EP0546937B1 - Operating platform, especially for the steam generator of a nuclear power plant - Google Patents

Operating platform, especially for the steam generator of a nuclear power plant Download PDF

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Publication number
EP0546937B1
EP0546937B1 EP92403343A EP92403343A EP0546937B1 EP 0546937 B1 EP0546937 B1 EP 0546937B1 EP 92403343 A EP92403343 A EP 92403343A EP 92403343 A EP92403343 A EP 92403343A EP 0546937 B1 EP0546937 B1 EP 0546937B1
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EP
European Patent Office
Prior art keywords
inflatable
working floor
closure element
floor according
annular space
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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EP92403343A
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German (de)
French (fr)
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EP0546937A1 (en
Inventor
Gérard Dohlen
Jean-Jacques Chapuzy
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Electricite de France SA
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Electricite de France SA
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Publication of EP0546937A1 publication Critical patent/EP0546937A1/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
    • F22B37/00—Component parts or details of steam boilers
    • F22B37/002—Component parts or details of steam boilers specially adapted for nuclear steam generators, e.g. maintenance, repairing or inspecting equipment not otherwise provided for
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
    • F22B37/00—Component parts or details of steam boilers
    • F22B37/02—Component parts or details of steam boilers applicable to more than one kind or type of steam boiler
    • F22B37/26—Steam-separating arrangements
    • F22B37/268—Steam-separating arrangements specially adapted for steam generators of nuclear power plants
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
    • G21F7/00—Shielded cells or rooms
    • G21F7/06—Structural combination with remotely-controlled apparatus, e.g. with manipulators

