Recent progress in passive gamma ray NDA techniques

The purpose of this study was to investigate the effect of spatial nonhomogeneity of nuclear material on passive gamma assay and to develop a quantitative description of the effect. The approach taken is twofold. First, nonhomogeneity was characterized by two parameters, and numerical calculations were performed to show a correlation, in first approximation, of the response with these parameters. Second, a series of experiments were carried out in conditions of controlled nonhomogeneity to verify the dependence of the effect on the nonhomogeneity parameters