Patent Number: 043081002
Section: description

DETAILED DESCRIPTION Referring first to FIG. 1 which shows in simplified manner a portion of the building forming the chamber of the reactor, the vessel 1 of the reactor which occupies the center of the building is shown here in readiness for a recharging operation, i.e. with its cover removed along with the upper apparatus for control of the control rods. The plane of the upper joint of the vessel on which the cover normally bears is then level with the bottom of the pool 2 of the reactor. During all of the recharging operations, the pool 2 is filled with boron-containing water. The manipulation device 3 which is the subject of the invention travels in the manner of a rolling bridge on the rails 5 just above the upper level of the pool. The device 3 can therefore be displaced between a position situated above the vessel of the reactor and another position above a trench of the pool where racks are provided to form transit stations for new combustible assemblies before they are put in place in the reactor or for spent combustible assemblies for evacuation. Reference is now made to the assembly in FIGS. 3-5 for the description of the manipulation device itself designated generally by reference numeral 3 in FIG. 1. As in the machines previously utilized, the device comprises a main platform 10 forming a beam for the rolling bridge which rolls on rails 5 by wheels 11. Taking into account the scale of the drawings and in order not to encumber the figures, neither the motors nor the drive apparatus for the longitudinal displacement of the assembly on the rails 5 is shown. Such apparatus is of conventional type for rolling bridges. Similarly, there is not shown in detailed fashion the means for effecting transverse displacement of the carriage 14 on the rail 15 carried by the platform 10, the carriage 14 being displaced in the same fashion as on a conventional rolling bridge. The carriage 14 supports a turnable turret 17 which can be driven in rotation by means of a reduction motor assembly 18 driving in conventional fashion a pinion in mesh with an exterior toothed ring around the turret 17. The turret 17 carries three vertical tubular masts 20,21, and 22 angularly equidistant with respect to the axis of rotation of the turret 17 and cross braces 23 connecting the masts. The assembly carrying mast 20 is adapted, as in conventional recharging machines, to manipulate the complete combustible assemblies, i.e. with their auxiliary cluster. For this purpose, the mast 20 comprises an interior tubular telescopic element 24 (FIG. 5) which includes longitudinal ribs 25 guided along the length of tube 20 by radial rollers 26 and lateral rollers 27. The lower portion of the telescopic tube 24 is provided with a mouth forming a grapple 29 which can be adapted to the upper portion of a complete assembly 30. Lifting is effected by a cable 32 fixed to the tube 24 and operable from a winch 34 disposed in a tower 35 forming the superstructure of the turret 17 and turnable therewith. From a totally retracted position, the operation of taking an assembly is effected by unwinding the cable 32. The tube 24 descends to the point where the grapple 29 centers itself by bearing on the extremity of the assembly 30 and engages the assembly thereat. Of course, the locking of the grapple 29 is remotely controlled by electrical and pneumatic means and the tower 35 also supports unwinders for the electrical and pneumatic supply channels in order to permit them to follow the movements of raising and lowering the telescopic tube 24 and the grapple 29. In the raised position, the assembly of the tube 24 and the assembly 30 is displaced as a unit up to the extreme position shown in FIG. 3 in which the assembly 30 penetrates totally into the tube 20. In this position, the machine can be freely displaced above the pool of the reactor, no element then projecting below the lower level of the tubes 20, 21 and 22 which are situated above the upper level of the vessel. The mast 21 is equipped in similar manner for the manipulation of the control clusters. Here the telescopic element sliding in the tube 21 and guided by the same type of rollers distributed along the length of the tube is constituted by a series of grills 40 connected by cross-pieces, the cut in each grill following the envelope of the absorbent rods and the star branches which connect them at their upper portions to the grapple member. The tube 21 is also associated with a lifting cable 41 and a locking grapple. The cable 41 is operated from a winch disposed in the superstructure 35 in the same manner as the winch 34 associated with the tube 20. Upon decent of the cable 41, the guide member with grills 40 descends, first to come to bear on the head of the assembly then the grappling apparatus continues to descend in the guide up to its locking on the cluster. In raising the control rods, the assembly 40 first rests fixed by bearing on the assembly and serves to guide the assembly of the rods of the control cluster; when this is entirely supported