EP0388296B1 - Intervention apparatus, particularly for the control, inspection and maintenance of heat exchangers - Google Patents

Description

The invention relates to an intervention device capable of hooking into the perforations of a tube plate of a heat exchanger fitted to a nuclear reactor and of moving on this plate, to carry out interventions such as operations of control, inspection and maintenance inside the exchanger tubes at the end of these tubes or on any other accessible part of the exchanger, using appropriate intervention tools.

Existing intervention systems can be classified into two categories.

In the first category, illustrated in particular by document FR-A-2 309 314, there are mobile devices which move by crawling on the tube plate of the steam generator. These devices, called "spiders", include a body in two parts able to move relative to each other in two orthogonal directions, parallel to the tube plate. Each of these parts of the device body is fitted with fastening means capable of engaging in the perforations of the tube plate. In order to allow the movement of the part which supports them, these attachment means also have the possibility of displacement in a direction perpendicular to the tube plate.

Intervention devices belonging to this first category have various drawbacks. In particular, the structure of the device limits its possibilities of movement to two imposed directions and according to an advance corresponding to the pitch of the network of perforations. As soon as the pitch of the network is changed, a different intervention device must therefore be used and devices of this type cannot be used when the perforations are not arranged in the two imposed directions. In addition, these limited displacement possibilities mean that certain tubes cannot be accessed when perforations are blocked or nonexistent.

These mobile intervention devices also have the disadvantage that they generally have to be introduced manually inside the exchangers. This introduction is always a delicate operation for the operator, taking into account the radioactivity which prevails inside the exchangers. In addition, if it has been envisaged to carry out the introduction and extraction of these intervention devices using auxiliary devices, these devices are relatively complex and difficult to use, so that they are not used in practice.

Finally, no intervention can be carried out when the vehicle is being moved.

In the second category of existing intervention devices, these devices include an anchoring block which is fixed at a well-determined point on the tube plate, so as to define a fixed point from which extends a arm, articulated or not, which supports an intervention tool at its free end. This type of device is illustrated in particular by the "ROSA" manipulator from the Westinghouse Company.

Such an intervention device generally has greater flexibility of use than mobile devices and can in particular be adapted to tube plates, the perforations of which are arranged in different networks and some of which may be blocked or nonexistent. However, it has in common with mobile intervention devices that interventions can only be made when all the organs that constitute it are immobile and perfectly positioned relative to the tube plate. In addition, the introduction of the intervention device into the exchanger also usually requires human intervention. Finally, when the anchoring block serving as a fixed point bears on the bottom of the exchanger cavity in which this device is placed, it is necessary to use different devices in exchangers having cavities of different dimensions.

The subject of the invention is precisely a mobile-type intervention device whose new, particularly simple design allows it to combine the advantages of mobile intervention devices and fixed-point intervention devices of the prior art, without present the disadvantages.

More specifically, the subject of the invention is a mobile intervention device designed so that it can be used on tube plates having perforations which may be closed off and arranged in any network, regardless of the dimensions of the cavity in which it is received, this device can also be inserted and extracted remotely and making it possible to carry out interventions at any time, even when it is moving.

• un bras de liaison articulé formé d'au moins deux segments rigides reliés entre eux par une articulation définissant un premier axe ;
• deux poignets montés à chacune des extrémités du bras de liaison et définissant chacun deux degrés de liberté de rotation autour d'un deuxième et d'untroisième axes orthogonaux entre eux ;
• deux plateaux supportés respectivement par chacun des poignets et comportant chacun des moyens de supportage d'au moins un outil d'intervention et des moyens d'accrochage aptes à venir en prise dans les perforations de la plaque ; et
• des moyens de motorisation aptes à commander des pivotements autour des premier, deuxièmes et troisièmes axes.

According to the invention, this result is obtained by means of an intervention device capable of hooking into the perforations of a tube plate of a heat exchanger and of moving on this plate, characterized by the fact that he understands:

• an articulated link arm formed of at least two rigid segments connected together by a joint defining a first axis;
• two wrists mounted at each end of the link arm and each defining two degrees of freedom of rotation about a second and a third orthogonal axis therebetween;
• two plates supported respectively by each of the wrists and each comprising means for supporting at least one intervention tool and attachment means capable of engaging in the perforations of the plate; and
• motorization means capable of controlling pivoting around the first, second and third axes.

