WO1992007363A1 - Device and method for performing repairs along a non-plane wall - Google Patents

Abstract

Device (18) and method for performing repairs in a space (7) defined by at least one non-plane wall (6), accessible by at least one opening (17, 17'). The device includes a moving support for a device (20) for performing repairs in said space, said moving support being suitable for insertion into the opening, means for guiding and supporting the moving support along the non-plane wall comprising a rail (29) for guiding and supporting the moving support, said means being suitable for insertion into the opening and being flexible in the longitudinal direction and rigid in the transverse direction. The device also includes clamping means (37, 37') for holding the rail against said wall, said clamping means being arranged to removably secure said rail on said wall, and means (32, 40, 40', 45, 46) for remotely controlling movement of the moving support along the rail.

Description

 DEVICE AND METHOD FOR INTERVENING ALONG A NON-ZERO CURVATURE WALL

The present invention relates to a device and a method of intervention in a space delimited by at least one non-zero wall of curvature, accessible by at least one opening.

It finds a particularly important, although not exclusive, application in the field of maintenance of nuclear reactor steam generators, which in particular requires interventions in the annular space formed by the external wall of the generator and the shell of the tube bundle, above the generator tube plate, for cleaning and / or observing the condition of the lower parts of the bundle tubes. This annular space is accessible by fist holes located opposite the bundle shell, above the tubular plate.

Intervention devices are already known which allow the cleaning and / or observation, on the secondary side, of the lower part of the tube bundle of a steam generator. These devices have drawbacks. In particular, they do not allow access to all of the tube feet, for example for cleaning. There is thus a device making it possible to move a tool between the two central plies of the tube bundle, below the ferrule, in the median plane located opposite a fist hole. Such a device does not allow access to a whole series of locations, in particular those located in the extension of the tubes of said plies. In addition, the devices of the prior art do not allow, in an effective and sufficient manner, to intervene while along the non-zero wall of curvature that constitutes the shell of the beam.

The present invention aims to provide a device and a method which respond better than those previously known to the requirements of practice, in particular in that it allows access all along the periphery of a wall of non-zero curvature in at least one space. delimited by said wall, accessible by at least one opening, over a length of up to several meters, and this in a simple manner, without modification of the physical integrity of the wall, with increased efficiency compared to the prior art and a reduced implementation cost.

In the case of an application of the invention to the maintenance of a steam generator, it allows access to the annular space around the entire periphery of the shell of the bundle, as well as to all the spaces between tubes located above the tube plate. I_e device can, moreover, be set up quickly and controlled remotely, which is advantageous in the case of its use in an environment made hostile by radioactivity.

For these purposes, the invention proposes in particular an intervention device in a space delimited by at least one non-zero curvature wall, accessible by at least one opening, characterized in that it comprises:

a carriage for supporting an intervention apparatus in said space, said carriage being suitable for being introduced through the opening,

- means for guiding and supporting the carriage along the non-zero curvature wall, comprising a guide rail and supporting the carriage, suitable for being introduced through the opening, flexible in the longitudinal direction and rigid in the direction transverse, and clamping means suitable for pressing the rail on said wall, arranged to removably fix said rail on said wall, and

means of remote control of the movement of the

_ carriage along the rail. o

In preferred embodiments, use is made of one and / or the other of the following arrangements:

- the guide rail is made of composite material based

„- of a thermosetting material reinforced with fibers or 10 threads;

- the rail is arranged to adopt a configuration in

S with radii of curvature less than 1 • order of

800mm when introduced through the opening;

„_ - the thermosetting material being an epoxy resin, the fibers or threads are essentially arranged parallel to the transverse direction of the rail; the rail has two parallel longitudinal bosses, for supporting the rail on the curvature wall

_Λt . not zero; 20

- Each boss comprises a cylindrical recess provided with an internal rod of longitudinal stiffening of the rail, of the piano string type;

the means for remote control of the movement of the carriage comprise a flexible strip in the longitudinal direction, integral with the carriage and arranged to be guided by the rail, and a motor assembly designed to exert a pulling or pushing force on said strip, and the rail has a longitudinal recess, open on the side opposite to the wall on which the rail is pressed, and having on each side a longitudinal flange for guiding the flexible strip integral with the carriage, the internal walls of said recess being able to cooperate with friction soft with said strip; - The electrical connection means of the carriage, and of the device which it supports, comprise a cable-carrying chain arranged to adopt an S-shaped configuration with radii of curvature less than around 800

5 _ mm.

