JPS6235639B2 - - Google Patents

Description

Claim 1: A pair of plates 1 are attached to a pair of shafts 7 so as to be insertable and removable between the ionizing radiation exit window 4 of the ionizing radiation source and the irradiated material, and completely absorb the ionizing radiation when inserted. The plates 1 are connected to each other at an angle so that the sides of the plates 1 are parallel to the long sides of the exit window 4, and are connected to the pair of shafts 7 by levers. , such that these axes 7 are coaxial with each other through the wall of the chamber 3 which is part of a radiation protection device that prevents radiation from escaping.
The plate 1, at least one lever 2 and one shaft 7 are rotatably mounted parallel to the long sides of the outlet window 4, and are provided with passages 11, 12 for cooling liquid to flow therethrough. 1. A protection device for irradiation equipment, characterized in that 13 are provided respectively.

FIELD OF THE INVENTION The present invention relates to acceleration technology, and more particularly to protection devices for irradiation equipment.

Description of the Prior Art Irradiation equipment is generally used in conjunction with a conveyor carrying objects to be exposed to radiation, or, in the case of exposing flexible materials to radiation, with means for extracting the material.

When treating materials with ionizing radiation, the intensity of the radiation and the speed at which the material to be treated is delivered are determined by
The nominal radiation dose of irradiation of the material is adopted to ensure the maximum capacity of the facility. However, the drive mechanism of the conveyor transporting the material exposed to radiation, and the mechanism of other equipment installed in the same operating line as the irradiation equipment, is not provided with a nominal speed without lag. In particular, it takes up to several tens of seconds in existing equipment to accelerate the conveyor to its nominal speed. Furthermore, if the material exposed to radiation lacks mechanical strength, it is necessary for the conveyor to start smoothly.

On the other hand, the time required to place the accelerator of the irradiation equipment in the rated beam current mode, that is, the time required for the beam current to rise from zero to the rated value, is:
It will take another few tens of seconds. Therefore, the ionizing radiation beam parameters can be changed from start-up of the irradiation equipment to
A problem arises in matching the feed rate of the material in time until the rated beam current and the rated feed rate of the material exposed to radiation are reached. The reason is that without that alignment, some of the material will become under-irradiated and will be discarded.

To solve this problem, during the transition period until the ionizing radiation parameters reach their rated values,
Protective devices are used in irradiation facilities to protect materials from exposure to radiation.

A protection device for irradiation equipment is known, which is essentially a damper, which is installed in the vacuum of the accelerator in the path of the beam to the scanner (see Patent Application Publication No. 2299/1964, patented in 1964). However, such protection devices are difficult because the damper is placed in front of the scanner and the energy of the beam is released onto a small area of the damper, thereby overheating that area and creating cooling problems. It is practically unsuitable for current irradiation equipment with accelerators with powers of as much as 100 kilowatts.

Protection devices for irradiation equipment are known in the prior art (see British Patent No. 1246478, issued in 1971). The protection device comprises a pair of lead plates mounted on a pair of parallel axes and arranged between the exit window of the radiation source and the material to be irradiated. Their axes can reciprocate in opposite directions perpendicular to the central axis of the radiation, and the plates along with them perform complex movements in a straight line, proportional to the distance from the axis of the shaft to the center of the radiation. rotate about its axis by an angle that When the plates move, the intensity of the radiation incident on the material changes, and the plates are accordingly moved relative to each other in one of their edge positions, thereby blocking the exit window and blocking the radiation exiting from it. At the fully absorbing and other end positions, they are separated from each other so that the exit windows are completely open and the intensity of the radiation incident on the irradiated material is maximum.

If the device of the British patent is used in irradiation equipment, the plate will move in a complicated manner, making the equipment unusable, especially in the case of equipment with powerful radiation sources, as the design of the equipment will be complicated and maintenance will be troublesome. There are disadvantages involved. These troublesome matters are determined by the following matters.

First, it is quite complicated to move the board;
A complicated drive means is used for the protection device. The drive means includes a pair of parallel chain transmission mechanisms holding guides that fix the axis of the plate. Those parts of the drive means are removed from the equipment〓〓〓〓〓
It must be placed in a chamber that is part of a radiation protection device that prevents radiation from leaking and protects the human body and other perishable materials.

Second, when operating with a powerful radiation source, it is important to cool the plate to completely absorb the radiant energy, but to be able to move the plate, a cooling fluid must be supplied to the plate. This is quite difficult to do with the structure of the protection device in question, as the hose must have some slack.