Definitions

  • the present invention relates to a work floor, intended in particular for closing an empty space in a steam generator of a nuclear power plant.
  • the invention finds a particularly advantageous application in the field of monitoring and maintenance of steam generators in nuclear power plants.
  • the aforementioned steam generators have empty spaces such as the annular space located near the water supply torus, in the upper part of the bundle of tubes, or even such as the orifices in the outlet zone of the separators cyclones of the dryers, also located in the upper part of the steam generators.
  • US-A-4,703,936 describes a device for controlling the level of water in an annular space delimited between an internal envelope and an external enclosure of a steam generator of a nuclear power station. More specifically, this device aims to free the annular space from the presence of the water therein under normal conditions (this water forms a shield against nuclear radiation from radioactive contaminants deposited on the internal walls of the exchanger tubes and contained in the primary water heated in the core of the nuclear reactor).
  • the water level control device comprises an elastomeric tube, full or hollow (in the latter case, the tube is inflatable by compressed air).
  • This tube is intended to close off an opening placing the annular space mentioned above in normal conditions in communication with the internal envelope of the generator, that is to say it is intended to maintain the level in the annular space water below the level existing in this internal envelope, so as to allow access for the persons responsible for maintenance in the annular space.
  • This possibly inflatable tube is essentially a seal and not a work floor. Furthermore, this tube does not constitute an effective barrier against the fall of working tools, such a barrier being defined by a toroidal metal tube placed above the tube forming a seal.
  • the work floor constituting a barrier against the fall of work tools is essentially constituted by this toroidal metal tube.
  • said work floor comprises at least an inflatable closure element comprising at least one inflatable bladder enclosed in a protective envelope.
  • the inflatable obturation element completely occupies the space where it is installed, which ensures a total seal against migrating objects.
  • the establishment of the work floor according to the invention is particularly quick and easy since no particular tool or complex procedure is required. The Applicant has carried out tests which have shown that ten minutes is sufficient for the installation of the work floor of the invention.
  • the work floor according to the invention can be very easily decontaminated and reused as many times as necessary. In addition, once emptied and folded, it is compact and easily transportable.
  • said work floor comprises at least one inflatable toroidal sealing element intended to be placed in said annular space between said walls.
  • Tests carried out by the Applicant have made it possible to conclude that after being inflated under sufficient pressure, 300 mb for example, the inflatable element underwent no sliding even under heavy loads, that the walls of the annular space were dry or wet.
  • This resistance to movement of the inflatable closure element can be taken advantage of, when applying the invention to the maintenance of the food toroid for example, to bring the water level to a maximum height so as to provide the highest possible natural protection against radiation.
  • This advantage could not be achieved with the traditional wooden floor, which on the contrary requires a large amount of water to prevent it from floating.
  • said work floor comprises a plurality of inflatable obturation elements in the form of arcs torus, the ends of said inflatable elements being provided with connection means intended to put in communication the homologous inflatable bladders of the inflatable obturation elements.
  • this variant Due to the discontinuity between the inflatable elements, this variant has the advantage of being able to bring the water level above the work floor itself and therefore to increase the protection of personnel who should only be equipped with boots or any other waterproof clothing.
  • At least one inflatable closure element has a water level detector at the bottom.
  • each inflatable closure element comprises a plurality of independent inflatable bladders forming at least one superposed configuration.
  • the invention provides that said inflatable bladders are connected to pressure control means.
  • said bladders are connected to pressure control means.
  • This arrangement also has the advantage, when the losses on a bladder are very significant (puncture for example), to allow the other bladders to immediately fill the space left free by the damaged bladder.
  • said work floor comprises an inflatable closure element comprising, on the one hand, a plurality of inflatable bladders, and, on the other hand, in the lower part, an inflatable bladder for centering on said orifice.
  • This last mode of implementation is particularly well suited to inspection visits to the area located at the outlet of the cyclone separators of the steam generators.
  • Figure la is a general sectional view of a steam generator of a nuclear power plant.
  • Figure 1b is a detailed sectional view of an annular space intended to be closed by the work floor according to the invention.
  • Figure 2a is a partial perspective view of a work floor according to the invention intended to close the annular space of Figure 1b.
  • Figure 2b is a sectional view of the work floor of the invention installed in the annular space of Figure 1b.
  • Figure 2c is a sectional view of an alternative embodiment of the working floor of Figure 2b.
  • Figure 3 is a diagram of a pressure control system for the working floor of Figure 2a.
  • Figure 4a is a top view of the outlet area of a cyclone separator of a steam generator according to Figure 1a.
  • Figure 4b is a top view of a working floor for sealing the orifices of the outlet area shown in Figure 4a.
  • Figure 4c is a front view of the work floor of Figure 4b.
  • the figure shows, in section, a nuclear power plant steam generator.
  • This steam generator has a number of empty spaces through which objects or tools of all kinds can fall, carried by the inspection or maintenance personnel of said generator. This is particularly the case for the annular space 10 located near the food toroid 30 and the bun 40 of tubes, and shown in enlarged form in FIG. 1b. During an intervention on the torus food 30, migrant objects passing through the annular space 10 can reach and deteriorate the tube plate 50 at the bottom of the steam generator.
  • the annular hole 10 is closed using a work floor formed by a plurality of inflatable shutter elements 100 which can be 3 in number for example forming toroid arcs of 120 °.
  • the working floor consists of an inflatable single closure element occupying the annular hole 10 over its entire periphery.
  • the inflatable elements 100 are intended to be placed in the annular space 10 between the walls 11 and 12 which limit it. As can be seen more particularly in FIGS. 2b and 2c, these inflatable elements 100 comprise a plurality of independent inflatable bladders 110, 120, 130 enclosed in a protective envelope 170.
  • said protective casing 170 is made of sulfur-free polyurethane, without chlorine or other halogen, so as to avoid the problem of stress corrosion.
  • the inflatable bladders can be made of flexible vinyl.
  • FIGS. 2a and 2b show that the casing 170 is extended by lateral flaps 141, 142 intended to be applied against the walls 11, 12 delimiting the annular space 10. These flaps guarantee a perfect seal on the edges of the annular hole and facilitate, by simple folding, the cleaning of the work floor.
  • the ends of said inflatable elements 100 are provided with connecting means 151, 152, 153 intended to put in place communicating the inflatable bladders 110, 120, 130 homologs of the inflatable obturation elements.
  • the independent inflatable bladders 110, 120, 130 form at least one superposed configuration.
  • This arrangement has the advantage of ensuring the maintenance of the work floor even when the inflatable bladder (s) of the upper part of the configuration superimposed will come to be punctured following any incident.
  • the work floor according to the invention comprises a rigid protective element 160 superimposed on each inflatable obturation element 100 , for example via flexible rods 161, 162 for centering.
  • This protective element 160 which may be made of Kevlar (registered trademark), ensures the flatness of the work floor and makes it possible to withstand not only impacts and sharp objects, but also incandescent projections from grinding or welding operations.
  • the Applicant has carried out a feasibility test with an inflatable element 2 m long and 300 mm in diameter, placed in a scale 1 model representative of the annular space located 1 m below the feed toroid d '' a 900 MW steam generator.
  • the walls of the model were painted to give them a smooth surface.
  • the inflatable element was first slightly inflated under a pressure of less than 50 mb in order to give it its geometric shape, then placed between the walls of the model. This operation is simple and very fast, a few seconds for a 2 m element. Then, the inflatable element was pressurized to 300 mb.
  • each inflatable bladder 110, 120, 130 is constantly monitored and slaved to a set pressure using servo means shown in Figure 3.
  • Housings 181, 182, 183 control detects any fluctuation in the pressure P around the set pressure and controls the regulators 191, 192, 193 of compressed air tanks, not shown, until the pressure has returned to the set pressure.
  • the inflatable bladders in the lower position would undergo an increase in volume due to their elasticity, which would cause a reduction in pressure which would be immediately compensated for with the using the servo means by an additional inflation of the bladders, which would then fill the space occupied by the punctured bladder.
  • Figure 4a shows a top view of the outlet area of a cyclone separator of the steam generator of Figure la. As can be seen, this area has empty spaces 20, divided into three sectors, formed by circular or lateral orifices through which migrant objects can pass during the annual inspection carried out in this area.
  • a working floor comprising an inflatable closure element 200 comprising for each section, on the one hand, a plurality of inflatable bladders 210, enclosed in an envelope 270, and, on the other hand, in the lower part, a bladder 220 for centering on said orifice 20.
  • the inflatable element 200 has the shape of a fan which, under the effect of the inflation, adapts to the geometry of the place where it is installed, here one third of the area to protect. It will also be noted that, in this particular case, a single layer of bladders is necessary and therefore a single pressure control device.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • High Energy & Nuclear Physics (AREA)
  • General Engineering & Computer Science (AREA)
  • Thermal Sciences (AREA)
  • Mechanical Engineering (AREA)
  • Manipulator (AREA)
  • Structure Of Emergency Protection For Nuclear Reactors (AREA)
  • Monitoring And Testing Of Nuclear Reactors (AREA)
  • Pressure Vessels And Lids Thereof (AREA)

Description

La présente invention concerne un plancher de travail, destiné notamment à obturer un espace vide dans un générateur de vapeur d'une centrale nucléaire.The present invention relates to a work floor, intended in particular for closing an empty space in a steam generator of a nuclear power plant.

