Handling and confinement hood, application to handling holders of samples of nuclear materials such as nuclear fuels

Abstract

The present invention concerns a hood for handling and confinement of at least two objects of slender shape, including an external enclosure and internal enclosures inside the external enclosure and at least one motor fixed above an internal enclosure and inside a barrel, the motor(s) being adapted to rotate the screw of the screw-nut mechanism of each internal enclosure and therefore the nut over a stroke A, and first and second mechanical control means, arranged in part above the cover of the external enclosure, respectively for manually guiding the internal enclosures in translation over a stroke A0 and manually pivoting the barrel in order to bring a holding member of one of the internal enclosures opposite the opening in the bottom of the external enclosure. Application to the handling and confinement of nuclear material sample holders.

Claims

1. A hood for confinement and handling of at least two nuclear material sample tubes comprising: an external first enclosure extending along a longitudinal axis X′, comprising a cover, a bottom provided with an opening and a valve for blocking the opening and thereby sealing the external enclosure; a second enclosure forming a barrel, extending along the axis X′ and guided in rotation about the axis X′ inside the external enclosure; and at least one internal third enclosure and one internal fourth enclosure each extending along a longitudinal axis X1, X2 parallel to the axis X′ and each adapted to accommodate a nuclear material sample tube, the at least two internal enclosures being fastened to each other and guided in translation in the barrel over a stroke A0; each internal enclosure comprising within it: a holding member adapted to pick up a nuclear material sample tube; a screw-nut mechanism comprising a lead screw guided in rotation about the axis X1, X2 and a nut around the screw and to which the holding member is fastened, the mechanism being adapted to guide the latter in translation in the internal enclosure over a stroke A greater than the stroke A0; and a bottom comprising an opening opposite the holding member to allow one of the nuclear material sample tubes picked up thereby to pass through; the hood further comprising: at least one motor fixed above at least one of the said internal enclosures and inside the barrel, the at least one motor being adapted to rotate the screw of the screw-nut mechanism of each internal enclosure and therefore the nut over the stroke A; a mechanical control arranged in part above the cover of the external enclosure for manually guiding the internal enclosures in translation over the stroke A0; and a mechanical control arranged in part above the cover of the external enclosure for manually pivoting the barrel in order to bring a holding member of one of the internal enclosures opposite the opening in the bottom of the external enclosure.

2. The confinement and handling hood of claim 1, further comprising an internal fifth enclosure also extending along a longitudinal axis X3 parallel to the axis X′ and adapted to accommodate a nuclear material sample tube, the three internal enclosures fastened to one another being distributed at 120° to one another inside the barrel.

3. The confinement and handling hood of claim 1, wherein the valve for blocking the opening in the bottom of the external enclosure is further defined as a guillotine valve.

4. The confinement and handling hood of claim 1, further comprising a metal bellows fixed under each opening of an internal enclosure to provide a seal between the latter and the opening of the external enclosure on translation of the internal enclosures in the barrel.

5. The confinement and handling hood of claim 1, further comprising at least two O-rings, each accommodated at least partly in a respective peripheral groove at the top and at the bottom of an external wall of the barrel to provide a seal between the latter and the external enclosure.

6. The confinement and handling hood of claim 1, further comprising a motor fixed above each of the internal enclosures and inside the barrel being adapted to rotate the screw of the screw-nut mechanism of said internal enclosure and therefore the nut over the stroke A.

7. The confinement and handling hood of claim 1, wherein the at least one motor is further defined as an electric motor.

8. The confinement and handling hood of claim 1, wherein the holding member is mounted on the nut of the screw-nut mechanism by means of a plate guided against an internal wall of the internal enclosure by at least two lugs projecting from the plate and forming centering devices.

9. The confinement and handling hood of claim 1, wherein the mechanical control for manually guiding the internal enclosures in translation over the stroke A0 is further defined as comprising a screw-nut mechanism comprising a lead screw on a portion of a rod guided in rotation about the axis X and passing through the cover and a nut around the screw and to which the internal enclosures are fastened.