Additionally, parts of the chain drive including shaft guides and cooling system liquid supply hoses are exposed to intense ionizing radiation and material-destroying X-rays;
Inside the chamber, which is part of the radiation protection device, is exposed to chemically active substances formed by the breakdown of the gaseous medium. Therefore, these components must be made of chemically strong and radiation resistant materials to prevent them from degrading too quickly.

When using the device in installations for irradiating wide materials, i.e. with exit windows of large dimensions, it becomes more difficult to synchronize the chain transmission mechanism of the drive means for moving the plates. .

Finally, since the chain drive mechanism is located in close proximity to the exit window, access to the exit window becomes more difficult and the task of replacing the exit window foil becomes more cumbersome.

SUMMARY OF THE INVENTION An object of the present invention is to simplify the construction of an irradiation equipment protection device and facilitate its maintenance.

The main object of the present invention is to provide a plate for absorbing ionizing radiation between the exit window of the ionizing radiation of the radiation source and the irradiated material, to assist in the supply of cooling fluid to said plate and for the radiation of the equipment. In order to be able to reduce the volume of the chamber that is part of the protective device,
It is an object of the present invention to obtain an irradiation equipment protection device which is adapted to be moved.

According to this main object of the invention, it comprises a pair of plates that completely absorb ionizing radiation, each plate being fixed to a shaft such that it can be inserted and removed between the ionizing radiation exit window of the ionizing radiation source and the irradiated material. irradiation equipment protection device according to the present invention, wherein the plates are joined at an angle to each other and connected to their axes by means of a lever, such that the sides of the plates are parallel to the long sides of the exit window; The axes are coaxial with each other and parallel to the long sides of the exit window, and are rotatably mounted in a wall that is part of the radiation protection device of the installation, with a plate and at least one A protection device for the irradiation installation is obtained, in which the shaft and one lever are provided with passages for the passage of cooling liquid.

A plate fixed to a rotatable shaft is adapted to be rotated about the axis of the shaft.
This is more convenient and provides additional advantages to the device of the present invention. Their advantages are:

A fairly simple drive means can be employed to rotate the shaft to which the plate is fixed, and furthermore, due to the fact that the shaft is installed through the wall of the chamber that is part of the radiation protection device, the drive means of the shaft need not be housed within this chamber, but instead can be located externally and connected to the end of one shaft extending outside the chamber that is part of the radiation protection device. In this way, it is possible to create a chamber that is part of a radiation protection device with a smaller volume and overall size than in conventional devices, and the task of replacing the foil of its exit window is made easier.

Because the shaft holding the plate is rotated,
the point at which the flexible hose of the cooling device is connected to the passageway in the shaft is substantially aligned with the axis of rotation of the shaft;
This minimizes the required travel distance of the hose, so that it is also easier to supply the plate with cooling liquid through the channels provided in the shaft.

Among the advantages of the configuration of the invention, it is also found that the drive means of the shaft and the flexible connecting hose of the cooling device, which are located outside the chamber that is part of the radiation protection device, are free from strong radiation and chemical There is also the advantage of being protected from exposure to corrosive gaseous media.

Joining the plates to each other at an angle provides rigidity to the plates, which might otherwise deform on their own. This is important for facilities that have large exit windows and therefore large boards.

The present invention will be better understood from the description of preferred embodiments taken in conjunction with the accompanying drawings.

[Brief explanation of the drawing]

FIG. 1 shows a protection device for irradiation equipment of the present invention,
Figure 2 is a cross-sectional view taken along the line - in Figure 1.
Ru.

BEST MODE FOR CARRYING OUT THE INVENTION Referring to FIG. 1, the irradiation equipment protection device of the invention comprises a pair of plates 1 joined together.
These plates 1 are rotatable on a lever 2 between the exit window 4 of the ionizing radiation of the ionizing radiation source 5 and the irradiated material 6 in a chamber 3 that is part of the radiation protection means of the installation. Supported. 1st
Only one plate 1 is visible in the figure. The plates 1 completely absorb the ionizing radiation and have sufficient dimensions to completely overlap the exit window of the ionizing radiation when in the lower position shown in FIGS. Two shafts 7 are supported by a bearing assembly 8 so as to be parallel to the long sides of the exit window 4 and on the same axis, and the levers 2 are each fixed to these shafts 7. The shaft 7, the lever 2 and the plate 1 are made of a chemically resistant material, such as stainless steel, for example. The end of the shaft 7 extends through a seal 9 to the outside of the chamber 3 which is part of the radiation protection means. The end of one shaft 7 is connected to an electric drive mechanism 10 .