L'invention trouve une application particulièrement avantageuse dans le domaine de la surveillance et de la maintenance des générateurs de vapeur de centrales nucléaires.The invention finds a particularly advantageous application in the field of monitoring and maintenance of steam generators in nuclear power plants.

Actuellement, les générateurs de vapeur précités présentent des espaces vides tels que l'espace annulaire situé à proximité du tore d'alimentation en eau, dans la partie haute du faisceau de tubes, ou encore tels que les orifices de la zone de sortie des séparateurs cyclones des sécheurs, également situés dans la partie haute des générateurs de vapeur.Currently, the aforementioned steam generators have empty spaces such as the annular space located near the water supply torus, in the upper part of the bundle of tubes, or even such as the orifices in the outlet zone of the separators cyclones of the dryers, also located in the upper part of the steam generators.

Il arrive très fréquemment que, lors de travaux de maintenance ou de simples inspections, des objets ou des outils comme des burins, tournevis, baguettes de soudure, grains de soudure ou de la limaille, etc., tombent à travers lesdits espaces vides, notamment l'espace annulaire de la partie haute du faisceau de tubes, pour atteindre la plaque à tubes dans la partie basse du générateur de vapeur. Outre qu'ils ne peuvent être récupérés compte tenu de la hauteur de l'installation, ces objets migrants risquent de détériorer la plaque à tubes.It very often happens that, during maintenance work or simple inspections, objects or tools such as chisels, screwdrivers, welding rods, grains of solder or filings, etc., fall through said empty spaces, in particular the annular space of the upper part of the tube bundle, to reach the tube plate in the lower part of the steam generator. In addition to the fact that they cannot be recovered given the height of the installation, these migrant objects risk damaging the tube plate.

Pour limiter ces inconvénients, on a généralement recours à un plancher de travail constitué par une plateforme en bois maintenue dans l'espace annulaire par exemple, grâce à des coins également en bois. Toutefois, l'expérience a montré que ce matériel laisse des passages importants sur toute la périphérie du plancher et, de ce fait, n'est pas efficace contre la chute des objets vers la plaque à tubes. De plus, ce type de plancher demande un temps de mise en place excessif, environ 1h30, sous un débit de dose élevé.To limit these drawbacks, use is generally made of a work floor consisting of a wooden platform maintained in the annular space for example, thanks to corners also made of wood. However, experience has shown that this material leaves significant passages around the entire periphery of the floor and, therefore, is not effective against falling objects to the tube plate. In addition, this type of floor requires excessive set-up time, around 1.5 hours, under a high dose rate.

Le brevet US-A-4 703 936 décrit un dispositif de contrôle du niveau de l'eau dans un espace annulaire délimité entre une enveloppe interne et une enceinte externe d'un générateur de vapeur d'une centrale nucléaire. De façon plus précise, ce dispositif vise à dégager l'espace annulaire de la présence de l'eau qui s'y trouve en conditions normales (cette eau fait écran de protection contre les radiations nucléaires provenant des contaminants radioactifs se déposant sur les parois internes des tubes échangeurs et contenus dans l'eau primaire chauffée dans le coeur du réacteur nucléaire). A cet effet, le dispositif de contrôle du niveau d'eau comporte un tube élastomère, plein ou creux (dans ce dernier cas, le tube est gonflable par de l'air comprimé). Ce tube est destiné à obturer une ouverture mettant en conditions normales l'espace annulaire évoqué plus haut en communication avec l'enveloppe interne du générateur, c'est-à-dire qu'il est destiné à maintenir dans l'espace annulaire le niveau de l'eau au-dessous du niveau existant dans cette enveloppe interne, de manière à permettre l'accès des personnes chargées de la maintenance dans l'espace annulaire. Ce tube éventuellement gonflable est essentiellement un joint d'étanchéité et non pas un plancher de travail. Au demeurant, ce tube ne constitue pas non plus une barrière efficace contre la chute d'outils de travail, une telle barrière étant définie par un tube métallique toroïdal disposé au-dessus du tube faisant joint d'étanchéité. Or, dans le brevet américain, le plancher de travail constituant une barrière contre la chute d'outils de travail est essentiellement constitué par ce tube métallique toroïdal. US-A-4,703,936 describes a device for controlling the level of water in an annular space delimited between an internal envelope and an external enclosure of a steam generator of a nuclear power station. More specifically, this device aims to free the annular space from the presence of the water therein under normal conditions (this water forms a shield against nuclear radiation from radioactive contaminants deposited on the internal walls of the exchanger tubes and contained in the primary water heated in the core of the nuclear reactor). For this purpose, the water level control device comprises an elastomeric tube, full or hollow (in the latter case, the tube is inflatable by compressed air). This tube is intended to close off an opening placing the annular space mentioned above in normal conditions in communication with the internal envelope of the generator, that is to say it is intended to maintain the level in the annular space water below the level existing in this internal envelope, so as to allow access for the persons responsible for maintenance in the annular space. This possibly inflatable tube is essentially a seal and not a work floor. Furthermore, this tube does not constitute an effective barrier against the fall of working tools, such a barrier being defined by a toroidal metal tube placed above the tube forming a seal. However, in the American patent, the work floor constituting a barrier against the fall of work tools is essentially constituted by this toroidal metal tube.