It is understood that a device thus designed has degrees of freedom which allow it to adapt to all types of perforation networks. In addition, an intervention is always possible on the plate whose hooking means are engaged in the perforations of the tube plate, while the second plate is moving. Since the travel time is much less than the duration of an intervention, two interventions can practically be carried out simultaneously, which constitutes a decisive time saving compared to current devices.

The intervention device according to the invention also makes it possible to adapt to the case where the tube plate comprises blocked or non-drilled tubes which would prohibit intervention on certain tubes with the existing devices. Indeed, the degrees of freedom of the wrists then allow, in many cases, to hang the tray in another position. In addition, if such a hooking is still impossible, the intervention can still be done using the device in the manner of a fixed point device hooked to the plate by the plate opposite to that carrying the tool which performs the 'intervention.

Advantageously, the first axis is orthogonal to a longitudinal axis of each of the segments and each of the second axes is parallel to this first axis. Since the plates have a suitable flat surface coming to bear on the tube plate, each of the third axes is then perpendicular to the flat surface of the plate supported by the wrist comprising this third axis.

In order to allow the device to be inserted and removed from a distance in the exchanger, the articulated link arm preferably has a maximum length such that, when the hooking means of one of the plates are engaged in the perforations of the tube plate, the other plate is located in a manhole formed in an outer casing of the heat exchanger or outside of the latter.

In this case, the device further comprises a table provided with perforations in which the hooking means of the plates can come into engagement, and lifting means making it possible to move this table between a low position, relatively distant from the heat exchanger. heat, and a high position, located opposite the manhole, in the immediate vicinity of the outer shell of the exchanger.

To complete the universal character of the device with respect to the networks of perforations formed in the plates of the exchangers, the plates are advantageously mounted on the wrists in a removable manner by removable fixing means.

• la figure 1 est une vue de côté représentant de façon schématique l'introduction d'un dispositif d'intervention conforme à l'invention dans la boîte à eau d'un générateur de vapeur ;
• la figure 2 est une vue de dessous représentant de façon schématique le dispositif d'intervention de la figure 1 suspendu à la plaque à tubes du générateur de vapeur ;
• la figure 3 est une vue en coupe représentant à plus grande échelle la motorisation de l'articulation reliant les deux segments rigides du bras de liaison articulé du dispositif d'intervention des figures 1 et 2 ;
• la figure 4 est une vue en coupe comparable à la figure 3 représentant les moyens de raccordement déconnectables des segments rigides qui sont associés à l'articulation reliant les segments ;
• la figure 5 est une vue de côté, partiellement en coupe, des moyens de raccordement déconnectables de la figure 4 ;
• la figure 6 est une vue de côté, en coupe partielle, représentant le poignet et le plateau qui sont montés à l'extrémité libre de chacun des segments rigides du bras de liaison articulé ; et
• la figure 7 est une vue de dessous, en coupe partielle, du plateau représenté sur la figure 6.

A preferred embodiment of the invention will now be described, by way of nonlimiting example, with reference to the appended drawings in which:

• Figure 1 is a side view schematically showing the introduction of an intervention device according to the invention in the water box of a steam generator;
• Figure 2 is a bottom view schematically showing the intervention device of Figure 1 suspended from the generator tube plate steam;
• Figure 3 is a sectional view showing on a larger scale the motorization of the articulation connecting the two rigid segments of the articulated link arm of the intervention device of Figures 1 and 2;
• Figure 4 is a sectional view comparable to Figure 3 showing the disconnectable connection means of the rigid segments which are associated with the joint connecting the segments;
• Figure 5 is a side view, partially in section, of the disconnectable connection means of Figure 4;
• Figure 6 is a side view, in partial section, showing the wrist and the plate which are mounted at the free end of each of the rigid segments of the articulated link arm; and
• FIG. 7 is a bottom view, in partial section, of the plate shown in FIG. 6.

