WO2011036192A1 - Improvements to a method and device for detecting deposits comprising at least one ferromagnetic material on or in the vicinity of the outer wall of a tube - Google Patents

Improvements to a method and device for detecting deposits comprising at least one ferromagnetic material on or in the vicinity of the outer wall of a tube Download PDF

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Publication number
WO2011036192A1
WO2011036192A1 PCT/EP2010/064014 EP2010064014W WO2011036192A1 WO 2011036192 A1 WO2011036192 A1 WO 2011036192A1 EP 2010064014 W EP2010064014 W EP 2010064014W WO 2011036192 A1 WO2011036192 A1 WO 2011036192A1
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WIPO (PCT)
Prior art keywords
tube
source
probe
deposit
magnetic
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PCT/EP2010/064014
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French (fr)
Inventor
Antoine Gemma
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Electricite De France
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Publication of WO2011036192A1 publication Critical patent/WO2011036192A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/72—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21C—NUCLEAR REACTORS
    • G21C17/00—Monitoring; Testing ; Maintaining
    • G21C17/017—Inspection or maintenance of pipe-lines or tubes in nuclear installations

Definitions

  • the present invention relates to the general field of magnetic detection methods and devices and more particularly to the field of methods and devices for detecting fouling or clogging by deposits of ferromagnetic materials on or in the vicinity of cooling tubes of a steam generator of a pressurized water nuclear reactor called REP.
  • each PWR nuclear power plant generally comprising three or four steam generators
  • said steam generator consists of a confinement enclosure 5 receiving the primary circuit 10 and the secondary circuit 15.
  • the heat exchange between the primary circuit 10 and the secondary circuit 15 is through a plurality of inverted U-shaped tubes 20.
  • Said tubes 20 are held in place by spacer plates 25 immobilized by tie rods fixed at the bottom of the steam generator.
  • FIG. 2 which shows a perspective view of a detail of the spacer plates 25 and tubes 20, said plates spacers 25 comprise cross-shaped holes 4 called quadrifollages through which pass said cylindrical tubes.
  • the amount of reagents to be injected depends on the amount of oxides present in the steam generators.
  • This type of method has the disadvantage of requiring a data acquisition analysis time of about 1 month significantly burdening costs.
  • the measurements obtained by this type of process have a low accuracy.
  • this probe has a low precision and requires the acquisition of video images.
  • One of the aims of the invention is thus to overcome these disadvantages by proposing a method and a deposit detection device comprising at least one ferromagnetic material on or near the outer wall of a tube, more particularly intended for the deposition detection on or near the tubes of a steam generator of a PWR nuclear power plant, simple and inexpensive design, with high accuracy and reliability.
  • a detection device comprising, as illustrated in FIG. 3, a probe 105, for example a magnet (s). ) and means 1 10 which comprise an electric motor 120, a gearbox 160 and a shaft 150 and which make it possible, thanks to a system of the screw-and-nut type, to move the probe inside the tube 1 with a given servo, for example at constant speed.
  • a system of the screw-and-nut type for example at constant speed.
  • the motor supply current varies. Analysis of the variation of this current thus makes it possible to detect the existence of fouling or clogging in the tube.
  • This solution overcomes a number of defects of the prior art but itself has disadvantages.
  • it is necessary to measure the variation of intensity of the supply current of the electric motor which is slaved to ensure a constant speed of the probe in the tube.
  • the disadvantage is that this measurement is noisy by the many mechanical disturbances inherent in the electric motor device guiding the probe: poor yields, friction, guiding and positioning problems.
  • the probe necessarily comprises in this solution an electric motor, which increases the size and length of said probe, and makes its introduction into the tubes difficult, particularly for the tubes located at the periphery.
  • the time required to implement the measurement acquisition is still too long, since it is necessary to position the probe at the entrance of each tube / spacer plate connection, then to make a round trip in the area of the tube located at this connection, which slows down the complete inspection of the tube and makes it jerky.
  • the number of spacer plates can be high.
  • the invention overcomes these disadvantages as well as the problems of the aforementioned prior art.
  • the invention provides a method for detecting fouling or clogging deposits comprising at least one ferromagnetic material, such as nickel, magnetite or the like, on or near the outer wall of a tube. characterized in that it comprises at least the following steps of:
  • the invention also proposes a device implementing said method.
  • the invention implements a direct measurement of the magnetic forces exerted on the magnetized source, or a mechanical quantity which is correlated to them, such as for example a force or a displacement.
  • the invention thus makes it possible to get as close as possible to the observed physical phenomenon, and to minimize the undesirable measurement noise that was known in the prior art.
  • an advantage of the invention is that it allows a reduction of the measurement noise.
  • Another advantage of the invention is that it provides a detection device with reduced space and whose manufacture is simple and inexpensive.
  • Yet another advantage of the invention is that it allows a complete inspection of one or more tubes in a reduced time.
  • FIG. 1 is a torn perspective view of a steam generator of the PWRs
  • FIG. 2 is a perspective view of a detail of the tubes passing through the quadrifollages of the spacer plates, said quadrifollings comprising so-called clogging deposits;
  • FIG. 3 is a diagrammatic representation, in longitudinal section, of a detection device according to the prior art introduced in a tube comprising a fouling deposit
  • FIG. 4 is a diagrammatic representation, in longitudinal section, of a detection device according to the invention introduced into a tube comprising a fouling deposit
  • FIG. 5 is a diagrammatic representation, in longitudinal section, of one embodiment of the detection device according to the invention introduced into a tube comprising a fouling deposit,
  • FIG. 6 is a schematic representation of the different positions with respect to a deposit of a magnetized source belonging to a probe according to the invention, magnetic forces exerted on said source as a function of the position of the probe, and a graphical representation of the axial component of these forces as a function of the position of the probe;
  • FIG. 7 is similar to FIG. 6, and represents the case of a tube presenting a clogging or fouling deposit with a large volume of input material;
  • FIG. 8 is a schematic representation of characteristic points of a measurement signal obtained with the device according to the invention.
  • the detection device 200 comprises a magnetized source 205 comprising one or more permanent magnets, measurement means 220 of at least one mechanical quantity correlated with the axial component of the magnetic forces exerted on the magnetic source 205, and means 230 for determining the position and / or the thickness and / or the volume and / or the length of a deposit 265 on or near the outer wall of the tube 215 according to variations in the mechanical quantity measured by the measuring means 220.
  • Mechanical quantity in the present description means a force or a force or a displacement or a deformation, and by axial component component parallel to the axis of revolution of the cylinder that forms the tube, in the direction of its length.
  • the magnetized source 205 and the measuring means 220 are included in an assembly 201 called probe 201 which is advantageously isolated from the outside via external walls.
  • the device further comprises displacement means 210 of the probe 201 inside and along the tube 215.
  • These displacement means 210 make it possible to move along the tube 215 the probe 201 comprising in particular the magnetized source 205 as well as the measurement means 220.
  • These displacement means 210 advantageously consist of a push-pull shooter system which pulls or pushes the magnetized source 5 and the measuring means 220 to move them along the tube in the desired direction, via the probe 201.
  • the pusher shooter system comprises a sheath made integral with the probe 201. This sheath is connected to a pusher puller hose which has a length sufficient to sweep the entire tube 215 in both directions.
  • the probe 201 itself is compact, easy to introduce into the tube and easy to guide. This significant advantage makes the use of the device according to the invention more practical under real operating conditions. This also allows a simpler and less expensive manufacture of the probe.
  • the magnetized source 205 consisting of one or more permanent magnets, near a deposit 265 comprising at least one ferromagnetic material, such as nickel, magnetite or the like, on or near the outer wall of the tube 215, magnetic attraction or repulsion forces are obtained which vary according to the volume, the thickness, the length of the deposit 265, the distance between the magnetic source 205 and the deposit 265, and the relative position between the magnetic source 205 and the deposit 265.
  • the term "length” refers to the dimension of the deposit along the tube, along an axis parallel to the axis of revolution of the cylinder that forms the tube.
  • the resultant of the magnetic forces exerted on the magnetized source 205 may be active or resistant, that is to say to promote the displacement or oppose displacement.
  • the method of controlling fouling and clogging on or near the outer wall of the tube thus consists in moving the magnetised source 205 at known speed inside and along the tube 215, this speed being advantageously constant, then measuring at least the axial component of said magnetic forces exerted on the magnetized source 205, or a mechanical quantity correlated thereto (force, deformation), which makes it possible to deduce therefrom via the determination means 230 the position and / or the thickness and / or volume and / or length of said deposit.
  • the acquired signals are compared with reference signals, such as the tube signal or calibrated signals representative of dimensional data of deposit forms. This step and the means implemented will be detailed later.
