TITLE: Intervention device on a nuclear fuel assembly

The present invention relates to an intervention device on a nuclear fuel assembly placed under water in a swimming pool.

A nuclear fuel assembly for a pressurized water nuclear reactor comprises a bundle of parallel nuclear fuel rods, kept spaced transversely from one another by a support skeleton comprising in particular a lower end and an upper end spaced along a longitudinal axis, guide tubes extending along the longitudinal axis and connecting the lower end piece and the upper end piece to each other, and retaining grids fixed to the guide tubes being distributed along said guide tubes.

The nuclear fuel rods extend along the longitudinal axis between the lower end piece and the upper end piece, passing through the retaining grids which longitudinally support the nuclear fuel rods and keep them transversely spaced from one another.

In known manner, the retaining grids consist of intersecting plates delimiting cells intended to be traversed by the guide tubes and the fuel rods. In general, the support grids are provided with a peripheral belt carrying guide fins projecting on their lower edge and / or on their upper edge and inclined towards the center of the support grid.

Each cell of a retaining grid through which a respective nuclear fuel rod passes is generally provided on internal surfaces of the cell with retaining elements, such as springs and / or bosses, for longitudinally supporting and transversely maintaining the cell. nuclear fuel rod passing through this cell.

In operation, a coolant circulates through the nuclear fuel assembly along the longitudinal axis, passing between the nuclear fuel rods and through the end caps and retaining grids.

Each cell of a retaining grid through which a respective nuclear fuel rod passes can further include one or more cooling fluid mixing fins.

During the operation of the nuclear reactor or during maintenance operations of the nuclear reactor, debris formed from small metal parts can be created.

Such debris is entrained by the coolant and can get stuck in the nuclear fuel assemblies, between the nuclear fuel rods, with the risk of damaging these nuclear fuel rods, and in particular of ultimately causing a loss. sealing of a nuclear fuel rod.

FR2633769A1 discloses a device for extracting debris from a nuclear fuel assembly placed under water, comprising a pole, a clamp mounted at a lower end of the pole and a mechanism for controlling the opening and closing of the clamp remotely.

However, this extraction device is inconvenient to use. Its positioning is imprecise and it does not allow easy access to all the places where debris can get stuck in a nuclear fuel assembly, nor to guarantee in all situations that the forces applied to the components of the nuclear fuel assembly. nuclear fuel do not damage elements of the device or the nuclear fuel assembly and in particular do not damage the retaining elements of a nuclear fuel rod, for example by applying too great a transverse force to said rod.

During the handling operations of nuclear fuel assemblies in the nuclear reactor, the peripheral wafers can be locally damaged by attachment with a contiguous element of the handling chain, for example a storage cell exhibiting a geometric discontinuity or a surface defect, an adjacent fuel assembly ..., during the longitudinal displacement of the nuclear fuel assembly with respect to this element, rendering the nuclear fuel assembly unsuitable for loading as it is in the core of the nuclear reactor.

FR2641 1 18A1 discloses a device for straightening the guide fins of the retaining grids of a nuclear fuel assembly comprising a pole, an intervention tool comprising a folding means and a means for supporting and moving the tooling. 'intervention.

However, this device for straightening the guide vanes is inconvenient. Its positioning is imprecise and it does not have sufficient degrees of freedom to allow efficient intervention in all configurations, nor to guarantee in all situations that the forces applied to the components of the nuclear fuel assembly do not come. not damage elements of the device or of the nuclear fuel assembly and in particular do not damage the retaining elements of a nuclear fuel rod, for example by applying too great a transverse force to said rod.

One of the aims of the invention is to provide an intervention device on a nuclear fuel assembly which facilitates interventions without inducing any risk of damage to the elements of the fuel assembly or of the device.

To this end, the invention provides an intervention device on a nuclear fuel assembly placed under water, the intervention device comprising an articulated robotic arm comprising a fixing base, an end member and at least one segment of the connecting arm. the base to the terminal member, and an intervention member carried by the terminal member, the intervention member being configured to intervene on the nuclear fuel assembly.

