EP1340939B1 - Method and apparatus for executing maintenance work in the secondary side of a nuclear steam generator - Google Patents

Description

The invention relates to a method and a device for performing maintenance on the secondary side of a nuclear steam generator, in particular for inspecting or recovering a foreign part, which is located between the heating tubes of a nuclear steam generator.

In the manufacture of a nuclear steam generator or in repair and maintenance work on its secondary side, it may happen that foreign parts remain within the tube bundle in the gaps between the heating tubes, which can lead to damage of the heating tubes by so-called fretting. The detection and recovery of such extraneous parts, which are usually in upright steam generators on the tubesheet, is due to the large number and the tight arrangement of opening into the tubesheet heating tubes - a nuclear steam generator usually contains about 4000 to 5000 only through a narrow gap separate heating pipes - problematic. So far, attempts have been made to reach to be recovered foreign parts with manually operated tools on the tubesheet and remove. This is problematic insofar as these salvage operations are relatively difficult due to the limited space and require a lot of time, which leads due to the high local dose rate in the interior of a steam generator to a relatively high radiation exposure of the operator.

In order to clean the tubesheet between heating tubes of such a steam generator, it is known, for example from WO90 / 09850 and EP 05 016 48 B1 to introduce into the relatively wide tube lane of such a steam generator, a flexible lance, which is deflected by 90 ° and from the Pipe alley can be inserted into the gap between the heating pipes. With these known devices, however, it is only possible to approach the pipe gaps in a direction perpendicular to the pipe alley. Impurities or extraneous parts, which are located behind the heating pipes when viewed from the pipe alley, can only be detected poorly. In addition, start-up of regions on the outer periphery of the heating tube bundle is problematic due to the flexibility of the lance used and the increasing instability of the lance end as the extension length increases.

Alternatively, it is known from DE 38 05 285 A1, to use a lance device in which is mounted on the outer periphery of the tube bundle on the steam generator floor a track on which a movable carriage is aufgleist from which a high pressure fluid through a window in a Heating tube bundle is sprayed on the outer circumference surrounding jacket in the heating tube bundle. However, the installation of such a track on the tube sheet is time-consuming and due to structural conditions (structural installations) for a variety of steam generators not possible.

Document FR-A-2 544 123 discloses a repair device with a wagon which can be driven both in the pipe alley and at the periphery of the pipe collar.

Alternatively, it is provided in the maintenance device disclosed in WO92 / 07363 to arrange on a jacket surrounding the heating tube bundle a rail which is flexible in its longitudinal direction and rigid in a transverse direction thereto. On this track, a vehicle is up. The vehicle For this purpose, it is arranged on a steel strip which is guided in the rail and can be unwound from or wound onto a supply roll arranged outside the steam generator so that the carriage moves on the rail in the circumferential direction around the heating tube bundle. However, the known device does not allow access to the interior of the pipe column.

During the operation of such a steam generator, it also occurs in the region of the tube plate between the heating pipes to deposits that can lead to stress corrosion cracking on the heating pipes and must be removed regularly.

The invention is based on the object of providing a method for carrying out maintenance work on the secondary side of a nuclear steam generator, in particular for inspecting or recovering a foreign part located between the heating tubes of a nuclear steam generator, with which on the one hand the health risks for the operating personnel are reduced, and on the other hand, the rate of successful salvage over the methods known in the art is improved. The invention is also based on the object to provide an apparatus for performing the method.

The first object is achieved according to the invention with a method having the features of claim 1. In the method according to the invention, a guide track is arranged on the circumference of the heating tube bundle, on which subsequently at least one vehicle is lined up and driven along the guide track to a position, in the extension direction of a mounted on the vehicle, extendable lance aligned with a gap between the heating tubes. After reaching this position, the lance with a arranged at its free end maintenance device, in particular an inspection device or a rescue tool, remotely introduced into the gap.