Le fait que ce joint d'étanchéité toroïdal ne peut pas être considéré efficace ni en tant que barrière contre la chute d'outils de travail, ni en tant que plancher de travail, - notamment en rapport avec l'espace annulaire de la partie haute du faisceau de tubes situé à proximité du tore alimentaire du générateur de vapeur -, revient à dire que le problème technique visant à réaliser un plancher de travail conforme au préambule, qui présenterait, notamment, une efficacité absolue contre la chute d'objets, ainsi qu'une mise en place rapide et aisée, n'a pas reçu de solution efficace dans l'art antérieur. La présente invention s'est donc donné pour but d'apporter une solution efficace à ce problème technique.The fact that this toroidal seal cannot be considered effective neither as a barrier against the fall of working tools, nor as a working floor, - in particular in relation to the annular space of the upper part of the bundle of tubes located near the food toroid of the steam generator -, amounts to saying that the technical problem aiming at achieving a work floor conforming to the preamble, which would present, in particular, an absolute effectiveness against falling objects, as well that a quick and easy installation, has not received an effective solution in the prior art. The present invention therefore aims to provide an effective solution to this technical problem.

La solution au problème technique posé consiste, selon la présente invention, en ce que ledit plancher de travail comporte au moins un élément gonflable d'obturation comprenant au moins une vessie gonflable enfermée dans une enveloppe de protection.The solution to the technical problem posed consists, according to the present invention, in that said work floor comprises at least an inflatable closure element comprising at least one inflatable bladder enclosed in a protective envelope.

Ainsi, sous l'effet de la pression, l'élément gonflable d'obturation occupe totalement l'espace où il est installé, ce qui assure une étanchéité totale aux objets migrants. D'autre part, la mise en place du plancher de travail selon l'invention est particulièrement rapide et facile puisqu'aucun outillage particulier ni procédure complexe n'est exigé. La Demanderesse a effectué des essais qui ont montré qu'une dizaine de minutes suffisait pour l'installation du plancher de travail de l'invention.Thus, under the effect of pressure, the inflatable obturation element completely occupies the space where it is installed, which ensures a total seal against migrating objects. On the other hand, the establishment of the work floor according to the invention is particularly quick and easy since no particular tool or complex procedure is required. The Applicant has carried out tests which have shown that ten minutes is sufficient for the installation of the work floor of the invention.

Il faut également remarquer que, contrairement à la plateforme de bois classiquement utilisée, le plancher de travail conforme à l'invention peut être très facilement décontaminé et réutilisé autant de fois que nécessaire. De plus, une fois vidé et plié, il est peu encombrant et aisément transportable.It should also be noted that, unlike the wooden platform conventionally used, the work floor according to the invention can be very easily decontaminated and reused as many times as necessary. In addition, once emptied and folded, it is compact and easily transportable.

Dans un premier mode de mise en oeuvre du plancher de travail selon l'invention, il est prévu que, ledit espace vide étant un espace annulaire limité par deux parois, ledit plancher de travail comporte au moins un élément gonflable d'obturation torique destiné à être placé dans ledit espace annulaire entre lesdites parois. Des essais réalisés par la Demanderesse ont permis de conclure qu'après avoir été gonflé sous une pression suffisante, 300 mb par exemple, l'élément gonflable ne subissait aucun glissement même sous des charges importantes, que les parois de l'espace annulaire soient sèches ou humides.In a first embodiment of the work floor according to the invention, it is provided that, said empty space being an annular space limited by two walls, said work floor comprises at least one inflatable toroidal sealing element intended to be placed in said annular space between said walls. Tests carried out by the Applicant have made it possible to conclude that after being inflated under sufficient pressure, 300 mb for example, the inflatable element underwent no sliding even under heavy loads, that the walls of the annular space were dry or wet.

Cette résistance au déplacement de l'élément gonflable d'obturation peut être mise à profit, lors de l'application de l'invention à la maintenance du tore alimentaire par exemple, pour amener le niveau d'eau à une hauteur maximale de façon à assurer la protection naturelle la plus élevée possible contre les radiations. Cet avantage ne pourrait être atteint avec le traditionnel plancher de bois qui exige au contraire une garde d'eau importante de manière à éviter qu'il ne puisse flotter.This resistance to movement of the inflatable closure element can be taken advantage of, when applying the invention to the maintenance of the food toroid for example, to bring the water level to a maximum height so as to provide the highest possible natural protection against radiation. This advantage could not be achieved with the traditional wooden floor, which on the contrary requires a large amount of water to prevent it from floating.

