A modelling approach to defining radiochemical separation requirements for gamma spectrometry analysis

A novel application of the GEANT4 toolkit has been developed to assess the impact of various radiochemical separation outcomes on the detection limit for particular radionuclides of interest. A high-purity germanium detector has been modelled using the toolkit and validated using experimental measurements with software developed to perform automated spectral analysis. This software has been shown to be capable of simulating high-purity germanium spectra with varying activities of target analyte(s) and impurities. The time taken to perform the separation is also considered. The primary product of this analysis is a design space for radiochemical separation, which contributes to the definition of requirements for chemical yield, purity, and speed. This allows for an assessment, on an individual sample basis, on which process improvements are likely to result in the greatest measurement benefit. Further uses of this work include the development of radiochemical separation methods, the utility of further sample purification, and evaluation of the impact of individual impurity radionuclides. Specific theoretical and applied examples have been analysed and are reported in this work.