Patent Number: 042257905
Section: summary

THE PRIOR ART As is shown in FIG. 1 of the accompanying drawings, systems for the handling of radioactive material 1 involve the provision of a storage unit 2 having a mass 3 of radiotion-shielding material with a passage 4 through it, in which the radioactive material can be safely stored when not in use, as is shown in FIG. 1 at A, and from which the radioactive material can be moved to a use location, as for making a radiograph, as is shown in FIG. 1 at C. Typically, the radioactive material 1 is connected to drive means comprising a flexible cable 5 in a guide tube 6. The guide tube is generally provided in three essentially equal-lengths 6A, 6B and 6C, each of which can be disconnectibly coupled to the storage unit 2. Under control of a reel and crank arrangement 7 the drive cable 5 pushes the radioactive material out of the passage 4 and through the third guide tube 6C to a snout 8 located where the radiograph is to be made, as shown in FIG. 1 at B and C. The portion of drive cable 5 in the second guide tube 6B supplies the cable necessary to fill the first and third guide tubes 6A and 6C when a radiograph is being made. A disconnectible coupler 9 is fitted in the drive cable 5 so that when the radioactive material 1 is in the stored position the drive cable can be parted outside the storage unit for uncoupling the cable 5 and the guide tubes 6A and 6B from the storage unit. The part of drive cable 5 between the coupler 9 and the radioactive material 1 is known as the leader 11, and the coupling apparatus 10 between the guide tubes 6A and 6B and the storage unit 2 generally contains means to lock the leader against movement through the passage 4 when the drive means are uncoupled and removed. U.S. Pat. Nos. 3,147,333 and 3,593,594 describe prior systems in which these features are found. As is seen in these patents, two lengths of guide tube 6A and 6B are typically furnished for guiding and protecting the cable 5 and, in use, both lengths of guide tube are laid out between the reel-and-crank arrangement 7 and the storage unit 2. GENERAL NATURE OF THE INVENTION The present invention provides improved control apparatus, in which only one guide tube, equivalent to guide tube 6A, is required to be laid out between the reel-and-crank arrangement 7 and the storage unit 2, the extra supply of cable 5 being housed in a second guide tube, equivalent to guide tube 6B, of relatively lighter weight that is permanently coiled at the same location as the reel-and-crank arrangement. This reduces the weight and the cost of systems for handling radiographic material, and simplifies the tasks of setting up and taking down the systems.