In FIG. 1, a part of the lower end of a steam generator of a nuclear reactor is shown diagrammatically, in which the intervention device according to the invention can be used. However, it will be observed that this application is not limiting and that the intervention device according to the invention can be used in heat exchangers of different types, such as condensers.

The steam generator partially shown in Figure 1 comprises an outer casing 10 having a vertical axis of symmetry. A horizontal tube plate 12 is connected to the casing 10 to delimit with the hemispherical bottom of the latter a primary cavity 14, generally called a water box. This cavity 14 is divided into an entry area and an exit area by a vertical partition 16. A manhole 18 normally closed by a door (not shown) is formed in the hemispherical lower part of the envelope 10, in order to allow access to each of the entry and exit zones of the primary cavity 14. Finally, a bundle of inverted U-shaped tubes 20 is connected to perforations 20a of the tube plate 12, so that each of these tubes opens at opposite ends respectively into the entry zone and into the exit zone of the primary cavity 14. The perforations 20a of the tube plate 12 are arranged in a network, the shape and pitch of which can vary according to the type of steam generator considered.

According to the invention, an intervention device 22 is used to remotely carry out all the tasks which must be carried out inside the steam generator. Among these tasks, mention will be made in particular of checking, inspecting and maintaining the tubes 20 or any other part accessible to the device. It is important to note that this device can be used regardless of the nature of the tasks to be performed, so that the list of tasks which has just been given should not be considered as limiting.

The intervention device 22 is provided for catching in the perforations 20a of the tube plate 12. It is also provided for moving on this plate 12, so as to be able to access the entire surface of the tube plate, whatever the shape and the pitch of the network formed by the perforations 20a, and despite the possible presence of blocked or non-pierced tubes, or bulky obstacles.

In order to illustrate the possibilities of introducing the intervention device 22 into the primary cavity 14 of the steam generator remotely and without human intervention, this device is represented in FIG. 1 in three different positions I, II and III which will be explained later. Previously, the structure of the intervention device 22 will be described briefly with reference to FIGS. 1 and 2.

The intervention device 22 firstly comprises an articulated connecting arm formed by two rigid segments 24a and 24b connected together by a hinge 26. Over most of their length, the rigid segments 24a and 24b have longitudinal axes rectilinear which are orthogonal to the pivot axis A defined by articulation 26.

The rigid segments 24a and 24b are of the same length and bear at their ends opposite the articulation 26 of the wrists 28a and 28b respectively. Each of these wrists defines two degrees of freedom of rotation about an axis B parallel to the axis A and an axis C orthogonal to the axis B.

Each wrist 28a and 28b supports a plate 30a and 30b having a flat surface 31a, 31b capable of coming to bear on the underside of the tube plate 12 and oriented perpendicular to the axis C of the wrist supporting this plate.

Each of the plates 30a and 30b of the intervention device comprises hooking means constituted by expandable members 32 which protrude beyond the flat face 31a, so as to be able to come into engagement in the perforations 20a of the plate to tubes 12. Each plate 30a supports for example four expandable members 32, arranged for example in a square as illustrated in FIG. 2, in accordance with the network formed by the perforations 20a.

Each of the plates 30a and 30b also includes a support 34 in which an intervention tool adapted to the task to be performed can be mounted.

Finally, motorization means which will be described later make it possible to control the relative rotational movements around the axes A, B and C.

As illustrated in FIGS. 1 and 2, the intervention device 22 according to the invention can move on the tube plate practically without limitation, since the degrees of freedom around the axes B and C presented by each of the wrists 28a and 28b make it possible to bring one of the plates, such as the plate 30b opposite any point of the tube plate when the other plate, for example 30a, is fixed on the latter by its expandable members 32. It is thus possible to position and orient the plate 30b in such a way that its expandable members can be introduced into the perforations 20a, even when some of these perforations are blocked or absent.

In addition, one can access relatively quickly a perforation remote from the anchor formed for example by the plate 30a.

