FR2676140A1 - Device for inserting an irradiation capsule into a cage (basket) integral with the internals of nuclear reactors - Google Patents

Abstract

The device comprises an elongate support mast (2), an element (14) for supporting and holding the support mast (2) in its in-use position, a tightening rod (10) mounted on the support mast (2) in a direction parallel to the axis of the support mast and along its upper part, a screw and nut assembly (17) whose screwing axis is parallel to the axis of the support mast and a thrust rod (12) linked in translation with the screw (30). A thrust which inserts the capsule (13) is exerted by the thrust rod (12), when the screw (30) is rotated via the tightening rod (10) introduced into a cavity in the screw.

Description

 The invention relates to a device for inserting an irradiation capsule into a basket integral with the internal equipment of a nuclear reactor.

 During the entire period of use of the nuclear reactors, this period being able to be very important, it is necessary to control the behavior of the material constituting the vessel in which the reactor core is placed and to verify at determined time intervals that this material still has satisfactory mechanical characteristics, despite the radiation doses received during long-term use.

 For this it is necessary to carry out mechanical tests on steel samples or test pieces of the same grade as that constituting the reactor vessel, after these specimens have undergone irradiations comparable to those which the vessel underwent during the same time interval. These tests are carried out at the time of the refueling of the reactor, that is to say approximately every five years, and at the time of the general inspection of the reactor, that is to say approximately every ten years.

 Irradiation capsules consisting of a tube, the upper part of which has a nozzle for handling the capsules and fixing them, are placed in welded baskets against the heat shield surrounding the reactor core and constituting part of its internal equipment. of the tube in the baskets, containing test pieces of steel identical to that of the reactor vessel, intended for mechanical tests such as tensile or resilience tests.

 When refueling or inspecting the reactor, some of the irradiation capsules are removed in order to extract the samples or test pieces they contain and to carry out the mechanical tests for which these samples or test pieces have been planned. It is thus possible to control the evolution of the material of the reactor vessel.

 The irradiation capsules which have been extracted from the baskets integral with the interns or from other capsules of identical characteristics containing samples of metal to be irradiated can be replaced in the baskets, before restarting the reactor.

 It may also be necessary to carry out permutations on the irradiation capsules arranged in baskets distributed around the thermal screen of the reactor, so that these capsules undergo, over time, comparable irradiations.

 To carry out the handling and permutations of the irradiation capsules, tools are used which can be moved and implemented from a work station located above the level of the reactor pool. The extraction and insertion of the irradiation capsules into the corresponding baskets secured to the internal equipment of the reactor can be carried out inside the tank in which the internal equipment has remained in its operating position or, on the internal equipment lower placed on a storage stand in the reactor pool.

 In all cases, these operations are carried out under a large height of water, after opening the tank and filling the reactor pool.

 Handling tools are known which consist of very long poles comprising at their lower end a gripper for gripping capsules with pivoting fingers which can be controlled from the work station.

 French patent 2,417,828 has described a tool comprising both a gripper with pivoting fingers and means for pushing the capsules into their housing inside the baskets.

 The irradiation capsules have at their upper part a hollow tulip made up of several flexible segments, by means of which the capsule is handled and inserted.

 The capsule is inserted by snapping on the tulip segments into a housing located at the top of the basket, the engagement and snap-on of the tulip segments being ensured by pushing on the irradiation capsule in the axial direction. The device according to FR-A-2,417,828 makes it possible to exert a thrust on the bottom of the tulip, by means of an operating tube carrying the pivoting handling fingers. The thrust is exerted by a jack and the corresponding forces are taken up by claws pivotally mounted on the chamber of the jack and intended to cooperate with part of the internal equipment of the reactor.

 Such a device which makes it possible to carry out all the handling and permutation operations on the irradiation capsules has a relatively complex structure and requires the use of a motor means constituted by a jack.

 As part of the current operation of nuclear reactors, it may be necessary to have a simple tool with fully manual operation which allows the insertion of irradiation capsules, after these capsules have been introduced into the baskets by a handling tool with pivoting fingers.

 Until now, such a simple structure insertion tool with entirely manual operation has not been known.

 The object of the invention is therefore to propose a device for inserting an irradiation capsule into a basket secured to the internal equipment - of a nuclear reactor placed under water in a swimming pool, which is of a simple structure. and fully manual operation.

