JPH04296700A - Apparatus for moving radioactive source accurately and quickly - Google Patents

Abstract

PURPOSE: To transfer a radioactive or neutron source quickly and accurately by composing a cable coupling means of a gear made of a soft material, press rollers arranged around the gear, and a cable guide. CONSTITUTION: The cable coupling means 16 for a cable moving structure 12 comprises a gear 18 made of a soft material, e.g. nylon, press rollers 20 arranged at constant intervals around the gear 18, and and a cable guide 22 arranged between the rollers 20. The cable 2 is used for introducing a radioactive or neutron source 6 into a biologically protected enclosure 8 or drawing out the source 6 therefrom through an asynchronous motor 14. Since the rollers 20 and the guide 22 bring the cable 2 into tight contact with the gear 18 with no deformation, linear speed of the cable 2 can be kept at about 2-5m/sec which satisfies the analytical conditions for activating fission products contained in the enclosure 8.

Description

[Detailed description of the invention]

0001

FIELD OF INDUSTRIAL APPLICATION The invention, in general terms, is intended for use in a radioactive or neutron source holder which is fixed at the end of a support cable and which cycles as a result of the cable translation, i.e. in the folding position - in the working position. Concerning the transfer of mobile radioactive or neutron sources.

0002

BACKGROUND OF THE INVENTION Such a device for carrying out analyzes by activation of fissile material contained in an enclosure protected against radiation is in particular described in French Patent No. 2,61.
Known from 9,622. In such devices, a neutron radiation source placed at the end of the cable is introduced into and extracted from the enclosure with the aid of a device incorporating a rotating drum rotated by a stepping motor, while the cable is placed at the end of the drum. fixed at one end and on the other hand to a neutron radiation source. The cable and the neutron radiation source are moved in a guide tube to the interior of an enclosure containing the fission products in which the neutron radiation source undergoes activation. During the movement of the neutron radiation source, inspection of the secondary radiation due to the activation of the fissile material by the neutron radiation source allows an evaluation of the nature and quantity of the fissile material contained within the enclosure.

Such elementary devices do not allow the acquisition of rapid movement speeds and reproducible precise positioning consistent with the compatibility of delayed secondary emissions without being disturbed by the emission of the neutron radiation source. .

0004

[Problem to be Solved by the Invention] In order to achieve such measurement quality, in the case of a typical neutron source, an interval of 2 to 5 meters can be covered with the neutron source within approximately 1 second with a positioning accuracy of ±1 mm. need to be able to. Currently known devices do not allow performance characteristics of this nature in automatic, continuous operation (cycles).

The object of the invention is to provide a device for quickly and accurately moving a radioactive or neutron source by means of a cable, which meets the above-mentioned needs, in which the radioactive or neutron source is fixed and uses simple and effective means. It's about doing.

[0006]

SUMMARY OF THE INVENTION The present invention therefore provides, in particular, a helically wound cable, at the end of which a radioactive or neutron source is fixed in its holder, adapted to the number of turns of the cable. and a storage magazine for storing said radioactive or neutron source and said cable in a folded position, in a particularly precise manner, within approximately one second, and a storage magazine for storing said cable in a folded position. A precise and rapid movement device for a radioactive source for rapidly moving a radioactive or neutron source between a working position and a folded position in a gear, wherein said cable drive means is made of a flexible material and one of the peripheral parts of said gear is
Pressure rollers distributed over the section and said pressure rollers arranged between said pressure rollers to prevent the formation of loops on the cable and loss of position reference during the rapid movement of said radioactive or neutron source. The present invention relates to an apparatus for accurately and quickly moving a radioactive source, characterized in that it is constituted by a gear and a cable guide that adopts the appearance of the pressing roller. The function of the rollers is to guide and maintain the cable wound helically around a gear or gear, said rollers being free to rotate.

Thus, it is possible to move radioactive or neutron holder cables in a fast and precise manner, for example using asynchronous or self-synchronous motor-gear transmissions, the performance characteristics of which are completely different from conventional stepping motors. This is a very special combination according to the invention that makes it possible.