In addition, since each of the plates 30a, 30b includes a support 34 capable of receiving a tool, the device is moved while one of the tools is in operation. The travel time is generally much less than the time necessary for an intervention, it can therefore be considered that the device according to the invention allows two simultaneous interventions on two different tubes included in the field of action of this device, without a rule fixed and imposed by the intervention device governs the relationship between the Cartesian coordinates of these two tubes.

As illustrated in FIG. 1, the intervention device 22 according to the invention is advantageously dimensioned so that the maximum length of the articulated connecting arm constituted by the two rigid segments 24a and 24b is such that, when the expandable members 32 associated to one of the plates such as the plate 30a are engaged in the perforations 20a of the tube plate, the plate 30b is located in the manhole 18 or outside the steam generator.

Thanks to this characteristic and by adding to the device a table 36 associated with lifting means constituted for example by a carriage 40 movable on a rail 38, it is possible to set up the intervention device 22 inside the generator. steam and extract it without the need for an operator in the immediate vicinity of the steam generator.

When the rail 38 and the carriage 40 carrying the table 36 have been put in place, the table 36 is placed in the low position and the expandable members of one of the plates, for example the plate 30b, are introduced into perforations 36a formed for this purpose on the upper face of the table 36.

The device 22 being placed in its fully expanded position, the introduction of the device inside the steam generator can be remotely controlled using an appropriate motorization system associated with the carriage 40 (position I on the figure 1). These motorization means make it possible to raise the table 36 carrying the intervention device 22, following a trajectory such that this device progressively penetrates into the primary cavity 14.

Given that each of the movements of the intervention device 22 is controlled by an appropriate motorization, it is thus possible, either by means of prior programming, or by manual control permitted thanks to the information provided by one or more cameras mounted, by example, on the plates 30a and 30b, bring the expandable members 32 of the other plate 30a opposite the perforations 20a of the tube plate 12 (position II in FIG. 1). The table 36 then occupies a high position located approximately at the level of the manhole 18. The attachment of the plate 30a is thus carried out on the tube plate. When the expandable members 32 of the tray 30a are fixed in the perforations 20a of the tube plate 12, the expandable members associated with the tray 30b can be released so as to separate the latter tray from the table 36. The latter is then lowered at least partially along the rail 38 and the device 22 can move to carry out the interventions to be carried out (position III in FIG. 1).

Different construction details of the intervention device 22 will now be described with reference to FIGS. 3 to 7.

In FIG. 3, the motorization means are shown making it possible to control the relative pivoting of the rigid segments 24a and 24b about their articulation axis A. It should be noted that these motorization means are identical to those which make it possible to control , in each of the wrists 28a and 28b, the pivoting around the axes B.

At its end corresponding to the joint 26, the rigid segment 24a carries a tubular external part 42 centered on the axis A. This external part 42 rotatably supports an internal tubular part 44, by means of two bearings 46.

The stator 48a of an electric motor 48 is fixed inside the external part 42, in a position offset along the axis A relative to the internal part 44. The rotor 48b of the motor 48 is fixed on a shaft 50 centered on the axis A and rotatably supported both in the part 42 and in the part 44, by means of two bearings 52. The motor 48 thus controls a relative rotation between the shaft 50 and the external part 48. This rotation is transmitted from the shaft 50 to the part 44 by a speed reduction mechanism 54 of the "Harmonic-drive" type. This reduction gear, shown very diagrammatically in FIG. 3, comprises in a known manner a deformable satellite 54a, mounted on the shaft 50 by an elliptical bearing, and which engages simultaneously on a sun gear 54b fixed to the external part 42 and on a planetary 54c fixed to the inner part 44.

As illustrated in FIG. 4, the end of the second rigid segment 24b corresponding to the articulation 26 is fixed to the part 44 by means of a disconnectable connection mechanism 56.

This mechanism comprises a dish 64 in the form of a bowl, fixed by its peripheral part to the part 44, on the side opposite to the motor 48, by means of screws 65. The bottom of the plate 64 projects outwards, away from the motor 48, and comprises in its center, placed on the axis A, an approximately rectangular slot 62. Furthermore, a cylindrical rod 58 is mounted along the axis A in a bore 59 formed in the segment 24b. The end of the rod 58 located on the side of the plate 64 comprises a head 60 provided with flats allowing it to pass through the slot 62, or on the contrary to be in abutment on the plate 64, according to its orientation around the axis A This orientation is limited by a circular arc groove 61 formed on the rod 58 and into which a screw 76 mounted in the end of the segment 24b penetrates. The cooperation of the screw 76 with the groove 61 also limits the axial movement of the rod 58 inside the bore 59.

