Patent GB-987462-A (GB)
Title: Improvements in and relating to the location of uranium ore deposits and apparatus therefor
IPC: G01N33/24
Filed: 1962-06-25
Abstract: 987,462. Wells; prospecting. UNION CARBIDE CORPORATION. June 25, 1962 [June 26, 1961], No. 24265/62. Heading E1F. [Also in Division G1] A method of locating uranium ore deposits comprises drilling a hole into the substrata region to be probed, sealing off a section or end portion of the hole, evacuating gas present in the substrata region surrounding the sealed-off section or end portion through a radon absorbing means, and measuring the quantity of radon absorbed by the absorbent by radioactive means to provide a measure of the amount of uranium producing the radon. The alpha activity of the absorbed sample may be measured directly. A more suitable technique is to seal the absorbed sample to allow the accumulation of decay products and to measure the resulting gamma radiation, the maximum intensity of which occurs about 135 minutes after sampling. Reference is made to the use of conventional scintillation and Geiger-Muller detectors. The absorbent may comprise activated cocoanut charcoal or activated carbon. A probe for use in carrying out the invention, Fig. 1, comprises head and end portions 100, 110 joined by a conduit 108 by which gas entering the head portion through radial apertures 104 may be evacuated through the absorbent contained in a chamber, Fig. 2 (not show). The two portions are also joined by an elastic tube 118, formed for example, of pure latex rubber, forming a chamber 120 surrounding conduit 108. The chamber is inflated by air through a conduit 116 until the tube assumes the shape of the surrounding drill hole thereby sealing off the end portion of the hole beyond the head portion 100. The inlet apertures are recessed so as to prevent mud contamination and plugging. A replaceable weighted point may be attached to portion 100 by thread 106 to facilitate penetration through clay. In a modified construction, Fig. 3 (not shown), suitable for use in large diameter drill holes, the head portion is fitted with a sand filter through which the gas passes before it enters the evacuation conduit. Fig. 5 shows a construction suitable for sealing off a section along a drill hole and particularly suitable for horizontal holes. The arrangement comprises leading and following assemblies 506, 508 and 516, 520 each constructed in a manner generally similar to that shown in Fig. 1 of head and end portions separated by elastic tubes 500, 502 which when inflated seal off the section of the hole between the assemblies. The leading assembly tube is inflated through conduits 532 and 512 which terminates with radial holes 514, whilst the following assembly tube is inflated through conduit 524. The gas is evacuated through conduits 522 and 518 which extends concentrically around conduit 532 and is formed with radial holes 530. A sand filter surrounds the portion containing holes 530. The specification includes dimensional details of particular constructions, discusses the methods of analysing the measurements obtained and describes briefly some practical applications of the invention.