GB693163A - Explosively operated apparatus for placing radio-active markers in boreholes - Google Patents

Abstract

693,163. Blasting cartridges; depth measurement of boreholes. GULF RESEARCH & DEVELOPMENT CO. Sept. 12 ' 1949 [Jan. 10, 1949; Jan. 10, 1949], Nos. 23505/49 and 23506/49. Classes 9(i) and 85 Shaped charge for inserting radioactive marking material in the wall of a borehole is held in a housing 2 closed at the rear 3 and having at the front end a screwthreaded flange by which the device may be mounted in a perforating gun. Wrenchholes 6 may be provided to facilitate removal from the gun. The charge 7 of detonating explosive is formed with a cavity 8 at the forward end and a detonator 10, which may be electric, is inserted in the rear of the charge, the lead wires 11 being taken through a hole in the housing. Alternatively a cord fuze may be led through the hole to the detonator. 10 per cent by weight or less of radioactive material, preferably of a refractory material, e.g. carnotite, is mixed with the explosive. The explosive mav be cast, the radioactive material being added when the explosive is liquid. The cavity 8 may have a liner 9 of ceramic or metal. The front end of the housing may be closed by a cover 21 resting on a shoulder 23 and held by a snap-ring 22, a gasket 20 sealing the cavity. The cavity liner 9 may be of the form disclosed in Specification 686,530. The inner face of the liner is coated with radioactive material, e.g. carnotite, mixed with an adhesive such as thermo-plastic cement, glue, pitch or caoutchouc. The mixture may be applied as a thick paint. Alternatively the radioactive material may be a frusto-conical element 14 held in place by adhesive, Fig. 4. Specification 693,164 also is referred to.