In its part opposite the head 60, the rod 58 has a threaded end 63 which projects into a recess 65 formed on the outer face of the segment 24b, along the axis A. A nut 67 screwed onto the threaded end 63 of the rod 58 is supported on a cylindrical rod 69 of axis perpendicular to the axis A, this rod 69 being crossed by the threaded end 63.

The cylindrical rod 69 is rotatably mounted on an operating lever 66 provided with a cam surface 66a eccentric with respect to the axis of the rod 69. A spring 68 interposed between the rod 58 and the segment 24b, at l 'Inside the bore 59 formed in the latter, allows to permanently press the nut 67 against the rod 69 and the cam surface 66a against the recess 65 formed on the outer surface of the segment 24b.

The lever 66 is normally held against the exterior surface of the segment 24b by a latch 70 as illustrated in FIG. 4. Any rotation of the rod 58 is then impossible and the orientation of the head 60 relative to the opening 62 is such that the segment 24b is secured to the plate 64. Complementary frustoconical surfaces formed on these two parts then make it possible to ensure correct centering around the axis A. In addition, these two parts cooperate by lugs 72 fixed on the plate 64 and penetrating into notches 74 formed in the segment 24b, as illustrated in FIG. 5, so that their relative angular positioning is ensured precisely.

When it is desired to separate the arms 24a and 24b, for example to transport the intervention device 22 to its site of use, the lock 70 is unlocked and the lever 66 is pivoted around the rod 69. Given that the axis of this rod is eccentric relative to the axis of the cam surface 66a, the rod 58 then moves slightly to the left when considering FIG. 4, under the action of the spring 68. A rotation of approximately 90 ° around the axis A of the assembly formed by the rod 58 and the lever 66 is then made possible. This rotation has the effect of bringing the head 60 into a position allowing it to pass through the slot 62 of the plate 64. The segment 24b can then be separated effortlessly from segment 24a.

The assembly of these two segments is carried out when desired by performing the opposite operations to those which have just been described.

The structure of the wrists and plates of the intervention device according to the invention will now be described in detail with reference to FIGS. 6 and 7.

In FIG. 6, the reference 78 generally designates a geared motor assembly similar to that which has been described previously with reference to FIG. 3, making it possible to control the pivoting movement around the axis B between the segment 24a and a square-shaped part 80 belonging for example to the wrist 28a. The structure of the wrists 28a and 28b and of the plates 30a and 30b being identical, the description which follows of the wrist 28a and of the plate 30a also applies to the wrist 28b and to the plate 30b.

The square-shaped part 80 is fixed by means of screws (not shown) on the part 44 (FIG. 3) of the geared motor assembly 78, so that it can rotate around the axis B. In addition, this part 80 rotatably supports, around the axis C, which is perpendicular to the axis B, an annular part 92, by means of a bearing 82.

The square-shaped part 80 also supports a second geared motor assembly 84 whose output shaft 86, of axis parallel to the axis C, drives a pinion 88 which meshes in an internal toothed ring 90 of the part 92. An actuation of the geared motor assembly 84 thus makes it possible to control a pivoting of the part 92 around the axis C, relative to the part in the form of a square 80.

As shown in Figures 6 and 7, the plate 30a is removably attached to the annular part 92 for example by means of screws 95. The plate 30a supports the expandable members 32 as well as the support 34 of the intervention tool, and it has the flat surface 31a, perpendicular to the axis C, capable of coming to bear on the underside of the tube plate 12.

This removable nature of the plate 30 carrying the expandable members 32 makes it very easy to adapt the intervention device 22 according to the invention to tube plates 12 whose perforations 20a are arranged according to different networks. Indeed, it suffices for this to fix on the annular part 92 of each wrist a plate 30a carrying expandable members 32 arranged in a network coinciding with that formed by the perforations of the tube plate.

