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 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 auxiliary seal for preparing a reactor coolant pump for vacuum degasification of the reactor coolant system includes at least a pair of sealing segments. The sealing segments are composed of metal and have semicircular shaped bodies with attaching ears and an anchoring flange fixed thereon. The attaching ears extend radially outward from opposite ends of the sealing segment bodies. The ears on one segment body when aligned with and attached by fasteners to the ears on the other segment body draw the sealing segments together in releasably attached relation to one another and in sealing and clamping engagement about a shaft of the pump. The segment bodies also have interior and exterior circumferential recesses with O-rings therein which seal respectively with a portion of the pump shaft and a portion of a housing of the pump. The annular flange extends radially outward from the sealing segment bodies and is attachable to the housing portion for anchoring the seal segments thereto.

Abstract: A method of treatment of a radioactive liquid waste containing fission products and a thermally decomposable sodium compound which comprises heating the liquid waste to convert the sodium compound into oxides of sodium, converting the oxides into sodium, hydroxide, reacting the sodium hydroxide with an alcohol to form a sodium alcoholate, separating the sodium alcoholate from an impurity residue essentially comprising fission products, decomposing the separated sodium alcoholate to form sodium hydroxide and recovering the sodium hydroxide.

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 process for removing radioactive species such as technetium from surfaces of components such as those formed from aluminum, and a process of treating the resulting effluents. For example, technetium trapped under an oxide layer present on an aluminum component is removed by removing the oxide layer with sulphuric acid, and treating the exposed technetium with a complexing agent such as citrate in the presence of an oxidizing agent. An oxide scavenger may be added to prevent reformation of the oxide layer. Actinides can be removed from the effluent by use of a chelating ion exchange material, and technetium by oxidation and use of a basic ion exchange material.

Abstract: A continuous dissolution apparatus for spent nuclear fuel in which a container (2) for holding a dissolution processing solution (1) is continuously supplied with nitric acid from a feed port (3), while the processing solution is continuously drawn out from an outlet (4). Baskets (71-74) in the container are packed with spent-fuel chops (6), which are continuously dissolved by the processing solution. The container is provided with a solution reserving section (4) for lowering the concentration of radioiodine contained in the dissolution processing solution, and a partition wall (10) is formed between the solution reserving section and a container body. The dissolution processing solution having overflowed from the upper edge of the partition wall flows into the solution reserving portion (14) through a perforated plate column (11).

Abstract: A method of cleaning a fuel assembly contaminated with a radioactive alkali metal in which the fuel assembly is subjected to heating with an inert gas followed by being placed under vacuum and finally cooled with an inert gas; the latter two steps being performed in repetitive cycles.

Abstract: A method of decreasing the danger associated with nuclear reactors is disclosed. According to the method, the coolant is treated to remove deuterium to prevent formation of dangerous tritium. The preferred process uses a distillation colummn to continuously remove heavy and intermediate-weight water from a bleed stream. Light water is returned to the coolant circuit.

Abstract: To separate tritium from gases and/or vapors escaping accidentally from a clear reactor, before the gases or vapor are discharged into the atmosphere, the gases or vapor are fed through a line 5 into a reservoir 3 of deionized light water which is maintained at its boiling point in a heat insulated vessel 1. The tritium is accumulated in the water in the reservoir 3 and any tritium which passes from the reservoir 3 in light water steam is condensed by surface condensors 8 in a steam dome 9. Any possible residue of tritium in the steam leaving through an outlet 10 at the top of the dome 9 is separated out in the form of droplets by a drier cyclone connected directly downstream of the outlet 10.

Abstract: Apparatus for the controlled venting of gases from the containment housing of a chemical or nuclear reactor. The vent path is configured as a manometer filled with a low melting point metal. Gases passing through the manometer are exhausted to a tank of scrubbing solution where toxic materials are removed prior to venting the gases from the containment housing.

