US 3088032 A
Description (OCR text may contain errors)
from the shielding position I tendency to kink limits the length of travel which may be material, which United States Patent Oflice 3,088,032 Patented Apr. 30, 1963 3,088,032 HOLDER FOR MOVABLE RADIOACTIVE SOURCE MATERIAL Donald C. Brunton, Pennington, N.J., assignor to Cur-tiss- Wright Corporation, a corporation of Delaware Filed July 27, 1959, Ser. No. 829,577 3 Claims. (Cl. 250-106) This invention relates to apparatus for shielding and exposing radioactive material.
For many applications it is desirable to expose materials to rays from radioactive material. It frequently is desirable to be able to convey the radioactive materials between positions wherein they may be used for subjecting objects to irradiation and other positions wherein the radio active materials are completely shielded. As illustrative examples of some of the uses of radioactive materials wherein it is desirable to be able to move the radioactive material between exposed and shielded positions, there may be mentioned industrial radiography, food irradiation and sterilization, and medicinal uses.
It has been proposed to mount the radioactive materials on the end of a cable which is used to move the radioactive material from a shielded position within a passageway in a shielding material to an exposed position, and to use the same cable to retract the radioactive material back into the shielding position. Since the cable must be flexible to allow it to pass through tortuous passageways used for shielding the radioactive materials, it necessarily has relatively little rigidity in compression. Where the radioactive materials must be moved through tortuous passageways, the flexible cable tends to bend and kink during the pushing operation. This tendency to bend limits the speedwith which the radioactive material may be pushed to the exposing position. The
used ,for pushing the radioactive material and presents problems with the radioactive material becoming stuck and the cable breaking or being rendered useless. These problems become progressively more acute when larger and heavier radioactive sources are used.
It is an object of the present invention to provide apparatus wherein radioactive material may be moved between a position for exposing objects to the radioactive rays and a positionwherein the radioactive material is completely shielded which will overcome the defects in prior apparatus.
It is a further object of this invention to provide apparatus for irradiating objects with rays from radioactive apparatus may be readily and easily adapted to uniformly irradiate objects of divers configurations.
It is a further object of this invention to provide means for rapidly moving the radioactive materials from the shielded position to the exposing position and means for rapidly and positively retracting the radioactive material to the shielded position.
It is a still further object to provide in such an apparatus means whereby the radioactive material can be returned to the shielded position for safety regardless of any possible power failures.
With the above objects in view, the present invention mainly consists of a device for shielding and exposing radioactive material comprising shielding material having at least one passageway therethrough for the radioactive material and conduit means attached to one end of each such passageway. Fluid pressure means is operatively connected to another end of each passageway for applying fluid pressure to the radioactive material to move the radioactive material rapidly from the passageway to the conduit means. Means is operatively connected to the radioactive material for braking the motion of the radioactive material responsive to the fluid pressure means and for retracting the radioactive material positively and rapid- 1y from the conduit means to the passageway in the shielding material.
The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read with the accompanying drawings in which:
FIGURE 1 is a partially perspective, partially schematic partially sectional elevation view of apparatus embodying the principles of this invention; and
FIGURE 2 is an enlarged detailed view partially in section of a portion of FIGURE 1.
Referring to the drawings, and more particularly to FIGURE 1, there is shown generally a device which includes a body of shielding material 11 and means 12 spaced therefrom for holding radioactive source 14 in an exposing position. The shielding material 11 and the means 12 are interconnected by a conduit 13.
More specifically, shielding material 11 has a plurality of passageways 16 therethrough for receiving the radioactive sources 14 in shielded positions. Shielding material 11 may be a mass of lead 17, for example, incased in a steel incasement 18. As illustrated in FIGURE 1, passageways 16 are of curved configuration so that when radioactive source '14 is contained near the center of passageway 16 there is no direct line-of-sight from the radioactive material to the outside surface of the shielding material. Passageway 16 also includes a stop 19 to prevent the radioactive source 14 from going completely I through the passageway.
Attached to passageway 16 at one end 2-1 thereof, is the conduit 13, for example a flexible metal hose, for permitting passage of the radioactive source 14 therethrough.
Attached to the end of conduit 13 remote from shielding means 11 is the holder '12 for holding the radioactive source 14 in an exposing position.
Attached to passageway 16 at the other end 22 thereof, is compressed air means 20 for introducing air under pressure through pipe 23 whenever desired. Air introduced through pipe 23 into passageway 16 is used for conveying radioactive source 14 from the central portion of passageway 16 through conduit 13 to holder 12. In air pipe 23, there is a T connection 24, the base of the T being connected to the source 20 of air under pressure and one arm of the T being connected to passageway 16. The other arm of the T is provided with a plug 25 having a small orifice therethrough.
