatably mounted within the housing with an internally threaded follower secured to the carriage assembly and mating with the threaded lead screw for reciprocating the carriage assembly relative to the housing in a direction substantially parallel to the control rod drive mechanism.

Abstract: A nuclear reactor includes a spaced sidewall and a core shroud defining a flow passage for channeling a coolant. A foreign object separator includes an arcuate endwall extending from the sidewall, with the core shroud including an intermediate portion spaced from the endwall to define an annular inlet for receiving coolant from the flow passage. The core shroud also includes a distal end spaced from the endwall to define a throat. A separator member has a proximal end joined to the endwall, and a distal end spaced from the core shroud to define an outlet. The distal end of the separator is spaced from its proximal end for allowing the coolant from the throat to impinge against the separator member for turning the coolant prior to discharge from the outlet and using centrifugal force to separate any foreign objects of predetermined size from the coolant. The separated foreign objects are retained adjacent to the separator member proximal end.

Abstract: A method of decontaminating radio nuclide-contaminated corrosion products, which are sparingly soluble in acid, from primary system surfaces in reactors of the pressurized water reactor type and the boiler reactor type with hydrogen dosage and similar, by oxidation and concurrent dissolution in an acidic decontamination solution of the acid soluble corrosion products obtained by said oxidation. The characteristic feature of the method is that said oxidation is performed with Ce.sup.4+ ions, ozone and chromic acid in the presence of perhalogen acid, preferably perchloric acid, at a pH below 3.

Abstract: A purifier for nuclear reactor cooling water, which contains, as an active ingredient,a titanium oxide-based solid solution of the formula (1)(Ti.sub.1-x Al.sub.x)O.sub.2 (1)wherein x is defined by 0<x<0.5, and/oran aluminum oxide-based solid solution of the formula (2)(Al.sub.1-y Ti.sub.y).sub.2 O.sub.3 (2)wherein y is defined by 0<y<0.5, and a method of purification of nuclear reactor cooling water, which comprises bringing nuclear reactor cooling water having a temperature of 100.degree. to 300.degree. C. into contact with the above purifier.

Abstract: A method for chemical decontamination of the surface of a metal component of a nuclear reactor plant includes treating the surface of the metal component in a single-step method with an aqueous solution that is free of carbonic acid oxalic acid and contains a different carbonic acid.

Abstract: A vacuum system for cleaning the base of a control blade guide tube comprises a vacuum source and a novel vacuum head. The vacuum source includes a conventional vacuum pump and filter, for trapping matter entrained in water driven by the pump. The vacuum head is disk-shaped and has an off-axis vacuum port which can scan the guide tube base when the disk is rotated 360.degree.. Elongated slots in the disk admit water down through the disk. Guide fins separate the slots from the vacuum port. The guide fins are shaped to provide a clearance over the guide tube base, effecting a highventuri action which helps sweep up debris on the guide tube base. An annular ridge on the disk surrounds a similar annular ridge on the base, isolating a control rod drive tube housing below the base from the vacuum. This prevents control rod drive components from being disturbed by the vacuum.

Abstract: A natural circulation type boiling light-water reactor comprises a pressure vessel, a reactor core disposed within said pressure vessel to heat light water so as to generate main steam, a steam outlet provided in a wall of said pressure vessel for drawing out the main steam therethrough to supply the same to a turbine system, and a steam path along which the main steam flows from the reactor core to the steam outlet. The reactor further comprises a steam guide for prolonging the steam path and/or a radially increased chimney for reducing the velocity of the main steam flowing through the steam path. These causes radioactive isotope .sup.16 N contained in the main steam to flow within the pressure vessel for a time period exceeding its own half-life, so that the inventory of .sup.16 N in the main steam directed towards the turbine system is reduced remarkably. In consequence, shield structures for piping and turbine systems can be reduced in size and weight.

Abstract: Both a system and a method for removing sludge and debris from the interior of the secondary side of a nuclear steam generator is disclosed. The method comprises the steps of introducing a sufficient amount of water in the secondary side to submerge at least the tubesheet, generating a succession of shock waves in the water by means of pulses of pressurized gas to create shock waves that loosen the sludge and debris, and vertically flushing the interior of the secondary side by suctioning water off from the bottom portion of the steam generator while simultaneously forcefully spraying water from the top portion of the generator over the bundle of heat exchanger tubes in order to remove the sludge and debris loosened by the shock waves.

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 nuclear reactor internal pump has a pump shaft connected to a motor and rotatably passing through the bottom of a nuclear reactor pressure vessel, an impeller fitted to a front end portion of the pump shaft, a diffuser disposed on the downstream side of the impeller and having an inner cylinder fixed to the bottom of the reactor pressure vessel to surround the pump shaft, a purge water passage defined between the pump shaft and the inner cylinder to communicate with the inside of the reactor pressure vessel and a purge water supply device for supplying purge water to reactor pressure vessel through the passage. Further, the nuclear reactor internal pump comprises a clad dropping preventive device for trapping clad coming from the reactor pressure vessel in the passage to prevent the clad from dropping.