  • the device 200 comprises measuring means 220 for the axial component of the magnetic forces exerted on the magnetized source 205, or a mechanical quantity correlated to the said axial force.
  • These measuring means 220 may advantageously comprise at least one force sensor, which, associated with the magnetized source 205, measures at least one component of the magnetic forces exerted on said magnetized source, and in particular the axial component, it is at the say the component parallel to the tube 215. Indeed, it is the axial component of the magnetic forces that gives the most information on the interaction between the magnetized source moved in translation and the deposit.
  • the force sensor is a sensor measuring the force exerted in tension and / or compression.
  • the force sensor may be based on any technology known to those skilled in the art. It may include a piezoelectric type sensor. Other technologies are possible, such as strain gauges, which measure a force from reactions related to local deformation. These gauges include, but are not limited to:
  • piezoresistive gauges also called piezoresistive gauges, based on the principle of the variation of the resistivity due to the elastic deformation of a silicon monocrystal
  • a force sensor to measure the axial force exerted on the source 205, which is homogeneous to a force divided by a surface.
  • the force sensors are based on the same types of technology as the previously described force sensors.
  • measuring means 220 at least one mobile element 245 whose movement is free with respect to the probe 201 in at least one direction of space.
  • This movable element is mechanically secured to the magnetised source 205 which transmits thereto the magnetic forces that it undergoes.
  • the magnetized source 205 is itself free to move relative to the probe 201 along the same direction of space.
  • the variation of the movement of the magnetised source 205 connected to the movable element 245 with respect to the probe 201 is measured in at least one direction of the space and the magnetic forces exerted on the source are deduced therefrom. magnetized 205 in this direction.
  • FIG. 5 schematizes two moving elements 245 being free in translation along the axis of the probe 201 and therefore of the tube 215, this direction corresponding to a traction or compression force exerted on the magnetised source 205.
  • These moving elements 245 are for example one or more calibrated springs or bellows, able to be stressed in compression and traction, associated with a distance sensor 255, for example a laser or infrared sensor.
  • This distance sensor 255 measures the axial displacement of the magnetized source 205 associated with said springs or bellows, which allows to deduce the axial component of the magnetic forces exerted via the known calibration of the spring or bellows.
  • the passage from the displacement measurement to the measurement of the magnetic force can be done by internal processing means to the measuring means themselves or by dedicated external processing means, this passage being well known to those skilled in the art. . It is of course not obligatory to perform the conversion of the measured axial displacement to the axial magnetic force, since the measurement of the displacement directly gives the information necessary for the evaluation of the deposit, the two mechanical quantities being directly correlated.
  • the deposit detection device comprising at least one ferromagnetic material, such as nickel, magnetite or the like, on or near the outer wall of a nonmagnetic tube.
  • the interaction between the magnetized source 205 and the deposit will generate a field of magnetic forces whose intensity depends in particular on the volume of material in the deposit.
  • the displacement of the probe along the tube at constant speed makes it possible to prevent variations in speed from disturbing the measurement of the magnetic forces. It is obvious that the speed is in practice never exactly constant, since the displacement means 210 of the probe have a certain drift. Nevertheless, these small variations in speed have little influence on the measurement of magnetic forces. Indeed, an advantage of the invention is that the magnetic source is very little dependent on the movements of the probe 201.
  • the permanent magnets of the magnetized source 205 will undergo magnetic forces, which vary in particular according to the relative position between the permanent magnets of the magnetized source 205 and the deposit 265, said relative position generating a variation of the attraction forces.
  • FIG. 6 makes it possible to understand the magnetic interactions of the magnetised source 205 of the probe 201 with the deposit 265 when it is subjected to the magnetic forces of attraction or repulsion and to draw the graphic elements therefrom to structure the analysis.
  • FIG. 6 shows for each relative position of the magnetised source 205 of the probe 201 with respect to the deposit 265 the diagram of the magnetic forces exerted on the magnetized source 205, and the graphical representation of the measurement of the axial component Fx of the magnetic forces exerted on the magnetized source 205 as a function of the axial position x of the probe 201 in the tube 215.
  • the x-axis is parallel to the tube 215.
  • the axial component Fx of the magnetic forces exerted on the magnetized source 205 is measured by the measuring means 220 previously described. It can be seen in the graphical representation of FIG. 6 that the points C and F correspond to maxima of amplitudes (in absolute value) of the axial component Fx of the magnetic forces exerted on the magnetised source 205.
  • the point A corresponds to an absence of magnetic force exerted on the magnetized source 205, because of the absence of interaction between the magnetic field of the magnetic source 205 and the deposit 265.
  • the point D corresponds to a matter equilibrium, that is to say that there is as much magnetic matter on both sides of the normal axis of the magnetised source 205. Consequently, the axial component of the resultant magnetic forces is zero.
  • a fundamental point of the invention is that the amplitude of the measured forces depends on the volume of the deposits encountered. This is visible in FIG. 7, where the curve measured is shown in the case of a deposit having a high volume 266 at the input.
  • FIG. 7 represents in this case the axial component Fx of the magnetic forces exerted on the magnetized source 205 as a function of the position x of the probe 201 in the tube 215.
  • the measurement curves of at least one mechanical quantity correlated to the axial component of the magnetic forces exerted on the magnetized source thus reflect the physiognomy and the position of the deposit.
  • one application of the method is the detection of deposits at the quenched passages of the spacer plates in connection with the tubes of a steam generator of a pressurized water-pressurized water reactor. REP.
  • the inspection of each tube is fast, since one can scan the entire tube without having to position each tube tube / spacer plate.
  • the probe comprising the magnetic source along the tube in a first direction and then in its opposite direction, which increases the number of measurement points and therefore the accuracy.
  • the entire tube is scanned by moving the probe in a first direction, then the probe is returned in the opposite direction to the zone where said probe was introduced via the moving means 220.
  • the position and / or the thickness and / or the volume and / or the length of the deposit are determined as a function of the variations of said measured magnetic forces.
  • the device comprises means 230 for determining the position and / or the thickness and / or the volume and / or the length of said deposit as a function of the variations of said measured magnetic forces.
  • the computer advantageously comprises one or more algorithms in the form of software recorded on a physical medium, such as the hard disk and / or the memory of the computer, and programmed to perform the analysis of the measurements.
  • Measurement analysis can take a variety of forms.
  • the computer has a signal database recorded on a physical medium, such as the hard disk and / or the memory of the computer.
  • This database is mainly made up of numerical simulations (simulations of deposition of fouling or clogging on or near a tube), laboratory measurements, measurements made on site, or measurements made by any other way simulation or measurement method, and makes it possible to provide reference measurement signals for magnetic forces (or a correlated mechanical quantity) as a function of the position of the probe in the tube.
  • the database associates with each signal the dimensional data of the deposits corresponding to the measured signals, that is to say the volume, the thickness, the length and the position of said deposits.
  • reference signals consisting of the variations of the magnetic forces measured when the probe is moved in a tube having no deposit.
  • the method according to the invention is applied to the tube / spacer plate connection, it is advantageous to use as the reference signal the difference of the plate input and output signals. If there is a clogging deposit, it is only present on one side of the spacer plate, which makes it possible to compare the corresponding signals.
  • the analysis consists in comparing the measured signals with the reference signals coming from the database, in order to deduce the position and / or the thickness and / or the volume and / or the length of the deposit.
  • the peak heights A, B and C are directly correlated to the thickness of the deposit.
  • the areas S, V and U of the measured signal are directly correlated to the volume of the deposit.
  • the distances D, E, G and H are directly correlated to the length of the deposit (along the axis parallel to the axis of revolution of the tube).
  • the curve also makes it possible to read the position of the deposit along the axis of the tube.
  • An advantage of the invention is that the measured signals are weakly noisy, since they consist in the direct measurement of the magnetic forces exerted on the magnetized source, or a mechanical quantity which is correlated to them.
  • the invention thus makes it possible to approach closer to the observed physical phenomenon.
  • the device according to the invention makes it possible to have a direct reading on the screen of the results by comparing the acquired signals with reference signals such as the reference tube signal or calibrated signals of the database.
  • the invention applies in particular to the detection of deposits at the quadrifolate passages of the spacer plates of a steam generator of a pressurized PWR nuclear reactor. It makes it possible to determine with a good sensitivity the physiognomy of these deposits, such as length and thickness.