By these measures, it is possible to remotely start a variety of columns from different circumferential positions, so that the maintenance is much easier. By the method according to the invention, on the one hand, the probability with which a foreign part is discovered is increased and, on the other hand, a thorough inspection of the foreign part is also possible, which facilitates the decision on a suitable rescue strategy. In addition, recovery from different approach positions is possible and thus improves the chance to successfully carry out a salvage. Cleaning work between the columns can also be carried out considerably more successfully by starting from different directions with a spray nozzle arranged at the free end.

In a particularly advantageous embodiment of the invention, the guide track in its longitudinal direction is flexible and transversely rigid and is braced on the circumference of the heating tube bundle by exerting a tensile force acting in the circumferential direction. The use of a strapped on the periphery of the heating tube bundle guide allows their particularly quick and easy installation, since the guideway is supported only on the heating pipes and other support elements are not required.

The second-mentioned object is achieved with the features of claim 6, whose benefits are mutatis mutandis from the result in the above-explained advantages of the method according to the invention.

Further advantageous embodiments of the invention will become apparent from the independent claims respectively subordinate subclaims.

Fig. 1

eine schematische Prinzipdarstellung einer Vorrichtung gemäß der Erfindung mit einer Mehrzahl von Fahrzeugen, die auf eine am Umfang des Rohrbündels angeordnete Führungsbahn aufgegleist sind,

Fig. 2

und 3 alternative Anordnungen der Führungsbahn am Umfang des Heizrohrbündels

Fig. 4

ein erfindungsgemäßes Fahrzeug in Arbeitsposition in einer Seitenansicht,

Fig. 5

das Fahrzeug in einem Querschnitt parallel zur Führungsbahn ebenfalls in einem aufgegleisten Zustand,

Fig. 6 und 7

eine alternative Ausgestaltung der erfindungsgemäßen Vorrichtung in einer Draufsicht senkrecht zur Führungsbahn bzw. parallel zur Führungsbahn.

For further explanation of the invention reference is made to the embodiment of the drawing. Show it:

Fig. 1

2 shows a schematic basic illustration of a device according to the invention with a plurality of vehicles which are mounted on a guideway arranged on the circumference of the tube bundle,

Fig. 2

and 3 alternative arrangements of the guideway at the periphery of the heating tube bundle

Fig. 4

an inventive vehicle in working position in a side view,

Fig. 5

the vehicle in a cross-section parallel to the guideway also in a flagged state,

6 and 7

an alternative embodiment of the device according to the invention in a plan view perpendicular to the guideway or parallel to the guideway.

Referring to FIG. 1, a nuclear steam generator 2 includes a heating tube bundle 4 containing a plurality of heating tubes 6 arranged in parallel rows. The heating tubes 6 are passed through a tube plate 8, which separates the primary side of the steam generator 2 from the secondary side. The heating pipes 6 are perpendicular to the tube sheet 8 and in the drawing perpendicular to the plane. A tube lane 10 divides the heating tube bundle 4 into two halves 4a, 4b, wherein on one half 4a, the cooling water of the primary circuit in the heating tube bundle 4 enters and 4b flows out of the heating tube 4 on the other half.

In the exemplary embodiment, the heating tubes 6 are arranged in mutually parallel rows such that the heating tubes 6 of adjacent rows are each offset by half a distance from each other.

The half 4a of the heating tube bundle 4 is provided at its outer periphery with a guide rail 12a shown only schematically in the figure, which is clamped by a arranged outside of the steam generator 2 tensioning device 14 on the outer periphery of the heating tube 4 and thus fixed to the heating tube 4. In the illustrated embodiment, the guideway 12a is braced only on the semicircular outer periphery of the inlet-side half 4a and guided over a guide 15 through the pipe lane 10 opposite hand holes 13 to the outside to the clamping device 14.

On the guideway 12a a plurality of identical vehicles 16-1 to 16-4 is performed, which are connected via control and Auswerteleitungen with an outside of the steam generator 2 arranged control and evaluation device 20, with which the individual vehicles 16-1 to 16 -4 driven and can be moved to different positions on the circumference of the heating tube bundle 4.