Abstract: An articulated lance for cleaning sludge located between steam generator tubes is disclosed. A plurality of radius blocks are attached to the end of manipulator member and are actuatable by a cam assembly to form an arc permitting the lance to be received between adjacent tubes within a tube bundle. A plurality of fluid passageways interconnect a fluid inlet on the manipulator member with one or more outlet orifices adjacent the end of the lance. The outlet orifices are positioned outwardly with respect to the end of the manipulator member so that fluid passing therethrough can be directed to impinge upon sludge surrounding the tubes. A spring backing place biases the radius blocks and the manipulator member back into the same plane upon deactuation of the cam assembly.

Abstract: The invention comprises a method for conducting a decontamination solution into a nuclear steam generator for radioactively decontaminating the nuclear steam generator. The invention also comprises controlling the level of the decontamination solution in the heat exchange tubes of the nuclear steam generator in a manner to raise and lower, sequentially, the level of the decontamination solution in the tubes so as to replenish the decontamination solution in the tubes and to carry away the radioactive contaminates.

Abstract: A completely submersible, remotely operated underwater suction device for collection of irradiated materials in a nuclear pool is disclosed. The device includes a pump means for pumping water through the device, a filter means for capturing irradiated debris, remotely operated releasable connector means, a collection means and a means for remotely maneuvering the collection means. The components of the suction device may be changed and replaced underwater to take advantage of the excellent radiation shielding ability of water to thereby minimize exposure of personnel to radiation.

Abstract: In the operation of a power reactor having a pressure bessel (2) containing a core and a plurality of thimbles extending into the core to provide passages for a flux detector, a movable support member (12) located outside of the pressure vessel (2) and carrying a plurality of tubular members (10) each detachably connected to a respective thimble, and a transfer unit (20) normally coupled to the tubular members (10) for introducing a flux detector into a selected thimble via a respective tubular member (10), obstructions are removed from a selected thimble while the reactor remains in operation, by the steps of:disconnecting at least the respective tubular member from the transfer unit (20);introducing an obstruction removal device (40,42) into the respective tubular member (10); andadvancing the obstruction removal device (40,42) through the respective tubular member (10) and into the selected thimble to the location of the obstruction.

Abstract: Chemical decontamination of large components and systems of metallic materials of nuclear reactors with a liquid reactor coolant, wherein the treatment is carried out by means of an aqueous solution of oxidizing chemicals which is moved through the large components and systems to be decontaminated. Nitrates, chromates or Ce-IV salts are added as oxidizing chemicals in the particularly borate-containing primary coolant and also an addition of ozone is used.

Abstract: The invention is directed to a method of washing a solvent in the reprocessing of irradiated nuclear fuel. The solvent is washed with an aqueous solution in a mixer-settler having at least one stage which includes a mixing chamber and a settling chamber. The pH of the dispersion in the mixing chamber is measured and an amount of washing solution is added which influences the pH toward the desired operational value. An apparatus for carrying out the method is also disclosed.

Abstract: A process for pretreatment of chromium-rich oxide surfaces of nuclear reactor cooling system components involves application of a dilute acidic reagent comprising potassium permanganate and chromic acid, at elevated temperatures.

Abstract: A gas/liquid separating and vent apparatus wherein gas trapped and/or entrained in a standpipe containing liquid medium is separated from the liquid and vented off. The valve can be power or manually operated. In both modes, the separator distinguishes between gas and liquid because of the differences in compressibility of the fluids. The venting of liquid is prevented if no significant amount of gas is present in the system.

Abstract: Disclosed is a method of decontaminating the metal surfaces in the cooling system of a nuclear reactor by contacting the metal surfaces with an aqueous solution containing about 0.5 to about 3% of a ceric acid which can be tetrasulfato ceric acid, hexasulfamato ceric acid, hexaperchlorato ceric acid, or mixtures thereof, and about 1 to about 5% of an inorganic acid that forms a complex with the ceric acid.The cerium III in the aqueous solution can be oxidized to cerium IV to increase the life and effectiveness of the solution. After oxidation, the aqueous solution can be passed through a hydrogen form cation exchange column to remove metal ions. If the aqueous solution contains uranyl or plutonyl ions these can be recovered by extraction for use in making fuel.Also disclosed is a decontaminating solution of water containing about 0.

Abstract: A process for the removal of iodine from aqueous solutions, particularly the trapping of radioactive iodine to mitigate damage resulting from accidents or spills associated with nuclear reactors, by exposing the solution to well dispersed silver carbonate which reacts with the iodine and iodides, thereby gettering iodine and iodine compounds from solution. The iodine is not only removed from solution but also from the contiguous vapor.

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.