The robotic arm equipped with an intervention unit makes it possible to move the intervention unit and to orient the intervention unit easily to insert it into the nuclear fuel assembly and to intervene on debris stuck in the A nuclear fuel assembly, for example between nuclear fuel rods, in a lower nozzle, in an upper nozzle or in a grid of the nuclear fuel assembly or on a component of the nuclear fuel assembly requiring intervention. The robotic arm can be controlled remotely easily, which makes interventions easier.

The intervention device may include one or more of the following optional characteristics, taken in isolation or in any technically possible combination:

the robotic arm has an arm segment articulated on the base and an actuator configured to move the arm segment relative to the base;

the robotic arm has at least two arm segments articulated between them and an actuator configured to rotate each arm segment with respect to one another;

the robotic arm has exactly two arm segments articulated between them, one being articulated on the base and the other carrying the terminal member;

- the arm segment carrying the terminal member extends along an axis of an arm segment, the intervention member being movable in rotation with respect to this arm segment about an axis of rotation that is substantially coaxial or parallel with the arm segment axis;

- the intervention unit is configured to seize a debris or a component of the nuclear fuel assembly;

the intervention unit is configured to deform a debris or component of the nuclear fuel assembly;

- the intervention unit is configured to cut a debris or a component of the nuclear fuel assembly;

- The intervention member is a clamp having two jaws movable relative to each other;

- the two jaws extend in a direction of extension, the intervention member being movable in rotation with respect to the segment of the arm carrying the terminal member about an axis of rotation substantially parallel to the direction of extension ;

- The intervention member is configured to suck up debris and comprises a suction cannula connected to a suction and filtration device;

- It comprises a support base, the robotic arm being mounted to move in translation with respect to the support base in at least one direction of translation;

- It comprises an actuator configured to move the robotic arm in translation relative to the support base in at least one direction of translation;

- The support base is configured to fit into the upper part of a receiving cell of a nuclear fuel assembly;

- it includes several interchangeable intervention tools.

The invention and its advantages will be better understood on reading the description which follows, given solely by way of non-limiting example and made with reference to the appended drawings, in which:

- Figure 1 is an elevational view of a nuclear fuel assembly;

- Figure 2 is a perspective view of an intervention device on a nuclear fuel assembly, in a first configuration;

- Figure 3 is a perspective view of the intervention device, in a second configuration;

- Figure 4 is a perspective view of the intervention device, in a third configuration; and

- Figures 5 to 8 are perspective views of interchangeable intervention members of the intervention device.

The nuclear fuel assembly 2 of Figures 1 and 2 comprises a nuclear fuel rod bundle 4 and a support skeleton 6 configured to support the nuclear fuel rods 4.

The nuclear fuel rods 4 extend parallel to each other and to a longitudinal axis L of the nuclear fuel assembly 2.

The longitudinal axis L extends vertically when the nuclear fuel assembly 2 is placed in a core of a nuclear reactor. In operation, a coolant flows vertically from bottom to top through the nuclear fuel assembly 2, as illustrated by arrow F.

In the remainder of the description, the terms “vertical”, “horizontal”, “longitudinal”, “transverse”, “top”, “bottom”, “upper” and “lower” are understood by reference to the assembly of nuclear fuel 2 arranged vertically.

The support skeleton 6 comprises a lower end 8, an upper end 10, a plurality of guide tubes 12 and a plurality of retaining grids 14.

The lower end piece 8 and the upper end piece 10 are spaced along the longitudinal axis L. The guide tubes 12 extend along the longitudinal axis L and connect the lower end piece 8 and the upper end piece 10 between them, by maintaining the distance between the lower nozzle 8 and the upper nozzle 10. The nuclear fuel rods 4 are received between the lower nozzle 8 and the upper nozzle 10.

Each guide tube 12 is open at its upper end to allow the insertion of a control bar (not shown) inside the guide tube 12, through the upper end 10. Such a control bar allows to control the reactivity of the nuclear reactor core in which the nuclear fuel assembly is inserted 2.