Through the orifice in the plug 25 is passed a closely fitting cable 26, one end of which is attached to the radioactive source 14 and the other end of which is attached to recovery reel 27. Recovery reel 27 is operatively connected to motor 28 through a clutch arrangement 128 and is also provided with a braking means 127 for stopping or retarding the motion of recovery reel 27. Reel 27 is also provided with a crank handle 29 which permits rotation by hand when desired.
Cable 26 which is attached to the radioactive source 14 serves several purposes. The cable 26, when being wound up on recovery reel 27 retracts radioactive source 14 from holder 12 through conduit 13 into the shielded position of passageway 16. Normally this retraction is accomplished by actuating recovery reel 27 by motor 28. However, should the power source fail for any reason, it is still possible to retract the radioactive material to a shielded position by winding cable 26 onto recovery reel 27 by use of hand crank 29.
It is normally desired to convey the radioactive material between the shielded position and the exposing posi- 3 tion as rapidly as possible. The air pressure produces a rapid motion of the source toward holder 12. The cable 26 acts as a brake to slow down and stop the rapid motion of the radioactive source when it arrives at holder 12. Control of this braking action of the cable is achieved by means of the brake 127 which acts on recovery reel 27. This prevents the radioactive material from slamming against any part of the structure for stopping its forward motion with the concomitant danger of breakage of the radioactive sources.
Conduit 13 may be of any length and of any type of I curved configuration without afiecting the operation of this device. Accordingly, it becomes possible to provide -a single shielding unit 11 which may contain a plurality .;of radioactive materials for uniformly irradiating many divers objects having difierent configurations. This versatility is accomplished in part because of the ease of repositioning holders 12 in configurations appropriate to the objects being irradiated while the radioactive sources 14 are in shielding unit 11.
Holders 12 are removably supported on grid plate 30, which may be provided with a plurality of orifices arranged in different configurations. For example, grid plate 30 may be a flat sheet of metal provided with orifices arranged in concentric circles about a common center or it may be provided with orifices arranged in a rectangular array or any other appropriate configuration. The configuration selected will be one wherein uniform irradiation may be achieved of samples placed in the field of radioactivity emitted from radioactive materials held in holders 12.
Each holder 12 is clamped to grid plate 30 at the appropriate location by clamping means 35. Since the radioactive sources 14 are retracted into shielding material 11, holders 12 may be repositioned on grid plate 30 without any special precautions or specialized remote handling equipment.
As is best illustrated in FIGURE 2, holder 12 may be formed from a metal tube 31 which is provided at the end remote from conduit 13 with a closure 32 having an orifice 33 therein. Closure 32 prevents the radioactive source 14 from escaping from the end of holder 12. Orifice 33 allows for the escape of the air which is pushed along ahead of the radioactive source 14 during its transfer from the shielded position to holder 12. A cushion of air trapped adjacent closure 32 ahead of the radio- 2 active source also serves to cushion the final impact of the radioactive source 14 should it hit closure 32. Holder 12 is also provided with a detent means 34 which cooperates with an annular groove 46 near the end of the radioactive source 14 for maintaining it at a fixed location 7 Within holder 12. Detent means 34 may be overridden by the force used in retracting the radioactive source 14 by means of cable 26.
Curved passageway 16 and flexible conduit 13 are designed to have a substantially constant internal diameter throughout their length, which diameter is made as small as practicable. The curved passageway 16 is made as small as possible in diameter to minimize the streaming of radioactivity through the curved passageway. The curved passageway 16 and flexible conduit 13 are made of substantially constant and equal diameter so as to act as a curved cylinder surrounding radioactive source material 14 which acts as a piston therein. This provides for the optimum utilization of the compressed air for movement of the radioactive soruce through these passageways.
To use the irradiator of this invention, the appropriate locations for the source holders are computed such as to provide uniform irradiation of the object to be treated. This is determined by the geometry and the relative densities of the various portions of the object to be irradiated and the relative strengths of the various sources used. Source holders 12 are then positioned in the appropriate uration by clamping them to grid plate 30 while sources 14 are contained Within shielding means 11. The objects to be irradiated may be positioned within the irradiation field or may be positioned on conveyer belts or the like adapted to carry them through the irradiation field. Once this preliminary setup has been finished, the irradiation area is cleared of all personnel.
Depending upon which source holders are to be in use for any particular operation, the appropriate sources 14 are transported to source holders 12, the remainder of the sources 14 being retained within shielding means 11. As desired, any number of sources 14 may be transported sequentially or simultaneously to source holders 12.