 To this end, the insertion device according to the invention comprises - an elongated support mast comprising a handling handle at one of its ends, a positioning means relative to the basket at its other end and distributed guide means along its length between the handling handle and the positioning means, - a support and holding element connected to the support mast in an intermediate position between its ends, intended to come to rest on the upper part of the internal equipment, in the position of the support mast service, in which the support mast is vertical, its upper part comprising the handling handle being above the level of the swimming pool and its lower part comprising the positioning means at the level of the irradiation basket, - a clamping pole mounted on the support mast in a direction parallel to the axis of the support mast and along at least its upper part, movable in rotation around its axis and in translation in the axial direction, inside a set of guide means, comprising drive elements of polygonal section at its upper end and at its lower end, - a screw assembly and nut whose screwing axis is parallel to the axis of the support mast, the nut being fixed on the support mast and the screw rotatably mounted in the nut, in the axial extension of the clamping rod and comprising a housing having a polygonal section corresponding to the section of the lower end element of the clamping pole, - and a thrust pole mounted movable in translation and immobilized in rotation relative to the support mast, in a second set of guide means of the support mast, in a direction parallel to the support mast and in the extension of the clamping rod, connected in translation to the screw located in its axial extension and free to rotate relative to to the screw, comprising an end part opposite the screw intended to come to bear on the capsule to exert a thrust, when the screw is rotated by means of the clamping pole inserted in the housing of the screw .

 In order to clearly understand the invention, a description will now be given, by way of nonlimiting example, with reference to the attached figures, of an embodiment of a device for inserting irradiation capsules into equipment. of a pressurized water nuclear reactor.

 Figure 1 is a schematic elevational view of the entire insertion device.

 Figure 1A is an elevational view of the upper part of the insertion device according to the invention.

 FIG. 1B is an elevation view of the lower part of the insertion device.

 Figure 2 is an elevational view in partial section on a larger scale of the clamping pole of the device shown in Figure 1A.

 Figure 3 is an elevational view in partial section on a larger scale of the central part of the device shown in Figures 1A and 1B.

 In FIGS. 1, 1A and 1B, the insertion device according to the invention can be seen generally designated by the reference 1 which comprises a support mast 2 consisting of three successive tubular sections 2a, 2b and 2c connected together by screwed flanges 3.

 The free end of the section 2a constituting the upper section of the support mast 2 in its service position is secured to a handling loop 4 connected to the section 2a by means of bearings and hinge pins.

 The free end of the section 2c constituting the lower end of the support mast 2 in its service position is secured to a positioning lug 5 comprising a notch intended to come to engage on the external surface of a basket 6 receiving a irradiation capsule fixed on the external surface of the heat shield 7 of the reactor constituting a part of its internal equipment located at the level of the core.

 The support mast 2 carries, laterally, a first set of guide plates 8 arranged in radial directions and distributed along the length of the upper section 2a of the support mast 2.

 The guide plates 8 of the first set allow the support and the guiding of a clamping rod 10 and of an operating rod 11 to be produced, as will be described below.

 The support mast 2 also carries a second set of guide plates 9 arranged laterally in radial directions and distributed along the length of the middle section 2b and of the lower section 2c of the support mast 2.

 The guide plates 9 make it possible to maintain and guide a pushing pole 12, as will be described later.

 An element for supporting and holding the mast 2 in the service position on the internal equipment of the reactor is engaged on the middle part of the mast 2, so as to come to cap, in the service position, with the interposition of a wedging ring, the upper flange 7a constituting the upper part of the lower internal equipment of the nuclear reactor.

 An internal support structure 15 is fixed to the mast 2, in ~ vis-à-vis the support member 14, in its service position.

 Below the support structure 15, is fixed the support 17 of a set of displacement with screw and nut of the pushing pole 12. This support 17 resumes the reaction of the pushing force during the insertion of the capsule.

 As can be seen in FIG. 2, the clamping pole 10 is constituted by a tube 18 of great length closed at one of its ends by a welded end 19 whose external part 19a has a prismatic shape with polygonal section and, at its other end, by a welded end piece 20 comprising a prismatic outer end portion 20a of polygonal section.

 The parts 19a and 20a of the clamping pole 18 preferably have a hexagonal section.

 A retaining washer 21 comprising a notch 21a of radial direction is fixed on the outer surface of the tubular body 18 of the clamping rod 12, in the vicinity of the end piece 19.

 As can be seen in FIG. 1A, the locking washer 21 is capable of cooperating with a retaining finger 22 to maintain the clamping rod 10 in its high position shown in FIG. 1A.

