JP2817073B2 - Accurate and rapid movement of radioactive or neutron sources - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention generally relates to a cycling or retracted position which is fixed in a radioactive or neutron source holder at the end of a supporting cable and as a result of translation of the cable. It relates to the movement of a radioactive or neutron source capable of moving to and from a working position.

[0002]

BACKGROUND OF THE INVENTION French Patent No. 2,619,622 is known in particular for the above-mentioned mobile device for performing an analysis by activating fissionable material contained in a radiation-protective enclosure. In such a device, a neutron radiation source located at the end of the cable is introduced into and extracted from the enclosure by a device having a rotating drum driven by a stepping motor. One of the cables is fixed to the end of the drum and the other is fixed to a neutron radiation source. The cable and neutron radiation source are moved within the guide tube to the interior of the enclosure containing the fission products that are activated by the neutron radiation source. During the movement of the neutron radiation source, examination of the secondary radiation by activation of the fission material by the neutron radiation source allows an assessment of the nature and quantity of the fission material contained within the enclosure.

[0003] In such a rudimentary device, the radiation source has a rapid moving speed and reproducibility without impairing compatibility with suppression of secondary emission that is delayed by emission from a neutron radiation source. Accurate positioning accuracy cannot be obtained.

[0004]

In order to achieve such a measurement quality, in the case of a conventional neutron source, the neutron source is positioned within 2 seconds at an interval of 2 to 5 meters with a positioning accuracy of ± 1 mm. It is necessary to have the ability to cover the surface. At present, the above-mentioned performance cannot be obtained under a condition of automatically and continuously operating (periodically) with a known device.

An object of the present invention, provides an apparatus for radioactive sources or neutron-ray source is fixed, to move simple and effective radioactive source said performance is obtained by means or neutron sources quickly and accurately Is to do.

[0006]

SUMMARY OF THE INVENTION Accordingly, the present invention is an apparatus for accurately and quickly moving a radioactive or neutron source between a working position and a retracted position, the apparatus comprising: A source holder for holding the source at one end,
A cable having a spiral projection formed therein, a storage magazine for storing the cable when the source is in the retracted position, and a tooth spacing substantially equal to a pitch of the projection formed on the cable; Cable driving means comprising a gear wheel which is rotationally driven in mesh with the cable; cable guide means for preventing the formation of a loop of the cable during rapid movement of the source; and A position detecting means for the cable enabling automatic control of the working cycle, the cable guiding means comprising a plurality of pressing rollers distributed over a part of the circumference of the gear wheel and formed of a flexible material. And a cable guide disposed between each of the adjacent pressing rollers. It has formed along the curved shape of the peripheral portion of the pressing roller to the correctness and speed moving device radioactive sources or neutron-ray source and said. The function of the pressing roller is to guide and hold the cable having the spiral projections on the gear wheel, and the pressing roller rotates freely.

[0007] Thus, it uses, for example, asynchronous or automatic synchronous motors and gear transmissions whose performance characteristics are completely different from conventional stepping motors. This combination according to the invention is a very special one that allows fast and accurate movement of the holder of the radioactive or neutron source.

In accordance with an important feature of the invention, holds a cable in a radial direction and the transverse direction, the pressing roller that is distributed around the gear wheel for directing accurately the cable to the gear wheel, the damage the cables It is made of a material that is sufficiently flexible so as not to create wear particles that do not contaminate the guide tube that supports the cable therein. Particularly advantageous materials are, for example, polyethylene or nylon.

[0009] According to another feature of the gear wheel, the space between two consecutive pressing roller is filled by a cable guide. The shape of the cable guide is formed along both the outer peripheral shape of the gear wheel and the outer peripheral shape of the pressing roller, and is made of a sufficiently flexible material that does not damage the cable, that is, from a polyethylene or nylon material, like the pressing roller. It is formed. These cable guides cooperate with the pressure roller in order to complete the operation of the pressure roller and to retain the cable with the spiral projection on the gear wheel. In this way, the translation speed and the positioning accuracy required of the cable are perfectly matched and the cable forms a local loop, thereby preventing the risk of the cable sliding or coming off the gear wheel.

