Fast and accurate approach to γ-spectrum modelling: A validation study with a shielded/unshielded voluminous uranium sample

γ-Spectrometry is a basic and widely applied method in nuclear security and nuclear safeguards areas. For addressing the growing needs in education and training, in research and development as well as in practical γ-spectrometry in these areas, Monte Carlo based web-accessible γ-spectrum modelling tools have been developed for the European Commission's Nucleonica portal at www.nucleonica.net. A recent validation study has demonstrated a good performance of the implemented simulation approach for modelling realistic γ-spectra from shielded and unshielded point-like sources. In the present work this approach has been further tested with the use of a 0.2 kg voluminous 4.46 wt% enriched uranium reference material and a portable 10% HPGe detector. The simulations for shielded and unshielded measurement conditions revealed a good agreement with the experimentally acquired γ-spectra, both for the detection efficiency values and for the overall spectrum shape and intensity in the energy range up to 2.6 MeV.