The retaining grids 14 are distributed along the guide tubes 12 being spaced from each other along the longitudinal axis L. Each retaining grid 14 is rigidly fixed to the guide tubes 12, the guide tubes 12 s 'extending through each retaining grid 14.

Each retaining grid 14 is configured to longitudinally support the nuclear fuel rods 4 while maintaining them in a configuration in which they are spaced apart from each other. The nuclear fuel rods 4 are preferably positioned laterally at the nodes of a substantially regular imaginary network.

Each retaining grid 14 comprises, for example, intersecting interior plates and a peripheral belt, surrounding the interior plates and formed by four peripheral plates 16, thus forming a plurality of cells.

Each cell intended to receive a respective nuclear fuel rod 4 is generally provided with retaining elements coming into contact with the external surface of the nuclear fuel rod 4 in order to maintain it longitudinally and transversely.

Each cell for receiving a respective nuclear fuel rod 4 may include at least one cooling fluid mixing fin projecting upwardly from the retaining grid with respect to the longitudinal axis L of the fuel assembly. nuclear 2 and being preferably inclined obliquely upward and inwardly of the cell.

The retaining elements of each cell comprise for example at least one elastic spring and / or at least one rigid boss, each spring being for example configured to push the nuclear fuel rod 4 into bearing against one or more boss (s).

Each retaining grid 14 is generally provided with a peripheral belt, formed for example of peripheral plates 16, carrying guide fins 18 projecting on its lower edge and / or on its upper edge, and inclined towards the center of the retaining grid 14, to guide the retaining grid 14 with the surrounding objects during handling operations of the nuclear fuel assembly 2.

With reference to FIG. 2, the intervention device 20 is configured to intervene on the nuclear fuel assembly 2 under water.

The nuclear fuel assembly 2 is submerged in a body of water, in a swimming pool of the nuclear power plant. The nuclear fuel assembly 2 is for example suspended in the body of water.

Only the lower part of the nuclear fuel assembly 2 is visible in Figure 2. The retaining grids 14 have been omitted in Figure 2 for the sake of clarity of the drawings.

The intervention device 20 comprises an articulated robotic arm 22 and an intervention member 24, here a clamp, carried by the robotic arm 22.

The robotic arm 22 comprises a base 26, located at one end of the robotic arm 22 for fixing the robotic arm 22 on a support, and a terminal member 28 located at the other end of the robotic arm 22, for securing the robotic arm 22. intervention unit 24 on the robotic arm 22.

The robotic arm 22 has at least one arm segment 30, 32 located between the base 26 and the terminal member 28. Each arm segment 30, 32 is elongated along a respective arm segment axis A1, A2.

The robotic arm 22 comprises for example several arm segments 30, 32 arranged in series between the base 26 and the terminal member 28. The arm segment 30 connected to the base 26 is articulated on the base 26, and each arm segment 32 following is articulated on the segment of the arm 30, 32 above.

In an exemplary embodiment, the arm segment axes A1, A2 are coplanar and the arm segments 30, 32 are articulated at the base 26 and between them only around distinct and parallel axes of rotation B1, B2, the axes of rotation B1, B2 being substantially perpendicular to the axes of arm segment A1, A2.

As a result, the arm segments 30, 32 move in a fixed displacement plane relative to the base 26, the displacement plane being defined by the arm segment axes A1, A2.

In an exemplary embodiment, each arm segment 30, 32 is movable in rotation relative to the base 26 or to the other arm segment on which it is mounted, over a stroke of at least 120 °, preferably over a stroke of about 180 °.

The robotic arm 22 here comprises exactly two arm segments 30, 32, namely a proximal arm segment 30 articulated on the base 26 and a distal arm segment 32, articulated on the proximal arm segment 30 and carrying the terminal member. 28.

