Abstract
Uranium contents in some rocks were determined by means of a conventional fission track method. For making the standard samples, an aliquot of standard uranium solution was mixed with the known amounts of fine silicagel powder. Both the standard and pulverized rock samples were pressed on muscovite into thin tablets using a hand press. These tablet samples were irradiated in a reactor, KUR, and then subjected to the chemical etching procedure of mica surface in HF solution. The number of fission tracks on mica was counted upon the microscopic photograph. The relationship between uranium contents and track number was linear as expected from the calculation. Thus the uranium contents of rocks could be easily determined by the use of a standard calibration curve. The effects of powder grain and of thorium, which is only one fissile element in naturc except uranium, were also investigated. Uranium contents of four U.S. Geological standard rocks together with JG-1 and JB-1 have been conveniently determined by this fission track technique and the results were compared with those by other works.