Selon une variante du premier mode de mise en oeuvre précité permettant une mise en place encore plus rapide, ledit plancher de travail comporte une pluralité d'éléments gonflables d'obturation en forme d'arcs de tore, les extrémités desdits éléments gonflables étant munies de moyens de raccordement destinés à mettre en communication les vessies gonflables homologues des éléments gonflables d'obturation.According to a variant of the aforementioned first embodiment allowing an even faster installation, said work floor comprises a plurality of inflatable obturation elements in the form of arcs torus, the ends of said inflatable elements being provided with connection means intended to put in communication the homologous inflatable bladders of the inflatable obturation elements.

Du fait de la discontinuité existant entre les éléments gonflables, cette variante de réalisation présente l'avantage de pouvoir amener le niveau d'eau au-dessus du plancher de travail lui-même et donc d'augmenter la protection des personnels qui devraient alors seulement être équipés de bottes ou tout autre vêtement imperméable.Due to the discontinuity between the inflatable elements, this variant has the advantage of being able to bring the water level above the work floor itself and therefore to increase the protection of personnel who should only be equipped with boots or any other waterproof clothing.

Dans le but de contrôler la hauteur d'eau, au moins un élément gonflable d'obturation comporte en partie inférieure un détecteur de niveau d'eau.In order to control the water level, at least one inflatable closure element has a water level detector at the bottom.

De façon à garantir une plus grande sécurité, notamment en cas de crevaison, il y a avantage, selon la présente invention, à ce que chaque élément gonflable d'obturation comporte une pluralité de vessies gonflables indépendantes formant au moins une configuration superposée. De cette manière, si par exemple un objet venait à percer une vessie supérieure de la configuration superposée, la stabilité du plancher de travail conforme à l'invention resterait parfaitement maintenue par les vessies gonflables en position inférieure dans ladite configuration superposée.In order to guarantee greater safety, in particular in the event of a puncture, there is an advantage, according to the present invention, in that each inflatable closure element comprises a plurality of independent inflatable bladders forming at least one superposed configuration. In this way, if for example an object were to pierce an upper bladder of the superimposed configuration, the stability of the work floor according to the invention would remain perfectly maintained by the inflatable bladders in the lower position in said superimposed configuration.

Toujours au titre d'une sécurité maximale, l'invention prévoit que lesdites vessies gonflables sont reliées à des moyens d'asservissement de la pression. Ainsi, il est assuré que, même en cas de pertes, lesdites vessies restent toujours gonflées à la pression de consigne. Cette disposition présente également l'avantage, lorsque les pertes sur une vessie sont très importantes (crevaison par exemple), de permettre aux autres vessies de combler immédiatement l'espace laissé libre par la vessie endommagée.Still for maximum security, the invention provides that said inflatable bladders are connected to pressure control means. Thus, it is ensured that, even in the event of losses, said bladders always remain inflated to the set pressure. This arrangement also has the advantage, when the losses on a bladder are very significant (puncture for example), to allow the other bladders to immediately fill the space left free by the damaged bladder.

Dans un deuxième mode de mise en oeuvre de l'invention, ledit espace vide étant formé par au moins un orifice, ledit plancher de travail comporte un élément gonflable d'obturation comprenant, d'une part, une pluralité de vessies gonflables, et, d'autre part, en partie inférieure, une vessie gonflable de centrage sur ledit orifice.In a second embodiment of the invention, said empty space being formed by at least one orifice, said work floor comprises an inflatable closure element comprising, on the one hand, a plurality of inflatable bladders, and, on the other hand, in the lower part, an inflatable bladder for centering on said orifice.

Ce dernier mode de mise en oeuvre est particulièrement bien adapté aux visites d'inspection de la zone située à la sortie des séparateurs cyclones des générateurs de vapeur.This last mode of implementation is particularly well suited to inspection visits to the area located at the outlet of the cyclone separators of the steam generators.

La description qui va suivre en regard des dessins annexés, donnés à titre d'exemples non limitatifs fera bien comprendre en quoi consiste l'invention et comment elle peut être réalisée.The description which follows with reference to the appended drawings, given by way of nonlimiting examples will make it clear what the invention consists of and how it can be implemented.

La figure la est une vue générale en coupe d'un générateur de vapeur d'une centrale nucléaire.Figure la is a general sectional view of a steam generator of a nuclear power plant.

La figure 1b est une vue détaillée en coupe d'un espace annulaire destiné à être obturé par le plancher de travail conforme à l'invention.Figure 1b is a detailed sectional view of an annular space intended to be closed by the work floor according to the invention.

La figure 2a est une vue partielle en perspective d'un plancher de travail selon l'invention destiné à obturer l'espace annulaire de la figure 1b.Figure 2a is a partial perspective view of a work floor according to the invention intended to close the annular space of Figure 1b.

La figure 2b est une vue en coupe du plancher de travail de l'invention installé dans l'espace annulaire de la figure 1b.Figure 2b is a sectional view of the work floor of the invention installed in the annular space of Figure 1b.

La figure 2c est une vue en coupe d'une variante de réalisation du plancher de travail de la figure 2b.Figure 2c is a sectional view of an alternative embodiment of the working floor of Figure 2b.

La figure 3 est un schéma d'un système d'asservissement de la pression pour le plancher de travail de la figure 2a.Figure 3 is a diagram of a pressure control system for the working floor of Figure 2a.

La figure 4a est une vue de dessus de la zone de sortie d'un séparateur cyclone d'un générateur de vapeur conforme à la figure 1a.Figure 4a is a top view of the outlet area of a cyclone separator of a steam generator according to Figure 1a.

