Abstract: An immersion heater for a fluidized bed decarbonation reactor includes an elongate cylindrical graphite heating element within a sealed chamber into which an inert gas, such as argon, is introduced for protecting the heating element from oxidation and from which the gas may be removed. The chamber is defined by a refractory metal sheath with longitudinal corrugations and externally covered by a protective layer formed by chromaluminization. An insulating refractory metal ring centers and holds the heating element within the sheath to prevent short circuits between the heating elements and the sheath. A composite metal plate holds the heating element and includes input and output electrical supply bars for providing power to the heater.

Abstract: A device for counting particles of ionizing radiation comprises a detector and a reference source on the input side of the detector delivering reference radiation the spectrum of which is situated outside the spectrum of the ionizing radiation to be detected. The device further comprises an arrangement for discriminating the amplitude and energy of the received ionizing radiation and means for adjusting the relative positions of the amplitude levels on a scale of amplitude and the amplitudes of the pulses generated by the reference radiation. The device may be applied to monitoring the flowrate of leakage between primary and secondary circuits of a nuclear power plant steam generator.

Abstract: Disclosed are a method and device for the identification of the leakiness of a neutron-capturing pencil, or control rod, of a nuclear reactor. The pencil is placed in an impervious chamber filled with an aggressive chemical solution. The solution is put under pressure in order to make it penetrate the defective pencil, then this pressure is relaxed in order to enable the solution to go out of the presumably defective pencil in the impervious chamber. The solution is analyzed in order to show up metallic salts of the constituent elements of the core of the pencil. Application is to routine checks on neutron-capturing pencils of a pressurized-water nuclear reactor.

Abstract: An amperometric method for the direct measurement of acidity in a medium which contains at least one ester of an acid containing oxygen, and whose dielectric constant is lower than 30. The method provides for maintaining a constant voltage between an ultramicroelectrode and a counterelectrode and measuring the current therebetween as an increasing quantity of diphenylphosphoric acid is added to the medium via a microburette. The measured current being indicative of the acidity of the medium under test. A predetermined curve is provided which represents the relationship between the acidity of the medium and the current measured by the system.

Abstract: A measurement device for on-line measurement of the gamma radiation emitted by the water in a nuclear reactor circuit, in particular the primary cooling circuit of a pressurized water nuclear reactor, the measurement device comprising:at least one volume (101, 102) for metering the fluid to be analyzed;a radiation detector (200) placed facing the volume; and a collimator interposed between the volume and the radiation detector, the collimator being constituted by a plurality of collimators (431, 432, 433) of different sizes mounted on a common member (400) which is movable relative to the volume-and-detector assembly, with the position of the moving member being determined automatically as a function of the measurement signal delivered by the detector so that the greater the intensity of the radiation revealed by the delivered signal, the smaller the size of the collimator interposed between the detector and the volume.

Abstract: The invention relates to inorganic ultrafiltration or microfiltration membranes, which are modified by adsorbing on one of the faces of said membrane at least one hydrophilic polymer or copolymer, such as polyvinylpyrrolidone or polyvinylimidazole. The inorganic membrane can comprise a macroporous support coated with a microporous metal oxide layer, such as zirconia or alumina.These membranes (3) can be used in the ultrafiltration apparatus (1) for carrying out the separation of proteins such as proteins of latoserum, bovine serum albumin or lysozyme.

Abstract: The apparatus comprises an endless conveyor band (2) of insulating material on which are mounted at even distances apart receptacles (7) composed of a metal adapted to receive separate portions of a dish to be cooked and inductors (10a, 10b) disposed below the upper reach (6) of the conveyor. The inductors have a diameter roughly equal to one-half of the diameter of the receptacles and are disposed in at least two rows in the direction of movement of the conveyor (2) symmetrically relative to the axis of movement of the receptacles. The inner edges of the inductors (10a, 10b) are located beyond a vertical plane containing the axis of movement of the receptacles (7) so as to insure a homogeneous heating of the receptacles.

Abstract: A system for working on the water box of a nuclear power station steam generator comprises a first member having a substantially elongate shape and forming a first arm of the system and a second member having a substantially elongate shape. The second member is articulated at one end to one end of the first member. The combination of the first and second arms is adapted to be inserted into the water box of the steam generator through the manhole. The second member may be moved to a deployed position relative to the first member. A vehicle mounted on and mobile relative to the second arm is used to scan and decontaminate the various parts of the water box of the steam generator. A working device such as a decontamination device is carried by the vehicle. It is able to reach a plurality of areas on the internal surface of the steam generator. A remote control system is provided for the vehicle and the working device.

Abstract: A machine (3) for cleaning tapped holes (2) distributed around the periphery of an opening (1), e.g., those tapped holes used for peripherally bolting on a cover for an armhole or an eyehole in a steam generator of a nuclear power station. The machine comprises a grip (4) for centering and clamping the machine on the opening, thereby enabling it to be positioned on the axis (12) of the opening and to be held in position by abutment against the wall (10) of the opening; and a brush (13) disposed at a fixed radial distance from the axis of the opening.

Abstract: The pyrometer includes at least one optical fibre (10) transparent to infra-red made of fluorite glass, a reference emitter (20) of infra-red flux, an infra-red detector (30) for receiving the infra-red flux emerging from the optical fibre (10) or the infra-red flux originating from the reference emitter (20), a mechanical modulator (40) for infra-red flux positioned, in the direction of flux propagation, upstream of the infra-red detector (30) for periodically and successively interrupting the infra-red fluxes emerging from the optical fibre (10) and originating from the reference emitter (20), an electronic means of demodulation (50) for receiving the output signal from the detector (30) and a servo-control signal emitted by the mechanical modulator (40) in order to ensure a synchronized measurement, and a measuring apparatus (60) connected to the electronic demodulation means (50) for indicating the temperature to be measured of the target irradiating the optical fiber.

