DE1194074B - Shock absorbing device for moving bodies in nuclear reactors - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. α .:

G 21

German KL: 21g -21/31

Number: 1194074

File number: G 30831 VIII c / 21 g

Filing date: November 1, 1960

Opening day: June 3, 1965

The invention relates to a shock-absorbing device for moving bodies in nuclear reactors, which consists of a plastically deformable tubular element, which between supports on two mutually movable parts is fitted and at 5 caused by the impacting body movement these parts are pressed together.

Means must be provided for the shutdown rods of a nuclear reactor to stop the rod, in the event that it is released to shut down the reactor, as well as means that the shock when stopped absorb so that the rod is not damaged. According to a construction known per se the rod consists of two parts that can be moved relative to one another, one of which has a locking member comes into engagement, for example, in the form of a guide socket that locks the rod, and is provided with a shock absorbing device in the form of a plastically deformable tube. This shock absorbing device allows a continuation of the movement of the other part and finally brings it to a standstill. The deformable tube is designed so that it gives way the pipe wall collapses axially in a row of folds. However, it is possible that with one such construction the deformation strength depends on a small change in the characteristic Properties of the pipe material and the temperature conditions prevailing inside the reactor can vary considerably. Therefore, this arrangement can result in unreliable performance to lead.

However, it is important that such shock absorbing devices even with the relatively work reliably at high temperatures above the reactor core.

The object of the invention is to provide an improved shock absorbing device of the above Type that works reliably under the operating conditions prevailing in a nuclear reactor.

This is achieved according to the invention in that the aforementioned two parts which can be moved relative to one another are made of consist of a tube and an elongated piston element which is axially movably mounted in this and said deformable element in the form of a helical tube wound around the piston element is trained.

In the drawing, the invention is shown in two exemplary embodiments. It shows

F i g. 1 shows a part of a vertical section of a first shut-off rod, the shock-absorbing device being shown in the normal position, shock-absorbing device in itself
moving bodies in nuclear reactors

Applicant:

The General Electric Company Limited, London

Representative:

Dr.-Ing. H. Ruschke, patent attorney,

Berlin 33, Auguste-Viktoria-Str. 65

Named as inventor:

Derek Boyd Jeffery, Erith, Kent (Great Britain)

Claimed priority:

Great Britain 3 November 1959 (37 296)

F i g. 2 one of the F i g. 1 similar illustration showing the shock absorbing device after this has become effective, and

F i g. 3 shows a vertical section through a second embodiment of the shut-off rod with a shock-absorbing one Contraption.

As shown in FIGS. 1 and 2 of the drawings, the shutdown rod has a component 1 which contains a neutron absorbing agent (not shown). This component is screwed into a tubular member 3 at the upper end and is held in this position by means of a screw 2. At the upper end of the tubular member 3, a flange member 4 is screwed, through which the body part is detachably connected to a support head 5, which flange member 4 with an annular part 6 inside the support head by shear pins? connected is. The head 5 has an outwardly protruding flange 8, which comes into engagement with a braking or hold-open member, for example in the form of a guide socket, when the rod is released to shut down the reactor, and a mushroom-shaped part 9, with the help of which the Rod can be withdrawn from an operating machine. A compression spring 10 is arranged between the support head 5 and the tubular member 3, the ends of which bear against the part 6 and against a shoulder 11 on the support head. A piston-like member 12 is fastened to the support head and projects axially into the tubular member 3 and is provided with a collar 13 at the lower end.

509 578/293

I 194

To the piston-like member, a helical tube 14 made of stainless steel is wound, the ends of which on Flange member 4 and rest on collar 13. The turns of the helix lie against one another and become deformed when the helix is compressed between said parts. The coil is on both ends open.

If the rod is released during operation to shut down the reactor, its movement is controlled by for example, the guide socket, which engages the flange 8, while the kinetic energy of the rod is absorbed at the end of the movement by the spring 10, which is between the part 6 and the Shoulder 11 is compressed. However, if the impact on impact exceeds a predetermined one Value that is determined by the shear strength of the pins 7, they are sheared off, so that the Rod can continue its movement with respect to the support head 5. With this relative movement, the helical tube between the flange member 4 and the collar 13 is compressed and plastically deformed and at the same time acts on the piston-like member with friction. In this way the kinetic Energy of the rod converted into heat.

It is relatively easy to use the helical tube as train and dimension that the stroke of the piston-like member is limited to a suitable value will. For example, the stroke of the piston-like member can be determined in that the diameter of the helix or the diameter of the tube or the caliber of the tube or the clearance between the tube and piston member changed will. In addition, the tube can be partially closed at the ends, thereby preventing it from escaping the air is restricted, the pressure inside the helical tube increasing when this is compressed.

Dte Fig / 3 shows a second embodiment of a Shut-off rod with a shock-absorbing device, in which there is a component 21, at the upper end of which is attached em support head 22, while at the lower end em piston-like impact member 23 is provided. The component 21 carries on Upper Eftde a component 24 with a wedge-shaped Seat, in the normalefweise the pawls 25, which are held by a sliding ring 26 in this position e are held, whereby the component 21 is fixed. The Ofeitrmg 26 is normally on the support head 22 held by the shear pins 7.

If the rod is released for the purpose of switching off the reactor, the sliding ring 26 arrives with a Brake or AttfiialtegKed engaged, the Pins 7 are sheared off so that the sliding ring 26 slides upwards. The pawls come loose 25 from member 24, and component 21 continues its fall. The rod is finally taken care of by a (not shown) braking or hold-open member braked at the lower end of the control rod channel, which against the Impact member 23 strikes. As before, the impact on impact will be from the plastically deformable one Coiled tube 14 absorbs which tube is wound around a hollow piston member 12 attached to member 23 is. The piston member 12 is slidably mounted in a stationary collar 30 so that the Helical tube 14 compressed between this collar and the upper part of the impact member 23 will.

In another arrangement, the shock absorbing device is instead of on the rod inside the Channel attached in the reactor core for the rod. In this case one of the relatively movable parts is Arranged stationary with respect to the reactor core, while the other part is a braking or hold-open element forms, which cooperates with a corresponding member on the rod.

The invention can also be used in braking devices for bodies other than shut-off rods find, for example, to slow down falling fuel assemblies to prevent damage. In this case, the shock-absorbing device would be assigned to a stationary braking device or built into it, which is arranged in the channel for the fuel assembly or the drop shaft, to absorb the shock when braking the fuel assembly.

Claims (1)

Claim: Shock absorbing device for moving bodies in nuclear reactors consisting of a There is a plastically deformable tubular element that is between supports on two of each other movable parts is fitted and in motion caused by the impacting body these parts is pressed together, characterized in that the two parts consist of a tube and a exist in this axially movably mounted elongated piston element and the deformable Element is designed in the form of a helical tube wound around the piston element. Considered publications:
Belgian patent specification No. 570 842. 1 sheet of drawings 509 578/293 5.65 © Bundesdruckerei Berlin