GB2064403A

GB2064403A - Remotely Controlled Shears for Cutting up Irradiated Nuclear Fuel Rods or Bundles of Rods

Info

Publication number: GB2064403A
Application number: GB8014142A
Authority: GB
Original assignee: Deutsche Gesellschaft fuer Wiederaufarbeitung von Kernbrennstoffen mbH
Current assignee: Deutsche Gesellschaft fuer Wiederaufarbeitung von Kernbrennstoffen mbH
Priority date: 1979-11-02
Filing date: 1980-04-29
Publication date: 1981-06-17
Also published as: JPS56124095A; GB2064403B; DE2944197A1; DE2944197C2; FR2468977A1; CH646812A5; FR2468977B1; JPS634679B2

Abstract

The shear comprises a shearing knife (7) displaceable transversely to the axis of the rod or bundle, a casing (5, 6) for receiving the knife (7) and in which the shearing knife is slidingly mounted, a feeding device (18, 19) for the rods or bundles of rods, the receiving bores of which are adapted to the shape of the rods or bundles of rods and are in alignment with cutting openings (20, 21) provided in the casing of the knife (7), a drop-out opening (23), said opening being opposite to the cutting openings (20, 21) and a driving device (11, 12) for actuating the shearing knife (7), in which the knife casing (5, 6), the driving device (11, 12) and the feeding device being positively and undisplaceably embedded in apertures 8-10 in a solid divisible shearing block which comprises parts (1, 2) which are detachably and positively locked relative to each other. <IMAGE>

Description

SPECIFICATION Remotely Controlled Shears for Cutting up Irradiated Nuclear Fuel Rods or Bundles of Rods into Sections The present invention concerns remotely controlled shears for cutting up nuclear fuel rods or bundles of rods into sections.

German Offenlegungsschrift No. 2161534 discloses a device in which bundles of nuclear fuel rods are fed intermittently, via a magazine, to a hydraulically actuated pressing and cutting device. Due to the pressing and cutting, the bundle is separated into individual rod-like portions which pass to another treatment device through a pipe socket connected to the device. In German Offenlegungsschrift No. 1815867, particularly Figure 5 thereof and associated description, a similar device is illustrated by means of which even individual rods or tubes can be cut up into short portions.

In the case of these devices difficulties and delays may occur during maintenance, particularly during the replacement of worn parts, in respect of remote control, since both maintenance-free and also maintenance-requiring parts have to be dismantled and readjusted and assembled for correct functioning. Stopping times needed for these purposes may considerably restrict the overall output of such shears.

It is an object of the present invention to provide remotely controlled shears for cutting up nuclear fuel rods or bundles of rods into sections so that the manipulations necessary for the remote controlled maintenance, particularly for the exchange of the knife blades and the driving device, are substantially simplified, thus achieving a reduction of stopping times.

According to the present invention there is provided remotely controlled shears for cutting up irradiated nuclear fuel rods or bundles of rods into sections, comprising a) a shearing knife displaceable transversely to the axis of the rod or bundle, b) a casing for receiving the knife and in which the shearing knife is slidingly mounted, c) a feeding device for the rods or bundles of rods, the receiving bores of which are adapted to the shape of the rods or bundles of rods and are in alignment with cutting openings provided in the casing of the knife, d) a drop-out opening for the sections, said opening being opposite to the cutting openings, and e) a driving device for actuating the shearing knife, in which:: A) a solid, divisible shearing block is provided having apertures in which the knife casing, the driving device and the feeding device are positively and undisplaceably embedded; and B) the shearing block comprises parts which are detachably and positively locked relative to each other.

The present invention discloses that the cutters and driving device can be removed with a minimum of manipulation, namely by simply removing the parts of the shearing block from each other. They can then be freely removed from their bearing position and replaced by new parts without requiring special adjusting blocks for the purpose and the disconnection and joining of connecting elements which are very difficult and time wasting to effect by remote control.

Preferably, the driving device comprising at least two hydraulically driven lifting devices, the piston rams of which engage on both the free end surfaces of the shearing knife, and in which the shearing knife has at least one opening, the crosssection of which is greater than that of the rod or bundle of rods to be dissected and the edge or edges of which are formed as cutting edges. Such arrangement makes it possible in particular for the driving device no longer to need to be mechanically connected to the shearing knife, thus also contributing to facilitating the replacement of these parts. At the same time, the breaking of the ram or seizing-up of the shearing knife is effectively prevented and the cutting output increased, since each stroke is a working stroke.

The shearing block may comprise only two solid parts so that it is sufficient to lift out the upper part in order to get to the worn parts.

