Gamma Ray Measuring Method for a Simple Determination of Radioactivity of Uranium in Waste Drums

Abstract

For determining radioactivity of waste drums using γ ray measurement, we showed a new analysis method deriving the linear relation between radiation source distribution and γ ray count rate under the homogeneous waste density. On the other hand, there was a problem applying the linear relation to the case of inhomogeneous waste density. We calculate the geometric mean of measurements at various positions on spherical surface surrounding the waste drum to create the approximately homogeneous waste density. As a result, we derived the relation between radiation source distribution and γ ray count rate by 1/(ln(k/R))² and n. R is the geometric mean of two γ ray (766keV and 1001 keV) ratios. k is the ratio of two γ ray emission rate. n is the geometric mean of γ ray (1001 keV) count rates. We calculated the several model by Monte Carlo simulation code to evaluate the validity of this method. The calculation results showed linearity between 1/(ln(k/R))² and n.