Patent Number: 048636746
Section: description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows the schematic process of charging or unloading the reactor vessel 1 with spherical operating elements. A cavity housing or container 2 surrounds the reactor vessel 1. The cover 3 of the cavity is bounded or enclosed by an external housing 4 which is equipped with a gate 5. A travelling frame 6 may be moved into or out of the building through gate 5. The travelling frame 6 uses a hydraulic lifting device 7 to carry transport container 8, thereby eliminating the need for a stationary lifting device in the building 4. The transport container is taken over by a mobile crane and placed on a transport carriage 10 after it has attained its horizontal position 9. FIG. 2 shows the area of the nuclear reactor installation taking part in the manipulation of the spherical operating elements 11. A pile 12 of spherical operating elements 11 is surrounded by a reflector 13. The operating elements may be fuel elements. The reflector exhibits channels 14 to receive the absorber rods 15. The operational lifetime of the stationary pile is in the range of several years. At the conclusion of the operating period, all of the operating elements are removed from the reactor vessel 1 and replaced by new ones. The transport container 8 is set onto the cover 3 of the cavity so that the transport container bottom 16 overlaps the cover access opening 17. A closure cover 19 (FIG. 3) fastened by screws 18 to the transport container is removed to expose bores 22, 22a prior to transport container placement. The bores 22, 22a pass through 21, 21a which are secured to the transport container bottom 16 by screws 20. The shielding cover 19 carries two shielding stoppers 23 to insure the shielding effect. The shielding stoppers 23 project into the bores 22, 22a when the closure cover is in place. A ball valve 24 actuable from the side of the transport container is arranged above each of the inserts and fastened by screws 25. The ball valves 24 are arranged in the bottom 16 and enable closure of the bottom passages leading above the bores 22, 22a. The ball valves 24 may be actuated by a rotational movement. A variable gas flow blower 26 rests on a supporting frame 27 connected the reactor vessel 1. A suction line 29 equipped with a closure fitting 28 leads to the bore 22a of the bottom 16 and suctions gas from the transport container 8 when the ball valve 24 is open. The bottom passage containing the suction line terminates below a filter in the form of an intermediate bottom 30 in order to prevent suctioning of dust particles from the transport container. The intermediate bottom is stable enough to support a pebble filling extending to the line 31. A stopper 64 located in the intermediate bottom 30 is opened during a subsequent unloading of the transport container for removal of burned operating elements. The pressure line 32 of the blower 26 conducts the gas suctioned in through a closure slide 33 associated with the reactor container in the direction of the arrow 34 into the reactor vessel pebble pile 12. A pebble conveyor line 36 is always maintained with its end facing the pile 12 at the height of the surface of the pile and rotated in a pendulum motion around its axis by a rotating and advance unit 35 mounted on the closure slide 33. As seen from FIGS. 2a and 2b, the pebble conveyor line 36 may be a corrugated pipe with internal longitudinal ribs 37. The operating elements 11 to be conveyed are better guided and more rapidly transported in a corrugated pipe than in a smooth pipe. The frontal side of the pebble conveyor line 36 facing the pile 12 is bevelled off and thus exhibits a non-horizontal outline. With a pendulum or reciprocating rotation of the pebble conveyor line 36 in the direction of the arrow 38 around its axle 39 the operating elements 11 enter the bevelled opening of the pebble conveyor line 36 easier. This increases the conveying capacity and blockage of the opening is avoided. The pebble conveyor line 36 extends concentrically through the rotating and advance line 35 and reaches with the ball valve 24 to open a guide tube resembling a walking stick. The guide tube 40 is fastened to the inside of the transport unit bottom 16 and extends approximately vertically upwards and reaches with its bent end the vicinity of the cover of the transport container 8. A covering sleeve 41 concentrically encompasses the pebble conveyor line 36 arranged between the rotating and advance unit 35 and the bottom 16. The sleeve 41 is fastened to the lower side of the transport container bottom by screws 42. The sleeve 41 is connected to the rotating and advance unit 35 by the insertion of folding bellows 43 in a dust-tight manner. The sleeve is assembled in the area of separation points 44 to enable mounting the pebble conveyor line 30. A spring 45 maintains the cover sleeve 41 to stabilize the connection to the folding bellows 43. FIGS. 4 to 6 show the configuration of the rotating and advance unit 35. The pebble conveyor line 36 extends through the center passage 46 and is supported slidingly over the rolls 47. A holding device 48 is rigidly connected to a housing 49 of the rotating and advance unit. Clamping jaws 50 may be pressured against the pebble conveyor line 36 by pressure medium passages 51 acting on the setting elements 52. In this holding position the pebble conveyor line 36 may be rotated by the rotating drive 53 engaging a toothed wheel 54 connected to the housing 49. The toothed wheel 54 is displaceably supported by groove bearings 55 relative to the support elements 56. The support elements 56 are in turn fastened with screws to the closure slide 33. A stepping piston 58, which by pressure medium connnections 59, 60 carries out a stroke of approximately 30 mm, is connected by the screws 61 to a transport device 62. The transport device is equipped through pressure medium line 63 with clamping jaws 50a similar to those of the holding device 48. Following the release by the holding device 48 of the pebble conveyor line 36, the transport device 62 may displace the latter always by a stroke of the stepping piston 58 in the vertical direction. The rotating and advancing unit 35 utilizes the stepping piston 58 in cooperation with the transport device 62 clamping jaws 50a and the holding device 48 clamping jaws 50, to axially displace the pebble conveyor line 36. To insert the pebble conveyor line the stepping piston 58 is raised. Clamping jaws 50a are then activated and clamping jaws 50 are deactivated whereupon the stepping piston 58 is advanced. Clamping jaws 50a are then deactivated and jaws 50 are activated. To further advance the pebble conveyor line the above is repeated; to withdraw the pebble conveyor line the above is reversed. The clamping jaws 50, 50a and the stepping piston 58 are operated by the introduction of pressure medium through the various pressure medium connections and lines in a fashion similar to pneumatic or hydraulic operating devices. If the pebble pile 12 is to be removed from the reactor vessel 1, a transport container 8 is brought into a loading position on the cover 3 of the cavity 2, following the removal of the closure cover 19 and the opening of the ball valves 24. The nuclear reactor installation is rendered pressureless, the cooling gas interposed and returned to the primary cooling loop after reloading. After the blower has been connected on the suction side to the transport container 8 and on the compression side to the reactor vessel 1, the constantly circulating gas flow moves the pebbles into the transport container. The pebble conveyor line 36 is maintained constantly at the height of the surface of the pile 12 and optionally rotated in a reciprocating fashion or the manner of a pendulum by the rotating and advance unit 35. The same apparatus is used in the loading of new operating elements. However, the container has thinner walls. Furthermore, it has no guide tube, so that the operating elements are free to drop into the reactor vessel 1. The gas flow with a reduced velocity serves as a brake for the pebbles.