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Abstract

The invention relates to a method for detecting fouling or clogging deposits comprising at least one ferromagnetic material such as nickel, magnetite, or the like, on or in the vicinity of the outer wall of a tube (215), wherein said method is characterized in that it comprises at least the following steps: moving a magnetized source (205) inside the tube (215) in the direction of the length thereof, measuring at least one mechanical quantity correlated with the axial component of the magnetic forces exerted on the magnetized source (205), determining the position and/or thickness and/or volume and/or length of said deposit (265) on the basis of the variations in the measured mechanical quantity.

Description

Perfectionnements à un procédé et dispositif de détection de dépôts comportant au moins un matériau ferromagnétique sur ou à proximité de la paroi externe d'un tube DOMAINE DE L'INVENTION  DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS AND METHOD FOR DETECTING DEPOSITS COMPRISING AT LEAST ONE FERROGAMIC MATERIAL ON OR NEAR THE OUTER WALL OF A PIPE
La présente invention concerne le domaine général des procédés et des dispositifs de détection magnétiques et plus particulièrement le domaine des procédés et des dispositifs de détection d'encrassement ou de colmatage par des dépôts de matériaux ferromagnétiques sur ou à proximité de tubes de refroidissement d'un générateur de vapeur d'un réacteur nucléaire à eau sous pression dit REP. The present invention relates to the general field of magnetic detection methods and devices and more particularly to the field of methods and devices for detecting fouling or clogging by deposits of ferromagnetic materials on or in the vicinity of cooling tubes of a steam generator of a pressurized water nuclear reactor called REP.
ARRIERE PLAN DE L'INVENTION BACKGROUND OF THE INVENTION
Dans le domaine des centrales électronucléaires de type REP selon l'acronyme « Réacteur à Eau sous Pression », il est bien connu que la chaleur produite dans le cœur du réacteur est transmise au moyen d'un circuit fermé dit circuit primaire dans lequel circule de l'eau à un circuit dit secondaire dont l'eau transformée en vapeur alimente les turbines pour la production d'électricité. In the field of nuclear power plants of the PWR type according to the acronym "pressurized water reactor", it is well known that the heat produced in the reactor core is transmitted by means of a closed circuit called primary circuit in which circulates from water to a so-called secondary circuit whose water transformed into steam supplies the turbines for the production of electricity.
En référence à la figure 1 qui représente un générateur de vapeur en perspective déchirée, chaque centrale électronucléaire de type REP comportant généralement trois ou quatre générateurs de vapeur, ledit générateur de vapeur est constitué d'une enceinte de confinement 5 recevant le circuit primaire 10 et le circuit secondaire 15. L'échange thermique entre le circuit primaire 10 et le circuit secondaire 15 se fait à travers une pluralité de tubes 20 en U inversé. Lesdits tubes 20 sont maintenus en place par des plaques entretoises 25 immobilisées par des tirants fixés en partie basse du générateur de vapeur.  With reference to FIG. 1, which represents a torn perspective steam generator, each PWR nuclear power plant generally comprising three or four steam generators, said steam generator consists of a confinement enclosure 5 receiving the primary circuit 10 and the secondary circuit 15. The heat exchange between the primary circuit 10 and the secondary circuit 15 is through a plurality of inverted U-shaped tubes 20. Said tubes 20 are held in place by spacer plates 25 immobilized by tie rods fixed at the bottom of the steam generator.
En référence à la figure 2 qui représente une vue en perspective d'un détail des plaques d'entretoises 25 et des tubes 20, lesdites plaques d'entretoises 25 comportent des trous 30 en forme de croix dits quadrifolliages au travers desquels passent lesdits tubes 20 cylindriques. Referring to Figure 2 which shows a perspective view of a detail of the spacer plates 25 and tubes 20, said plates spacers 25 comprise cross-shaped holes 4 called quadrifollages through which pass said cylindrical tubes.
Il est connu que des dépôts de colmatage 35 se forment au niveau des quadrifolliages 30 (figure 2) entre les tubes 20 et les plaques d'entretoises 25. Ces dépôts 35 ont pour conséquence d'une part, en fonctionnement normal, de modifier les contraintes mécaniques sur les tubes 4 et d'autre part, en cas d'incident ou d'accident, d'augmenter les efforts sur les plaques d'entretoises 25 augmentant ainsi le risque de rupture des tubes 20.  It is known that clogging deposits 35 are formed at the quadrifollages 30 (FIG. 2) between the tubes 20 and the spacer plates 25. These deposits 35 have the consequence, on the one hand, in normal operation, of modifying the mechanical stresses on the tubes 4 and on the other hand, in the event of an incident or an accident, to increase the stresses on the strut plates 25 thus increasing the risk of rupture of the tubes 20.
De plus, il est également connu que des dépôts dits d'encrassement se forment sur la surface externe des tubes 20 causant une diminution des performances de l'échange thermique dans le générateur de vapeur.  In addition, it is also known that so-called fouling deposits form on the outer surface of the tubes 20 causing a decrease in the performance of the heat exchange in the steam generator.
Afin de supprimer ces dépôts de colmatage ou d'encrassement, il est bien connu de nettoyer les tubes et les plaques d'entretoise par des procédés de nettoyage chimiques. Ces procédés consistent à injecter des réactifs chimiques dans le circuit secondaire des générateurs de vapeur afin de déstructurer et dissoudre ces dépôts d'oxydes tels que des magnétites.  In order to remove these clogging or fouling deposits, it is well known to clean the tubes and spacer plates by chemical cleaning processes. These methods involve injecting chemical reagents into the secondary circuit of the steam generators in order to destructure and dissolve these oxide deposits such as magnetites.
Toutefois, la quantité de réactifs à injecter dépend de la quantité présente d'oxydes dans les générateurs de vapeur.  However, the amount of reagents to be injected depends on the amount of oxides present in the steam generators.
Par conséquent, il est préalablement nécessaire de déterminer la quantité d'oxydes.  Therefore, it is first necessary to determine the amount of oxides.
A cet effet, on connaît bien des procédés et des dispositifs de détection de dépôts de magnétites utilisant une sonde axiale à courant de Foucault basse fréquence, ladite sonde étant introduite dans les tubes du générateur de vapeur, dont les mesures sont corrélées avec des images télévisuelles ou des étalons en ligne représentatifs des dépôts rencontrés.  For this purpose, methods and devices for detecting magnetite deposits using a low-frequency eddy-axial axial probe are well known, said probe being introduced into the tubes of the steam generator, the measurements of which are correlated with television images. or online standards representative of the deposits encountered.
Ce type de procédé présente l'inconvénient de nécessiter un temps d'analyse des acquisitions des données d'environ 1 mois grevant de manière considérable les coûts. De plus, les mesures obtenues par ce type de procédé présentent une faible précision.  This type of method has the disadvantage of requiring a data acquisition analysis time of about 1 month significantly burdening costs. In addition, the measurements obtained by this type of process have a low accuracy.
On connaît, par ailleurs, le procédé et le dispositif de détection de dépôts décrit dans le brevet américain US 4,088,946. Ledit dispositif comporte une sonde à courant de Foucault qui est déplacé à vitesse constante dans un tube pour détecter des dépôts. In addition, the method and the device for detecting deposits described in US Pat. No. 4,088,946 are known. Said device has an eddy current probe that is moved at a constant rate in a tube to detect deposits.
De la même manière que précédemment, cette sonde présente une faible précision et nécessite l'acquisition d'images vidéo.  In the same way as before, this probe has a low precision and requires the acquisition of video images.
D'autres procédés et dispositifs de détection de dépôt sur la paroi externe de tubes présentant les mêmes inconvénients sont notamment décrits dans la demande de brevet français FR 2 459 490 et dans le brevet américain US 4,700,134. BREVE DESCRIPTION DE L'INVENTION  Other methods and devices for detecting deposition on the outer wall of tubes having the same disadvantages are described in particular in French patent application FR 2,459,490 and in US Pat. No. 4,700,134. BRIEF DESCRIPTION OF THE INVENTION
L'un des buts de l'invention est donc de remédier à ces inconvénients en proposant un procédé et un dispositif détection de dépôts comportant au moins un matériau ferromagnétique sur ou à proximité de la paroi externe d'un tube, plus particulièrement destiné à la détection de dépôt sur ou à proximité des tubes d'un générateur de vapeur d'une centrale électronucléaire de type REP, de conception simple et peu onéreuse, et présentant une grande précision ainsi qu'une grande fiabilité. One of the aims of the invention is thus to overcome these disadvantages by proposing a method and a deposit detection device comprising at least one ferromagnetic material on or near the outer wall of a tube, more particularly intended for the deposition detection on or near the tubes of a steam generator of a PWR nuclear power plant, simple and inexpensive design, with high accuracy and reliability.
Il a déjà été proposé par la société demanderesse dans sa demande de brevet français FR0853200 (non publiée au jour du présent dépôt) un dispositif de détection comportant, ainsi qu'illustré sur la figure 3, une sonde 105, par exemple à aimant(s) permanent(s), ainsi que des moyens 1 10 qui comportent un moteur électrique 120, un réducteur 160 et un arbre 150 et qui permettent, grâce à un système du type à vis et écrou, de déplacer la sonde à l'intérieur du tube 1 15 avec un asservissement donné, par exemple à vitesse constante. Selon l'épaisseur des dépôts 165 ferromagnétiques (nickel, magnétite ou similaire) qui se trouvent sur ou à proximité de la paroi du tube 1 15, le courant d'alimentation du moteur varie. L'analyse de la variation de ce courant permet donc de détecter l'existence d'encrassement ou de colmatage dans le tube.  It has already been proposed by the applicant company in its French patent application FR0853200 (not published today) a detection device comprising, as illustrated in FIG. 3, a probe 105, for example a magnet (s). ) and means 1 10 which comprise an electric motor 120, a gearbox 160 and a shaft 150 and which make it possible, thanks to a system of the screw-and-nut type, to move the probe inside the tube 1 with a given servo, for example at constant speed. Depending on the thickness of the ferromagnetic deposits (nickel, magnetite or the like) on or near the wall of the tube 1 15, the motor supply current varies. Analysis of the variation of this current thus makes it possible to detect the existence of fouling or clogging in the tube.