La figure 4b est une vue de dessus d'un plancher de travail pour obturer les orifices de la zone de sortie montrée sur la figure 4a.Figure 4b is a top view of a working floor for sealing the orifices of the outlet area shown in Figure 4a.

La figure 4c est une vue de face du plancher de travail de la figure 4b.Figure 4c is a front view of the work floor of Figure 4b.

La figure la montre, en coupe, un générateur de vapeur de centrale nucléaire. Ce générateur de vapeur présente un certain nombre d'espaces vides à travers lesquels peuvent tomber des objets ou outils de toutes sortes portés par le personnel d'inspection ou de maintenance dudit générateur. C'est le cas notamment de l'espace annulaire 10 situé à proximité du tore alimentaire 30 et du chignon 40 de tubes, et représenté de façon agrandie sur la figure 1b. Lors d'une intervention sur le tore alimentaire 30, des objets migrants traversant l'espace annulaire 10 peuvent atteindre et détériorer la plaque 50 à tubes à la partie inférieure du générateur de vapeur.The figure shows, in section, a nuclear power plant steam generator. This steam generator has a number of empty spaces through which objects or tools of all kinds can fall, carried by the inspection or maintenance personnel of said generator. This is particularly the case for the annular space 10 located near the food toroid 30 and the bun 40 of tubes, and shown in enlarged form in FIG. 1b. During an intervention on the torus food 30, migrant objects passing through the annular space 10 can reach and deteriorate the tube plate 50 at the bottom of the steam generator.

Comme l'illustrent les figures 2a, 2b et 2c, le trou annulaire 10 est obturé à l'aide d'un plancher de travail formé d'une pluralité d'éléments gonflables 100 d'obturation qui peuvent être au nombre de 3 par exemple formant des arcs de tore de 120°. Bien entendu, on peut également envisager que le plancher de travail soit constitué d'un élément gonflable d'obturation unique occupant le trou annulaire 10 sur toute sa périphérie.As illustrated in FIGS. 2a, 2b and 2c, the annular hole 10 is closed using a work floor formed by a plurality of inflatable shutter elements 100 which can be 3 in number for example forming toroid arcs of 120 °. Of course, it can also be envisaged that the working floor consists of an inflatable single closure element occupying the annular hole 10 over its entire periphery.

Les éléments gonflables 100 sont destinés à être placés dans l'espace annulaire 10 entre les parois 11 et 12 qui le limitent. Ainsi qu'on peut le voir plus particulièrement sur les figures 2b et 2c, ces éléments gonflables 100 comprennent une pluralité de vessies gonflables 110, 120, 130 indépendantes enfermées dans une enveloppe 170 de protection.The inflatable elements 100 are intended to be placed in the annular space 10 between the walls 11 and 12 which limit it. As can be seen more particularly in FIGS. 2b and 2c, these inflatable elements 100 comprise a plurality of independent inflatable bladders 110, 120, 130 enclosed in a protective envelope 170.

De façon pratique, ladite enveloppe 170 de protection est réalisée en polyuréthane sans soufre, sans chlore ou autre halogène, de façon à éviter le problème de corrosion sous tension. Par contre, les vessies gonflables peuvent être en vynile souple. Les figures 2a et 2b montrent que l'enveloppe 170 se prolonge par des bavettes latérales 141, 142 destinées à s'appliquer contre les parois 11, 12 délimitant l'espace annulaires 10. Ces bavettes garantissent une parfaite étanchéité sur les bords du trou annulaire et facilitent, par simple rabattement, le nettoyage du plancher de travail.In practice, said protective casing 170 is made of sulfur-free polyurethane, without chlorine or other halogen, so as to avoid the problem of stress corrosion. On the other hand, the inflatable bladders can be made of flexible vinyl. FIGS. 2a and 2b show that the casing 170 is extended by lateral flaps 141, 142 intended to be applied against the walls 11, 12 delimiting the annular space 10. These flaps guarantee a perfect seal on the edges of the annular hole and facilitate, by simple folding, the cleaning of the work floor.

Comme l'indique la figure 2a en relation avec la figure 2b, dans le cas d'une pluralité d'éléments gonflables d'obturation, les extrémités desdits éléments gonflables 100 sont munies de moyens 151, 152, 153 de raccordement destinés à mettre en communication les vessies gonflables 110, 120, 130 homologues des éléments gonflables d'obturation.As indicated in FIG. 2a in relation to FIG. 2b, in the case of a plurality of inflatable obturation elements, the ends of said inflatable elements 100 are provided with connecting means 151, 152, 153 intended to put in place communicating the inflatable bladders 110, 120, 130 homologs of the inflatable obturation elements.

On peut observer sur les figures 2b et 2c que, pour chaque élément gonflable 100, les vessies gonflables indépendantes 110, 120, 130 forment au moins une configuration superposée. Cette disposition présente l'avantage d'assurer le maintien du plancher de travail même lorsque la (les) vessie(s) gonflable(s) de la partie supérieure de la configuration superposée viendrai(en)t à être crevée(s) à la suite d'un incident quelconque.It can be observed in FIGS. 2b and 2c that, for each inflatable element 100, the independent inflatable bladders 110, 120, 130 form at least one superposed configuration. This arrangement has the advantage of ensuring the maintenance of the work floor even when the inflatable bladder (s) of the upper part of the configuration superimposed will come to be punctured following any incident.