[0010] cable speed and two devices satisfying the positioning conditions have been developed. They correspond in drive principle to the above arrangement, but differ in the way the cables are stored. The first device has a storage with a drum having a spiral groove and the second device involves the storage of the cable in a straight tubular sleeve.

In an embodiment of the present invention, the storage magazine for unused portions of the cable corresponds to a drum for winding the cable.

In another preferred embodiment of the invention, the storage magazine for the unused portion of the cable is constituted by a straight tubular sleeve, the length of which is determined by the retracted position of the radioactive or neutron source and its working position. Approximately corresponds to the length of the cable between.

[0013] Finally, according to a very interested feature of the device according to the present invention, straight tubular sleeve, in the two ends near the during the radioactive source or neutron-ray source is moved, actuation cable It has a series of magnetic position detectors on the cable that allow automatic control of the cycle.

[0014] The straight tubular sleeve may conveniently be comprised of several parts, in which case it may be an adjustable and easily removable structure. The end of the tubular sleeve furthest from the motor is plugged in such a way as to prevent premature withdrawal of the source during a malfunction. This closure is constituted, for example, by a stopper provided with a buffer spring and fixed to the tubular sleeve. The tubular sleeve and the guide tube are connected to the motor block so that the cable is always guided. This connection means is preferably easily removable.

The source assembly from the source holder to the spirally projecting cable is replaced by a guide tube made of a rigid material. However, it can be bent, and in the embodiment of the present invention, a stainless steel material is suitably applied.

If the guide tube is located in an area where humans cannot enter (after the source has been drawn out), it is arranged in the sleeve so that it can be changed if necessary. In that case, the guide tube is drawn out of the area and cut off. If human intervention is possible, the use of such a sleeve is not very correct.

If the guide tube has to cross a wall (for example a biological protection wall), the recess in the wall is provided with a bush or a grab finger fixed in the wall. It is also located on the guide tube and on the sleeve side if present.

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

[0019] Hereinafter, non-limiting examples of the present invention, and will be described in more detail with reference to the accompanying drawings.

[0020]

FIG. 1 shows a cable 2 having a helical projection formed in a metal sleeve which serves as a guide along its path. At the end of the cable 2 a radioactive or neutron source 6 containing a gamma or neutron source used by a remote control method is arranged. Typically, in the applications contemplated by the present invention, the cable 2 is used to introduce a radioactive or neutron source 6 into a biologically protected enclosure indicated by reference numeral 8. At the other end of the cable 2 is provided a straight tubular sleeve 10 which is used as a storage magazine for unused parts of the cable when the radioactive or neutron source 6 is in the position retracted from the enclosure 8. The straight tubular sleeve 10 serves as a stopper and terminates in a portion 12 which prevents the cable from being pulled out. Spring 14
Enables the movement of the cable to be stopped by restricting the movement of the cable if this is necessary.

A quick and accurate cable moving assembly 12 is located between the active end of the cable 2 with the source holder 6 and the end of its unused portion located within the straight tubular sleeve 10. You. The assembly 12 has, for example, an asynchronous motor 14 with the required reduction gears and coupling means 16 for coupling a cable to the motor shaft of the asynchronous motor 14. One of the unique features of the device according to the invention, this coupling means 16 is constituted by a toothed wheel or gear wheel 18 whose teeth are formed spirally on the cable 2 to be moved. The protrusion has an interval corresponding to the pitch of the protrusion. This cable 2 is forced with the aid of a device having pressing rollers 20 distributed over a peripheral portion of the gear wheel 18 so as to maintain the cable and the gear wheel in contact without deformation and without loops,
In addition, a cable guide 22 disposed in a space between the pressing roller 20 and the gear wheel 18 forcibly forces the two continuous pressing rollers 20 to stay in tight and undeformed contact with the gear wheel 18. Is done. In this way, the linear movement speed of the cable 2 can reach 2 to 5 m / s in order to meet the special requirements of the analysis by activation of fission products contained in the enclosure 8. The structure including the pressing roller 20 and the cable guide 22 is fixed to a flange 24 which is screwed to a structure for holding the motor 14.