In order to increase the rigidity of the plate, according to the invention, the plate 1 is angled so that the sides of the plate 1 are parallel to the long sides of the exit window 4, as shown in FIG. and are joined together.

The plate 1 is provided with passages 11 which are configured to pass cooling water for cooling the plate and communicate with each other. A shaft 7 and a lever 2 connected to it are used for supplying cooling liquid to the passages 11 of the plate 1 and for discharging it therefrom, i.e.
Passages 12 (FIG. 1) and 13 are formed so as to go around the pair of plates 1, respectively. The shaft 7 with the passage 12 is provided with a union 14 for connection to a cooling device (not shown). The flow direction of the cooling liquid at the entrance of the passage 12 is indicated by arrows A and B in FIG.
is shown.

In the device shown in FIG. 1, a pair of passages 13 are formed in one shaft 7 located on the left side of the drawing, and a pair of passages 12 are formed in the lever 2 also located on the left side of the drawing. is constructed so that it goes around these passages and each passage 11 of the two plates 1. Therefore, although the lever 2 and shaft 7 located on the right side of the drawing transmit heat to the plate 1, they do not cool themselves. This means that there is no active cooling means to do so. If the lever 2 located on the right side of the drawing
If you want to actively cool the shaft 7 as well, first form one passage in each of the lever 2 and the shaft 7 located on the left side of the drawing, and connect them to the passage 11 of the two plates 1. On the other hand, one passage is also formed in each of the lever 2 and the shaft 7 located on the right side of the drawing to communicate with the passage 11 of the two plates 1, and the cooling liquid is supplied from one side of the chamber 3. What is necessary is to discharge it from the other side. In this case, the shaft 7 located on the right side of the drawing is lengthened so that it protrudes outside the chamber 3, and a part of the outer surface of the shaft 7 is exposed between the electric drive mechanism 10 and the chamber. Thus, a union must be established here.

In order to feed the material 6 to be irradiated under the exit window 4, the feeding means 15 (FIG. 2) is moved from an electric drive 16. Indicated by dashed lines in FIG. 2 and referenced 1
Shown generally at 7, 18 is the open position of the plate 1. When in position 17, these plates 1 are seen in holes formed by a movable block 19 of chamber 3, which is part of the radiation protection device, and when exiting from said movable block 19, an exit The board 1 can always be placed in position 18 when the foil of the window 4 is to be replaced.

The device of the invention operates as follows. When the irradiation device is started, the plate 1 is in the lower position, ie between the exit window 4 and the material 6 to be irradiated. When the beam current emitted by the ionizing radiation source 5 reaches the rated value, the electric drives 10 (FIG. 1) and 16 (FIG. 2) are switched on and the transport means 1
5 feeds material 6, for example in the direction indicated by arrow C in FIG. By suitably selecting the speed of movement of the material 6 and plate 1 by means of adjustable electric drives 10 (FIG. 1), 16 (FIG. 2), the exit window 4 is fully opened and the feed means 15 are Until its rated travel speed is reached, the material 6 can receive the appropriate irradiation dose.

A similar operation is performed in the case of an emergency stop of the feeding means 15. In this case, the electric drive 10 (FIG. 1) is switched on via an electrical interlock and the plate 10 is moved to its lower position covering the exit window 4.
is lowered, but the ionizing radiation source 5 is kept on and the parameters of the emitted beam are unchanged.
left strange. This ensures a normal operating mode of the radiation source 5 and reduces idle time of the irradiation device.

In order to access the exit window 4, for example to replace the foil of the exit window 4, the block 19 (FIG. 2) of the chamber 3 of the partial radiation protection means must be removed and the seal of the coolant passages destroyed. This is done by moving the plate 1 from the irradiation area to the position 18 without any process.

Commercial Applicability The present invention can be widely used in commercial irradiation equipment and in laboratory irradiation equipment for research in the field of radiochemistry. The present invention can be used to maximum advantage in irradiation devices with powerful radiation sources. The proposed configuration of this protection device is quite simple, reliable, convenient to operate and allows partial The overall dimensions of the chamber of the radiation protection means can be reduced by 10-12%.

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