Cette solution permet de pallier un certain nombre de défauts de l'art antérieur mais présente elle-même des inconvénients. Dans cette solution, il est nécessaire de mesurer la variation d'intensité du courant d'alimentation du moteur électrique qui est asservi pour assurer une vitesse constante de la sonde dans le tube. L'inconvénient est que cette mesure est bruitée par les nombreuses perturbations mécaniques inhérentes au dispositif de motorisation électrique guidant la sonde : mauvais rendements, frottements, problèmes de guidage et de positionnement. This solution overcomes a number of defects of the prior art but itself has disadvantages. In this solution, it is necessary to measure the variation of intensity of the supply current of the electric motor which is slaved to ensure a constant speed of the probe in the tube. The disadvantage is that this measurement is noisy by the many mechanical disturbances inherent in the electric motor device guiding the probe: poor yields, friction, guiding and positioning problems.
De plus, la sonde comprend nécessairement dans cette solution un moteur électrique, qui accentue l'encombrement et la longueur de la dite sonde, et rend son introduction dans les tubes difficile, en particulier pour les tubes situés en périphérie.  In addition, the probe necessarily comprises in this solution an electric motor, which increases the size and length of said probe, and makes its introduction into the tubes difficult, particularly for the tubes located at the periphery.
Enfin, le temps nécessaire à la mise en œuvre de l'acquisition des mesures est encore trop long, puisqu'il est nécessaire de positionner la sonde à l'entrée de chaque liaison tube/plaque entretoise, puis d'effectuer un aller-retour dans la zone du tube située au niveau de cette liaison, ce qui ralentit l'inspection complète du tube et la rend saccadée. De plus, le nombre de plaques entretoise peut être élevé.  Finally, the time required to implement the measurement acquisition is still too long, since it is necessary to position the probe at the entrance of each tube / spacer plate connection, then to make a round trip in the area of the tube located at this connection, which slows down the complete inspection of the tube and makes it jerky. In addition, the number of spacer plates can be high.
L'invention pallie ces inconvénients ainsi que les problèmes de l'art antérieur précités.  The invention overcomes these disadvantages as well as the problems of the aforementioned prior art.
A cet effet, l'invention propose un procédé de détection de dépôts d'encrassement ou de colmatage comportant au moins un matériau ferromagnétique, tel que du nickel, de la magnétite ou similaire, sur ou à proximité de la paroi externe d'un tube, caractérisé en ce qu'il comporte au moins les étapes suivantes de :  For this purpose, the invention provides a method for detecting fouling or clogging deposits comprising at least one ferromagnetic material, such as nickel, magnetite or the like, on or near the outer wall of a tube. characterized in that it comprises at least the following steps of:
- déplacement d'une source aimantée à l'intérieur du tube dans le sens de sa longueur,  - displacement of a magnetised source inside the tube in the direction of its length,
- mesure d'au moins une grandeur mécanique corrélée à la composante axiale de forces magnétiques exercées sur la source aimantée, measuring at least one mechanical quantity correlated with the axial component of magnetic forces exerted on the magnetised source,
- détermination de la position et/ou de l'épaisseur et/ou du volume et/ou de la longueur dudit dépôt en fonction des variations de la grandeur mécanique mesurée. L'invention propose également un dispositif mettant en œuvre ledit procédé. determination of the position and / or the thickness and / or the volume and / or the length of said deposit as a function of the variations of the measured mechanical quantity. The invention also proposes a device implementing said method.
Comme on peut le constater, l'invention met en œuvre une mesure directe des forces magnétiques exercées sur la source aimantée, ou d'une grandeur mécanique qui leur est corrélée, comme par exemple un effort ou un déplacement.  As can be seen, the invention implements a direct measurement of the magnetic forces exerted on the magnetized source, or a mechanical quantity which is correlated to them, such as for example a force or a displacement.
L'invention permet ainsi de s'approcher au plus près du phénomène physique observé, et de minimiser les bruits de mesure indésirables que l'on connaissait dans l'art antérieur.  The invention thus makes it possible to get as close as possible to the observed physical phenomenon, and to minimize the undesirable measurement noise that was known in the prior art.
Ainsi, un avantage de l'invention est qu'elle permet une réduction du bruit de mesure.  Thus, an advantage of the invention is that it allows a reduction of the measurement noise.
Un autre avantage de l'invention est qu'elle propose un dispositif de détection à l'encombrement réduit et dont la fabrication est simple et peu coûteuse.  Another advantage of the invention is that it provides a detection device with reduced space and whose manufacture is simple and inexpensive.
Un autre avantage encore de l'invention est qu'elle permet une inspection complète d'un ou plusieurs tubes dans un temps réduit.  Yet another advantage of the invention is that it allows a complete inspection of one or more tubes in a reduced time.
BREVE DESCRIPTION DES DESSINS D'autres avantages et caractéristiques ressortiront mieux de la description qui va suivre, de plusieurs variantes d'exécution, données à titre d'exemples non limitatifs, du dispositif de détection de dépôts magnétiques sur ou à proximité d'un tube amagnétique conforme à l'invention, à partir des dessins annexés sur lesquels : BRIEF DESCRIPTION OF THE DRAWINGS Other advantages and features will become more apparent from the following description of several alternative embodiments, given by way of non-limiting examples, of the device for detecting magnetic deposits on or near a tube. non-magnetic device according to the invention, from the attached drawings in which:
- la figure 1 est une vue en perspective déchirée d'un générateur de vapeur des centrales électronucléaires de type REP,  FIG. 1 is a torn perspective view of a steam generator of the PWRs,
- la figure 2 est une vue en perspective d'un détail des tubes passant dans les quadrifolliages des plaques d'entretoise, lesdits quadrifolliages comportant des dépôts dit de colmatage,  FIG. 2 is a perspective view of a detail of the tubes passing through the quadrifollages of the spacer plates, said quadrifollings comprising so-called clogging deposits;
- la figure 3 est une représentation schématique, en coupe longitudinale, d'un dispositif de détection selon l'art antérieur introduit dans un tube comportant un dépôt d'encrassement, - la figure 4 est une représentation schématique, en coupe longitudinale, d'un dispositif de détection selon l'invention introduit dans un tube comportant un dépôt d'encrassement, FIG. 3 is a diagrammatic representation, in longitudinal section, of a detection device according to the prior art introduced in a tube comprising a fouling deposit, FIG. 4 is a diagrammatic representation, in longitudinal section, of a detection device according to the invention introduced into a tube comprising a fouling deposit,
- la figure 5 est une représentation schématique, en coupe longitudinale, d'un mode de réalisation du dispositif de détection selon l'invention introduit dans un tube comportant un dépôt d'encrassement, FIG. 5 is a diagrammatic representation, in longitudinal section, of one embodiment of the detection device according to the invention introduced into a tube comprising a fouling deposit,
- la figure 6 est une représentation schématique des différentes positions par rapport à un dépôt d'une source aimantée appartenant à une sonde selon l'invention, des forces magnétiques exercées sur ladite source en fonction de la position de la sonde, et d'une représentation graphique de la composante axiale de ces forces en fonction de la position de la sonde; FIG. 6 is a schematic representation of the different positions with respect to a deposit of a magnetized source belonging to a probe according to the invention, magnetic forces exerted on said source as a function of the position of the probe, and a graphical representation of the axial component of these forces as a function of the position of the probe;
- la figure 7 est similaire à la figure 6, et représente le cas d'un tube présentant un dépôt de colmatage ou d'encrassement avec un fort volume de matière en entrée ;  FIG. 7 is similar to FIG. 6, and represents the case of a tube presenting a clogging or fouling deposit with a large volume of input material;
- la figure 8 est une représentation schématique de points caractéristiques d'un signal de mesure obtenu avec le dispositif selon l'invention.  FIG. 8 is a schematic representation of characteristic points of a measurement signal obtained with the device according to the invention.
DESCRIPTION DETAILLEE DE L'INVENTION DETAILED DESCRIPTION OF THE INVENTION
En référence à la figure 4, le dispositif de détection 200 suivant l'invention comporte une source aimantée 205 comprenant un ou plusieurs aimants permanents, des moyens de mesure 220 d'au moins une grandeur mécanique corrélée à la composante axiale des forces magnétiques exercées sur la source aimantée 205, et des moyens de détermination 230 de la position et/ou de l'épaisseur et/ou du volume et/ou de la longueur d'un dépôt 265 sur ou à proximité de la paroi externe du tube 215 en fonction des variations de la grandeur mécanique mesurée par les moyens de mesure 220. With reference to FIG. 4, the detection device 200 according to the invention comprises a magnetized source 205 comprising one or more permanent magnets, measurement means 220 of at least one mechanical quantity correlated with the axial component of the magnetic forces exerted on the magnetic source 205, and means 230 for determining the position and / or the thickness and / or the volume and / or the length of a deposit 265 on or near the outer wall of the tube 215 according to variations in the mechanical quantity measured by the measuring means 220.
On entend par grandeur mécanique dans la présente description une force ou un effort ou un déplacement ou une déformation, et par composante axiale la composante parallèle à l'axe de révolution du cylindre que forme le tube, dans le sens de sa longueur. Mechanical quantity in the present description means a force or a force or a displacement or a deformation, and by axial component component parallel to the axis of revolution of the cylinder that forms the tube, in the direction of its length.