10. The confinement and handling hood of claim 1, wherein the mechanical control for manually pivoting the barrel comprises a gear mechanism consisting of a gear on a portion of a rod guided in rotation parallel to the axis X′ and passing through the cover and a toothed ring meshing internally with the gear and to which the barrel is fastened.

11. The confinement and handling hood of claim 1, wherein the holding member comprises a holding head adapted to be accommodated in an interior tube constituting a nuclear material sample tube to be picked up, the interior tube itself being adapted to be inserted in an exterior tube which cannot be held by the holding head.

12. The confinement and handling hood of claim 11, wherein the exterior tube is a measuring instrument holder tube.

13. The confinement and handling hood of claim 12, wherein the measurement instrument holder tube is adapted to accommodate at least one measurement sensor and/or a cooling system.

Description

DETAILED DESCRIPTION

(1) Other advantages and features of the invention will emerge more clearly on reading the detailed description of embodiments of the invention given by way of nonlimiting illustration with reference to the following figures, in which:

(2) FIG. 1 is a diagrammatic view in the installed irradiation configuration of a sample-holder (SH) tube in an instrumentation-holder (IH) tube in a research nuclear reactor;

(3) FIG. 2 is a diagrammatic partly exploded view of an attachment device connected to an interior tube in accordance with the patent application U.S. Pat. No. 9,449,722;

(4) FIG. 3 is a diagrammatic view of the interior of the interior tube showing a detail of the attachment device in accordance with the patent application U.S. Pat. No. 9,449,722 with the optional return means for its locking hook;

(5) FIGS. 4A to 4J are perspective sectional views showing the various steps of holding the interior tube by the holding member simultaneously with unlocking between the interior and exterior tubes in accordance with the patent application U.S. Pat. No. 9,449,722;

(6) FIGS. 5A to 5J are perspective sectional views showing the various steps of releasing the interior tube of the holding member simultaneously with the locking between interior and exterior tubes in accordance with the patent application U.S. Pat. No. 9,449,722;

(7) FIG. 6 is a plan view of the handling and confinement hood in accordance with the invention;

(8) FIG. 6A is a view of the hood from FIG. 6 in longitudinal section taken along the line A-A;

(9) FIG. 6B is a view of the hood from FIG. 6 in cross section taken along the line B-B;

(10) FIGS. 6C and 6D are views of the hood from FIG. 6 in longitudinal section taken along the lines C-C and D-D, respectively;

(11) FIGS. 6E, 6F and 6H are views of the hood from FIG. 6 in cross section taken along the lines E-E, F-F and H-H, respectively;

(12) FIG. 7 is a bottom view of the handling and confinement hood in accordance with the invention;

(13) FIG. 8 is a view in partial longitudinal section of an internal enclosure of the hood from FIG. 6;

(14) FIG. 9 is a partial perspective view in longitudinal section of the hood from FIG. 6;

(15) FIGS. 9A and 9B are detail views of FIG. 9.

(16) There is shown in FIG. 1 an interior tube 1, 10 with longitudinal axis X constituting a sample-holder tube intended to accommodate a sample of nuclear materials, such as nuclear fuels, such that it must be locked in an exterior tube 2 constituting a measurement instrumentation holder intended to house measurement sensors and a cooling system for the purposes of irradiation experiments in a water pool 3 of a research nuclear reactor.

(17) To be more precise, the interior tube 1 includes a tubular lower portion in which is housed a sample of nuclear materials, such as a stack of nuclear fuel pellets, and a tubular upper portion 10 by which it is held by a holding member 6.

(18) Prior to any irradiation experiment, it must be possible for the interior tube 1 to be brought up to and introduced into the exterior tube 2 by lowering a holding member and then locked to the exterior tube 2 and for the holding member to be released from the interior tube 1 in order to be raised.

(19) After one or more irradiation experiments, it must be possible for the interior tube 1 to be unlocked from the interior of the exterior tube 2 in which it is housed and for the holding member to grasp the interior tube 1 that has been unlocked and rise with the latter to extract it from the pool 3.

