Patent Number: 
Section: description

In all the figures of the drawing, sub-features and integral parts that correspond to one another bear the same reference symbol in each case. Referring now to the figures of the drawing in detail and first, particularly, to FIGS. 1 and 2 thereof, there is shown a lance shaft 1 which is in the form of a tube. Measuring lances that carry sensors may be disposed in the lance shaft 1. The sensors determine the state inside a reactor pressure vessel. The lance shaft 1 is inserted into the reactor pressure vessel from outside in a pressure-tight manner. To this end, it is guided in a nozzle 2 of a cover of the reactor pressure vessel and is sealed off from the nozzle 2. The sealing is ensured by pressing a sealing ring 5 via an integrally formed portion 4 on the lance shaft 1 into a seat 10 on a threaded socket 14 connected to the nozzle 2, in the course of which the sealing ring 5 is likewise pressed against the nozzle 2. For pressing the sealing ring 5 into place, a force is exerted on a pressing plate 3 which bears against the nozzle 2, a factor which leads to an opposed force being exerted on the lance shaft 1 by a mechanical force transmission, and this force presses the integrally formed portion 4 of the lance shaft 1 against the seat 10. In the known device (FIG. 1), the force on the pressing plate 3 is produced via pressing screws 11. For the mechanical force transmission to the lance shaft 1 there is a plate 15, which is firmly connected to the lance shaft 1 and has threads for accommodating the pressing screws 11. When the pressing screws 11 are screwed in, the plate 15 and thus also the lance shaft 1 are lifted. The combination of the pressing screw 11 and the plate 15 constitutes the basic form of a pressure element. The pressing screws 11 do not act directly on the pressing plate 3 but on an additional pressing plate 12, one or more disk springs 6 being located between the pressing plate 3 and the additional pressing plate 12. The disk springs 6 ensure a preloading force, which is supplemented by the force of the pressing screws 11. The pressure element may consist of the pressing screw 11, the plate 15 and the disk springs 6. The preloading force of the disk springs 6 must be reset after every inspection, a factor which necessitates additional work on the device, and this additional work must be carried out with protective precautions taken. The device according to the invention (FIG. 2) correspondingly has the additional pressing plate 12 and one or more of the disk springs 6 which are disposed in the same way. The difference from the known device consists in the fact that pressure parts 7 that are hydraulically actuated take the place of the pressing screws 11. The pressure parts 7 may be, for example, so-called HYTORC nuts. The pressure part 7 alone constitutes the basic form of a pressure element. The pressure part 7 and the disk springs 6 may then together form the pressure element, the pressure part 7 producing a force and the disk springs 6 producing a preloading force (preloading). For the mechanical force transmission from the pressure part 7 to the lance shaft 1, the pressure part 7 has two parts moving in opposite directions. If the outer part 7a is moved downward, the inner part 7b is lifted and takes the lance shaft 1 with it, since it is firmly connected to it. For driving the pressure parts 7 there is provided a hydraulic tool 16 (FIG. 3), which is connected to a hydraulic line 8, in which a pump 13 for the hydraulic medium is fitted. A pressure gauge 9 is connected to the hydraulic line 8. The pressure gauge 9 measures the pressure of the hydraulic medium, which enables the instantaneous preloading force of the disk springs 6 to be inferred. The preloading force of the disk springs 6 can be set by varying the pressure by the pump 13. The hydraulic tool 16 covers or surrounds the top part of the lance shaft 1 and the entire pressure part 7 and rests on the additional pressing plate 12, which, configured as a ring, surrounds the lance shaft 1 shown in FIG. 2. The lance shaft 1 extends inside the tubular nozzle 2, a factor which cannot be seen in FIG. 3, and if need be also inside the pressing plate 3, the disk springs 6 and the additional pressing plate 12, all of which surround the lance shaft 1 in an annular manner. The hydraulic tool 16 (FIG. 3) may have an opening through which the lance shaft 1 can pass upward. With the device according to the invention, on the one hand sealing of the lance shaft 1 in the nozzle 2 can be effected quickly and reliably in a remote-controlled manner solely via the hydraulic line 8 and with the pump 13, and in addition the preloading force of the disk springs 6 can be monitored by the pressure gauge 9 and can be varied or set by the pump 13. Advantageously, it is not necessary for personnel in protective suits to work directly at the leadthrough.