Abstract: The invention comprises subjecting shellfish (2) to infrared radiation (4,6) for a time preferably between 30 seconds and 3 minutes and involves three phases during which the shellfish (2) are exposed to radiation firstly from above, then over the entire shell surface and finally from below.The installation comprises an endless conveyor (12) equipped with upper emitters (16) placed above the conveying part (14) and lower emitters (18) positioned laterally.The invention is used in an industrial installation for washing, sand removal, preparation and conditioning of shellfish.

Abstract: A mist is formed by an ultrasonic generator (5) from a liquid solution containing a dopant, and the mist is inserted into the tube blank to be doped (4) by means of a flexible pipe (2) in order to deposit microdrops on the inside surface of said tube blank. The flexible pipe is withdrawn progressively so that deposition takes place along the entire length of the tube blank. The deposit is dried and a new layer of glass is deposited thereon. The dopant from the deposit is heat diffused into the glass of the tube blank and of the new layer of glass. The invention is particularly applicable to fabricaitng rare-earth-doped silica preforms for the purpose of drawing optical fibers that can be used to constitute lasers or sensors.

Abstract: Plant for the hydrocracking of a feedstock of high-molecular hydrocarbons comprising a fluidized bed of particles within a chamber, injection tube for injecting a fluidizing gas into the bottom of the chamber, tube reactor means on said container for letting said fluidizing gas escape, and a plasma torch of a gas containing hydrogen, which is suitable for injecting the plasma inside the chamber into the fluidized bed of particles.

Abstract: The interferometer comprises an emitter arm (10) excited by a source (11) and a receiver arm (20) associated with a photodetector (21) united by an optical coupler (50) so as to form a reference arm (30) and a measurement arm (40) terminating in a sensor (41). The arms (30) and (40) are constituted by one and the same optical fiber whose diopter of its free end (31) acts as a partially transparent mirror for the reference optical wave. This end (31) is coupled to the sensor (41) which returns the measurement optical wave through said diopter. Application in particular in the measurement of temperatures, for example in turbo-machines or of fluctuations of flow density.

Abstract: A device for counting particles of ionizing radiation comprises a detector and a reference source on the input side of the detector delivering reference radiation the spectrum of which is situated outside the spectrum of the ionizing radiation to be detected. The device further comprises an arrangement for discriminating the amplitude and energy of the received ionizing radiation and means for adjusting the relative positions of the amplitude levels on a scale of amplitude and the amplitudes of the pulses generated by the reference radiation. The device may be applied to monitoring the flowrate of leakage between primary and secondary circuits of a nuclear power plant steam generator.

Abstract: A self-regulating heating element (1) comprising a crosslinked copolymer based on ethylene and a comonomer of vinyl acetate in which the proportion of vinyl acetate is less than 10% and more than 2% by weight, more especially from 9 to 2% by weight and, in practice, from 9 to 5% by weight, said copolymer containing from 13 to 30% by weight carbon black and having a ratio ##EQU1## of greater than 10.sup.4.

Abstract: In a pressurized water nuclear reactor, the neutron flux is measured by introducing a probe into a glove finger tube, whose end is normally located in the reactor core. Each glove finger tube passes into a vertical instrumentation column, which is terminated by a nozzle (124) below one of the core assemblies. A clearance is provided around the glove finger tube in order to permit the outflow of cooling water from the core. To prevent vibration of the tubes level with nozzles (124), the latter are traversed by a passage (124a) having a constant diameter over most of its length and up to an upper planar face (124b).

Abstract: Method of underwater arc welding comprising the steps of placing a welding electrode nearby a parent material to be welded, immerged in water; generating a high frequency voltage between the electrode and the parent material for starting a striking arc and supplying a high frequency current to said electrode, after said striking arc has been initiated; generating a welding voltage for producing a weld at the parent material and; simultaneously sustaining the high frequency current, superimposed to the welding current, for stabilizing said welding arc during the time duration of the underwater arc welding.

Abstract: Pulley usable in single or double form.It comprises a guidance structure (3) for segments (4) displaceable in accordance with the setting of the rods (7), which are advantageously symmetrically extended with respect to a pivot (9) and carrying an opposite counterweight. The segments (4) are circular arcs in order to ensure a good adhesion of the belt. Advantageously the counterweights are segments (42), which makes it possible to obtain a double pulley formed from two coaxial pulleys, whose diameters vary in opposite directions. The centrifugal force on segments (4) can be balanced.Application to continuous speed variators.

Abstract: An autocontrol circuit for a resonance current or voltage undulator comprising a power supply, a parallel or series resonant circuit connected to the supply, and circuit elements (K.sub.1 to K.sub.4) for reversing the polarity of the resonant circuit's connection to the power supply. The power supply comprises a DC voltage generator and an inductive or capacitive element (2). The autocontrol circuit comprises circuit elements for detecting the voltages or currents of both the DC voltage generator and the output of the power supply. Differences between these two measured quantities are related to the load variations of the resonant circuit. The autocontrol circuit also comprises a comparator (11) for determining these differences, and circuit elements to use the comparator's output to produce signals which control switches (K.sub.1 to K.sub.4) which determine the polarity of the resonant circuit's connection to the power supply.