 The clamping pole 10 is freely engaged in openings passing through the guide plates 8 and allowing the displacement of the pole 10 in rotation about its axis and in axial translation.

 The clamping rod 10 can be moved downwards, by rotating it around its axis, to make the notch 21a of the washer 21 coincide with the retaining finger 22.

 The clamping pole 10 is also guided in axial translation, by a lug 23 secured to the support and holding element 14 and, when it moves towards its low position.

 The element 14 comprises a tubular body 14a engaged with gentle friction on the support mast 2 and a stirrup 14b fixed on the tubular body 14a in a lateral arrangement.

 The operating rod 11 is connected at its lower part to the support and holding element 14 which is slidably mounted on the mast 2, by means of a tubular body 14a.

 The upper end of the operating rod 11 constitutes an operating handle 11a which is accessible from the work station situated above the level of the reactor pool, in which the internal equipment of the reactor comprising the heat shield is immersed. 7.

 The mast 2 comprises, in its middle part on which the tubular body 14a of the support and holding element 14 is engaged, a lumen 24 of longitudinal direction in which is engaged a pin 25 integral with the tubular body 14a.

 By pulling on the operating rod 11, from the work station, the support and holding element 14 can be moved, between its support position shown in FIG. 1A and a high out-of-service position in which the pin 25 abuts on the upper part of the light 24.

 The operating rod 11 can be locked in the high position by means of a washer 26 bearing on a stop means carried by the support plate 8b.

 As can be seen in FIG. 3, the support 17 of the device for moving the screw and nut of the push rod 12 comprises a transverse element 17a fixed on two side plates and traversed by an opening in which is fixed a nut 28. A screw 30 is engaged in the tapped opening of nut 28.

 The screw 30 comprises at its upper part a housing 31 of prismatic shape with polygonal section, the shape of which corresponds to the shape of the end portion 20a of the clamping pole 10.

 The housing 31 opens at the upper end of the screw 30, via an engagement opening 31a whose frustoconical shape corresponds to the shape of the connection part between the cylindrical part of the end piece 20 and the prismatic end 20a of the clamping pole 10.

 The screw 30 comprises, at its lower end, a second housing 32 of cylindrical shape in which is engaged the end part of a rod 33 secured to a nozzle 34 closing the upper end of the tubular body 35 of the pole thrust 12.

 The end of the rod 33 engaged in the opening 32 constitutes a development 36 having an end surface in the form of a spherical cap. Two half-rings 39 fixed by screws 40 on the lower end of the screw 30, around the opening 32, make it possible to ensure the axial retention of the pushing pole 12 which is suspended at the lower end of the screw 30.

 The pushing pole 12 is engaged in aligned openings of the guide plates 9 which maintain and guide it in the axial direction.

 The clamping rod 10, the screw 30 and the thrust rod 12 are arranged in the axial extension of one another and in a position offset laterally relative to the axis of the support mast 2.

 When the support mast 2 is placed on the internal equipment of the nuclear reactor, as shown in FIGS. 1A and 1B, the axes of the clamping rod 10, of the screw 30 and of the thrust rod 12 are aligned with the 'axis of the basket 6 into which is introduced an irradiation capsule.

 The tubular body 35 of the push rod 12 is closed at its lower end opposite the screw 30, by a nozzle 41 whose end 41a constitutes a pusher which can be introduced into the interior cavity of the tulip of a capsule d irradiation 13 engaged in the basket 6 secured to the internal equipment.

 The body 35 of the pushing pole 12 comprises a longitudinal slot 43, in which the ends of an axis 44 are engaged, carrying two holding pins.

 During its movements in the axial direction, the pushing rod 12 is guided by the light 43 in which are engaged the ends of the axis 44 itself immobilized, by means of cheeks 45, welded on the fixed guide plate 9b.

 The pushing pole 12 therefore does not undergo any rotation, when it is moved in translation by the screw and nut assembly 30, 28, the end of the pole 12 formed by the rod 33 being free to rotate inside. of screw 30.

 We will now describe the implementation of the insertion device according to the invention, for carrying out the insertion of an irradiation capsule 13 inside a basket 6 carried by the lower internal equipment of a reactor. nuclear.

 The internal equipment of the nuclear reactor is placed under water in the reactor pool, for example on their storage stand.

 An irradiation capsule 13 has been previously introduced into the basket 6, the upper part of the tulip of this capsule by means of which the capsule is locked in the basket, remaining protruding above the end upper basket 6.