La source aimantée 205 et les moyens de mesure 220 sont inclus dans un ensemble 201 appelé sonde 201 qui est avantageusement isolée de l'extérieur par l'intermédiaire de parois externes.  The magnetized source 205 and the measuring means 220 are included in an assembly 201 called probe 201 which is advantageously isolated from the outside via external walls.
Le dispositif comprend en outre des moyens de déplacement 210 de la sonde 201 à l'intérieur et le long du tube 215.  The device further comprises displacement means 210 of the probe 201 inside and along the tube 215.
Ces moyens de déplacement 210 permettent de déplacer le long du tube 215 la sonde 201 comprenant notamment la source aimantée 205 ainsi que les moyens de mesure 220.  These displacement means 210 make it possible to move along the tube 215 the probe 201 comprising in particular the magnetized source 205 as well as the measurement means 220.
Ces moyens de déplacement 210 consistent avantageusement en un système de type tireur pousseur qui tire ou pousse la source aimantée 5 et les moyens de mesure 220 pour les déplacer le long du tube selon le sens voulu, par l'intermédiaire de la sonde 201 . Dans ce cas, le système de tireur pousseur comprend une gaine rendue solidaire de la sonde 201 . Cette gaine est reliée à un flexible du tireur pousseur qui possède une longueur suffisante pour permettre de balayer l'ensemble du tube 215 dans les deux sens.  These displacement means 210 advantageously consist of a push-pull shooter system which pulls or pushes the magnetized source 5 and the measuring means 220 to move them along the tube in the desired direction, via the probe 201. In this case, the pusher shooter system comprises a sheath made integral with the probe 201. This sheath is connected to a pusher puller hose which has a length sufficient to sweep the entire tube 215 in both directions.
Comme la source aimantée 205 et les moyens de mesure 220 sont peu encombrants, la sonde 201 est elle-même peu encombrante, facile à introduire dans le tube et facile à guider. Cet avantage notable rend l'utilisation du dispositif selon l'invention plus pratique dans des conditions d'exploitation réelles. Ceci permet également une fabrication plus simple et moins coûteuse de la sonde.  As the magnetic source 205 and the measuring means 220 are compact, the probe 201 itself is compact, easy to introduce into the tube and easy to guide. This significant advantage makes the use of the device according to the invention more practical under real operating conditions. This also allows a simpler and less expensive manufacture of the probe.
En présentant la source aimantée 205, constituée d'un ou plusieurs aimants permanents, à proximité d'un dépôt 265 comportant au moins un matériau ferromagnétique, tel que du nickel, de la magnétite ou similaire, sur ou à proximité de la paroi externe du tube 215, on obtient des forces magnétiques d'attraction ou de répulsion qui varient en fonction du volume, , de l'épaisseur, de la longueur du dépôt 265, de la distance entre la source aimantée 205 et le dépôt 265, et de la position relative entre la source aimantée 205 et le dépôt 265. On entend par longueur la dimension du dépôt le long du tube, selon un axe parallèle à l'axe de révolution du cylindre que forme le tube. By presenting the magnetized source 205, consisting of one or more permanent magnets, near a deposit 265 comprising at least one ferromagnetic material, such as nickel, magnetite or the like, on or near the outer wall of the tube 215, magnetic attraction or repulsion forces are obtained which vary according to the volume, the thickness, the length of the deposit 265, the distance between the magnetic source 205 and the deposit 265, and the relative position between the magnetic source 205 and the deposit 265. The term "length" refers to the dimension of the deposit along the tube, along an axis parallel to the axis of revolution of the cylinder that forms the tube.
En déplaçant la source aimantée 205 à vitesse connue le long du tube 215, avantageusement à vitesse constante, on obtient une variation des forces magnétiques exercées sur la source aimantée 205, qui, comparée à un modèle de référence connu, permet de détecter la présence de dépôt et d'avoir une estimation des différentes caractéristiques dimensionnelles du dépôt 265 (volume, épaisseur, longueur...). La résultante des forces magnétiques exercées sur la source aimantée 205 peut être active ou résistante, c'est-à-dire favoriser le déplacement ou s'opposer au déplacement.  By moving the magnetized source 205 at a known speed along the tube 215, advantageously at a constant speed, a variation of the magnetic forces exerted on the magnetized source 205 is obtained, which, compared to a known reference model, makes it possible to detect the presence of deposit and have an estimate of the different dimensional characteristics of the deposit 265 (volume, thickness, length ...). The resultant of the magnetic forces exerted on the magnetized source 205 may be active or resistant, that is to say to promote the displacement or oppose displacement.
Le procédé de contrôle de l'encrassement et du colmatage sur ou à proximité de la paroi externe du tube consiste donc à déplacer la source aimantée 205 à vitesse connue à l'intérieur et le long du tube 215, cette vitesse étant avantageusement constante, puis à mesurer au moins la composante axiale desdites forces magnétiques exercées sur la source aimantée 205, ou une grandeur mécanique lui étant corrélée (effort, déformation), ce qui permet d'en déduire via les moyens de détermination 230 la position et/ou l'épaisseur et/ou le volume et/ou la longueur dudit dépôt.  The method of controlling fouling and clogging on or near the outer wall of the tube thus consists in moving the magnetised source 205 at known speed inside and along the tube 215, this speed being advantageously constant, then measuring at least the axial component of said magnetic forces exerted on the magnetized source 205, or a mechanical quantity correlated thereto (force, deformation), which makes it possible to deduce therefrom via the determination means 230 the position and / or the thickness and / or volume and / or length of said deposit.
Avantageusement, les signaux acquis sont comparés à des signaux de référence, comme le signal tube ou des signaux calibrés représentatifs de données dimensionnelles de formes de dépôts. Cette étape ainsi que les moyens mis en œuvre seront détaillés dans la suite.  Advantageously, the acquired signals are compared with reference signals, such as the tube signal or calibrated signals representative of dimensional data of deposit forms. This step and the means implemented will be detailed later.
Comme cela apparaît en figure 4, et comme explicité plus haut, le dispositif 200 selon l'invention comprend des moyens de mesure 220 de la composante axiale des forces magnétiques exercées sur la source aimantée 205, ou d'une grandeur mécanique corrélée à la dite force axiale.  As it appears in FIG. 4, and as explained above, the device 200 according to the invention comprises measuring means 220 for the axial component of the magnetic forces exerted on the magnetized source 205, or a mechanical quantity correlated to the said axial force.
Ces moyens de mesure 220 peuvent avantageusement comprendre au moins un capteur de force, qui, associé à la source aimantée 205, mesure au moins une composante des forces magnétiques exercées sur ladite source aimantée, et en particulier la composante axiale, c'est à la dire la composante parallèle au tube 215. En effet, c'est la composante axiale des forces magnétiques qui donne le plus d'informations sur l'interaction entre la source aimantée déplacée en translation et le dépôt. Dans ce cas, le capteur de force est un capteur mesurant la force exercée en traction et/ou compression. These measuring means 220 may advantageously comprise at least one force sensor, which, associated with the magnetized source 205, measures at least one component of the magnetic forces exerted on said magnetized source, and in particular the axial component, it is at the say the component parallel to the tube 215. Indeed, it is the axial component of the magnetic forces that gives the most information on the interaction between the magnetized source moved in translation and the deposit. In this case, the force sensor is a sensor measuring the force exerted in tension and / or compression.
Le capteur de force peut être basé sur toute technologie connue de l'homme du métier. Il peut notamment comprendre un capteur de type piézoélectrique. D'autres technologies sont envisageables, comme les jauges de contrainte, qui permettent de mesurer une force à partir de réactions liées à une déformation locale. Ces jauges incluent par exemple mais de manière non limitative:  The force sensor may be based on any technology known to those skilled in the art. It may include a piezoelectric type sensor. Other technologies are possible, such as strain gauges, which measure a force from reactions related to local deformation. These gauges include, but are not limited to:
- des jauges métalliques, basés sur le principe de mesure de la résistance d'un conducteur soumis à une déformation ;  - metal gauges, based on the principle of measuring the resistance of a conductor subjected to deformation;
- des jauges à semi-conducteur également appelées jauges piézorésistives, basées sur le principe de la variation de la résistivité due à la déformation élastique d'un monocristal de silicium ;  - Semiconductor gauges also called piezoresistive gauges, based on the principle of the variation of the resistivity due to the elastic deformation of a silicon monocrystal;
- des jauges piézoélectriques, basées sur le principe de variation de la force électromotrice d'une céramique piézoélectrique soumise à une déformation ;  - Piezoelectric gauges, based on the principle of variation of the electromotive force of a piezoelectric ceramic subjected to a deformation;
- des jauges de contrainte optique.  optical strain gages.
On peut bien sur envisager une combinaison de plusieurs capteurs et/ou de plusieurs technologies différentes, afin d'améliorer la précision.  One can of course consider a combination of several sensors and / or several different technologies to improve accuracy.
Il est également avantageux d'utiliser un capteur d'effort pour mesurer l'effort axial exercé sur la source 205, qui est homogène à une force divisée par une surface. Les capteurs d'effort sont basés sur les mêmes types de technologie que les capteurs de force précédemment décrits.  It is also advantageous to use a force sensor to measure the axial force exerted on the source 205, which is homogeneous to a force divided by a surface. The force sensors are based on the same types of technology as the previously described force sensors.