Abstract: The present invention relates to a decontamination method in which an object to be decontaminated is immersed in a liquid, bubbles are produced by blowing vapor in the liquid, and these bubbles are caused to burst on a solid surface which constitutes the object to be decontaminated which is brought into contact with the liquid, whereby substances adhered to the solid surface are separated and removed by the impulsive force produced when the bubbles burst. Also provided is a method of decontaminating solid surfaces which exhibits a high degree of efficiency and a high level of safety.

Abstract: The invention relates to a method of and apparatus for the regregation of radioactive iodine isotopes from fluid samples. The method consists in leading the degassed and in certain cases also otherwise prepared sample into a column filled with an amorphous solid medium for binding quantitatively the cations, fluoride anions and contaminations of colloidal state, then the effluent flow continuously through an energy-selective gamma detector and continuously recording the signals generated in the detector by the radioactive iodine isotopes. The proposed apparatus comprises a sampling unit (MV), a degassing vessel (G), fluid transfer pumps (P1, P2), pipings, cocks (CS), a bubble removing cell (BC), a column (K) with amorphous material filling, an energy-selective detector system (GD) for measuring gamma radiation, and a signal processing and recording unit (JR).

Abstract: A process and apparatus for decontaminating parts of nuclear power plants which are contaminated with radioactive material, wherein surface layers are removed from the parts. The parts to be decontaminated are treated with a jet of pressurized water which contains a granular abrasive and which may contain admixed air. The mixed effluent consisting of water, abrasive and detached particles is separated into an aqueous phase and a sludge phase, the sludge phase is dried, and the resulting dry material is separated into abrasive and particles smaller in diameter than the abrasive. The purified abrasive is recycled to the water for forming the jet of water under pressure, and the separated particles are made available for safe disposal.

Abstract: Process for decontaminating an exhaust gas from a fusion reactor fuel cycle of exhaust gas components containing at least one heavy hydrogen isotope selected from tritium and deuterium in compound form, the compound form being ammonia and hydrocarbon, the exhaust gas containing CO and hydrogen isotopes and in which the at least one heavy hydrogen isotope is liberated from its compound, separated out from the exhaust gas and fed back into the fuel cycle, comprising(a) carrying out a catalytic oxidation reaction at a temperature of from 200.degree. C. to 250.degree. C., to oxidize the exhaust gas components, without changing the ammonia, as follows: CO to CO.sub.2, hydrocarbon to CO.sub.2 +water, and the hydrogen isotopes to water,(b) bringing the gas admixture resulting from step (a) into contact with a metal bed at a temperature in the range of 200.degree. C. to 400.degree. C. to selectively transform the water into hydrogen isotopes and to remove O.sub.

Abstract: A centrifuge for the removal of solids from liquids, for example, the removal of solid fission products from dissolved nuclear fuel. The centrifuge is mounted behind a solid wall and is provided with a pivotable catch tray which cooperates with a feed inlet extending through the wall of a casing about the bowl of the centrifuge. The catch tray is pivotable between a first position at which it cooperates with the feed inlet to introduce feed liquid into the bowl and a second position at which it is removed out of cooperation with the feed inlet to permit withdrawal of the bowl from the casing through a removable plug in the wall.

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: An ultrasonic cleaning device for a venturi flow nozzle in a pipe in a fluid system which includes one more transducer assemblies for generating and transmitting sound waves to the nozzle to effect a cleaning action.

Abstract: A lance assembly designed to clean sludge from the portion of the OTSG tube bundle which is inaccessible from the open tube lane. A track assembled between the OTSG outer shell and circular shroud around the tube bundle substantially opposite the open tube lane has a motorized carriage driven on the track which directs high pressure fluid through a plurality of nozzles toward the tube bundle through windows in the circular shroud. The nozzles are attached to a nozzle block which is capable of being moved vertically on the carriage to vary the flow impact area on the tube bundle.