The proximal arm segment 30 is hinged to the base 26 about a single axis of rotation B1, and the distal arm segment 32 is hinged to the proximal arm segment 30 about a single, separate and parallel axis of rotation B2. to the axis of rotation B1 of the arm segment 30 relative to the base 26.

Optionally, the intervention member 24 is mounted to be movable in rotation relative to the arm segment carrying the terminal member 28, here the distal arm segment 32, about an axis of rotation B3 coaxial with or parallel to the axis of extension A2 of this arm segment 32.

Preferably, when the arm segments 30, 32 move in a fixed displacement plane relative to the base 26, the axis of rotation of the intervention member 24 relative to the arm segment carrying the terminal member 28 is located in the displacement plane of the arm segments 30, 32

Once the intervention member 24 is positioned using the robotic arm 22, the rotation of the intervention member 24 around the axis of rotation B3 makes it possible to orient the intervention member 24 to facilitate its insertion into the nuclear fuel assembly 2, for example between the nuclear fuel rods 4 or into the lower nozzle 8 or the upper nozzle 10.

In an exemplary embodiment, the robotic arm 22 is configured such that the intervention member 24 mounted on the robotic arm 22 is movable in rotation around the axis of rotation B3 over 360 °. The intervention member 24 is preferably mobile in rotation without angular limitation. The intervention member 24 can perform several turns in one direction or the other.

The robotic arm 22 has at least one actuator 34, 36, 38 to control the movements of the robotic arm 22 and, optionally, the movements of the intervention member 24. The robotic arm 22 here has an actuator 34 to control the operation. orientation of the arm segment 30 proximal to the base 26 and an actuator 36 for controlling the orientation of the arm segment 32 distal to the arm segment 30 proximal.

The robotic arm 22 optionally incorporates an actuator 38 for controlling the orientation of the intervention member 24 around the axis of rotation B3. The actuator 38 is for example integrated inside the arm segment carrying the intervention member 24, here the distal arm segment 32, which is streamlined.

In the configuration illustrated in Figure 2, the intervention device 20 comprises a translation assembly 42 on which is mounted the robotic arm 22, the translation assembly 42 being configured to move the robotic arm 22 in translation in a direction of translation T 1.

The direction of translation T1 is substantially perpendicular to the plane of movement of the segment (s) of the arm 30, 32 of the robotic arm 22. The direction of translation T1 is thus substantially parallel to the axis of rotation B1, B2 of each segment of the arm 30. , 32 relative to the base 26 or to the previous arm segment.

The translation assembly 42 comprises an actuator 44 configured to control the movement of the base 26 in translation along the direction of translation T1. The actuator 44 is here a linear actuator, for example a hydraulic actuator or an electric actuator.

The translation assembly 42 comprises a base 46 and a carriage 48 slidably mounted on the base 46 in the direction of translation T1, the actuator 44 being arranged between the base 46 and the carriage 48 to control the movement of the carriage 48 relative to the base 46.

The robotic arm 22 is mounted on the carriage 48 by fixing the base 26 on the carriage 48.

The translation assembly 42 defines a robotic "translation table" making it possible to move the robotic arm 22 in translation.

In the configuration of FIG. 2, the intervention device 20 is designed to be placed on a cell present in the swimming pool and intended to receive a nuclear fuel assembly 2 under water, for example a storage cell or a lowering basket. .

To this end, the intervention device 20 comprises a support base 50 configured to fit into the upper part 52 of the cell.

A cell generally has the shape of a tube extending vertically and having a section of generally square shape.

The support base 50 comprises an insertion element 54 adapted to fit vertically into the upper part 52 of the cell, and a support element 56 supporting the robotic arm 22 cantilevered with respect to the cell. insert 54.

Once the insertion element 54 has been inserted into the upper part 52 of the cell, the intervention device 20 is held in place by its own weight.