De façon à éviter ce type d'incident, et comme on peut le voir sur la figure 2b, il est avantageusement prévu que le plancher de travail selon l'invention comporte un élément rigide 160 de protection superposé à chaque élément gonflable 100 d'obturation, par l'intermédiaire par exemple de joncs souples 161, 162 de centrage. Cet élément 160 de protection, qui peut être en Kevlar (Marque déposée), assure la planéité du plancher de travail et permet de résister non seulement aux chocs et aux objets coupants, mais également aux projections incandescentes provenant des opérations de meulage ou de soudure.In order to avoid this type of incident, and as can be seen in FIG. 2b, it is advantageously provided that the work floor according to the invention comprises a rigid protective element 160 superimposed on each inflatable obturation element 100 , for example via flexible rods 161, 162 for centering. This protective element 160, which may be made of Kevlar (registered trademark), ensures the flatness of the work floor and makes it possible to withstand not only impacts and sharp objects, but also incandescent projections from grinding or welding operations.

La Demanderesse a effectué un essai de faisabilité avec un élément gonflable de 2 m de longueur et de 300 mm de diamètre, placé dans une maquette à l'échelle 1 représentative de l'espace annulaire situé à 1 m sous le tore d'alimentation d'un générateur de vapeur 900 MW. Les parois de la maquette ont été peintes pour leur donner un état de surface lisse.The Applicant has carried out a feasibility test with an inflatable element 2 m long and 300 mm in diameter, placed in a scale 1 model representative of the annular space located 1 m below the feed toroid d '' a 900 MW steam generator. The walls of the model were painted to give them a smooth surface.

L'élément gonflable a d'abord été légèrement gonflé sous une pression inférieure à 50 mb afin de lui donner sa forme géométrique, puis placé entre les parois de la maquette. Cette opération est simple et très rapide, quelques secondes pour un élément de 2 m. Ensuite, l'élément gonflable a été mis sous pression à 300 mb.The inflatable element was first slightly inflated under a pressure of less than 50 mb in order to give it its geometric shape, then placed between the walls of the model. This operation is simple and very fast, a few seconds for a 2 m element. Then, the inflatable element was pressurized to 300 mb.

Trois personnes sont montées sur l'élément gonflable. Celui-ci est très dur sous l'effet du gonflage, ce qui permet une excellente stabilité pour une marche normale. Plusieurs sauts ont été effectués par les trois personnes, d'un poids total de 200 kg. Aucun déplacement de l'élément gonflable n'a été constaté.Three people are mounted on the inflatable element. It is very hard under the effect of inflation, which allows excellent stability for normal walking. Several jumps were made by the three people, with a total weight of 200 kg. No displacement of the inflatable element was noted.

Les parois ont été ensuite mouillées avec de l'eau. Les mêmes opérations ont été recommencées comme pour l'essai précédent. Aucun déplacement n'a été davantage constaté.The walls were then wetted with water. The same operations were repeated as for the previous test. No displacement was further noted.

En fonctionnement, la pression de chaque vessie gonflable 110, 120, 130 est constamment contrôlée et asservie à une pression de consigne à l'aide de moyens d'asservissement montrés sur la figure 3. Des boîtiers 181, 182, 183 de commande détectent toute fluctuation de la pression P autour de la pression de consigne et commande les détendeurs 191, 192, 193 de réservoirs d'air comprimé, non représentés, jusqu'à ce que la pression soit revenue à la pression de consigne.In operation, the pressure of each inflatable bladder 110, 120, 130 is constantly monitored and slaved to a set pressure using servo means shown in Figure 3. Housings 181, 182, 183 control detects any fluctuation in the pressure P around the set pressure and controls the regulators 191, 192, 193 of compressed air tanks, not shown, until the pressure has returned to the set pressure.

Si une vessie supérieure, telle que la vessie 110 de la figure 2b, venait à être crevée, les vessies gonflables en position inférieure subiraient une augmentation de volume du fait de leur élasticité, ce qui provoquerait une diminution de pression qui serait immédiatement compensée à l'aide des moyens d'asservissement par un gonflage supplémentaire des vessies, lesquelles viendraient alors combler l'espace qu'occupait la vessie crevée.If an upper bladder, such as the bladder 110 of FIG. 2b, were to be punctured, the inflatable bladders in the lower position would undergo an increase in volume due to their elasticity, which would cause a reduction in pressure which would be immediately compensated for with the using the servo means by an additional inflation of the bladders, which would then fill the space occupied by the punctured bladder.

La figure 4a montre en vue de dessus la zone de sortie d'un séparateur cyclone du générateur de vapeur de la figure la. Comme on peut le voir, cette zone présente des espaces vides 20, répartis en trois secteurs, constitués par des orifices circulaires ou latéraux à travers lesquels des objets migrants peuvent passer lors de l'inspection annuelle effectuée dans cette zone.Figure 4a shows a top view of the outlet area of a cyclone separator of the steam generator of Figure la. As can be seen, this area has empty spaces 20, divided into three sectors, formed by circular or lateral orifices through which migrant objects can pass during the annual inspection carried out in this area.