Abstract: Chemical decontamination of metallic parts of nuclear reactor installation in which an oxidative treatment with a permanganic acid solution is applied before dicarbonic acids are used for further treatment. Rinsing operations are eliminated and smaller amounts of dicarbonic acids needed. Also the primary system of the nuclear reactor no longer requires emptying before effecting decontamination treatment.

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 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: Disclosed is a method of decontaminating metal surfaces contaminated with a radioactive deposit by passing over the coating an aqueous solution of a water soluble condensation reaction product of (1) a hydrazine compound having the general formula ##STR1## where each R group is independently selected from hydrogen and alkyl to C.sub.4 and (2) a water soluble aliphatic polycarboxylic acid. The method includes the additional last steps of passing an aqueous oxidizing solution over the deposit followed by passing a decontamination solution over the deposit a second time. The solution is circulated through a cationic exchange column which can be preloaded with hydrazine ion. The decontamination solution can be decomposed by the addition of an oxidant to form nitrogen, carbon dioxide, and water.

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 method and apparatus for removing from the tube sheet and transfer tubes of a nuclear steam generator sludge deposits which occur from the use of all volatile treatment water chemistry. A continuously activated suction apparatus maintains at a low level the water/sludge inventory on the tube sheet. A high pressure first water lance is oscillated and stepped inwardly along the central tube lane of the generator to dislodge the sludge from the tube plate and heat exchange tubes. After this lance has been stepped inwardly to a predetermined position, a low pressure second water lance is activated and periodically advanced to a position just short of the first lance and functions both to dislodge sludge and to form a water barrier which prevents redeposition of sludge in the clean area.

Abstract: A method of decontaminating radionuclide-contaminated acid insoluble corrosion products from primary system surfaces in pressurized water reactors by oxidation and concurrent dissolution in an acidic decontamination solution of the corrosion products which have been made acid-soluble by the oxidation. The characterizing feature of the method is that the oxidation is carried out at relatively low temperatures with a water-based oxidation agent having a pH below 7 and containing cerium nitrate, chromic acid and ozone.

Abstract: With the reactor vessel (1) open and filled with water, and the core assemblies removed, means for measuring alignment (50) and means for measuring clearances (56, 58, 59) are mounted on the upper internal equipment (13). The upper equipment (13) is introduced into the vessel and is deposited on the lower equipment (3). Measurements of alignment are carried out and, if appropriate, the alignment is corrected by moving the upper internal equipment on the lower equipment (8). The clearances of the upper core plate are measured and, if appropriate, the upper internal equipment (13) is moved as a function of these measurements. The clearances around the centering and alignment pins are measured and adapters are machined and then fixed to the upper internal equipment (13) to reduce the clearances around the pins to a low, predetermined value. The invention also relates to the device for measuring and adapting the position of the internal equipment.

Abstract: The process according to the present invention mainly consists in successively bringing the surface of the contaminated materials into contact with a solution of sodium carbonate for some time, bringing the surface of the contaminated materials into contact with a solution of diluted nitric acid, while potassium permanganate is being added, bringing the contaminated materials into contact with a solution of oxalic acid (COOH--COOH.2H.sub.2 O), and finally rinsing and drying said materials.

Abstract: Process for the elimination of corrosion products formed on the tube plate and in the gaps between the tubes and the spacer plates of a steam generator of a pressurized water nuclear reactor, in order to prevent the appearance of a corrosion phenomena, which can lead to necking or denting of tubes by oxide growth.The process consists of reacting with said oxides at between 50.degree. and 100.degree. C., an aqueous solution containing 6 to 8% gluconic acid, 3 to 5% citric acid, approximately 0.5% of a corrosion inhibitor and ammonia until a pH between approximately 3 and 9.5 is obtained.