Advantageously, the intervention device 20 is placed on the basket of the lowering device in the high position, that is to say when the upper part 52 of the cell is out of water, to facilitate docking of the device. intervention 20 and the insertion of the insertion element 54. The intervention device 20 is then submerged by lowering the descender, at the same time submerging any power cables and control of the intervention device 20, until the intervention device 20 is placed at the desired height vis-à-vis the nuclear fuel assembly 2 and with sufficient water height to carry out the intervention in complete safety.

During the intervention, the nuclear fuel assembly 2 is for example suspended in water using a lifting tool.

In the configuration of Figure 2, the translation assembly 42 is fixed on the support base 50, more precisely on the support element 56, and the robotic arm 22 is fixed on the translation assembly 42.

As an option, the translation assembly 42 is fixed on the support base 50 so as to be able to adjust the position of the translation assembly 42 in a direction of translation T2 perpendicular to the direction of translation T1 of the carriage 48, in several adjustment positions, for example discrete adjustment positions.

To do this, the support base 50 is for example provided with at least one rail 58, for example two rails 58, each rail 58 extending in the direction of translation T2 and being provided with several fixing holes 59 distributed around the along rail 58.

Optionally, the intervention device 20 comprises a receptacle for depositing the debris extracted from the nuclear fuel assembly 2 and for receiving the debris which could fall during the intervention on the nuclear fuel assembly 2. The receptacle is for example provided in the form of a plate 60 provided with a rim.

Optionally, the intervention device 20 comprises a guide system 62 configured to position the nuclear fuel assembly 2 and the intervention device 20 relative to each other.

The guide system 62 is advantageously configured to bear on a lateral face of the nuclear fuel assembly 2 at one point or more points spaced along the nuclear fuel assembly 2.

Advantageously, in operation, the nuclear fuel assembly 2 is suspended under water, attached to an independent lifting tool. In this configuration, the support force of the guide system 62 on the nuclear fuel assembly 2 is limited. Indeed, the nuclear fuel assembly 2 being held in a pendulum manner, it is pushed back by the guide system 62 when the bearing force of the guide system 62 increases.

The guide system 62 comprises a guide element 64 in the form of a fork with two teeth intended to be applied against a side face of the nuclear fuel assembly 2, the nuclear fuel assembly 2 being received between the two teeth.

The guide element 64 is here carried by a bracket 66 fixed to the support base 50.

The plate 60 is for example provided with a notch formed in an edge of the plate 60 and designed to receive the nuclear fuel assembly 2 to ensure the relative positioning of the intervention device 20 and of the nuclear fuel assembly 2.

Thus, the intervention device 20 rests on the nuclear fuel assembly 2 at two points spaced apart along the nuclear fuel assembly 2.

In the configuration of Figure 3, the intervention device 20 is configured to intervene from below the lower end piece 8 of the nuclear fuel assembly 2.

The intervention device 20 is provided with an intermediate support 68 having a vertical fixing surface 68A, the base 26 of the robotic arm 22 being fixed on this fixing surface 68A.

This makes it possible to modify the orientation of the robotic arm 22 relative to the nuclear fuel assembly 2 to facilitate the work of the robotic arm 22. In particular, the robotic arm 22 makes it possible to move the intervention member 24 parallel to the fixing surface 68A, ie here vertically to insert the intervention member 24 into the lower end piece 8.

The intermediate support 68 is here fixed to the carriage 48 of the translation assembly 42.

As illustrated in FIG. 3, the intervention device 20 comprises a removable receptacle 69 in which the operator will deposit the debris or pieces of components extracted or cut by the intervention member 24.

The receptacle 69 is accessible by rotation of the arm segments 30, 32 about the axes of rotation B1, B2.

Furthermore, the plate 60 provided with a notch has been replaced by a rectangular or square plate 70, able to extend under the nuclear fuel assembly 2 so as to receive the debris or pieces of components which would fall from nuclear fuel assembly 2 during the response.

It will be noted that, with respect to the configuration of FIG. 2, the translation assembly 42 has been offset in the second direction of translation T2 relative to the support base 50.

The device of Figure 3 allows in particular, by a rotational movement of the terminal member 28 to extract debris type chips or helical springs which have partially passed through the lower end 8.