- The device is arranged to be used to intervene in the annular space located, grille side, above a horizontal tubular plate of heat exchanger, the opening being constituted by a fist hole, located opposite of the ferrule of the bundle of tubes constituting the non-zero curvature wall.

By fist hole is meant an inspection opening, in the wall of the generator, of diameter, between 100 and 200 mm.

15

The invention also provides a method of intervention in the annular space located around the tube bundle and above the tube plate of a steam generator of a nuclear reactor,

__._ characterized in that: 20

- Introduced through a fist hole opposite the shell of the tube bundle, a flexible rail in the longitudinal direction, and rigid in the transverse direction, for supporting a carriage for guiding and holding a device d 'intervention,

- The rail is removably fixed on the ferrule or on the internal face of the generator wall, by pressing it on said ferrule, or wall, by clamping and tensioning, or compression, of the rail in the longitudinal direction against said ferrule, or wall,

- the carriage is introduced through the fist hole,

- said carriage is hung on the guide rail and, after fixing of the intervention apparatus on the carriage, - the carriage is moved longitudinally and at a distance along the rail to bring it to a determined position relative to the ferrule, to allow

1 • intervention.

In an advantageous embodiment, the steam generator having two diametrically opposed fist holes, the rail is fixed with a length substantially equal to a half-perimeter of the ferrule, by putting it in tension against said ferrule, between the 1 „0__ , two fist holes. Another solution is to put the rail between the two fist holes, in compression on the internal face of the generator wall.

The invention will be better understood on reading the following description of a particular embodiment given by way of non-limiting example.

The description refers to the accompanying drawings in which:

Figure 1 is an exploded schematic view of a nuclear reactor steam generator, on which are advantageously used the device and method according to the invention.

FIG. 2 is an exploded artist view, showing diagrammatically an embodiment of a part of the device of the invention, applied to the control of the steam generator of FIG. 1.

Figure 3 is a cross-sectional view of the flexible rail of the embodiment of Figure 2 more particularly described here.

FIG. 4 is a partial top view of the embodiment of a device of the type shown in FIG. 2, disposed between two diametrically opposite fist holes of the steam generator of FIG. 1. FIG. 5 is a diagram showing, in the form of blocks, the various elements of the control means of the device of FIG. 4.

Figure 1 shows a heat exchanger 1, said

_ steam generator, in exploded view, of the type 5 commonly used in pressurized water nuclear reactors.

It comprises a cylindrical envelope 2 which contains a bundle of U-shaped tube 3, the parts of which

. ₀ terminals 4 pass through a tubular plate 5. The bundle 2 comprises an envelope, or external ferrule,

6 cylindrical which delimits with the internal wall of

1 • envelope 2, an annular space 7 over part of the height of the generator. The ferrule 6 is fixed to the bundle and comprises a lower part 8 situated at a distance of several cm from the plate 5, thus freeing access to the feet 9 of the tubes, and to the inter-tube spaces, above the plate 5. This delimits with the bottom 10 of the generator and a partition

__ 11, a cold water box 12 and a hot water box 13. The water from the primary circuit of the reactor follows the paths indicated by the arrows 14.

Part 15 of the steam generator between the casing 2 and the bundle 3 is occupied, during operation, by the secondary coolant of the reactor and therefore belongs to the secondary circuit. This part 15 is isolated and drained, for maintenance or repair, in a manner known per se.

The envelope 2 comprises in the lower part 16, two fist holes 17, with diameters of the order of 150 mm, diametrically opposite, for access to the annular space 7.

Figure 2 shows, in artist view, part of the embodiment of the device 18 according to the invention more particularly described here, arranged on the shell 6 of the bundle 3 of the generator 1.

The device 18 comprises a carriage 19 for supporting an apparatus 20 for intervention in space

_* - annular 7, on the feet 9 of the tubes 21 of the bundle

3, and in the inter-tube spaces 22, above the plate 5, over the entire thickness of the beam.

The intervention apparatus 20 is, for example and without limitation, a lance for cleaning

M _Q supplied with high pressure water (for example 50 bars), or a television inspection system with lighting device and built-in miniature television camera, or a combination of the two. The carriage and the device are arranged so that _they can be introduced through the fist hole 17.