 The insertion device 1 according to the invention is suspended, by means of its handle 4, from the hook of a lifting and handling means such as an overhead crane disposed above the level of the reactor pool .

 The support and holding element 14 of the tool 1 is placed in its upper position, by pulling on the operating rod îla which is locked in its high position, at the level of the guide plate 8b.

 The clamping pole 10 is held in the high position by rotating it to make the washer 21 pass over the retaining finger 22 while passing through the notch 21a.

 The tool 1 is brought into the axial alignment of the basket 6 and engaged by its lower part on the external surface of the basket by means of the positioning tab 5.

 The height positioning of the tool 1 is precisely adjusted and the support and holding element 14 is placed in its low position, by unlocking and actuating the operating rod 11. In this position, the stirrup 14b of the element 14 covers the upper part of the flange 7a of the internal equipment which is crossed by a passage opening of the irradiation capsule and the internal support element 15 comes to bear against the internal surface of this flange 7a.

 The device 1 is then perfectly maintained and positioned in height on the internal equipment, via the element 14 and a support wedge.

In this position, as shown in FIGS. 1A and 1B, the pushing rod 12, the screw 30 and the clamping rod 10 are in axial alignment with the opening passing through the flange 7a, the basket 6 and the cavity. of the tulip of the irradiation capsule 13.

 The support of the retaining washer 21 is then released on the retaining finger 22, by rotating the clamping rod 10, as described above. The clamping pole guided by the plates 8 and the flange 23 is then lowered in its axial direction until the engagement of the profiled end portion 20a in the housing 31 of the screw 30. The engagement of the part 20a in the housing 31 is facilitated by the presence of the flared opening 31a.

 The clamping rod 10 is then manually rotated around its axis, in the screwing direction, using a manual tool such as a wrench engaged on the end part 19a of the clamping rod 10.

 The rotation of the clamping rod 10 causes the rotation of the screw 30 which moves by screwing inside the fixed nut 28.

 As explained previously, the displacement in rotation and in translation of the screw 30 causes a displacement in translation of the push rod 12 which does not undergo any rotation, owing to the fact that it is freely connected in rotation to the screw 30 and guided in translation by the light 43 and the axis 44.

 The end portion 41a of the push rod 12 constituting the pusher penetrates inside the cavity of the tulip of the irradiation capsule 13 and exerts a push on the capsule, so as to achieve its latching and locking inside the basket 6.

 The screw travel of the screw 30 corresponds to the travel necessary to engage the irradiation capsule.

 The clamping pole is then rotated in the direction of unscrewing so as to cause the screw 30 and the pushing pole 12 which is suspended at its bottom to rise.

 The support and holding element 14 is replaced in the high position out of service and the operating rod 11 is locked in the corresponding position.

 Likewise, the clamping pole 10 is raised to the high position and locked by rotation, passing through the notch 21a of the washer 21, to come to bear on the finger 22.

 The insertion device can be moved to come vertically from a second irradiation basket into which the insertion of a second irradiation capsule is carried out.

 During the insertion of the irradiation capsule, the clamping force exerted via the clamping pole 10 can be easily controlled by using a torque wrench engaged on the end part 19a of the clamping pole 10.

 The device according to the invention has a simple structure and comprises only manually actuated elements which can be easily implemented and controlled from the work station above the reactor pool.

 However, the operation of the device according to the invention is very safe and the insertion of the irradiation capsules into the baskets can be carried out in a completely satisfactory manner, with remote control.

 The installation of the tools at the level of a radiation basket can be controlled by means of a video camera.

 The invention is not limited to the embodiment which has been described.

 This is how the support mast can have a structure different from that which has been described and that it can comprise handling and support elements of any type adapted to the shape of the internal equipment of the nuclear reactor and to the mode. intervention planned.

 Likewise, the clamping pole and the thrust perc 9 can be produced in a manner different from that which has been described.

 Finally, the device according to the invention can be used to carry out the insertion of irradiation capsules into the internal equipment of any nuclear reactor, within the framework of operations for changing or permutation of irradiation capsules implementing a independent device for handling and inserting capsules into baskets attached to internal equipment.