(20) In accordance with the patent application U.S. Pat. No. 9,449,722, there is provided a new holding and locking/unlocking system of which the embodiment from FIGS. 2 to 5I is reproduced here. The system with at least one attachment device 4 is provided on the one hand for the releasing of the interior tube 1 by the holding member 6 and by the same movement of the holding member 6 the sealed locking of the interior tube 1 to the exterior tube 2 and on the other hand for the unlocking of the interior tube 1 housed in the exterior tube 2 and by the same movement of the holding member 6 the holding of the interior tube 1 by the holding member 6.

(21) The exterior tube 2 and the holding member 6 include respective grooves 20, 60. The interior tube 1, 10 includes at least one notch 11 at its upper end 10a. The holding head of the holding member 6 has an outside diameter matching the inside diameter of the interior tube 1.

(22) An attachment device 4 in accordance with the patent application U.S. Pat. No. 9,449,722 is connected to the upper end 10a of the interior tube 10. The attachment device consists of a double hook 40, 41 of which one hook 40 is mounted to pivot about a pin 42, Y1 orthogonal to the longitudinal axis X of the interior tube. As shown in FIGS. 2 and 3, this pin 42 may be mounted in two spaced-apart lugs 12 themselves fixed to the upper end 10a of the interior tube 1, 10. The two lugs may be made in one piece with the interior tube 1, 10.

(23) To be more precise, the attachment device 4 firstly includes a locking hook 40 mounted to pivot about the pin 42, Y1 orthogonal to the longitudinal axis X of the interior tube, between a locking position in which it is housed in the groove 20 of the exterior tube 2 to lock the latter to the interior tube 1 and an unlocking position in which it is away from said groove 20.

(24) The attachment device 4 also includes a holding hook 41 mounted to pivot on the locking hook about a pin 43, Y2 also orthogonal to the longitudinal axis X of the interior tube 1 between a holding position in which it is housed in the groove 60 of the holding head 6 to hold the interior tube and at least one release position in which it is away from said groove 60.

(25) The attachment device 4 also includes an actuating lever 44 mounted to pivot about the axis Y1 of the locking hook 40 between a first neutral position in which it is away from the notch and does not project inside the interior tube 1 and a second neutral position in which it is housed in the notch 11, passing through an actuation position in which it projects inside the interior tube 1. The actuating lever 44 is connected to the locking hook 40 to rotate with it between its actuation position and its second neutral position and free to rotate relative to the locking hook 40 between its first and second neutral positions, as explained hereinafter with reference to FIGS. 4A to 4I. As shown in all the figures, the actuating lever may consist in a simple lug 44 in line with the locking hook 40.

(26) The holding and locking/unlocking system in accordance with the patent application U.S. Pat. No. 9,449,722 finally includes elastic return means 5 for returning the holding hook 41 from a release position toward its holding position. As shown in FIG. 6, the elastic return means may advantageously consist in a torsion spring 5 mounted around the pivot pin 43, Y2 of the holding hook 41 with its two end turns fixed and a central bearing turn 50 conformed to bear against the holding hook 41.

(27) The system in accordance with the patent application U.S. Pat. No. 9,449,722 may further include additional elastic return means 7 for returning the locking hook 40 from its unlocking position toward its locking position.

(28) In the embodiment shown in FIG. 4A to 5I, the system in accordance with the U.S. Pat. No. 9,449,722 includes three attachment devices 4 like that described, arranged at 120° from one another relative to the longitudinal axis (X) of the interior tube 2. Such an embodiment is advantageous because it enables an isostatic distribution of the holding and locking forces. In the same embodiment, the respective grooves 20, 60 of the exterior tube 2 and the holding member 6 are each produced around all the periphery of the latter.

(29) It is specified here that the arrows D indicate descent of the holding member 6 while the arrows R indicate rising of the holding member 6.

(30) It is also specified that the stroke A designates the stroke achieved by the holding member 6 at the end of its descent when holding the interior tube 1 locked to the exterior tube 2 (FIGS. 4A to 4J).