[0022] Again, according to the present invention, the first guide block 26 at the inlet of the guide tube 4 surrounding the cable device
In addition, the cable 2, which is fixedly held at the second guide block 28 at the outlet of the same device and is wound around the gear wheel 18, has a helical projection formed on the gear wheel 18. Clearly free to the guide by the method of correctly engaging with the.

In accordance with an important feature of the invention, the linear tubular sleeve 10 of the cable, the sleeve 10 at any time
There are two rows of magnetic position detectors 30, 32 which allow the end position of the cable 2 to be evaluated in the interior. These two groups of magnetic position detectors 30, 3
2 are respectively near the two ends of the straight tubular sleeve 10 so as to be separated in the enclosure 8 by a distance corresponding to the cable length (travel distance of the cable 2) between the retracted position and the working position. Be placed. In this manner, the presence or absence signal of the cable end associated with detectors 30 and 32 automatically controls the cable actuation cycle, i.e., initiates or moves, during movement of the source in either direction. Can be used for stop control.

The magnetic position detector works as follows (FIG. 1). The command given to the motor 14 causes the cable 2 to move slowly to move the source 6 to the retracted position. When the cable end passes in front of the detector 30, an “operation” control is given to quickly move the source 6 to the irradiation position, and a stop command is given when the cable end passes the detector 32. Can be The cable 4 then stops with a small response inertia.

[0025] After the irradiation time has elapsed, the motor 14 is started, the source 6 is removed at a very fast rate. The end of the cable 2 passes in front of the detector 30 and starts the 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 actual details of which are shown in FIGS. 3 and 4, the same means as those shown in FIG. 1 bear the same reference numbers. However, in this embodiment, with respect to the flange 24, the gear wheel 1
It is necessary to consider the second flange 36 which defines the space in which the coupling device 8 and its coupling device 16 are arranged.

FIG . 3 is a sectional view of the embodiment of the apparatus shown in FIG. 2 provided with the drum 34, the gear wheel 18, the cable 2, and the coupling device 16 for the cable 2 to the gear wheel 18. This cross-section shows the shape and the good working of the cable 2 against the gear wheel 18 and the pressing roller 20 and the cable guide 22 made of a flexible material, for example polyethylene or Teflon. Like.

[0028] Finally, FIG. 4 shows a side view of the apparatus shown in FIGS. FIG. 4 shows a reduction gear 38 and its rotating shaft 4.
0 with a gear wheel 18
Engages with the cable 2. FIG. 4 shows a pressing roller 20 for holding the cable 2 in close contact with the gear wheel 18.
Is shown.

In this embodiment, the winding drum 34
Has a surface 34 mounted for rotation about an axis 42 with splines and having a spline (or groove) around its circumference, on which the cable 2 is moved during its movement. It is wound. The automatic control of the translation of the take-up drum 34 as a result of this rotation
The automatic control device is capable of translating on a groove of the spline shaft 42 of the spline shaft 42 and meshes with a casing 52 fixed to a machine frame 54 via a ball screw device 50. This device operates as follows. When the take-up drum 34 is rotated in one or the other direction, the spline shaft 42 drives the part 48, and the part 48 is connected to the casing 52 through the connection with the ball of the ball screw device 50.
In the axial direction. In this manner, the cable 2 is wound along the spiral path into the groove 44 on the surface of the drum 34.

In this application, the magnetic position detection can be replaced by a coder 55 mounted on the gear wheel shaft, which supplies cable position information directly to the motor and gear transmission.

