Segmented Gamma Scanning of Conditioned Radioactive Wastes: Development, Experimental Validation, and Application of an Angular Scanning Procedure for Hot-Spot Characterization

The "angular scanning" method allows both localization of hot spot(s) and the evaluation of the corresponding activity. Taking into account the experimental setup parameters (e.g., drum geometry, drum-detector distance, collimator geometry, etc.), the peak count rate versus the angular displacement is modeled as a theoretical analytical function of three independent variables (unknowns) for each hot spot: the two coordinates of the hot-spot center of mass and the corresponding activity value. Solutions for unknowns are obtained from equating, for each angular displacement, the experimental count rate to the corresponding theoretical one. Such a procedure has been applied to the SRWGA gamma scanner of the Casaccia Research Center utilizing a set of Waste Packages Reference Standards (with different matrices) where the gamma sources in different radial-azimuthal positions can be located.