(31) For its part, the stroke B designates the stroke achieved by the holding member 6 at the end of its descent on releasing the interior tube 1 and locking the latter to the exterior tube 2 (FIGS. 5A to 5J).

(32) There will now be described the kinematics of the holding of the interior tube 1 by the holding member 6 and, in the same movement of the holding member 6, the unlocking of the interior tube 1 and the exterior tube 2 that the configuration of the system in accordance with the invention allows.

(33) When the interior tube 1 and the exterior tube 2 are locked together by the locking hook 40 and it is required to extract the interior tube 1, the holding member is lowered (FIGS. 4A and 4B).

(34) As it descends, when the holding member 6 comes into abutting engagement against the actuating lever 44, the latter pivots and the locking hook 40, rotationally connected to the lever 44, simultaneously pivots about the axis Y1 toward the interior of the tube 1, 2 from its locking position towards its unlocking position (FIG. 4C-4D). Because of its contact with the exterior surface of the holding head, the holding hook 41 pivots through an angle of a few degrees towards the exterior of the tubes.

(35) The descent of the holding member 6 continues, which causes the actuating lever 44 to be lodged in its neutral position in the notch 11 and simultaneously causes the complete release of the locking hook 40 from the groove 20 of the exterior tube 2, i.e. in an unlocking position (FIG. 4E). The unlocking of the interior tube 1 from the exterior tube is effectively achieved. In this position, the holding hook 41 begins to pivot toward the groove 60 of the holding member 6 under its own weight and because of the action of the torsion spring 5 which urges said hook 41 toward the interior of the tubes 1, 2.

(36) The descent of the holding member is then interrupted at the end of the stroke A, the holding hook 41 continuing to pivot toward the interior of the tube 1 toward its holding position (FIG. 4F).

(37) Raising of the holding member 6 can then begin, the pivoting of the holding hook 41 continuing until it has penetrated into the groove 60 of the holding member 6, i.e. has reached its holding position (FIG. 4G). The holding and locking of the interior tube 1 to the holding member 6 are then effectively achieved and the unlocking of the interior tube 1 relative to the exterior tube 2 is also achieved. Accordingly, when holding the interior tube, the operative is protected against the risks of damaging the holding system, the interior tube itself or the connection between them. This point is particularly important if the operations are carried out blind or remotely, for example through an opaque cover or slab, as will be the case in the Jules Horowitz irradiation reactor. The control of the two strokes A and B, for example by an automatic mechanism, ensures the safety of these operations.

(38) The raising of the holding member 6 is then continued (FIGS. 4H to 4J). The holding member and the attachment device(s) 4 are sized to overcome the friction forces of the seal(s) 8 accommodated in grooves 80 at the periphery of the interior tube 1 on extraction of the latter from the exterior tube 2 (FIG. 4J).

(39) There will now be described the kinematics of the sealed locking of the interior tube 1 in the exterior tube 2 and, in the same movement of the holding member 6, the release of the interior tube 1 from the latter that the configuration of the system in accordance with the patent application U.S. Pat. No. 9,449,722 allows.

(40) When the interior tube 1 is picked up by the holding member and locked to the latter by the holding hook 41 in its holding position and it is required to lock the interior tube 1 to the exterior tube 2, the holding member 6 is lowered (FIGS. 5A and 5B). The holding member 6 and the attachment device(s) 4 are sized to overcome the friction forces of the seal(s) 8 accommodated in grooves 80 at the periphery of the interior tube 1 on introduction of the latter into the exterior tube 2 (FIG. 5A).

(41) Once introduction of the interior tube 1 into the exterior tube 2 has begun, the descent of the holding member 6 continues (FIG. 5C) until it comes into abutting relationship toward the bottom of the interior tube 1 (FIG. 5D). In this position, the upper end 10a of the interior tube 1 is at the level of that of the exterior tube 2.

(42) The descent of the holding member is continued, which causes the release of the holding hook 41 from the groove 60 of the holding member 6 (FIG. 5 E).