Pour obturer ce type d'orifices, il est prévu, ainsi que l'illustrent les figures 4b et 4c, un plancher de travail comportant un élément gonflable 200 d'obturation comprenant pour chaque section, d'une part, une pluralité de vessies gonflables 210, enfermées dans une enveloppe 270, et, d'autre part, en partie inférieure, une vessie 220 de centrage sur ledit orifice 20.To close this type of orifice, there is provided, as illustrated in FIGS. 4b and 4c, a working floor comprising an inflatable closure element 200 comprising for each section, on the one hand, a plurality of inflatable bladders 210, enclosed in an envelope 270, and, on the other hand, in the lower part, a bladder 220 for centering on said orifice 20.

Dans l'exemple montré aux figures 4b et 4c, l'élément gonflable 200 a la forme d'un éventail qui, sous l'effet du gonflage, s'adapte à la géométrie du lieu où il est installé, ici un tiers de la zone à protéger. On notera également que, dans ce cas particulier, une seule couche de vessies est nécessaire et donc un seul dispositif d'asservissement de la pression.In the example shown in FIGS. 4b and 4c, the inflatable element 200 has the shape of a fan which, under the effect of the inflation, adapts to the geometry of the place where it is installed, here one third of the area to protect. It will also be noted that, in this particular case, a single layer of bladders is necessary and therefore a single pressure control device.

Claims (9)

  1. A working floor intended, in particular, for closing an empty space (10; 20) in a steam generator of a nuclear power station, the floor being characterized in that it includes at least one inflatable closure element (100; 200) comprising at least one inflatable bladder (110, 120, 130; 210) enclosed in a protective envelope (170; 270).
  2. A working floor according to claim 1, characterized in that when said empty space is an annular space (10) delimited by two walls (11, 12), said working floor includes at least one toroidal inflatable closure element (100) for placing in said annular space (10) between said walls.
  3. A working floor according to claim 2, characterized in that it includes a plurality of inflatable closure elements (100) in the form of arcs of a torus, the ends of said inflatable elements being provided with coupling means (151, 152, 153) for putting corresponding inflatable bladders (110, 120, 130) in the inflatable closure elements into communication with one another.
  4. A working floor according to claim 2 or 3, characterized in that each inflatable closure element (100) includes a plurality of independent inflatable bladders (110, 120, 130) forming at least one superposed configuration.
  5. A floor according to any one of claims 1 to 4, characterized in that said inflatable bladders (110, 120, 130) are connected to pressure servo-control means (181, 182, 183, 191, 192, 193).
  6. A working floor according to any one of claims 2 to 5, characterized in that each inflatable closure element (100) includes lateral bibs (141, 142) designed to bear against said walls (11, 12) delimiting said annular space (10).
  7. A working floor according to any one of claims 1 to 6, characterized in that at least one inflatable closure element includes a water level detector in the top portion thereof.
  8. A working floor according to claim 1, characterized in that when said empty space is formed by at least one orifice (20), said working floor includes an inflatable closure element (200) that comprises firstly a plurality of inflatable bladders (210), and secondly a bottom inflatable bladder (220) for centering it in said orifice (20).
  9. A working floor according to any one of claims 1 to 8, characterized in that it includes a rigid protective element (160) superposed over each inflatable closure element (100).
EP92403343A 1991-12-10 1992-12-09 Operating platform, especially for the steam generator of a nuclear power plant Expired - Lifetime EP0546937B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9115264 1991-12-10
FR9115264A FR2684791B1 (en) 1991-12-10 1991-12-10 WORK FLOOR, ESPECIALLY FOR STEAM GENERATOR OF NUCLEAR POWER PLANTS.

Publications (2)

Publication Number Publication Date
EP0546937A1 EP0546937A1 (en) 1993-06-16
EP0546937B1 true EP0546937B1 (en) 1996-02-07

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP92403343A Expired - Lifetime EP0546937B1 (en) 1991-12-10 1992-12-09 Operating platform, especially for the steam generator of a nuclear power plant

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EP (1) EP0546937B1 (en)
CN (1) CN1032171C (en)
DE (1) DE69208239T2 (en)
ES (1) ES2083715T3 (en)
FR (1) FR2684791B1 (en)
ZA (1) ZA929522B (en)

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA1141611A (en) * 1979-02-02 1983-02-22 Timothy H. Wentzell Nozzle plug for submersible vessel
US4703936A (en) * 1984-11-13 1987-11-03 Westinghouse Electric Corp. Sealoff device and method for controlling the level of a fluid within first and second communicating confined regions
US5048570A (en) * 1986-04-21 1991-09-17 Combustion Engineering Inc. Multisectioned nozzle dam
US4932441A (en) * 1988-05-18 1990-06-12 The Presray Corporation Nozzle dam seal assembly for nuclear steam generator or the like

Also Published As

Publication number Publication date
ES2083715T3 (en) 1996-04-16
FR2684791A1 (en) 1993-06-11
FR2684791B1 (en) 1994-05-20
EP0546937A1 (en) 1993-06-16
CN1074552A (en) 1993-07-21
CN1032171C (en) 1996-06-26
DE69208239T2 (en) 1996-08-29
ZA929522B (en) 1993-06-15
DE69208239D1 (en) 1996-03-21

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