Passive ray measurements for a simple determination of radioactivity of uranium in waste drums

Yokoyama, Kaoru; Sugitsue, Noritake

Intending to apply to radioactive waste drums for trench disposal, we have developed a new analysis method on measuring radioactivity of uranium enclosed in each of the waste drums using passive ray measurement. We propose a new evaluation function which gives a unique relation between source positions and ray count rate. This evaluation function has been derived from the measurement method using two opposing detectors. The new evaluation function is given by Z=1/(ln(k/R(1))ln(k/R(2))), where "R(1)" and "R(2)" are the ratios of different energy (766 keV and 1001 keV) ray count rates measured by the detectors. "k" is the ratio of emission rates of the two energy rays. We have discovered that the evaluation function uniquely relates Z and (nn), where "n" and "n" are the ray count rates measured by the detectors.