The device 20 is fixed to the carriage 19 by means 23 for vertically moving the device along the shell, as well as between the lower part 8 of the latter and the tube plate 5.

₂₀ The design of the means 23 is within the reach of the skilled person, and may for example comprise a machined rod ball screw shown schematically at 24 in Figure 2, whose rotation is actuated by a stepper motor to numerical control 25, the device rising _g or descending along the rod 24 due to this rotation.

The exact position of the device along the vertical axis 26 of the rod 24 is determined in a manner known per se, for example by an encoder system _fl (not shown).

Means for rotating the device 20 around the vertical axis 26, to bring it into a determined position, are provided. Advantageously, a part 27 of the apparatus, of the camera or high pressure lance tip type, is moreover arranged to rotate. around the horizontal axis 28 or pivot in a vertical plane, relative to this axis. The assembly constituted by the carriage, the means for supporting and moving and / or rotating the apparatus, and _ the apparatus itself, weighs for example on the order of 3 kg.

The device 18 of the invention also comprises a rail 29, for guiding and supporting the carriage, suitable for being introduced by the punch hole _1Q 17, flexible in the longitudinal direction 30 and rigid in the transverse direction 31, so as to be able to be pressed against the outer shell 6 of the tube bundle 3.

The rail is arranged to be able to adopt, during

1.5_ its introduction, an S-shaped configuration with radii of curvature less than around 800mm, given the limited space available at this location, in the building cell where the steam generator is located.

_2Q The carriage 19 is provided with an upper part 19 ′, partially in the form of a hook or an inverted U, which allows it to be hung on the upper part 29 ′ of the rail. The internal surface of the hook is for example a friction surface intended to

__ interact with the bearing surface of the upper part 29 'of the rail; other arrangements can be made, for example a system of rollers with vertical axes integral with each branch of said hook, making it possible to minimize friction between rail and. cart. The body of the trolley itself is of design within the reach of those skilled in the art, and is moreover provided with means, such as a wheel encoder for example, of measuring the distance traveled by the trolley on the rail. There is shown in phantom in Figure 2, schematically, a strip 32 constituting a part of the remote control means of the movement of the carriage 19 along the rail 29, which go

. be detailed later.

FIG. 3 is a cross-sectional view of the rail 29 of FIG. 2 pressed against the ferrule 6.

The rail is made of composite material, for example aramid fibers of the Kevlar type, and of epoxy resin, the Kevlar fibers being essentially arranged parallel to the transverse direction of the rail, for example of the order of 80% of the fibers by weight. are parallel to the transverse direction.

Its width is, for example, 5 cm and its _ length can be several meters, for example of the order of 3 meters. It is in fact a function of the perimeter of the ferrule of the tube bundle, and of the use of one or two fist holes, to fix the rail on the ferrule. The rail is, ₀ elsewhere, arranged to be used at a temperature of up to about 60 ^β C with 100% humidity in the presence of condensation, and in an environment where the dose rate can be of '' order of 20 Rd / hour (0.2 gray / h). g The rail 29 comprises, for example, two longitudinal, parallel bosses 33, bearing on the wall of the ferrule 6.

Each boss comprises a cylindrical recess 33 ′ provided with an internal ring 34 of ₀ longitudinal stiffening, of the piano string type.

The means for remote control of movement of the carriage 19 comprise the strip 32 shown in phantom in Figures 2 and 3. The strip is secured to the carriage, for example by being fixed to the carriage by screws; it is for example made in metallic alloy based on copper and nickel; it is flexible in the longitudinal direction and is arranged to be guided by the rail.

In the embodiment more particularly described here, this guidance is done as follows:

The rail 29 has a longitudinal recess 35, open on the side opposite to the bosses 33. The recess 35 has on each side, a longitudinal edge 36, the internal walls of said recess being able to cooperate with gentle friction with the strip. The carriage 19, not shown in Figure 3, is hung on the upper edge 29 'of the rail.

Figure 4 shows in top view, the device 18 of the invention according to the embodiment more particularly described here, installed on the outer ring of the bundle between the two fist holes 17 and 17 '. The view in Figure 4 has been fragmented to show only the significant parts of the device.