According to an important feature of the invention, the pressure rollers distributed around the gear wheel in order to maintain the cable radially and laterally and apply the cable accurately to the gear wheel do not damage the cable and The cable is made of a sufficiently flexible material so as not to generate wear particles that contaminate the guide tube in which it is supported. Particularly advantageous materials are, for example, polyethylene or nylon.

According to another feature of the gear, the space between two successive pressure rollers is filled by a cable guide;
The shape of the cable guide adopts the appearance of gears and pressure rollers and is made of a material that is sufficiently flexible not to damage the cable and can also be polyethylene or nylon. These cable guides complete the action of the pressure rollers and are strong with the pressure rollers in maintaining the helically wound cables on the gears,
This thus completely compromises the advancement and advancement precision required of the cable, thereby preventing the risk of the cable sliding or dislodging to locally form undesired loops.

Two devices have been developed that comply with speed and position requirements. Although they agree in driving principle, they differ in the way the cables are stored. The first device involves storage with a drum with spiral grooves, while the second device involves storage of cables in a straight tubular magazine.

According to a first embodiment of the invention, the storage magazine for the useless parts of the cable is a drum for winding the cable.

According to another preferred embodiment of the invention, the storage magazine for the useless part of the cable is constituted by a straight tubular sleeve, the length of which is equal to the folding position of the radioactive or neutron source and its working position. approximately corresponds to the advancing length of the cable between

Finally, according to a very interesting feature of the device according to the invention, the straight tubular sleeve, near its two ends, provides automatic control of the working cycle of the cable during the movement of the radioactive or neutron source. A series of magnetic position transducers are provided in conjunction with the cable to allow for.

The straight tubular sleeve advantageously consists of several parts, which in that case makes it possible to obtain an adjustable and easily removable structure. The end of the magazine sleeve furthest from the motor is cut off in such a way that an untimely evacuation of the radioactive or neutron source is prevented in the event of a failure. This interruption is constituted, for example, by a plug equipped with a damping spring and fixed to the tubular sleeve. The tubular magazine sleeve and the guide tube are connected to the motor block in such a way that the cable is always guided. The connecting means are preferably easily removable.

Radioactive or Neutron Source Holder - A helically wound cable source structure is moved into a guide tube made of a rigid material but capable of being bent, and this material is used in the preferred application of the invention. Made of stainless steel material.

In cases where humans cannot enter the area in which the guide tube is placed (after extracting the radioactive or neutron source), the guide tube is designed such that this guide tube can be changed if necessary. placed within the sleeve in a suitable manner. From outside the area, the guide tube is then extracted and cut. If human intervention is possible, the use of sleeves is less likely to be justified.

In the case where the guide tube has to traverse a wall (biological protection wall), the recess in the wall is a guide tube and, if present, a bush or bushing which is also fixed in the wall in which the sleeve is arranged. It is equipped with a grab finger in advance.

If necessary, support means are provided on the guide tube or sleeve.

The invention will now be explained in more detail with reference to non-limiting examples and the accompanying drawings, in which: FIG.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a cable 2 encircled by its helical sliding within a metal sleeve which serves as a guide along its path. At the end of the cable 2 a radioactive or neutron source 6 is arranged which houses a neutron source or gamma-emitting source used in remote methods. Typically, in the applications envisaged by the invention, the cable 2 is used to introduce a radioactive or neutron source 6 into a biological protection enclosure, denoted by 8 . At the other end of the cable 2 there is a straight tubular sleeve 10 for use as a storage magazine for the useless part of the cable when the radioactive or neutron source 6 is in a position removed from the enclosure 8.
is provided. The straight tubular sleeve 10 has a portion 12 which serves as a plug and prevents removal of the cable to the outside.
Terminates at. Spring 14 makes it possible to stop the movement of the cable by limiting its advancement if this is necessary.