Abstract: A system for removing debris from a nuclear fuel assembly includes a work platform disposable on the fuel assembly racks in a spent fuel pol. A support stand is mounted on the work platform and has a sliding support plate movable between a support position engageable with the lower end of the fuel assembly, and a retracted position permitting lowering of the fuel assembly through an opening in the work platform into one of the racks. A tool manipulation assembly is disposable on the platform and includes a rotatable turret-type tool mount carrying four different cleaning tools, including a pick, a brush, a water lance and a water-actuated tweezers. The tool manipulating assembly includes drive means for effecting X-Y-Z movement of the tool mount for working on the fuel assembly. Each tool is resiliently mounted in a tool holder which yields if the tool engages the fuel assembly in a given direction with a predetermined force, generating an alarm signal to prevent damage to the tool assembly.

Abstract: A sludge lancing method comprises providing a lancing nozzle and a barrier nozzle for respectively emitting cleaning and barrier streams of fluid along two channels between columns of heat exchange tubes in a nuclear steam generator vessel, the two channels being spaced apart by at least two columns of tubes. The barrier stream prevents dislodged sludge from being moved laterally past it into previously cleaned areas. The streams may be rotated between the center and the periphery of the tube sheet. The barrier nozzle comprises three jets angularly disposed with respect to one another for increased coverage of the barrier channel.

Abstract: A method for operating a nuclear reactor having reactor coolant including an exhaust gas source and an exhaust gas system connected to the exhaust gas source, the exhaust gas system having at least one compressor connected to the exhaust gas source, a gas cooler connected to the compressor, a first reducing valve connected to the gas cooler, a switching valve connected to the first reducing valve, a moisture adsorber connected to the switching valve, a delay line normally connected in parallel with the moisture adsorber, a gas loop connected between the moisture adsorber and the compressor, a flue connection set at a given pressure during normal operation, and a second reducing valve connected between the delay line and the flue connection, includes interconnecting the delay line and the moisture adsorber in series, setting the flue connection to a pressure at least twice as high as the given pressure, reversing the switching valve thus allowing the exhaust gas to pass from the moisture adsorber to the delay

Abstract: A nuclear reactor, particularly a light water reactor or a helium-cooled high-temperature reactor, is provided with a pressure relief system for relieving pressure resulting under fault conditions from coolant in the reactor pressure vessel and/or the protective vessel of the reactor, wherein the coolant is conducted from the vessel or vessels to a pressure relief station downstream thereof. At the pressure relief station the coolant is fed into a liquid reservoir 4 from which the coolant in gaseous or vapor form is fed sequentially through a washing cyclone 13 and a drying cyclone 25. Most of the radioactive fission products carried by the coolant will have been removed by the liquid reservoir 4 and the washing cyclone 13, and the coolant leaving the cyclone 25 may be safely discharged to atmosphere. Both the liquid reservoir 4 and the washing cyclone 13 are provided with cooling circuits 8 to 12 and 14 to 23 respectively for the liquids.

Abstract: During local cleaning of metallic surfaces (15, 24) on parts included in the primary circuit of a nuclear reactor, which surfaces are coated with corrosion products, in connection with inspection of the surfaces, the coated surface, while being located below the surface of the reactor water (13) in the reactor vessel (10) or reactor pool (12) of the nuclear reactor, is arranged in contact with an electrolytically permeable spacer (16) of an electrically insulating material which, at a distance from the coated surface, is arranged in contact with a body (170 of electrically conductive material. An electrolyte (21) is supplied to the spacer and an electrical potential difference is maintained between the coated metallic surface and the body of conductive material by connecting the surface to the positive pole (18) and the body to the negative pole (19) of a voltage source (20).

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: Disclosed is an oxidizing composition of water, about 0.1 to saturation of an alkali metal hypohalite, and sufficient alkali metal hydroxide to raise the pH of the solution to at least about 12. A method of decontaminating metal surfaces having a coating thereon which contains radioactive substances is also disclosed. The composition is passed over the coating at a temperature of about 50.degree. to about 120.degree. C. followed by passing a decontamination solution over the coating.