As described above, it comprises the carriage 19 hooked on the guide rail 29. The rail

29 is applied to the ferrule 6 by the means 37 and

37 'of clamping suitable for pressing the rail on said ferrule, and arranged to thus detachably fix the rail on the ferrule.

Each clamping means 37, 37 'comprises a clamping arm 38, 38' passing through the corresponding fist hole 17, 17 '. These arms comprise means known in themselves, for example hydraulic, suitable for pressing the rail on the ferrule by exerting a thrust in the radial direction of the ferrule 6, on the one hand, and tangential to the ferrule towards the side opposite rail 29, on the other hand. Each clamping arm is fixed on the outer periphery of the fist hole correspondents 17, 17 *, via bases

39, 39 'of fixing.

The means for remote control of the movement of the carriage along the rail 29 comprise a motor assembly 40, 40 ′ designed to exert a pulling or pushing force on the strip 32 integral with the carriage. These means comprise, for example, two stepping motors 41, 41 *, electric with numerical control, for winding and unwinding the strip ₀ , around drums 42, 42 ′ actuated in rotation by said motors via for example toothed pinions ( not shown) and fixed to means 39, 39 '. the electrical connections of the carriage 19 and of the device which it supports, comprise a cable-carrying chain 43, arranged to adopt, at the passage 44 of the fist hole 17, an S configuration with a radius of curvature of the order of 50 cm.

The cable-carrying chain is also provided for conveying the water or air pressure pipes which are, for example, fixed therein in a removable manner and known per se.

The remote control means include a box 45 for local control and a remote control unit 46 by an operator 47 located at a distance from the exchanger.

FIG. 5 shows a diagram essentially showing in the form of blocks, the various elements of the control means of the device of FIG. 4.

As we have seen, these control means comprise the motor assemblies 40, 40 'for moving the carriage, arranged near the fist holes 17, 17' and connected to the box 45 for local control. The device also comprises a set 47 of actuation and vertical displacement, in rotation and in inclination relative to the horizontal plane, of the intervention apparatus 20 fixed to the carriage.

The assembly 47 is connected to the box 45.

A video box 48 is provided, controlled by the box 45. It is connected on one side to a matrix camera with charge coupling 49, called CCD, for observing the top of the tube plate.

The camera is fixed to the carriage and is provided with ^• an illumination system, the light being supplied from outside of the exchanger in a manner known per se, for example by optical fiber.

The video box 48 is connected on the other side to a PC type microcomputer, arranged to process and reconstruct the digital images from the CCD camera 49.

The control box 45 is programmable. It is connected to a microcomputer of the PC type, which allows the programming of the movement of the carriage along the rail, the operation of the video means and / or the cleaning device (for example), as well as the movement means. of the device relative to the device, with great precision (for example to within ± 2 mm for moving the carriage on the rail).

We will now describe the method of the invention applied to the annular space located around the tube bundle and above the tube plate, between two fist holes, of the steam generator of FIG. We will refer in particular to FIG. 4.

After stopping the reactor and emptying the steam generator 1, secondary side, the fist holes 17 and 17 'are open. One end of the flexible rail 29, which is pushed horizontally into the annular space which guides it, is introduced manually by one of them, for example 17, until this appearance of said screw end 1 • another punch hole 17 •, by which it is recovered.

The supports 39 and 39 'of the clamping arms are then fixed outside the fist holes by means known per se. The clamping arms are introduced and actuated to press the rail 29 against the ferrule 6 by exerting a pressure force perpendicular to the rail, on the ferrule, and a tensile force, parallel to the rail, towards the outside of the latter.

Then introduced through the hole 17 a first part of the strip 32, which is slid into the recess 35 of the rail provided with an enlarged insertion part provided for this purpose. The carriage 19, previously fixed to the strip is then introduced in turn, manually into the annular space, through the fist hole 17, then hung on the rail.

The fixing means 23 of the device 20, and the device 20, are then fixed manually on the carriage; the cable-carrying chain is arranged and the m - different electrical connections and possibly the connection of the various fluid supplies necessary for the operation of the device 20, are carried out.