The flexible guide track 12a is placed at a height of about 250 to 300 mm above the tube sheet 8 around the outer periphery of the inlet side or outlet side heating tube bundle 4 and tensioned by the tensioning device 14 spring loaded. The tensioning device 14 is designed so that the forces acting on the guideway 12 a tensile forces uniformly on the on Distribute outer circumference arranged heating pipes 6 far below the permissible load application limits.

Two other vehicles 16-5 and 16-6 are aufgege on another guideway 12b, which is identical to the guideway 12a. The guideway 12b is passed through the tube lane 10 and applied to the edge of the tube lane 10 forming heating tubes 6 of the half 4b of the heating tube bundle 4, wherein in the figure for reasons of clarity, the tensioning of the guideway 12b required clamping devices are not shown.

Each vehicle 16-1 to 16-6 can be controlled independently with the aid of the control and evaluation device 20, so that the vehicles 16-1 to 16-6 can be moved both independently of one another and those on the vehicles 16-1 to 16 6 each maintenance, inspection or recovery equipment for each vehicle 16-1 to 16-6 can be controlled separately remotely.

1 shows a situation in which a foreign part 30 is located in the interior of the inlet-side heating tube bundle 4. This foreign part 30 can now be achieved starting from different positions on the outer circumference of the heating tube bundle 4 or in the tube lane 10. In the exemplary embodiment, these are due to the hexagonal arrangement of the heating tubes 6 six directions illustrated by arrows 31 to 36 directions or gaps, which open at the periphery of the heating tube bundle 4 in the positions 41 to 46. In these positions 41 to 46, the vehicles 16-1 to 16-6 are now moved by the control and evaluation device 20.

On each of the vehicles 16-1 to 16-6 is an extendable lance, the extension direction is aligned with one of the achievable in the positions 41 to 46 column.

With the help of the vehicles 16-1 to 16-6 each inner position can thus be approached from 6 different directions. This allows a precise inspection of a foreign part 30 from different directions, so that the decision for a suitable mountain strategy, that is, the selection of a suitable recovery tool and the mountain direction is facilitated.

In the alternative arrangement of the guideway 12 according to FIG. 2, this unitarily wraps around the entire heating tube bundle 4, d. H. both halves 4a and 4b, on the outer bundle circumference.

In the arrangement according to FIG. 3, the guideway 12a, wrapped in one piece, wraps around the half 4a of the heating tube bundle 4 on the outer circumference, which is formed by the outer semicircle and the rectilinear circumferential part of the tube lane 10. The other guideway 12b surrounds the heating tube bundle half 4b only on the outer half circle.

According to FIG. 4, the guideway 12 comprises an approximately 50 to 100 mm wide band 120, which is flexible in its longitudinal direction, ie perpendicular to the plane of the drawing, so that it can conform to the arcuate periphery of the heating tube bundle 4. Transverse thereto, ie parallel to the heating tubes 6, the band 120 is rigid, so that this can not twist around the longitudinal axis when the vehicle 16 is glued on. On the side facing away from the vehicle 16 flat side of the belt 120, with which it rests against the heating pipes 6, also an anti-slip coating 122 is arranged, which prevents vertical slipping. The Mounting height h of the guideway 12 is, while about 250 to 300 mm.

On the belt 120 is a roller chain 124, arranged in the exemplary embodiment, a multi-roller chain, the chain links 156 is provided on both sides in each case with an angle bracket 126, which together form a mehrgliedrige rail on which the vehicle 16 is positively locked by means of a clamping lever lock 128.