Abstract: Process and apparatus for confining the pollution of an isostatic pressing enclosure.At the end of an isostatic pressing operation, a glove box is sealingly fixed above the enclosure, the plug is removed from the latter and deposited within the glove box, after which the sampling and inspection operations necessary for detecting any contamination are performed.Application to the compression of radioactive waste by isostatic pressing.

Abstract: A medium power, high temperature pebble bed nuclear reactor, which includes a means for introduction and withdrawal of operating elements. The installation is provided in such a way that it can be more economically built and operated. The installation includes several input stations above a prestressed concrete pressure vessel, and charging hatch blocks positioned on top of the prestressed concrete pressure vessel. The blocks include selectors through which the pebble-shaped operating elements, after traversing helical and meandering charging conduits, reach into the reactor core. The selectors and charging conduits are installed within armored ducts which penetrate the prestressed concrete pressure vessel. Similar armored ducts are provided for exit ducts for withdrawal of pebbles from the core, and a first common exit hatch block is connected to the exit ducts. The block is arranged within foundation walls which support the prestressed concrete pressure vessel.

Abstract: A procedure for vacuum degassing of a reactor coolant system which basically utilizes existing equipment to degas and refill the coolant system. The level of radiogas and non-radiogas concentration is reduced to low residual levels in less than two hours to expedite shutdown operations. The procedure enhances residual heat removal by using the steam generators as reflux condensers. During draindown of the reactor coolant to the midplane of the reactor vessel outlet nozzles, a two-phase pump is used and a vacuum is established in the vapor space created in the reactor pressure vessel, and the steam generators.

Abstract: This invention relates to apparatus and processes for the removal and recovery of concentrated acid such as HNO.sub.3 and radioactive cations such as cesium (Cs.sup.+) from a radioactive acidic waste stream resulting in the recovery of a decontaminated water product. The invention employs a combination of membrane electrodialysis stacks with each having its own specific cell configuration for performing a specific salt removal or salt concentrating step in the decontamination process.

Abstract: A process and an installation for the securing against excessive pressure in a prestressed concrete pressure vessel of a gas cooled high temperature reactor and for the prevention of activity release into the environment. The process comprises three steps and in each step pressure reducing installations become effective upon the rise of pressure in the prestressed concrete pressure vessel over a predetermined value. In the first step the pressure vessel is relieved by means of the operational gas purification apparatus and a conveying blower into the storage vessels for the cooling gas. In case of a further rise in pressure, in a second step a discharge path equipped with a safety valve and a check valve is opened, which also relieves into the storage vessels while by-passing the gas purification installation.

Abstract: A process for the treatment of radioactive sodium is provided which comprises the steps of forming radioactive sodium amalgam by mixing radioactive sodium with mercury; reacting the radioactive sodium amalgam with water to form mercury and radioactive sodium hydroxide; recycling the mercury into the step of forming radioactive sodium amalgam to be mixed with the radioactive sodium; and solidifying the radioactive sodium hydroxide in the presence of a solidifying material to be confined in a stable solidified body.

Abstract: A repair device for removing an inner surface layer on a feed-water connector of a reactor pressure vessel received in a reactor housing having an assembly platform with a carriage displaceable thereon transversely to the reactor pressure vessel, the repair device includes centering means located at a lower end of a telescopically extensible upright tube suspended from the carriage for centering the lower end of the upright tube in the pressure vessel, the centering means having at least two outwardly swingable supports and a hydraulic system for swinging the two supports outwardly umbrella-like; a supporting frame for a feed rod also disposed at the lower end of the upright tube, the feed rod being horizontally self-supporting at an end thereof; a drive motor connected to the feed rod for rotating the feed-rod; means located at the self-supporting end of the feed rod for centrally fixing the self-supporting end in the feed-water connector of the reactor pressure vessel; and a horizontally displaceable turnin

Abstract: A ventilation system for a storage or transfer canal for radioactive materials comprises a series of air emitting nozzles spaced along one side of and above the upper surface of the canal to produce an air curtain completely covering the surface of the canal, and a series of exhaust hood openings on the opposite side of the canal to capture and exhaust the air in the air curtain and a part of the air above the air curtain.