Actuation of compressed air source 20 pushes the desired radioactive sources 14 from shielding means 11 to the source holders 12. In order to control the speed of movement of sources 14 through the passageway 16, conduit 13, and holder 12, and in order to brake the movement of source 14 within holder 12, a retarding force is applied to cable 26 by braking reel 27. When source 14 is within holder 12, detent means 34 engages annular groove 46 insource 14 to hold source 14 inits proper position even though compressed air source 20 is turned olf.
When it is desired to retract sources 14 from holders 12 to shielding means 11, as for example, after the appropriate irradiation period of the material being irradiated or when it is desired to change the configuration of holders 12 or grid plate 30, etc., motor 28 is actuated and the clutch 128 is engaged turning recovery reel 27 This winds up cable 26 and withdraws source 14 from holder 12 through conduit 13 to passageway 16 in shielding means 11. After return of radioactive source 14 to shielding means 11, the irradiated objects may be removed and replaced with others, the source holders 12 may be repositioned on grid plate 30, or any maintenancework or other modifications of the apparatus may be made without the necessity of remote handling equipment and without any special precautions.
'It is thus seen that there has been provided an apparatus wherein radioactive material may be moved rapidly from a shielded position to an exposing position and rapidly and positively retracted to the shielding position with the maximum of safety and with the least chance of undesirable interruptions due to malfunctioning of the apparatus. An apparatus also is provided which has a maximum of versatility for adapting it to irradiate materials of divers configurations.
While the invention has been illustrated and described as embodied in an irradiating apparatus, it is not intended to be limited to the details shown, since various modifications and changes may be made without departing in any way from the spirit of the present invention as defined in the claims.
Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications Without omitting features that, from the standpoint of prior art fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should be and are intended to be comprehended within the meaning range of equivalents of the following claims.
What is claimed as new and desired to be secured by Letters Patent is:
l. A device for shielding and storing a radioactive source in a first position and for exposing said radioactive source in a second position comprising, in combination, a radioactive source having a recess formed therein; a body of shielding material having a passageway therethrough for storing the radioactive source in said first position, said passageway having at least a first end portion and a second end portion; conduit means connected between said second position and to a first end portion of said passageway; fluid pressure means operatively connected to a second end portion of said passageway for applying fluid pressure to said radioactive source to move said radioactive source rapidly from said passageway to said second position; holding means including a detent for cooperating with said recess in said radioactive source to secure said radioactive source in said second position; and means operatively connected to said radioactive source for braking the motion of said radioactive source during movement responsive to said fluid pressure means and for retracting said radioactive source rapidly and positively from said conduit means to said passageway in said body of shielding material.
2. An irradiator comprising, in combination, a plurality of radioactive sources, each of said radioactive sources having a recess therein; a body of shielding material in a first position having a plurality of passageways therethrough, each of said passageways for receiving and storing one of said radioactive sources, a plurality of holding means spaced from said body of shielding material in a second position, each of said holding means including a yieldable detent for entering the recess of said radioactive sources to retain said radioactive sources in said second position; a plurality of conduit means interconnecting said passageways and said holding means, thereby providing a different respective continuous passage for each of a plurality of radioactive sources; and means for supporting said plurality of holding means in a preselected configuration.
3. An irradiator comprising, in combination, a plurality of radioactive sources; a body of shielding material having a plurality of passageways therethrough; a plurality of holding means spaced from said body of shielding material; a plurality of conduit means interconnecting one of said passageways and one of said holding means, thereby providing a different respective continuous passage for each of said plurality of radioactive sources; means for moving each of said radioactive sources through its respective said conduit between its respective said passageway and its respective said holder whenever desired; and means for supporting said plurality of holding means in a preselected configuration, said means -for supporting said plurality of holding means in a preselected configuration comprising a plate having a plurality of apertures therein over which said holding means are supported and through which said radioactive sources pass, said apertures being spaced in a preselected configuration whereby said radioactive sources when secured in said holding rneans establish a uniform field of irradiation of predetermined configuration.
References Cited in the file of this patent UNITED STATES PATENTS Re. 24,544 Morganstern Sept. 30, 1958 2,750,517 Baum June 12, 1956 2,798,164 Untermeyer July 2, 1957 2,862,108 Meilink Nov. 25, 1958 2,872,587 Stein Feb. 3, 1959 OTHER REFERENCES International Conference on the Peaceful Uses of Atomic Energy, vol. 15, pages 18 0 to 193, United Nations Press, 1955.