The expandable members 32 can be produced in any way, according to techniques well known to specialists. Thus and only by way of example, these members may comprise a segmented tubular part whose increase in diameter is controlled by the axial displacement of a ball actuated by a pneumatic cylinder. Conduits 96 allowing the control fluid to be conveyed from these jacks are then provided in the annular part 92, as illustrated in FIG. 6.

The control of the electric motors ensuring the various movements of the axes A, B and C, as well as the control of the expandable members 32 are carried out remotely, by means of a set of cables and conduits shown very schematically at 98 on the figure 1. These cables and conduits can also be used to convey other information, such as information delivered by coders (not shown) which can be associated with each of the gearmotor assemblies and by cameras which can in particular be mounted on the plates 30a and 30b or any other point inside the primary cavity 14 of the exchanger.

The intervention device according to the invention is remotely controlled, by means of a control system 100 to which the cables and pipes 98 terminate and which can be produced in different ways. Thus, a "sight" command can be envisaged with the help of the information provided by the cameras. This "sight" command can also be supplemented by means for controlling the various movements between them, making it possible to maintain the intervention device permanently in a posture favoring the introduction of the expandable members 32 into the perforations 20a of the plate. with tubes, during its displacement. Finally, it is also possible to provide for a fully automated movement of the intervention device 22, by means of a previously established program, for example by means of a learning operation.

Of course, the invention is not limited to the embodiment which has just been described. Thus, it will be understood in particular that the articulated link arm can be formed of three or more rigid segments, in certain specific cases, and that these segments can be of equal length or of different lengths. It will also be understood that each of the plates can support more than one tool and that the removable nature of the articulation connecting the two segments of the arm can be eliminated or produced differently. The removable nature of the trays can also be eliminated in certain applications. Finally, the lifting means making it possible to move the table carrying the device when it is inserted into the steam generator and when it is extracted can be produced in a different way, for example by means of several rails or a cable system.

Claims (8)

1. Intervention device which can be fastened into the perforations of a tube plate of a heat exchanger and can move on said plate, characterized in that it comprises an articulated connecting arm formed by at least two rigid segments (24a, 24b) introduced by an articulation (26) defining a first axis, two handles (28a, 28b) mounted at each of the ends of the connecting arm and each defining two degrees of rotation freedom about second and third axes (B, C) orthogonal to one another, two plates (30a, 30b) respectively supported by each of the handles and each having means (34) for supporting at least one intervention tool and fastening means (32) which can engage in perforations of the plate and motorization means (48, 78, 84) able to control the pivoting about the first, second and third axes.
2. Device according to claim 1, characterized in that the first axis (A) is orthogonal to a longitudinal axis of each of the segments (24a, 24b) and in that each of the second axes (B) is parallel to said first axis.
3. Device according to either of the claims 1 and 2, characterized in that each of the plates (30a, 30b) has a planar surface (31a, 31b) able to bear on the tube plate and in that each of the third axes (C) is perpendicular to the planar surface of the plate supported by the handle having said third axis.
4. Device according to any one of the preceding claims, characterized in that there is also a table (36) provided with perforations (36a) and in these can engage the fastening means (32) of one of the plates and lifting means (38, 40) making it possible to move the table between a bottom position, relatively remote from the heat exchanger, and a top position facing the manhole and in the immediate vicinity of the external envelope of the heat exchanger.
5. Device according to claim 4, characterized in that the articulated connecting arm has a length such that when the fastening means of one of the plates are in engagement in the perforations (36a) of the table (36) and when the latter is in the top position, the fastening means (32) of the other plate can engage in the perforations of the tube plate.
6. Device according to any one of the preceding claims, characterized in that there are also means (56) for the disconnectable coupling of the rigid segments associated with said articulation.
7. Device according to any on of the preceding claims, characterized in that the plates (30a, 30b) are mounted on the handles (28a, 28b) in detachable manner by dismantlable fixing means (95).
8. Device according to any one of the preceding claims, characterized in that the motorization means (48, 78) controlling the pivoting about the first and second axes (A, B) are identical.

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