Abstract: A boiling water type nuclear fuel rod assembly used in a nuclear reactor and having radioactive scale deposited thereon is taken out of a fuel pool and disposed in a substantially sealed vertical tank, while the scale is still wetted by water. Gas in the tank is heated to a temperature higher than room temperature by the heat of nuclear fission or an electric heater to dry and peel off the scale. A mixture of the scale and water collected in a bottom portion of the tank is sent to a water-scale separator. To rapidly and perfectly remove the scale, after completing the step described above, water is sprayed onto the fuel rod assembly to wet any remaining scale. Then, drying of the scale with hot gas is repeated again.

Abstract: A fission product scrubbing system comprises a water tank in the containment building; a dividing wall extending into the water tank for separating it into first and second compartments; a collection plenum normally hermetically sealed from the containment space and the environment externally of the containment building and being at least in part formed by the dividing wall and the level of water stored in the second compartment and a communication passage in the dividing wall underneath the water level in the first and second compartments for maintaining communication between the water stored therein. There is further provided a standpipe which extends from the containment space into the second compartment and which has flow distribution holes situated in the second compartment below the water level and above the communication passage, whereby gases passing from the containment space into the standpipe travel upwardly from the distribution holes through the water into the collection plenum.

Abstract: A method for extracting debris from the bottom of a water-filled nuclear reactor vessel. The method includes steps of removing the vessel closure head, upper internals and at least some fuel assemblies from the reactor vessel to expose a flow hole which is contained in the lower core plate and which has a perimeter, wherein imaginary vertical projection lines extending from the perimeter define an obstructed volume between the lower core plate and the bottom of the vessel, lowering a pipe having an open free end into the vessel so that the pipe extends through the exposed flow hole in the lower core plate and has its free end in close proximity to the bottom of the vessel, applying suction to the end of the pipe remote from the open free end to withdraw water and debris from the bottom of the vessel through the pipe, and removing the debris from the water withdrawn from the vessel and discharging the debris-free water into a reservoir.

Abstract: An ultrasonic decontamination robot removes radioactive contamination from the internal surface of the inlet and outlet headers, divider plate, tube sheet, and lower portions of tubes of a nuclear power plant steam generator. A programmable microprocessor controller guides the movement of a robotic arm mounted in the header manway. An ultrasonic transducer having a solvent delivery subsystem through which ultrasonic action is achieved is moved by the arm over the surfaces. A solvent recovery suction tube is positioned within the header to remove solvent therefrom while avoiding interference with the main robotic arm. The solvent composition, temperature, pressure, viscosity, and purity are controlled to optimize the ultrasonic scrubbing action. The ultrasonic transducer is controlled at a power density, frequency, and on-off mode cycle such as to optimize scrubbing action within the range of transducer-to-surface distance and solvent layer thickness selected for the particular conditions encountered.

Abstract: A method for decontaminating metal surfaces having radioactive oxide deposits thereon is disclosed which comprises preparing a decontamination solution having a pH of about 1.5 to about 4 comprising water, about 0.02 to about 0.5% of a water soluble organic acid which has an equilibrium constant in a complex with ferric ion of at least about 10.sup.9 and which is capable of producing a pH of about 2 to about 3 in water, and about 0.01 to about 0.4% of a chelate in free acid form which has an equilibrium constant in a complex with ferric ion of about 10.sup.15 to about 10.sup.19 and which is at least 0.4% soluble at 40.degree. C. in water having a pH of about 2 to about 3. An apparatus for performing the above method is disclosed.

Abstract: A blast head including a plurality of spray nozzles mounted in a chamber for receiving a workpiece. The several spray nozzles concurrently direct a plurality of streams of a pressurized gas and abrasive grit mixture toward a peripheral portion of the workpiece to remove particulates or debris therefrom. An exhaust outlet is formed in the chamber for discharging the particulates and spent grit.