The combination of the special means of the coupling device 16 and the optional grooved drum can be performed at high speeds (2
(8 meters per second), the source holder cable can be moved in both the introduction direction and the retraction direction, and can be performed accurately. This cannot be achieved with conventional devices.

[0032]

As described above, the present invention is an apparatus for accurately and quickly moving a radioactive or neutron source between a working position and a retracted position, the apparatus comprising one end. A cable having a helical projection formed therein, a storage magazine for storing the cable when the source is in the retracted position, and a projection formed on the cable. Cable driving means having a tooth spacing substantially equal to the pitch of the gears and being rotatably driven in mesh with the projections; and cable guide means for preventing loop formation of the cable during rapid movement of the source. And position detecting means for the cable, which allows automatic control of the operating cycle of the cable during movement of the source, wherein the cable guiding means comprises a gear wheel. A plurality of pressing rollers distributed over a part of the portion and formed of a flexible material, and a cable guide disposed between each of the adjacent pressing rollers, wherein the cable guide includes a peripheral portion of a gear wheel and It is characterized in that it is formed along the curved shape of the peripheral portion of the adjacent pressing roller. To this end, the radioactive or neutron source is fixed to the cable and a device for quickly and accurately moving the radioactive or neutron source meeting the above demands using simple and effective means. Can be provided.

[Brief description of the drawings]

FIG. 1 is a general view showing an apparatus according to an embodiment of the present invention incorporating a straight tubular sleeve as a cable storage magazine.

FIG. 2 is a schematic view showing an embodiment of the present invention in which the cable storage magazine is a winding drum.

FIG. 3 is a cross-sectional view of the apparatus shown in FIG. 2 showing a gear wheel provided with a pressing roller and a cable guide.

FIG. 4 is a side view showing a control device for cable translation on the winding drum of FIGS. 2 and 3;

[Description of Signs] 2 Cable with spiral projections 6 Radioactive or neutron source 8 Enclosure 10 Storage magazine 12 Cable moving structure 16 Cable coupling means 18 Gear wheel 20 Press roller 22 Cable guide 30 Magnetic position detector 32 Magnetic position detector 34 Winding drum

Claims (5)

(57) [Claims] The method according to claim 1] radioactive source or neutron-ray source, a device for moving accurately and rapidly between a working position and a retracted position, the apparatus comprising a radiation source for holding the radiation source at one end Helical with holder
A cable having protrusions formed thereon, a storage magazine for storing the cable when the radiation source is in the retracted position, and a tooth gap substantially equal to a pitch of protrusions formed on the cable.
Cable driving means comprising a gear wheel having a gap and being rotatably driven in mesh with the projection; cable guiding means for preventing the formation of a cable loop during rapid movement of the source; While moving, the cable's working cycle
Position detecting means for the cable enabling dynamic control
If, consists, said cable guide means comprises a plurality of pressing rollers which are formed of a flexible material is distributed over a portion of the periphery of the gear wheel, is arranged on each between the pressing roller adjacent
Cable guides, the cable guides being located around and adjacent to the gear wheel.
Precise and rapid movement apparatus periphery radioactive sources or neutron-ray source, characterized in that formed along the curved shape of the pressure rollers that. Wherein said storage magazine, said cable (2) of the winding drum (34) radioactive source or neutron-ray source according to claim 1, characterized in that it is a for accurate 及
And quick moving device. 3. The storage magazine is a straight tubular sleeve (10), the length of the straight tubular sleeve being the cable length between the working position and the retracted position of the source (6).
Precise and rapid movement apparatus substantially corresponding radioactive sources or neutron-ray source according to claim 1, characterized in that the the. 4. The position detecting means according to claim 3, wherein the position detecting means comprises a magnetic position detector (30, 32) near two ends of the straight tubular sleeve (10). precise and rapid movement apparatus of radioactive sources or neutron source. 5. The movement of the source (6) is performed by a motor and a gear.
Accurate and <br/> rapid movement apparatus radioactive sources or neutron sources of any one of claims 1 to 4, characterized in that the A transmission.