by the grills 40 the assembly is raised as a unit to totally penetrate into the tube 21 thus leaving all freedom of movement to the assembly of the manipulation machine 3. In a further analogous fashion, the mast 22 is equipped with a lower telescopic element, a cable and a raising grapple with special accessory devices determined for the manipulation of the clusters of consumable poisons or of sealing clusters. The three masts, 20,21, and 22 are thus each equipped with their proper manipulation means, their telescopic element and their proper cable and raising winch and can each take three positions by rotation of the turret 17. One of these positions, fixed with respect to the carriage, is an active work position where the manipulations are possible. In FIGS. 2,3 and 4 it is the mast 20 which occupies the active position. We have not described here the safety locking apparatus which can be of any conventional type adapted to prevent the movement of the mast other than that in the active work position nor those means adapted to prevent the movement of the turret and the carriage whenever the manipulated mast has not been returned to totally retracted position. The turret 17 also carries, along the axis of rotation, an auxiliary telescopic mast 45 which does not extend beyond the lower level of the tubes 20,21 and 22; in extended position it permits carrying a T.V. camera 46 or the like up to the upper level of the assemblies. With a machine thus realized according to the invention a complete operation of recharging comprises, for example, the raising of a used combustible assembly, a transposition of the assemblies in the core and the transport of a new combustible assembly effected according to the following sequences after raising the cover of the vessel and the mechanism for control of the control rods. The machine 3 is taken above an assembly to be raised with the mast 20 in working position. One then raises the used assembly with the sealing cluster with which it has been associated and the assembly is taken to the transfer position where the assembly is deposited into a container. After retracting the telescopic arm 24 and without moving the carriage 14 one can turn the turret 120 degrees to place the arm 22 above the assembly in the container and extract the sealing cluster from the assembly. The machine 3 is then moved above the vessel to a position above an assembly just completing the second tier of its cycle and still provided with a control cluster. By effecting a new rotation of 120 degrees of the turret 17, the arm 21 is put in working position and it is utilized to raise the control cluster. Without displacing the machine 3 or the carriage 14, by effecting rotation of 120 degrees of the turret the arm 22 already carrying the sealing cluster is brought above the assembly used through the second tier which then receives the sealing cluster for the last tier of its activity in the reactor. The machine thus carrying a control cluster can then be utilized with its arm 20 which is free to transport a complete assembly from the periphery towards the center of the vessel. Finally, while carrying a control assembly on the arm 21 the machine is taken to the transfer station above a new assembly while waiting but still without a cluster. The new assembly is then provided with the control cluster by means of arm 21 and the assembly is raised by the arm 20 to be then taken to its place. It is seen that there is thus effected with the same machine both transfer or transposition of a complete assembly while also realizing transposition of clusters, mostly in the intermediate time between operations, by a simple rotation of one stage of rotation of the turret 17. All these operations are realized with visual control due to the camera 46 which also permits examination of the state of different clusters in the course of their manipulation. Of course the sequence described above is only one example from a greater number of possible sequences depending on the particular conditions of use of the reactor and the nature of the different clusters utilized. However, one will find in all cases the same benefit realized from the success of operations by simple rotation of the turret without having to displace the bridge 10 or the carriage 14. As a consequence, a substantial gain of time is first obtained in the operations of recharging but additionally the possibility is achieved of effecting these diverse manipulations with a single operator. The simultaneous reduction of the number of persons necessary to enter the chamber of the reactor and the time during which it must close down is an important safety factor in the protection against radiation. Of course, the invention is not strictly limited to the single embodiment which has been described by way of example but it also covers embodiments which differ only by details and variants of execution or by the utilization of equivalent means. One could thus also imagine an analogous machine with four arms on the turret, each arm then having a still more powerful specialization.