In the configuration of Figure 4, the intervention device 20 is configured for intervention on top of the upper nozzle 10 of the nuclear fuel assembly 2.

The robotic arm 22 is mounted at the lower end of a handling pole 71 which can be manipulated from the surface of the body of water in which the intervention is carried out.

The base 26 is fixed here on a fixing surface 72 facing downwards. The fixing surface 72 is inclined relative to a horizontal plane by an angle of between -60 and + 60 ° and preferably between -30 ° and + 30 °. Such a fastening makes it possible to orient the robotic arm 22 so as to intervene in the upper end piece 10, in particular under the edges of the upper end piece 10. The shape of the fastening surface 72 and in particular the angle of inclination can be adapted as needed.

The robotic arm 22 is preferably configured to receive several interchangeable intervention members. In particular, the terminal member 28 of the robotic arm 22 is configured for the removable fixing of each intervention member.

Different intervention units 24 are shown in Figures 5 to 8.

Each intervention member 24 is provided with a fixing system 74 for fixing the intervention member on the terminal member 28 of the robotic arm 22. The fixing system 74 is for example of the bayonet type allowing a fixing of the intervention member 24 by translation along an axis then rotation about this axis.

In other embodiments, the system for fixing the intervention member 24 may for example be a mechanical assembly of the tenon and mortise or dovetail or ball pin type, etc. or a screw connection.

The response device illustrated in Figure 5 is a gripper 76 configured for gripping debris located between the nuclear fuel rods 4 of the nuclear fuel assembly 2.

The clamp 76 comprises a first jaw 78 and a second jaw 80 in the form of elongated blades in a direction of extension E. The first jaw 78 and the second jaw 80 define between them a gripping space 82.

The first jaw 78 and the second jaw 80 are movable relative to each other so as to vary a dimension of the gripping space 82 to grip or release debris.

The first jaw 78 has a curved end portion 84. The gripping space 82 is delimited between the curved end portion 84 and the end of the second jaw 80.

The first jaw 78 and the second jaw 80 are movable relative to each other in the direction of their length (ie along the direction of extension E) to vary a dimension of the gripping space 82 to grip or release debris.

In an exemplary embodiment, the first jaw 78 is fixed and the second jaw 80 is movable in translation in the direction of its length (ie in the direction of extension E)

The clamp 76 here has a linear actuator 86 arranged to move the first jaw 78 and the second jaw 80 relative to each other, here to move the second jaw 80 relative to the first jaw 78.

The curved end portion 84 is provided with a rounded edge 84A which constitutes the most advanced end of the clamp 76. This rounded edge 84A prevents damage to the nuclear fuel rods 4 during the insertion of the clamp. 76 between these.

The clamp 76 has a low clamping power and is particularly advantageous for removing small debris or debris located in areas that are difficult to access: in the nuclear fuel rod bundle 4, between the nuclear fuel rods 4 and the end caps. 8, 10, in the retaining grids 14 or in hidden areas of the end pieces 8, 10, for example under rims.

The intervention member 24 illustrated in Figure 6 is also a clamp 88. It differs from that of Figure 5 in that it has a first jaw 90 and a second jaw 92 in the form of levers and mounted. rotating around respective axes of rotation M1, M2 parallel to each other so as to separate or bring together the gripping ends 90A, 92A of the first jaw 90 and the second jaw 92.

The first jaw 90 and the second jaw 92 are further shorter, and their gripping ends 90A, 92A are pointed. This clamp 88 makes it possible to extract debris the extraction of which requires a greater clamping force or to bend locally, for example a portion of a wafer.

peripheral 16 of a retaining grid 14 of a nuclear fuel assembly 2, in particular a guide fin 18 so that it returns to its original geometry.

Gripper 88 has a linear actuator 94 for controlling the opening and closing of gripper 88, connected to jaws 90, 92 by a transmission mechanism 96 configured to convert linear motion of actuator 94 to rotational motion of. each of the first jaw 90 and the second jaw 92.