The carriage position is initialized, as is that of the intervention device. The carriage (and the device) is then moved, simultaneously exerting a pushing force on one side of the strap and a pulling force on the other side to bring the carriage into a determined position along the shell, within ± 2 mm . The movement of the carriage and the operation of the apparatus are controlled in semi-automatic or automatic manual mode, and remotely, by a single operator protected from irradiation coming from the generator.

The cables and pipes for supplying fluid run and rewind automatically at the same time as the cable-carrying chain and the strip by means known in themselves (not shown).

In the event of a power supply failure, the motors 41, 41 ′ can be disengaged and the carriage and the device manually removed from the annular space of the generator.

Claims

1. Device (18) for intervention in a space (7) delimited by at least one wall (6) of non-zero curvature, accessible by at least one opening (17, _s 17 •), characterized in that it comprises: a carriage (19) for supporting an apparatus (20) for intervention in said space, said carriage being suitable for being introduced through the opening, - means for guiding and supporting the carriage along the non-zero curvature wall, comprising a rail (29) for guiding and supporting the carriage, suitable for being introduced through the opening, flexible in the longitudinal direction and rigid in the transverse direction, and clamping means (37, 37 ') suitable for pressing. the rail on said wall, arranged to removably fix said rail on said wall, and - remote control means (32, 40, 40 ', 45, 46) for the movement of the carriage along the rail. 2. Device according to claim 1, _ characterized in that the guide rail is made of composite material based on a thermosetting material reinforced with fibers or son. 3. Device according to claim 2, characterized in that, the thermosetting material “Being an epoxy resin, the fibers or threads are essentially arranged parallel to the transverse direction of the rail. 4. ' Device according to any one of the preceding claims, characterized in that the m _om -, rail is arranged to adopt an S-shaped configuration with a radius of curvature less than around 800mm, when it is introduced through the opening. 5. Device according to any one of the preceding claims, characterized in that the rail has two longitudinal bosses (33) parallel, support of the rail on the non-zero curvature wall. 6. Device according to claim 5, characterized in that each boss (33) comprises a ₅ cylindrical recess (33 •) provided with an internal rod (34), for longitudinal stiffening of the rail, of the piano cord type. 7. Device according to any one of the preceding claims, characterized in that the m, m means for remote control of the movement of the carriage comprise a strip (32) flexible in the longitudinal direction, integral with the carriage (19) and arranged for be guided by the rail, and a motor assembly (40, 40 ') designed to exert a traction force or . _f , of thrust on said strip, and in that the rail comprises a longitudinal recess (35), open on the side opposite to the wall on which the rail is pressed, and having on each side a longitudinal flange (36) for guiding the flexible strip integral with the carriage, the internal walls of said recess being able to cooperate with gentle friction with said strip. 8. Device according to any one of the preceding claims, characterized in that it “ ₅ comprises means for electrical connection of the carriage and of the device that it supports, comprising a cable-carrying chain (43) arranged to adopt an S-configuration with radii of curvature less than around 800 mm. ₃₀ 9. Device according to any one of the preceding claims, characterized in that it is used to intervene in the annular space located, calender side, above a tubular plate (5) horizontal of a heat exchanger (1 ), the opening being constituted by a fist hole (17), located in opposite the shell of the tube bundle (3), constituting the non-zero curvature wall. 10. Intervention method in the annular space located around the tube bundle (3) and above the tube plate (5) of a steam generator (1) of a nuclear reactor, characterized in that: - A rail is introduced through a fist hole (17, 17 ') opposite the ferrule (6) of the tube bundle _{1 {J} flexible (29) in the longitudinal direction, and rigid in the transverse direction, for supporting a carriage (19) for guiding and holding an intervention apparatus (20), - The rail (29) is removably fixed on the ferrule, _ or on the internal face of the wall of the generator by pressing it on said ferrule, or wall, by clamping and tensioning, or compression, of the rail in the longitudinal direction against said ferrule, - introducing the carriage (19) by the punched hole ₂₀ - is hung said carriage on the guide rail and, after attachment of 1'appareil • response on the carriage, or wall, - the carriage is moved longitudinally and at a distance along the rail to bring it to a position „Determined in relation to the shell, to allow the intervention. 11. Method according to claim 9 characterized in that, the steam generator having two fist holes (17, 17 ') diametrically opposite, the _3fl rail of length substantially equal to a half-perimeter of the ferrule, by putting it in tension against said ferrule, between the two fist holes.