In a preferred embodiment of the invention the casing of the knife comprises a fixed knife plate having cutting openings and a knife guiding member of U-shaped cross-section and the base plate of which, serving as a stop for the rods or bundle of rods, is in contact with the shearing knife and has one or more drop-out openings which are axially displaced relatively to the cutting openings. Thus, the thickness of the shearing knife determines the length of the portions to be cut, since the rods or bundles of rods can be introduced into the feeding device until they come into contact with the base plate of the knife guiding member of the knife case. After each stroke, the portions fall through the drop-out opening in the guiding member of the knife and through an opening adjacent thereto in the shearing block.

The present invention will be further illustrated, by way of example, with reference to the accompanying drawing, in which the single Figure is a schematic view of shears in accordance with the invention is cross-section.

The shearing block comprises a lower part 1 and an upper part 2, whilst the separating join (broken line 3) between these parts is formed in stages. The stages are designed so that both parts are locked relatively to each other in the horizontal direction, but, on the other hand, in a vertical direction the upper part 2 can be freely removed from the lower part 1. A cutter is embedded in a recess 4 of the lower part 1, said cutter comprising a knife casing 5. 6 and a shearing knife 7 sliding therein in a horizontal direction. Recesses 8 and 9 in the parts 1, 2 serve to receive two hydraulically driven lifting devices 11, 12 provided with retaining flanges, whilst recess 10 serves to receive a feeding device 13 for the rods or bundles of rods to be cut up.Piston rams 14, 1 5 point towards each other and are disposed by their ends against the free faces 1 6, 17 of the shearing knife 7. The feeding device 13 has tubes 18, 1 9 with funnel-shaped attachments by which the rods can be fed to the blades of the knife 7. The casing comprises a knife guiding member 5 of U-shaped cross-section and a knife plate 6 secured thereto. The knife plate 6 has cutting openings 20, 21 which are in alignment with the tubes 1 8, 19 and the cross-section thereof is adapted to that of the rods to be cut, whilst the shearing knife 7 has an opening 22, the cross-section of which is greater than that of the rods. Both the edges of the openings 20,21 and the edges of the opening 22 are formed as cutting edges.

As may also be seen from the Figure, the base plate of the knife guiding member 5 has a drop out opening 23 which is axially displaced relatively to the cutting openings 20, 21 so that the base plate directly in contact with the shearing knife 7 simultaneously forms a stop for the rods. The drop-out opening 23 is followed by another opening 24 in the lower part of the shearing block.

The rods to be cut up are fed to the tubes 18, 19 and pass in stages-when fed vertically, for example, due to their specific gravity through the cutting openings 20, 21 and then, when the knife is in a suitable position, through the opening 22 to the stop surface of the base plate of the knife guiding member 5.

Since the knife plate 6 is also in contact with the shearing knife 7, the thickness of the shearing knife determines the length of the portions of rod to be cut. If the lifting device 11 is loaded with a pressure means 25, the shearing knife 7 is displaced from left to right, shearing a portion from a fed rod, conveys it to the drop-out opening 23 and in a further movement receives a portion of rod from the tube 19. The return stroke is effected in a corresponding manner by applying a pressure means 26 to the lifting device 12 so that no idle stroke can occur.

For maintenance, the upper part 2 of the shearing block is lifted from the lower part 1 so that the lifting devices 11, 12 and the cutting members 5, 6, 7 are freely accessible and can be removed directly from their bearing position and replaced by new parts without the removal of additional connecting members.

Claims

1. Remotely controlled shears for cutting up irradiated nuclear fuel rods or bundles of rods into sections, comprising (a) a shearing knite displaceable transversely t the axis of the rod or bundle, (b) a casing for receiving the knife and in which the shearing knife is slidingly mounted.

(c) a feeding device for the rods or bundles of rods, the receiving bores of which are adapted to the shape of the rods or bundles of rods and are in alignment with cutting openings provided in the casing of the knife, (d) a drop-out opening for the sections, said opening being opposite to the cutting openings, and (e) a driving device for actuating the shearing knife, in which: (A) a solid, divisible shearing block is provided having apertures in which the knife casing, the driving device and the feeding device are positively and undisplaceably embedded; and (B) the shearing block comprises parts which are detachably and positively locked relative to each other.

2. Remotely controlled shears as claimed in claim 1, in which the driving device comprising at least two hydraulically driven lifting devices, the piston rams of which engage on both the free end surfaces of the shearing knife, and in which the shearing knife has at least one opening, the crosssection of which is greater than that of the rod or bundle of rods to be dissected and the edge or edges of which are formed as cutting edges.

3. Remotely controlled shears as claimed in claim 2, in which the shearing block comprises two parts, the separating join being formed in stages between these parts.

4. Remotely controlled shears as claimed in any one of claims 1, 2 or 3, in which the casing of the knife comprises a fixed knife plate having cutting openings and a knife guiding member of U-shaped cross-section and the base plate of which, serving as a stop for the rods or bundle of rods, is in contact with the shearing knife and has one or more drop-out openings which are axially displaced relatively to the cutting openings.

5. Remotely controlled shears, substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.