Between the active end of the cable 2 with the radioactive or neutron source holder 6 and its useless end located in a straight tubular sleeve 10 a fast and precise cable movement structure 12 is arranged. . For this purpose, structure 1
2 is, for example, an asynchronous motor 1 with the necessary reduction gear
4, as well as a device 16 for coupling a cable to the motor shaft of the asynchronous motor 14. This coupling means 16, which is one of the original features of the device according to the invention, is constituted by a toothed wheel or gear 18, the teeth of which have a spacing that corresponds to the helix of the cable 2 to be moved. This cable 2 is connected with the aid of a device having pressure rollers 20 distributed over a portion of the circumference of the gearwheel 18, as well as pressure rollers 20, so as to maintain the cable and the gearwheel in deformation-free and loop-free contact. The cable guide 22 is forced to remain in tight, undeformed contact with the gear 18 between two successive pressure rollers 20 arranged in the space between the cable guide 22 and the gear 18 . In this method the linear velocity of the cable 2 can reach 2 to 5 meters/sec in order to meet the special requirements of the analysis by activation of the fission products contained in the enclosure 8. The structure consisting of the pressure roller 20 and the cable guide 22 is fixed to a flange 24 which is threaded onto the structure for holding the motor 14.

Again, according to the invention, the guide tube 4 surrounding the cable is connected to the first guide block 26 at the entrance of the device.
And at the exit of the same device the part of the cable 2 which is held fixedly in a second guide block 28 and which winds around the drum 18 is clearly in such a way that the helix 2 can mesh correctly with said gear 18. Free from guides.

According to an important feature of the invention, the straight tubular storage sleeve 10 for the cable always has its sleeve 1
It is equipped with two rows of magnetic detectors 30, 32, which allow evaluation of the position of the end of the cable 2 within 0. These two groups of magnetic detectors 30, 32 are arranged in two straight tubular sleeves 10 such that they are separated in the enclosure 8 by a spacing that approximately corresponds to the linear advancement distance of the cable 2 between the folded position and the working position. Each is placed near the end. Thus, the detector presence or absence signals associated with detectors 30 and 32 can be used to automatically control, i.e. start or stop, cable actuation cycles during movement of the radioactive or neutron source in either direction. can be used.

The detector works as follows (FIG. 1). A command applied to the motor 14 causes the cable 2 to slowly advance to bring the radioactive or neutron source 6 into the folded position. When the cable end passes in front of the detector 30, a "movement" control is applied and the radioactive or neutron source 6 is quickly brought to the irradiation position and a stop command is given when the cable end passes in front of the detector 32. will be granted. The cable 4 then stops due to the small response inertia.

After the irradiation time has elapsed, the motor 14 is started and the radioactive or neutron source 6 is removed very quickly. The end of the cable 2 passes in front of the detector 30 and starts stop control. If necessary, an auxiliary standby detector (not shown) can be added.

FIG. 2 shows a variant of the device according to the invention in which the storage magazine for the cable 2 is a winding drum 34. In this embodiment, the relevant details of which are shown in FIGS. 3 and 4, means identical to those of FIG. 1 have the same reference numerals. However, in this embodiment, in relation to the flange 24, a second flange 36 defines a space in which the gear 18 and its coupling device 16 are arranged.
It is necessary to consider.

FIG. 3 shows the drum 34, gear 18, and cable 2.
2 shows in cross-section an embodiment of the device according to FIG. 2, in which a coupling device 16 for the cable 2 to the drum 18 is provided. This cross-sectional view provides a better understanding of the shape and therefore the operation of the pressure roller 20 and cable guide 22, which hold the cable 2 against the gear 18 and are made of a flexible material, such as polyethylene or Teflon, for example.

Finally, FIG. 4 shows a side view of the device of FIGS. 2 and 3. FIG. 4 shows the motor 14 with its reduction gear 38 as well as its axis of rotation 40, which gear 18 meshes with the cable 2. FIG. 4 shows one of the pressure rollers 24 that maintains the cable 2 in close contact with the gear 18.

In this embodiment, the winding drum 34
is mounted for rotation about a splined axis 42 and has a splined surface 3 around its periphery.
4, around which splines or grooves the cable 2 is wound throughout its movement. For this purpose, an automatic control device for the translation of the winding drum 34 as a result of its rotation is designated by reference numeral 4.
6, the automatic control device includes a casing 5 which is movable in translation on the groove of the spline shaft 42 and is fixed to the machine frame 54 via a ball nut arrangement 50.
meshes with 0. This device operates as follows. As the winding drum 34 rotates in one direction or the other, the splined shaft 42 drives the section 48 and thus, through the ball connection of the screw-nut type 50, rotates the axis of the section 48 in relation to the casing 52. Causes directional movement. The cable 2 thus winds up in the groove 44 on the surface of the drum 34 following a helical path.

