Year
1973
Abstract
A general method for surveying for U-235 using a portable single channel analyzer with a 1/2 in. x 1 in. Nal(Tl) crystal detector is presented. Surveys of plane surfaces, rectangular cavities, and cylindrical sources are described as examples of how the method is used. If thorium is present with the U-235, a correction coefficient is derived that will eliminate the thorium contribution to the count rate. The statistical analysis of the data obtained from the survey method is described, and a procedure for determining the limit of error is outlined which includes nonuniform distribution of the U-235, background, ratemeter counting errors, and the errors in the calibration coefficients. This survey method has been used successfully for determining the amount of U-235 holdup in ventilation duct work and a complex geometry incinerator system.