On the vehicle 16, a lance 130 is supported, which can be linearly retracted and extended, as illustrated by the double arrow 132. As a lance 130, a steel strip is provided, which is guided in a arranged on the vehicle 16 deflecting unit 134, which deflects the steel strip by 90 ° and this by means of a toothed pulley drive 136 which engages positively in recesses of the belt drives. The deflecting unit 134 is arranged pivotably about a first pivot axis 140 by means of a first pivot drive 138, with which the lance 130 can be aligned on one of the pipe gaps (see FIG. 1) that can be reached in the respective driving position. With a second pivot drive 142, the deflection unit 134 can be pivoted about a second pivot axis 144. The first pivot axis 140 extends parallel to the heating tubes 6 and the second pivot axis 144 perpendicular thereto, ie horizontally (perpendicular to the plane). By pivoting about the second pivot axis 144, the free end of the lance 130, which carries a maintenance device, an inspection device or a rescue tool 150, be positioned at different altitudes relative to the guideway 12, so that each point on the tube sheet 8 can be approached.

At the end of the free lance 130, a micro-endoscope or a camera is also arranged, which, or the exact positioning of the lance head and thus the recovery tool or the 150 permits. An arranged on the vehicle 16 camera 148 with lighting allows remote controlled approaching a pipe gap position to allow insertion of the lance 130 in the pipe gap.

Alternatively, the lance 130 may also be used as a support for a flexible cleaning lance with one or more spray nozzles or as a support for probes.

The electrical cables required for the inspection probes or the camera located at the free end of the belt or the pneumatically actuated mechanical shifting cables required for tool actuation, for example, are guided in the belt body.

5, two synchronously running sprocket drives 152 are arranged on the vehicle 16, each driving a sprocket 154, which is engaged with the chain links 156 of the multi-roller chain 124. In the figure, the attached to each chain link on the outside angle plates 126 can be seen, which form a longitudinally flexible rail on which the vehicle 16 is aufgleist. The toothed disk drive 136 for the band-shaped lance 130 can also be seen in the FIGURE.

Instead of a roller chain 124, as shown in FIG. 6, a flexible toothed belt 160 may also be provided as a guide track 12, which has a central web 162 which meshes with a drive wheel 164 disposed on the vehicle 16. In the embodiment, two synchronously driven drive wheels 164 provided, which are pivotally mounted on the vehicle 16 and spring loaded by a leg spring 165 are brought into engagement with the toothed belt 160.

The toothed belt 160 has on both side edges (longitudinal sides) as a guide element 166 has a rear milling, which forms a rail for derailing a constructively adapted to the toothed belt 160 vehicle 16. Arranged on the vehicle 16 L-shaped tabs 168 engage behind the toothed belt 160 in the Hinterfräsungen 166. Also in this embodiment, the vehicle 16 is secured by means of a clamping lever lock 170 on the rail formed by the two-sided guide elements 166.

The flexible band forming the lance 130 is carried on the vehicle 16 in a spring-loaded return cassette 172 from which it can be retracted and extended by means of the toothed-disk drive 136.

In Fig. 7, the rear handle of the L-shaped tabs 168 is clearly visible in the Hinterfräsungen 166. In this illustration, the pivot drives 138 and 142 for the pivotal movement of the lance 130 about the first and second pivot axis 140 and 144 are visible.

LIST OF REFERENCE NUMBERS

2

steam generator

4

Heating tube

6

heating pipe

8th

tube sheet

10

Rohrgasse

12

guideway

13

hand hole

14

jig

15

guide

16

vehicle

20

Control and evaluation device

30

foreign part

31-36

arrow

41-46

position

120

tape

122

Anti-slip covering

124

roller chain

126th

angle bracket

128

Tension lever lock

130

lance

132

double arrow

134

Return unit

136

Toothed disk drive

138

first quarter turn actuator

140

first pivot axis

142

second quarter turn actuator

144

second pivot axis

148

camera

150

mountains tool

152

sprocket

154

Sprocket

156

link

160

toothed belt

162

center web

164

drive wheel

165

Leg spring

166

relief milling

168

flap

170

Tension lever lock

172

Rückholkassette

Claims (16)