[0030] In this application, magnetic positioning detection is
Supplying cable position information directly to the motor gear transmission,
It is attached to the gear shaft and replaced by the coder 55.

The special means of the drive device 16 and optionally the combination of a grooved drum make it possible to generate a movement of the radioactive or neutron source holder cable at high speeds of up to 1 second (2 to 8 meters/sec) and compared to conventional devices. Be precise during introduction and removal as can never be achieved.

[0032]

As stated above, the present invention provides a helically wound cable, at the end of which a radioactive or neutron source is fixed in its holder, the spacing being adapted to the number of turns of the cable. within approximately one second and in a precise manner, in particular within an enclosure, comprising motor means for driving means for coupling said cable to a gearwheel and a storage magazine for storing said radioactive or neutron source and said cable in a folded position; A precise and rapid movement device for a radioactive source for rapidly moving a radioactive or neutron source between a working position and a folded position, wherein said cable drive means is made of a flexible material and extends over a portion of the circumference of said gear wheel. Adopting the appearance of distributed pressure rollers and said gears and said pressure rollers arranged between said pressure rollers to prevent the formation of loops on the cable during the rapid movement of said radioactive or neutron source. A device for quickly and accurately moving a radioactive or neutron source by means of a cable, meeting the above-mentioned needs, with a configuration consisting of a cable guide, so that the radioactive or neutron source is fixed thereto, and using means that are simple and effective. can be provided.

[Brief explanation of drawings]

1 shows an overall view of the device according to the invention in an embodiment incorporating a straight tubular sleeve as a cable storage magazine; FIG.

FIG. 2 is a schematic illustration of an embodiment of the invention in which the cable storage magazine is a winding drum;

3 is a sectional view of the device of FIG. 2 showing the toothed wheel or gear with its pressure roller and cable guide; FIG.

4 shows a side view of the device for moving the cables on the drum magazine of FIGS. 2 and 3; FIG.

[Explanation of symbols]

2 Helically wound cable 6 Radioactive or neutron source 8 Enclosure 10 Storage magazine 12 Motor means 16 Driving means 18 Gear 20 Press roller 22 Cable guide 30 Magnetic position detector 32 Magnetic position detector 34 Winding drum

Claims (5)

[Claims] Claim 1. A radioactive or neutron source (6
) is fixed in its holder, a helically wound cable (2), motor means (12) for driving the means for coupling said cable to a gearwheel (18) with a spacing adapted to the number of turns of said cable. ) and a storage magazine (10) for storing said radioactive or neutron source and said cable in a folded position, within approximately one second and in a precise manner, in particular in an enclosure (8), between a working position and a folded position. In an apparatus for precise and rapid movement of radioactive sources for rapidly moving a radioactive or neutron source (6) between pressure rollers (20) distributed over the pressure rollers (20) and said gears (18) arranged between said pressure rollers to prevent the formation of loops on the cable during rapid movement of said radioactive or neutron source;
) and a cable guide (22) adopting the appearance of the pressure roller (20). 2. The storage magazine is connected to the cable (2).
2. Device according to claim 1, characterized in that it is a winding drum (34) for a radioactive source. 3. The storage magazine is a straight tubular sleeve (10), the length of which approximately corresponds to the cable advancement length between the folded position of the radioactive or neutron source (6) and its working position. The device for accurately and quickly moving a radioactive source according to claim 1, characterized in that: 4. The straight tubular sleeve (10), near its two ends, is associated with the cable allowing automatic control of the working cycle of the cable throughout the movement of the radioactive or neutron source. Device according to claim 3, characterized in that it comprises a series of magnetic position detectors (30, 32). 5. The periodic operation of the radioactive or neutron source (6) is automatic and continuous as a result of an asynchronous or self-synchronous motor-gear transmission group. 4. The apparatus for accurately and rapidly moving a radioactive source according to item 4.