The transmission mechanism 96 comprises a control rod 98 movable in translation in the direction of extension E and connected to the end of each of the first jaw 90 and the second jaw 92 opposite the gripping end of this jaw, by a respective connecting rod 99.

The intervention member 24 illustrated in Figure 7 is a clamp 100. It differs from that of Figure 6 by the shape of the first jaw 102 and the second jaw 104 which are configured to cut. The ends 102A and 104A of the first jaw 102 and the second jaw 104 are formed by cutting edges. The pliers 100 is a cutting pliers.

Advantageously, the clamp 100 is provided with a clamping device 106 configured to hold the element to be cut before the cut and after the cut, and thus to avoid the dispersion of pieces after the cut.

The clamping device 106 comprises, for example, elastic linings 108, 1 10 arranged on the jaws 102, 104 to clamp the element to be cut together.

The elastic gaskets 108, 1 10 are for example made of an elastomeric material, for example of the Eladip® type.

This clamp 100 makes it possible to cut and extract debris, the extraction of which in a single piece is not possible given the local configuration. It also makes it possible to locally cut, for example, a portion of the peripheral plate 16 of a retaining grid 14 of a nuclear fuel assembly 2, in particular a guide fin 18 when it is not possible to make it regain its geometry. original or a portion of retaining grid 14 having an overflow following a local tearing in handling.

The intervention member 24 illustrated in Figure 8 is a suction member 1 12 having a suction cannula 1 14 fluidly connected via a suction pipe 1 16 to a suction and filtration device 1 18. The debris is retained by the suction and filtration device 1 18. The water from the swimming pool sucked up with the debris is rejected into the swimming pool at the outlet of the suction and filter device 1 18.

The suction and filtration device 1 18 is here integrated into the suction member 1 12. As a variant, the suction and filtration device 1 18 is offset relative to the suction member 1 12, and is located, for example, near the free surface of the swimming pool water. The suction and filtration device 1 18 is then fluidly connected to the suction member 1 12 by a pipe.

Like the clamp 76 of Figure 5, this suction member 1 12 is able to recover small debris or debris located in areas difficult to access as long as this debris is not firmly stuck in the fuel assembly nuclear 2.

As illustrated in Figures 2 to 4, the intervention device 20 optionally comprises a camera 120 mounted on the robotic arm 22 so as to film the intervention area. The intervention member 24 carried by the robotic arm 22 is located in the axis of the camera 120. The camera 120 is for example fixed to the segment of the arm carrying the terminal member 28, here the distal arm segment 32. and covers a transverse field, ie according to the direction of translation T 1.

Advantageously, the intervention device 20 comprises a second camera 122 mounted on the bracket 66 so as to film the intervention zone from another angle. As illustrated in Figures 2 and 3, the camera 122 covers a field along the longitudinal axis L.

The cameras 120, 122 facilitate the remote control of the intervention device 20 by allowing the operator to better see the intervention zone.

Preferably, each actuator 34, 36, 38, 44, 86, 94 is a motor whose power is electronically limited to limit the pushing or pulling force that can be applied to the elements of the nuclear fuel assembly 2.

Advantageously, the actuators 86, 94 are designed so that the clamps 76, 88, 100 open in the event of an electrical failure to avoid any risk of the intervention device 20 jamming in the nuclear fuel assembly 2.

A return cable 124 visible in Figure 2 and not shown in Figure 3, allows to exert a return force in the direction of translation T2 to ensure the withdrawal of the intervention member 24 engaged in the assembly of nuclear fuel 2 in the event of an element failure.

The return cable 124 is here arranged to act on the translation assembly 42 (or translation table).