(43) The descent of the holding member 6 is continued until the stroke B greater than the stroke A is achieved (FIG. 5F). In this position, the actuating lever 44 is no longer held in its neutral position in the notch 11 by the release member 6.

(44) The locking hook 40 then pivots about the axis Y1 toward the exterior of the tubes 1, 2 under its own weight and because of the action the torsion spring 7, which simultaneously causes pivoting of the actuating lever 44 rotationally coupled to the locking hook 40 and also pivoting of the holding hook 41 to its release position in which it is retained by the torsion spring 5. The pivoting of the locking hook 40 continues until the latter has reached its locking position (FIG. 5G). In this position, the effective locking between the interior tube 1 and the exterior tube 2 is effectively achieved by the locking hook 40.

(45) The holding member 6 is then raised, which causes the actuating lever 44 to pivot upward from its actuating position (FIG. 5G) towards its neutral position (FIG. 5H) in which it does not project inside the interior tube 1 (FIG. 5I).

(46) The raising of the holding member 6 may then continue, the actuating lever 44 pivoting downward under its own weight until it returns to its initial actuating position (FIG. 5I).

(47) To assure on the one hand the conditioning of new and irradiated SH tubes 1 without breaking the required confinement barriers in the reactor pool and on the other hand the holding of an SH tube and its locking/unlocking to/from an IH tube 2 with precise long-term control of the strokes A and B, the invention provides a hood 8 that is described next with reference to FIGS. 6 to 9B.

(48) The handling and conditioning hood 8 in accordance with the invention includes first of all an external enclosure 80 that extends along a longitudinal axis X′, including a cover 800, a bottom 801 provided with an opening 802 and a valve 803 for blocking the opening and thereby sealing the external enclosure.

(49) Inside the external enclosure 80 a second enclosure 81 forming a barrel also extending along the axis X′ is guided in rotation about this axis X′. In order to prevent water from the reactor pool penetrating into the space between the external enclosure 80 and the barrel 81, two O-rings 13 are advantageously provided, each accommodated at least in part in a peripheral groove 14 respectively at the top and at the bottom of the external wall of the barrel 81, as shown better in the detail FIGS. 9A and 9B.

(50) Each of the three identical internal enclosures 82A, 82B, 82C fastened together extends along a longitudinal axis X1, X2, X3 parallel to the axis X′. They are distributed at 120° from one another inside the barrel 81. Each is adapted to accommodate an SH tube and they are guided in translation in the barrel over a stroke A0. The stroke A0 is very short compared to the stroke A and enables the latter to be completed to achieve the aforementioned stroke B. In other words, the stroke B is equal to the stroke A plus the stroke A0.

(51) Each of these three internal enclosures 82A, 82B, 82C includes within it a holding member 6 with a groove 60 adapted for holding and locking an SH tube as described above with reference to FIGS. 2 to 5J.

(52) Each also includes a screw-nut mechanism 9A, 9B, 9C consisting of a lead screw 90A, 90B, 90C guided in rotation about the axis X1, X2, X3 and a nut 91A, 91B, 91C around the screw and to which the holding member 6 is fastened. The lead screw 90A, 90B, 90C is preferably a screw with a trapezoidal thread.

(53) As FIG. 8 shows more clearly, in accordance with one advantageous assembly variant, the holding member 6 is mounted on the nut 91A, 91B, 91C of the screw-nut mechanism 9A, 9B, 9C by means of a plate 92 guided against the internal wall of the internal enclosure by at least two lugs 93 projecting from the plate and forming centring devices. The rotation of the lead screw 90A, 90B, 90C relative to the corresponding internal enclosure 82A, 82B, 82C is guided by bearing systems 94 on either side of the screw. The types of bearing are of course adapted as a function notably of the length of the lead screw 90A, 90B, 90C and the load to be supported.

(54) Such a screw/nut mechanism is adapted to guide the holding member 6 in translation in the internal enclosure 82A, 82B, 82C along the stroke A, i.e. over all the length of the internal enclosure. For an SH tube length of the order of 3.5 m, the stroke A is typically equal to this length of 3.5 m and the stroke A0 to be reached to effect the stroke B for unlocking the SH tube 1 from the holding member 6 (FIGS. 5F and 5G) is of the order 7.5 to 10 mm.