1. Method for carrying out maintenance work on the secondary side of a nuclear steam generator, in particular for inspecting or recovering a foreign element (30) located between the heating tubes (6) of a nuclear steam generator (2), wherein a guideway (12) is arranged at the circumference of the bundle (4a, 4b) of heating tubes, onto which guideway (12) at least one vehicle (16; 16-1 to 16-6), with an extendable lance (130) mounted thereon, may subsequently be rerailed and moved by remote control along the guideway (12) into a position (41-46) in which the lance (130) may be extended toward a gap, extending inside the bundle (4a, 4b) of tubes, between the heating tubes (6) and may be introduced into the gap by remote control using a maintenance device, in particular an inspection device or recovery tool (150), arranged at the free end of said lance.
2. Method according to Claim 1, wherein the vehicle (16; 16-1 to 16-6) is self propelled.
3. Method according to either Claim 1 or 2, wherein the guideway (12) is flexible in its longitudinal direction and resistant to bending transversely thereto, and is secured relative to the circumference of the bundle (4a, 4b) of heating tubes by means of the exertion of a tensile force acting in the circumferential direction.
4. Method according to Claim 1, 2 or 3, wherein the lance (130) is oriented toward the plane of the gap or the position of the foreign element (30) in the gap by being swivelled about a first pivot axis (140) and a second pivot axis (142) perpendicular thereto.
5. Method according to Claim 2, 3 or 4, wherein a plurality of vehicles (16-1 to 16-6), which are moved independently of one another, is rerailed and a maintenance process, an inspection process, or a plurality of simultaneous or successive processes, required for the recovery, for handling the foreign element (30) is/are carried out simultaneously from a plurality of directions (31-36).
6. Device for carrying out maintenance work on the secondary side of a nuclear steam generator, in particular for inspecting or recovering a foreign element (30) located between the heating tubes (6) of a nuclear steam generator (2), comprising a lance (130), which may be introduced into a gap between the heating tubes (6), which carries at its free end a maintenance device, in particular an inspection device or a recovery tool (150), and is extendably arranged on a vehicle (16), characterised by a guideway, which may be attached to the circumference of the bundle of heating tubes and along which the vehicle may be moved, wherein the lance may be introduced into the gap by remote control.
7. Device according to Claim 6, wherein the vehicle (16) is self propelled.
8. Device according to either Claim 6 or 7, wherein the guideway (12) is flexible in its longitudinal direction and resistant to bending transversely thereto, and may be secured relative to the heating tubes (6) arranged at the circumference of the bundle (4a, 4b) of heating tubes by means of the exertion of a tensile force.
9. Device according to Claim 8, wherein the guideway (12) comprises a roller chain (124), the chain links (156) of which are each provided on their outer lateral flanks with a guide element (126), the guide elements (126), which may swivel relative to one another, forming a rail that is flexible in the longitudinal direction.
10. Device according to Claim 8, wherein the guideway (12) comprises a flexible toothed belt (160), which is provided on its outer lateral flanks with a respective guide element (166), the guide elements (166) forming a rail that is flexible in the longitudinal direction.
11. Device according to any one of Claims 6 to 10, wherein the lance (130) is mounted on the vehicle (16) such that it may pivot about a first pivot axis (140) and a second pivot axis (144) perpendicular thereto.
12. Device according to Claim 11, wherein the first pivot axis (140) extends parallel to the transverse axis of the guideway (12) when the vehicle is rerailed on the guideway (12).
13. Device according to Claim 12, wherein the second pivot axis (144) extends parallel to the direction of travel of the vehicle (16).
14. Device according to any one of Claims 6 to 13, wherein the lance (130) is a flexible band that is driven by a toothed wheel drive (136) arranged on the vehicle (16).
15. Device according to any one of Claims 6 to 14, comprising a control and evaluation device (20) for remotely controlling a plurality of vehicles (16-1 to 16-6).
16. Device according to Claim 15, wherein the vehicles (16-1 to 16-6) are automotive and may be moved and operated independently of one another.

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