Alternativement, et comme illustré en figure 5, on peut utiliser comme moyens de mesure 220 au moins un élément mobile 245 dont le mouvement est libre par rapport à la sonde 201 selon au moins une direction de l'espace. Cet élément mobile est mécaniquement solidaire de la source aimantée 205 qui lui transmet les forces magnétiques qu'elle subit. La source aimantée 205 est elle-même libre en mouvement par rapport à la sonde 201 selon cette même direction de l'espace. Alternatively, and as illustrated in FIG. 5, it is possible to use as measuring means 220 at least one mobile element 245 whose movement is free with respect to the probe 201 in at least one direction of space. This movable element is mechanically secured to the magnetised source 205 which transmits thereto the magnetic forces that it undergoes. The magnetized source 205 is itself free to move relative to the probe 201 along the same direction of space.
Dans ce cas, on mesure la variation du mouvement de la source aimantée 205 liée à l'élément mobile 245 par rapport à la sonde 201 selon au moins une direction de l'espace et l'on en déduit les forces magnétiques exercées sur la source aimantée 205 dans cette direction.  In this case, the variation of the movement of the magnetised source 205 connected to the movable element 245 with respect to the probe 201 is measured in at least one direction of the space and the magnetic forces exerted on the source are deduced therefrom. magnetized 205 in this direction.
En figure 5, on a schématisé deux éléments mobiles 245 étant libres en translation le long de l'axe de la sonde 201 et donc du tube 215, cette direction correspondant à une force de traction ou de compression exercée sur la source aimantée 205.  FIG. 5 schematizes two moving elements 245 being free in translation along the axis of the probe 201 and therefore of the tube 215, this direction corresponding to a traction or compression force exerted on the magnetised source 205.
Ces éléments mobiles 245 sont par exemple un ou plusieurs ressorts ou soufflets étalonnées, aptes à être sollicités en compression et traction, associés à un capteur de distance 255, par exemple un capteur laser ou infrarouge. Ce capteur de distance 255 mesure le déplacement axial de la source aimantée 205 liée aux dits ressorts ou soufflets, ce qui permet d'en déduire la composante axiale des forces magnétiques exercées, via l'étalonnement connu du ressort ou du soufflet. Le passage de la mesure de déplacement à la mesure de la force magnétique peut se faire par des moyens de traitement internes aux moyens de mesure eux-mêmes ou par des moyens de traitement externes dédiés, ce passage étant bien connu de l'homme du métier. Il n'est bien sûr pas obligatoire d'effectuer la conversion du déplacement axial mesuré à la force magnétique axiale, puisque la mesure du déplacement donne directement les informations nécessaires à l'évaluation du dépôt, les deux grandeurs mécaniques étant directement corrélées.  These moving elements 245 are for example one or more calibrated springs or bellows, able to be stressed in compression and traction, associated with a distance sensor 255, for example a laser or infrared sensor. This distance sensor 255 measures the axial displacement of the magnetized source 205 associated with said springs or bellows, which allows to deduce the axial component of the magnetic forces exerted via the known calibration of the spring or bellows. The passage from the displacement measurement to the measurement of the magnetic force can be done by internal processing means to the measuring means themselves or by dedicated external processing means, this passage being well known to those skilled in the art. . It is of course not obligatory to perform the conversion of the measured axial displacement to the axial magnetic force, since the measurement of the displacement directly gives the information necessary for the evaluation of the deposit, the two mechanical quantities being directly correlated.
On expliquera maintenant le fonctionnement du dispositif de détection de dépôts comportant au moins un matériau ferromagnétique, tel que du nickel, de la magnétite ou similaire, sur ou à proximité de la paroi externe d'un tube amagnétique.  We will now explain the operation of the deposit detection device comprising at least one ferromagnetic material, such as nickel, magnetite or the like, on or near the outer wall of a nonmagnetic tube.
Lorsque l'on déplace la sonde 201 comprenant la source aimantée 205 dans le tube amagnétique 215, l'interaction entre la source aimantée 205 et le dépôt va générer un champ de forces magnétiques dont l'intensité dépend en particulier du volume de matière dans le dépôt. When the probe 201 comprising the magnetic source 205 is moved in the non-magnetic tube 215, the interaction between the magnetized source 205 and the deposit will generate a field of magnetic forces whose intensity depends in particular on the volume of material in the deposit.
Il est à noter qu'outre les forces magnétiques, il existe des forces d'attraction gravitationnelles, mais qui sont extrêmement négligeables par rapport aux forces magnétiques considérées. On ne considérera donc que les forces magnétiques.  It should be noted that, in addition to magnetic forces, there are gravitational attraction forces, which are extremely negligible compared to the magnetic forces considered. Only the magnetic forces will be considered.
Par ailleurs, le déplacement de la sonde le long du tube à vitesse constante permet d'éviter que des variations de vitesse ne viennent perturber la mesure des forces magnétiques. Il est bien évident que la vitesse n'est en pratique jamais exactement constante, étant donné que les moyens de déplacement 210 de la sonde présentent une certaine dérive. Néanmoins, ces faibles variations de vitesse ont peu d'influence sur la mesure des forces magnétiques. En effet, un avantage de l'invention est que la source magnétique est très peu dépendante des mouvements de la sonde 201 .  Moreover, the displacement of the probe along the tube at constant speed makes it possible to prevent variations in speed from disturbing the measurement of the magnetic forces. It is obvious that the speed is in practice never exactly constant, since the displacement means 210 of the probe have a certain drift. Nevertheless, these small variations in speed have little influence on the measurement of magnetic forces. Indeed, an advantage of the invention is that the magnetic source is very little dependent on the movements of the probe 201.
Les aimants permanents de la source aimantée 205 vont subir des forces magnétiques, qui varient notamment en fonction de la position relative entre les aimants permanents de la source aimantée 205 et le dépôt 265, ladite position relative générant une variation des forces d'attraction.  The permanent magnets of the magnetized source 205 will undergo magnetic forces, which vary in particular according to the relative position between the permanent magnets of the magnetized source 205 and the deposit 265, said relative position generating a variation of the attraction forces.
La figure 6 permet de comprendre les interactions magnétiques de la source aimantée 205 de la sonde 201 avec le dépôt 265 lorsqu'elle est soumise aux forces magnétiques d'attraction ou de répulsion et d'en tirer les éléments graphiques pour structurer l'analyse. Cette figure 6 montre pour chaque position relative de la source aimantée 205 de la sonde 201 par rapport au dépôt 265 le diagramme des forces magnétiques exercées sur la source aimantée 205, et la représentation graphique de la mesure de la composante axiale Fx des forces magnétiques exercées sur la source aimantée 205 en fonction de la position axiale x de la sonde 201 dans le tube 215. L'axe x est parallèle au tube 215.  FIG. 6 makes it possible to understand the magnetic interactions of the magnetised source 205 of the probe 201 with the deposit 265 when it is subjected to the magnetic forces of attraction or repulsion and to draw the graphic elements therefrom to structure the analysis. FIG. 6 shows for each relative position of the magnetised source 205 of the probe 201 with respect to the deposit 265 the diagram of the magnetic forces exerted on the magnetized source 205, and the graphical representation of the measurement of the axial component Fx of the magnetic forces exerted on the magnetized source 205 as a function of the axial position x of the probe 201 in the tube 215. The x-axis is parallel to the tube 215.
La composante axiale Fx des forces magnétiques exercées sur la source aimantée 205 est mesurée par les moyens de mesure 220 précédemment décrits. On constate sur la représentation graphique de la figure 6 que les points C et F correspondent à des maxima d'amplitudes (en valeur absolue) de la composante axiale Fx des forces magnétiques exercées sur la source aimantée 205. The axial component Fx of the magnetic forces exerted on the magnetized source 205 is measured by the measuring means 220 previously described. It can be seen in the graphical representation of FIG. 6 that the points C and F correspond to maxima of amplitudes (in absolute value) of the axial component Fx of the magnetic forces exerted on the magnetised source 205.
Le point A correspond à une absence de force magnétique exercée sur la source aimantée 205, à cause de l'absence d'interaction entre le champ magnétique de la source aimantée 205 et le dépôt 265.  The point A corresponds to an absence of magnetic force exerted on the magnetized source 205, because of the absence of interaction between the magnetic field of the magnetic source 205 and the deposit 265.
Le point D correspond à un équilibre matière, c'est-à-dire qu'il y a autant de matière magnétique de part et d'autre de l'axe normal de la source aimantée 205. En conséquence, la composante axiale de la résultante des forces magnétiques est nulle.  The point D corresponds to a matter equilibrium, that is to say that there is as much magnetic matter on both sides of the normal axis of the magnetised source 205. Consequently, the axial component of the resultant magnetic forces is zero.
Un point fondamental de l'invention est que l'amplitude des forces mesurées dépend du volume des dépôts rencontrés. Ceci est visible en figure 7, où l'on a représenté la courbe mesurée dans le cas d'un dépôt présentant un fort volume 266 en entrée.  A fundamental point of the invention is that the amplitude of the measured forces depends on the volume of the deposits encountered. This is visible in FIG. 7, where the curve measured is shown in the case of a deposit having a high volume 266 at the input.
La figure 7 représente dans ce cas la composante axiale Fx des forces magnétiques exercées sur la source aimantée 205 en fonction de la position x de la sonde 201 dans le tube 215.  FIG. 7 represents in this case the axial component Fx of the magnetic forces exerted on the magnetized source 205 as a function of the position x of the probe 201 in the tube 215.
Ainsi, si l'on compare les courbes mesurées des figures 6 et 7, on constate que le pic B est plus intense sur la courbe de la figure 7 en raison du fort volume de matière 266.  Thus, if one compares the measured curves of FIGS. 6 and 7, it can be seen that peak B is more intense on the curve of FIG. 7 because of the high volume of material 266.
De plus, un nouveau pic B' fait son apparition, également causé par la présence du fort volume de matière 266.  In addition, a new peak B 'appears, also caused by the presence of the high volume of material 266.