Claims (10)

 1.- Device for inserting an irradiation capsule (13) into a basket (6) secured to the internal equipment (7) of a nuclear reactor placed under water, in a swimming pool, characterized in that it comprises - an elongated support mast (2) comprising a handling handle (4) at one of its ends, a positioning means (5) relative to the basket at its other end and guide means (8, 9) distributed along its length between the handling handle (4) and the positioning means (5), - a support and holding element (14) connected to the support mast (2) in an intermediate position between its ends, intended for come to rest on the upper part (7a) of the internal equipment, in the service position of the support mast (2), in which the support mast (2) is vertical, its upper part comprising the handling handle (4) being at above the level of the swimming pool and its lower part comprising the positioning means nt (5) at the level of the irradiation basket (6), - a clamping pole (10) mounted on the support mast (2) in a direction parallel to the axis of the support mast (2) and along its upper part at least, movable in rotation about its axis and in translation in the axial direction, inside a set of guide means (8), comprising drive elements (19a, 20a) of polygonal section at its upper end and at its lower end, - a screw and nut assembly (17, 28, 30) whose screwing axis is parallel to the axis of the support mast (2), the nut (28) being fixed on the support mast (2) and the screw (30) rotatably mounted in the nut (28), in the axial extension of the clamping pole (10) and comprising a housing (31) having a polygonal section corresponding to the section of the lower end element of the clamping pole (10), and a thrust pole (12) mounted movable in translation and immobilized e n rotation relative to the support mast (2) in a second set of guide means (9) of the support mast (2), in an arrangement parallel to the support mast (2) and in the extension of the clamping pole (10) , connected in translation to the screw (30) located in its axial extension and free to rotate relative to the screw (30), comprising an end portion (41a) opposite the screw (30) intended to come to bear on the capsule (13) for exerting a thrust, when the screw (30) is rotated by means of the clamping rod (10) inserted in the housing (31) of the screw (30).  2.- insertion device according to claim 1, characterized in that the support mast (2) consists of successive tubular sections (2a, 2b, 2c) in its axial direction, connected together by connection flanges (3).  3.- insertion device according to any one of claims 1 and 2, characterized in that the guide means (8, 9) distributed along the length of the support mast (2) are constituted by plates fixed laterally on the support mast (2) in radial directions and comprising openings for passage and for guiding the clamping pole (10) or the pushing pole (12).  4.- insertion device according to any one of claims 1 to 3, characterized in that the positioning means (5) of the support mast (2) relative to the irradiation basket (6) is constituted by a plate fixed to the lower end of the support mast (2) in a radial direction and comprising a recess intended to come into engagement on the external surface of the irradiation basket (6).  5.- Device according to any one of claims 1 to 4, characterized in that the support and holding element (14) of the support mast (2) on the internal equipment comprises a tubular body (14a) mounted sliding on the support mast (2), with a certain latitude of axial movement and a stirrup (14b) disposed laterally relative to the tubular body (14a) intended to come to cover the upper part (7a) of the internal equipment, by displacement in the direction axial of the support mast (2).  6.- Device according to claim 5, characterized in that the support and holding element (14) is connected to the end of an operating rod (11) slidably mounted in a set of guide elements (8) of the support mast (2) and comprising an upper part situated at the level of the upper part of the support mast (2) constituting an operating handle (la), to effect the axial displacement of the support and holding element (14).  7.- insertion device according to any one of claims 1 to 6, characterized in that the push rod (12) comprises a connecting rod (13) at its upper part having one end (36) constituting a development engaged in an opening (32) formed in the lower part of the screw (30) and fixed inside this housing (32) by screwed fasteners (39).  8.- insertion device according to claim 7, characterized in that the opening (36) has a surface in the form of a spherical cap directed towards the bottom of the housing (32) of the screw (30).  9.- insertion device according to any one of claims 1 to 8, characterized in that the clamping pole (10) and the insertion pole (12) are made in the form of closed tubular elements of sealed at their ends by end caps (19, 20, 34, 41).  10.- Insertion device according to any one of claims 1 to 9, characterized in that a retaining finger (2) is fixed in a lateral position and in a substantially radial direction on the handling axis ( 4) and that a retaining washer (21) comprising a radial notch (21a) is fixed on the upper part of the clamping rod (10) so as to project radially with respect to the external surface of the clamping rod (10) and to come to rest on the retaining finger (22), when the clamping pole (10) is in a high position, the polygonal section drive element (20a) of the clamping pole (10) being outside and above the housing (31) of the screw (30), the clamping pole (10) being able to be moved downwards after a rotation around its axis to coincide the notch ( 21a) of the retaining ring (21) with the retaining finger (22).