Patent Number: 042119286
Section: description

The storage unit 20 shown in FIGS. 2 and 4-8, inclusive, has a mass 23 of radiation-shielding material through which a straight tube 24 provides a straight passage 25. At a first end the tube 24 is fitted with a coupling assembly, generally indicating by reference 30, for manipulating means. This coupling assembly may take any form that is suitable for safety and operational requirements that are current at the time of use; for example, as shown in one of the above-referenced U.S. Pat. Nos. 3,147,383 or 3,593,594. The coupling assembly 30 which is illustrated is described and claimed in a copending joint application of one of the present inventors and another, Ser. No. 964078, filed concurrently with this application, and assigned to the same assignee as the present application. At a second end the tube 24 is fitted with a shutter 40 having a hole 42 through it which can be placed in register with the passage 25. The shutter 40 is movable transverse to the passage 25, between first and second limits. In FIGS. 2 and 5, the shutter is shown in a first limit, blocking the passage. In FIG. 7, the shutter is shown in the second limit, with the hole 42 in register with the passage 25. Radioactive material 31 (FIG. 3) is housed in a capsule 32 which has a pivotal member 33 connected to it via a pin 34. The capsule is connected by a ball joint 36 to the leader 11, at the other end of which is the female part 98 of the cable connector 9. The leader 11 is made of a chain of cylindrical members 37 of the same diameter all coupled together via ball-joint links 38 having the same diameter. The cable connector has a portion 39 of reduced diameter for locking engagement in the coupling assembly 30 when the radioactive material is to be held in the stored position. The latch portion 39 is locked in a slot (not shown) in a block 31 that is slidably retained in the coupling assembly. Details of the locking mechanism are set forth in the above-identified co-pending application, and forming no part of the present invention will not be repeated in this specification. Forward of the leader 11, toward the shutter 40, the capsule 32 is connected via a cylindrical member 37 and ball-joint link 38 to a shutter-control plug 44 having a diameter which is larger than the diameter of the cylindrical members 37. The tube 24 is enlarged internally at a portion 46 adjacent the shutter, and stops short of the shutter. A shutter latch tube 48 fits telescopically within the enlarged portion 46, for slidable motion toward and away from the shutter. The latch tube 48 has a portion at the end 50 confronting the shutter which is enlarged in diameter externally to essentially the same outer diameter as the straight tube 24, and a coil spring 52 surrounds the latch tube between a shoulder 54 on the enlarged end 50 and the confronting end 56 of the straight tube 24. At the inner end 58 remote from the shutter 40 the latch tube has a portion of reduced inner diameter providing a shoulder 60 against which the inner end 62 of the shutter control plug 44 can bear. When the radioactive material 31 is returned to the stored position, as by manipulating the crank assembly 7 to withdraw it back from the snout 8, the shutter control plug 44 can be operated to pull the shutter latch tube 48 back from the shutter against the action of the spring 52, by continuing to apply cranking force in the direction of withdrawal. The shutter 40 is slidably mounted in its support 66 and is urged by springs 68 to a position in its first limit, shown in FIGS. 2, 4 and 5. Whenever the latch tube 48 is pulled away from the shutter the shutter 40 is free to take up a position in its first limit. The shutter can be placed in its second limit, shown in FIG. 7, by pulling (upward in the drawings) on the knob 70, which is connected to the shutter by a rod 72. When the shutter is open the knob 70 extends up above the main body of the storage unit, and is shown in dashed line in FIG. 2, acting as a tell-tale. A safety feature is provided for preventing movement of the shutter to the open limit when the guide tube 6C for the snout 8 is not coupled to the storage unit. A connector 74 for that guide tube is represented by dashed lines in FIGS. 2, 5, 6 and 7. This connector couples to a nipple 76 which is a permanent part of the storage unit and is internally bored to provide a continuation 78 of the passage 25. The shutter 40 is fitted with a latch-pin 80 having a stem 82 (shown in FIG. 6) which extends through a hole 67 forward of the shutter housing 66 where it can be pushed by the connector 74 as it is fitted to the nipple 76. The latch pin has a main body that is urged by a spring 84 into a recess 86 in the back wall of the shutter. A slot 88 in the shutter provides a slide-way for the stem 82 when the latch pin is pushed back from the recess 86. When the guide tube 6C is connected, then the shutter 40 can be opened. When the shutter is opened, by pulling up on the knob after connecting the guide tube coupler 74 to the nipple 76, the hole 42 is moved into register with the passage 25. An annular recess 90 around the hole in the back wall of the shutter has an internal diameter large enough to accept the enlarged end 50 of the shutter latch tube 48. To reduce sliding friction against the back wall of the shutter that end is desirably internally bevelled. The spring 52 urges the latch tube into the recess 90. To avoid permanently compressing the spring 52 with the shutter control member 44 when the capsule 32 is put in the stored position, cranking force at the crank assembly is preferably relaxed after the latch tube 48 has been pulled away from the shutter and the shutter has moved to the closed position, and before the coupler 9 is uncoupled and the leader 11 locked in the coupling assembly 10 of the system. The latch portion 39 of the coupler portion 98 shown in FIG. 2 is long enough to slide in the direction of the passage 25 when the coupler is locked in the coupling assembly 30.