Les courbes de mesure d'au moins une grandeur mécanique corrélée à la composante axiale des forces magnétiques exercées sur la source aimantée reflètent donc la physionomie et la position du dépôt.  The measurement curves of at least one mechanical quantity correlated to the axial component of the magnetic forces exerted on the magnetized source thus reflect the physiognomy and the position of the deposit.
Grâce au procédé selon l'invention, il est possible d'inspecter un tube en déplaçant de manière continue la sonde le long du tube, sans que des arrêts à certaines positions du tube ne soient nécessaires.  With the method according to the invention, it is possible to inspect a tube by continuously moving the probe along the tube, without stopping at certain positions of the tube are necessary.
Ainsi, une application du procédé est la détection de dépôts au niveau des passages quadrifoliés des plaques entretoises en liaison avec les tubes d'un générateur de vapeur d'un réacteur nucléaire à eau sous pression dit REP. Dans ce cas, l'inspection de chaque tube est rapide, puisqu'on peut balayer l'ensemble du tube sans avoir à se positionner à chaque liaison tube/plaque entretoise. Thus, one application of the method is the detection of deposits at the quenched passages of the spacer plates in connection with the tubes of a steam generator of a pressurized water-pressurized water reactor. REP. In this case, the inspection of each tube is fast, since one can scan the entire tube without having to position each tube tube / spacer plate.
Il est avantageux de déplacer la sonde comprenant la source aimantée le long du tube dans une première direction puis dans sa direction opposée, ce qui permet d'augmenter le nombre de points de mesure et donc la précision. En particulier, on balaye l'intégralité du tube en déplaçant la sonde dans une première direction, puis on fait revenir la sonde dans la direction opposée jusqu'à la zone où l'on avait introduit ladite sonde, via les moyens de déplacement 220.  It is advantageous to move the probe comprising the magnetic source along the tube in a first direction and then in its opposite direction, which increases the number of measurement points and therefore the accuracy. In particular, the entire tube is scanned by moving the probe in a first direction, then the probe is returned in the opposite direction to the zone where said probe was introduced via the moving means 220.
Dans le procédé selon l'invention, on détermine la position et/ou l'épaisseur et/ou le volume et/ou la longueur du dépôt en fonction des variations desdites forces magnétiques mesurées.  In the method according to the invention, the position and / or the thickness and / or the volume and / or the length of the deposit are determined as a function of the variations of said measured magnetic forces.
Pour ce faire, le dispositif comprend des moyens de détermination 230 de la position et/ou de l'épaisseur et/ou du volume et/ou de la longueur dudit dépôt en fonction des variations desdites forces magnétiques mesurées.  To do this, the device comprises means 230 for determining the position and / or the thickness and / or the volume and / or the length of said deposit as a function of the variations of said measured magnetic forces.
Il s'agit le plus souvent d'un ordinateur de type PC enregistrant les mesures effectuées par les moyens de mesure 220, éventuellement via une carte d'acquisition, et permettant l'analyse en temps réel ou a posteriori desdites mesures.  This is most often a PC type computer recording the measurements made by the measuring means 220, possibly via an acquisition card, and allowing the analysis in real time or a posteriori of said measurements.
L'ordinateur comprend avantageusement un ou plusieurs algorithmes se présentant sous la forme d'un logiciel enregistré sur un support physique, tel que le disque dur et/ou la mémoire de l'ordinateur, et programmé pour effectuer l'analyse des mesures.  The computer advantageously comprises one or more algorithms in the form of software recorded on a physical medium, such as the hard disk and / or the memory of the computer, and programmed to perform the analysis of the measurements.
L'analyse des mesures peut prendre diverses formes. Avantageusement, l'ordinateur dispose d'une base de données de signaux enregistrée sur un support physique, tel que le disque dur et/ou la mémoire de l'ordinateur. Cette base de données est notamment constituée à partir de simulations numériques (simulations de dépôt d'encrassement ou de colmatage sur ou à proximité d'un tube), de mesures en laboratoire, de mesures réalisées sur site, ou de mesures réalisées par tout autre moyen de simulation ou de mesure, et permet de fournir des signaux de mesure de référence de forces magnétiques (ou d'une grandeur mécanique corrélée) en fonction de la position de la sonde dans le tube. Measurement analysis can take a variety of forms. Advantageously, the computer has a signal database recorded on a physical medium, such as the hard disk and / or the memory of the computer. This database is mainly made up of numerical simulations (simulations of deposition of fouling or clogging on or near a tube), laboratory measurements, measurements made on site, or measurements made by any other way simulation or measurement method, and makes it possible to provide reference measurement signals for magnetic forces (or a correlated mechanical quantity) as a function of the position of the probe in the tube.
La base de données associe à chaque signal les données dimensionnelles des dépôts correspondants aux signaux mesurées, c'est-à- dire le volume, l'épaisseur, la longueur et la position desdits dépôts.  The database associates with each signal the dimensional data of the deposits corresponding to the measured signals, that is to say the volume, the thickness, the length and the position of said deposits.
Tous ces signaux constituent donc un modèle de référence permettant d'interpréter les mesures.  All these signals are therefore a reference model for interpreting measurements.
Avantageusement, l'on dispose de signaux de référence consistant en les variations des forces magnétiques mesurées lorsque la sonde est déplacée dans un tube ne comportant aucun dépôt.  Advantageously, there are reference signals consisting of the variations of the magnetic forces measured when the probe is moved in a tube having no deposit.
Dans le cas où l'on applique le procédé suivant l'invention à la liaison tube/plaque entretoise, il est avantageux d'utiliser comme signal de référence la différence des signaux entrée et sortie de plaque. S'il y a un dépôt de colmatage, il n'est présent que d'un côté de la plaque entretoise, ce qui permet de comparer les signaux correspondants.  In the case where the method according to the invention is applied to the tube / spacer plate connection, it is advantageous to use as the reference signal the difference of the plate input and output signals. If there is a clogging deposit, it is only present on one side of the spacer plate, which makes it possible to compare the corresponding signals.
L'analyse consiste à comparer les signaux mesurés avec les signaux de référence issus de la base de données, pour en déduire la position et/ou l'épaisseur et/ou le volume et/ou de la longueur du dépôt.  The analysis consists in comparing the measured signals with the reference signals coming from the database, in order to deduce the position and / or the thickness and / or the volume and / or the length of the deposit.
En particulier, il est avantageux de considérer des valeurs caractéristiques du signal mesuré, comme cela est représenté en figure 8.  In particular, it is advantageous to consider characteristic values of the measured signal, as shown in FIG. 8.
Les hauteurs de pic A, B et C sont directement corrélées à l'épaisseur du dépôt.  The peak heights A, B and C are directly correlated to the thickness of the deposit.
Les aires S, V et U du signal mesuré sont directement corrélées au volume du dépôt.  The areas S, V and U of the measured signal are directly correlated to the volume of the deposit.
Les distances D, E, G et H sont directement corrélées à la longueur du dépôt (selon l'axe parallèle à l'axe de révolution du tube).  The distances D, E, G and H are directly correlated to the length of the deposit (along the axis parallel to the axis of revolution of the tube).
La courbe permet également de lire la position du dépôt le long de l'axe du tube.  The curve also makes it possible to read the position of the deposit along the axis of the tube.
En comparant ces valeurs caractéristiques mesurées à des valeurs caractéristiques connues issues de la base de données précédemment décrite, on en déduit le volume, l'épaisseur, la longueur et la position du dépôt. Comparing these measured characteristic values to known characteristic values from the database previously described, we deduce the volume, thickness, length and position of the deposit.
Un avantage de l'invention est que les signaux mesurés sont faiblement bruités, puisqu'ils consistent en la mesure directe des forces magnétiques exercées sur la source aimantée, ou d'une grandeur mécanique qui leur est corrélée. L'invention permet ainsi de s'approcher au plus près du phénomène physique observé.  An advantage of the invention is that the measured signals are weakly noisy, since they consist in the direct measurement of the magnetic forces exerted on the magnetized source, or a mechanical quantity which is correlated to them. The invention thus makes it possible to approach closer to the observed physical phenomenon.
Un autre avantage est que le dispositif suivant l'invention permet d'avoir une lecture directe à l'écran des résultats en comparant les signaux acquis à des signaux de référence comme le signal tube de référence ou des signaux calibrés de la base de données.  Another advantage is that the device according to the invention makes it possible to have a direct reading on the screen of the results by comparing the acquired signals with reference signals such as the reference tube signal or calibrated signals of the database.
L'invention s'applique en particulier à la détection de dépôts au niveau des passages quadrifoliés des plaques entretoises d'un générateur de vapeur d'un réacteur nucléaire à eau sous pression dit REP. Elle permet de déterminer avec une bonne sensibilité la physionomie de ces dépôts, comme la longueur et l'épaisseur.  The invention applies in particular to the detection of deposits at the quadrifolate passages of the spacer plates of a steam generator of a pressurized PWR nuclear reactor. It makes it possible to determine with a good sensitivity the physiognomy of these deposits, such as length and thickness.
Enfin, il va de soi que les exemples que l'on vient de donner ne sont que des illustrations particulières en aucun cas limitatives quant aux domaines d'application de l'invention.  Finally, it goes without saying that the examples that we have just given are only particular illustrations in no way limiting as to the fields of application of the invention.