The intervention device of the invention makes it possible to facilitate the operations for extracting debris in a nuclear fuel assembly and the operations for reconfiguring the geometry of the components of the nuclear fuel assembly. The robotic arm can be easily remotely controlled to position and actuate the gripper or suction cannula carried by the robotic arm. The robotic arm has sufficient degrees of freedom for adequate positioning of the intervention tool for the required interventions. It is possible if necessary to add arm segments and / or axes of rotation or translation if additional degrees of freedom are required

The robotic arm allows easier positioning and control of the intervention tool compared to a tool carried at the end of a pole and operated manually. This limits the risk of damaging the nuclear fuel assembly, and in particular the fuel rods and / or the elements holding the nuclear fuel rods in the holding grids.

The intervention device is easily configurable to perform various interventions, for example the extraction of debris stuck between the nuclear fuel rods, the extraction of debris under or on the lower nozzle, a retaining grid and / or the upper end, the resetting of a retaining grid, for example by folding a guide fin or by cutting out a tear-off.

The intervention device makes it possible to generate sufficient clamping power for the extraction of strongly stuck debris, and even to use a cutting pliers to cut a debris, for example to remove it more easily. The wire cutters can also be used to cut a deformed part of a part which could damage other parts during the operation of the nuclear reactor or during the handling of the nuclear fuel assembly.

The intervention device can be implemented easily, for example by a single operator controlling the robotic arm remotely.

CLAIMS

1. Intervention device on a nuclear fuel assembly (2) placed under water, the intervention device comprising an articulated robotic arm (22) comprising a base (26) for fixing, an end member (28) and at least an arm segment (30, 32) connecting the base (26) to the terminal member (28), and an intervention member (24) carried by the terminal member (28), the intervention member ( 24) being configured to act on the nuclear fuel assembly (2).

2. Intervention device according to claim 1, wherein the robotic arm (22) has an arm segment (30) articulated on the base (26) and an actuator (34) configured to move the arm segment (30). relative to the base (26).

3. Intervention device according to claim 1 or 2, wherein the robotic arm (22) has at least two arm segments (30, 32) articulated between them and an actuator (36) configured to rotate each arm segment. (30, 32) relative to each other.

4. Intervention device according to claim 3, wherein the robotic arm (22) has exactly two arm segments (30, 32) articulated together, one being articulated on the base (26) and the other bearing the terminal organ (28).

5. Intervention device according to any one of the preceding claims, wherein the arm segment (32) carrying the terminal member (28) extends along an axis of the arm segment (A2), the member d the intervention (24) being movable in rotation with respect to this arm segment (32) about an axis of rotation (B3) substantially coaxial or parallel with the axis of the arm segment (A2).

6. An intervention device according to any preceding claim, wherein the intervention member (24) is configured to seize a debris or a component of the nuclear fuel assembly (2).

7. Intervention device according to any one of the preceding claims, wherein the intervention member (24) is configured to deform a debris or component of the nuclear fuel assembly (2).

8. An intervention device according to any preceding claim, wherein the intervention member (24) is configured to cut a debris or a component of the nuclear fuel assembly (2).

9. An intervention device according to any preceding claim, wherein the intervention member (24) is a clamp (76, 88, 100) having two jaws movable relative to each other.

10. Intervention device according to claim 9, wherein the two jaws extend in an extension direction (E), the intervention member (24) being movable in rotation relative to the segment of the arm (32). ) carrying the terminal member (28) around an axis of rotation (B3) substantially parallel to the direction of extension (E).

11. An intervention device according to claim 6, wherein the intervention member (24) is configured to suck up debris and comprises a suction cannula (1 14) connected to the suction and filtration device (1 18).

12. Intervention device according to any one of the preceding claims, comprising a support base (50), the robotic arm (22) being mounted movable in translation relative to the support base (50) in at least one direction of translation (T1).

13. An intervention device according to claim 12, comprising an actuator (48) configured to move the robotic arm (22) in translation relative to the support base (50) in at least one direction of translation (T1).

14. An intervention device according to claim 12 or claim 13, wherein the support base (50) is configured to fit into the upper part (52) of a cell for receiving a nuclear fuel assembly. (2).

15. Intervention device according to any one of the preceding claims, comprising several intervention tools (24) interchangeable.