(55) Finally, as shown more clearly in FIG. 8 in relation to the internal enclosure 82A, each internal enclosure 82A includes a bottom 820A provided with an opening 821A facing the holding member 6 to allow a picked up SH tube 1 to pass through.

(56) To rotate the screw 90A, 90B, 90C of each screw-nut mechanism 9A, 9B, 9C, an electric motor 83A, 83B, 83C is fixed above each internal enclosure 82A, 82B, 82C and inside the barrel 81. This therefore moves the above screwed nut 91A, 91B, 91C over the stroke A. The coupling between a lead screw 90A, 90B, 90C and the output shaft of a corresponding motor 82A, 82B, 82C may be advantageously provided by keys and gripping jaws, not shown, designed for transmission shafts.

(57) The hood 8 further includes mechanical control means 84 arranged in part above the cover 800 of the external enclosure 80 to guide manually in translation the internal enclosures 82A, 82B, 82C over the stroke A0. In the embodiment shown in FIGS. 6 to 9B, these means include a screw-nut mechanism 87 consisting of a lead screw 870 on a portion of a rod 871 guided in rotation about the axis X′ and passing through the cover 800 and a nut 872 around the screw and to which the internal enclosures 82A, 82B, 82C are fastened.

(58) Thus according to the invention a double control system is provided offering precise long-term control that consists in: lowering the holding member over the greatest stroke A by means of a screw-nut mechanism 9A, 9B, 9C actuated in rotation by a motor 83A, 83B, 83C accommodated between the internal enclosure 82A, 82B, 82C on which it is mounted and the cover 800 of the external enclosure 80; lowering the holding member 6 to unlock a tube 1 between the stroke A and the slightly greater stroke B by means of a screw-nut mechanism 87 actuated manually in rotation by a rod 870 from outside the reactor pool.

(59) The hood 8 also includes mechanical control means 85 arranged in part above the cover 800 of the external enclosure 80 for pivoting the barrel 81 manually in order to bring a holding member 6 of one of the internal enclosures 82A, 82B, 82C opposite the opening 802 in the bottom 801 of the external enclosure 80. In the embodiment shown in FIGS. 6 to 9B, these means 85 include a gear mechanism 88 consisting of a gear 880 on a portion of a rod 881 guided in rotation parallel to the axis X′ and passing through the cover 800 and a toothed ring 882 meshing internally with the gear 880 and to which the barrel 81 is fastened. In other words, a compact mechanism usually called a turntable is obtained at the top of the barrel 81.

(60) At the bottom of the opening 821A, 821B, 821C of each internal enclosure 82A, 82B, 82C there is arranged between the latter and the external enclosure 80 a metal bellows 86A, 86B, 86C that provides the seal during movement in translation of the internal enclosures by the screw-nut mechanism 87 over the stroke A0.

(61) In order to be able to move the hood 8 in accordance with the invention in the reactor pool and extract it therefrom, lugs 89 welded to the cover 80 and referred to as slinging lugs are advantageously provided: it is therefore possible to attach to its slings that enable introduction and movement within or extraction from the pool.

(62) Thus the hood 8 in accordance with the invention that has just been described enables execution of operations of handling and confining an irradiated SH tube and its replacement by a new SH tube precisely and with no risk of breaking the confinement barriers. This is all the more advantageous when the operations are carried out blind, for example through a slab or an opaque cover, as will be the case in the Jules Horowitz irradiation reactor. The control of the two strokes A and B by the precise long-term double control of the hood 8 makes it possible to ensure that these operations are safe.

(63) Although described with reference to handling and confinement of SH tubes, the hood 8 that has just been described can serve to handle any object of slender shape in environments that offer little available space and in which safety constraints are very strict, in particular nuclear environments.

(64) The invention is not limited to the examples that have just been described; features of the examples shown may notably be combined with each other in variants that are not shown.