Claims

REVENDICATIONS
1 . Procédé de détection de dépôts d'encrassement ou de colmatage comportant au moins un matériau ferromagnétique, tel que du nickel, de la magnétite ou similaire, sur ou à proximité de la paroi externe d'un tube (215) caractérisé en ce qu'il comporte au moins les étapes suivantes de : 1. A method for detecting clogging or clogging deposits comprising at least one ferromagnetic material, such as nickel, magnetite or the like, on or near the outer wall of a tube (215), characterized in that comprises at least the following steps of:
- déplacement d'une source aimantée (205) à l'intérieur du tube (215) dans le sens de sa longueur,  moving a magnetic source (205) inside the tube (215) in the direction of its length,
- mesure d'au moins une grandeur mécanique corrélée à la composante axiale de forces magnétiques exercées sur la source aimantée measurement of at least one mechanical quantity correlated with the axial component of magnetic forces exerted on the magnetised source
(205), (205)
- détermination de la position et/ou de l'épaisseur et/ou du volume et/ou de la longueur dudit dépôt (265) en fonction des variations de la grandeur mécanique mesurée.  determining the position and / or the thickness and / or the volume and / or the length of said deposit (265) as a function of the variations of the measured mechanical quantity.
2. Procédé selon la revendication 1 , caractérisé en ce que ladite source aimantée (205) est déplacée dans le tube à une vitesse constante. 2. Method according to claim 1, characterized in that said magnetic source (205) is moved in the tube at a constant speed.
3. Procédé selon l'une des revendications 1 ou 2, caractérisé en ce que l'on mesure la composante axiale desdites forces magnétiques par l'intermédiaire d'au moins un capteur de force. 3. Method according to one of claims 1 or 2, characterized in that the axial component of said magnetic forces is measured by means of at least one force sensor.
4. Procédé selon l'une des revendications 1 à 3, caractérisé en ce que l'on mesure la variation du mouvement de la source aimantée (205) par rapport à la sonde (201 ) selon la direction axiale du tube. 4. Method according to one of claims 1 to 3, characterized in that one measures the variation of the movement of the magnetized source (205) relative to the probe (201) in the axial direction of the tube.
5. Procédé selon l'une des revendications 1 à 4, caractérisé en ce que l'on mesure l'effort mécanique axial subi par la source aimantée (205). 5. Method according to one of claims 1 to 4, characterized in that one measures the axial mechanical force undergone by the magnetized source (205).
6. Procédé selon l'une quelconque des revendications 1 à 5, caractérisé en ce que la source aimantée (205) est déplacée le long du tube (265) dans une première direction puis dans sa direction opposée. 6. Method according to any one of claims 1 to 5, characterized in that the magnetic source (205) is moved along the tube (265) in a first direction and then in its opposite direction.
7. Procédé selon l'une quelconque des revendications 1 à 6, caractérisé en ce que l'étape de détermination de la position et/ou de l'épaisseur et/ou du volume et/ou de la longueur dudit dépôt comporte une étape de comparaison de la variation de la grandeur mécanique mesurée avec un modèle de référence. 7. Method according to any one of claims 1 to 6, characterized in that the step of determining the position and / or thickness and / or volume and / or the length of said deposit comprises a step of comparing the variation of the measured mechanical quantity with a reference model.
8. Dispositif de détection (200) de dépôts d'encrassement ou de colmatage comportant au moins un matériau ferromagnétique, tel que du nickel, de la magnétite ou similaire, sur ou à proximité de la paroi externe d'un tube (215) caractérisé en ce qu'il comporte : 8. Device for detecting (200) fouling or clogging deposits comprising at least one ferromagnetic material, such as nickel, magnetite or the like, on or near the outer wall of a tube (215) characterized in that it comprises:
- une sonde (201 ) comprenant  a probe (201) comprising
o au moins une source aimantée (205), et o des moyens de mesure (220) d'au moins une grandeur mécanique corrélée à la composante axiale de forces magnétiques exercées sur la source aimantée (205) ; at least one magnetic source (205), and measurement means (220) for at least one mechanical quantity correlated with the axial component of magnetic forces exerted on the magnetised source (205);
- des moyens de déplacement (210) de ladite sonde (201 ) à l'intérieur dudit tube (215) dans le sens de la longueur ; means (210) for displacing said probe (201) inside said tube (215) in the direction of the length;
- des moyens de détermination (230) de la position et/ou de l'épaisseur et/ou du volume et/ou de la longueur dudit dépôt en fonction des variations de ladite grandeur mécanique mesurée.  means for determining (230) the position and / or the thickness and / or the volume and / or the length of said deposit as a function of the variations of said measured mechanical quantity.
9. Dispositif suivant la revendication 8, caractérisé en ce que la source aimantée (205) consiste en au moins un aimant permanent. 9. Device according to claim 8, characterized in that the magnetic source (205) consists of at least one permanent magnet.
10. Dispositif suivant l'une quelconque des revendications 8 ou 9, caractérisé en ce que les moyens de mesure (220) de la grandeur mécanique comprennent au moins un capteur de force. 10. Device according to any one of claims 8 or 9, characterized in that the measuring means (220) of the mechanical quantity comprise at least one force sensor.
1 1 . Dispositif suivant la revendication 10, caractérisé en ce que le capteur de force est un capteur piézoélectrique ou une jauge de contrainte. 1 1. Device according to Claim 10, characterized in that the force sensor is a piezoelectric sensor or a strain gauge.
1 2. Dispositif selon l'une des revendications 8 à 1 1 , caractérisé en ce que les moyens de mesure (220) comprennent : 1 2. Device according to one of claims 8 to 1 1, characterized in that the measuring means (220) comprise:
au moins un élément mobile (245) mécaniquement solidaire de la source aimantée (205), dont le mouvement est libre par rapport à la sonde (201 ) selon une direction axiale du tube, et  at least one movable element (245) mechanically secured to the magnetised source (205), whose movement is free with respect to the probe (201) in an axial direction of the tube, and
un capteur de distance (255) pour mesurer les variations dudit mouvement.  a distance sensor (255) for measuring variations of said movement.
1 3. Application du procédé suivant l'une quelconque des revendications 1 à 7 à la détection de dépôts dans les quadrifolliages des entretoises d'un générateur de vapeur d'un réacteur nucléaire à eau sous pression dit REP. 3. Application of the process according to any one of claims 1 to 7 to the detection of deposits in the quadrifollages of the spacers of a steam generator of a pressurized PWR nuclear reactor.
PCT/EP2010/064014 2009-09-24 2010-09-23 Improvements to a method and device for detecting deposits comprising at least one ferromagnetic material on or in the vicinity of the outer wall of a tube WO2011036192A1 (en)

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FR0956612 2009-09-24
FR0956612A FR2950433B1 (en) 2009-09-24 2009-09-24 IMPROVEMENTS IN A METHOD AND DEVICE FOR DETECTING DEPOSITS COMPRISING AT LEAST ONE FERROMAGNETIC MATERIAL ON OR NEAR THE OUTER WALL OF A TUBE

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FR3028042B1 (en) * 2014-11-05 2016-12-16 Electricite De France DEVICE AND METHOD FOR DETECTING DEPOSITS OF AT LEAST ONE FERROMAGNETIC MATERIAL ON THE OUTER WALL OF A TUBE

Citations (6)

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US4088946A (en) 1975-07-28 1978-05-09 Westinghouse Electric Corp. Magnetic bridge transducer formed with permanent magnets and a hall effect sensor for identifying the presence and location of ferromagnetic discontinuities within or on a tubular specimen
FR2459490A1 (en) 1979-06-18 1981-01-09 Electric Power Res Inst METHOD AND DEVICE FOR DETECTING MAGNETITE DEPOSITS IN HEAT EXCHANGERS AND THE LIKE
US4700134A (en) 1985-01-10 1987-10-13 Anco Engineers, Inc. Method and apparatus for determining the amount of magnetic debris adhering to the exterior of a tube
US4889679A (en) * 1988-02-16 1989-12-26 Westinghouse Electric Corp. Eddy current probe apparatus having an expansible sleeve
DE4338752A1 (en) * 1993-11-12 1995-05-18 Siemens Ag Detection means for ferromagnetic particles from within pipes
FR2928024A1 (en) * 2008-02-22 2009-08-28 Areva Np Sas Water passage clogging rate detecting and measuring device for pressurized water nuclear reactor, has eddy current and magnetic field detectors connected to amplification and visualization system to amplify and visualize signal variations

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Publication number Priority date Publication date Assignee Title
US4088946A (en) 1975-07-28 1978-05-09 Westinghouse Electric Corp. Magnetic bridge transducer formed with permanent magnets and a hall effect sensor for identifying the presence and location of ferromagnetic discontinuities within or on a tubular specimen
FR2459490A1 (en) 1979-06-18 1981-01-09 Electric Power Res Inst METHOD AND DEVICE FOR DETECTING MAGNETITE DEPOSITS IN HEAT EXCHANGERS AND THE LIKE
US4700134A (en) 1985-01-10 1987-10-13 Anco Engineers, Inc. Method and apparatus for determining the amount of magnetic debris adhering to the exterior of a tube
US4889679A (en) * 1988-02-16 1989-12-26 Westinghouse Electric Corp. Eddy current probe apparatus having an expansible sleeve
DE4338752A1 (en) * 1993-11-12 1995-05-18 Siemens Ag Detection means for ferromagnetic particles from within pipes
FR2928024A1 (en) * 2008-02-22 2009-08-28 Areva Np Sas Water passage clogging rate detecting and measuring device for pressurized water nuclear reactor, has eddy current and magnetic field detectors connected to amplification and visualization system to amplify and visualize signal variations

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