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

The use of a CZT detector with robotic systems

This work is focused on the use of a CZT detector for a radiation mapping with an industrial robotic arm. Measurements were carried out within the RadioRoSo experiment (Radioactive Waste Robotic Sorter), under the umbrella of EU FP7 project ECHORD++. In tests with a dual-arm robot and standard point sources of ¹³⁷Cs and ⁶⁰Co, a Magnox waste was mimicked. Thereafter, for relevant measurement geometries and selected shielding materials, full energy peak efficiencies were calculated using the MCNP transport code. Simulated FEP efficiency values were used for minimum detectable activity assessments for expected measurement conditions. Obtained results would be also applicable for cases of shielded lost/orphan point-like sources.

Implementation of FLUKA for γ-ray applications in the marine environment

The FLUKA code was implemented to simulate pulse-height spectra of a NaI(Tl) detector (excluding its resolution), considering radioactive sources of naturally occurring and artificial radionuclides present in the marine environment. For this purpose, a user-defined routine was developed for the proper simulation of the emitted γ-rays. The results were compared with simulations performed using the MCNP-CP code. The comparison of the recorded counts in the full-energy peaks, for the high intensity (emission probability >15%) emitted γ-rays for each radionuclide, yielded a satisfactory agreement (calculated ratios from 0.93 ± 0.05 to 1.07 ± 0.02) in all the studied cases.

The validation of synthetic spectra used in the performance evaluation of radionuclide identifiers

This work has evaluated synthetic gamma-ray spectra created by the RASE sampler using experimental data. The RASE sampler resamples experimental data to create large data libraries which are subsequently available for use in evaluation of radionuclide identification algorithms. A statistical evaluation of the synthetic energy bins has shown the variation to follow a Poisson distribution identical to experimental data. The minimum amount of statistics required in each base spectrum to ensure the subsequent use of the base spectrum in the generation of statistically robust synthetic data was determined. A requirement that the simulated acquisition time of the synthetic spectra was not more than 4% of the acquisition time of the base spectrum was also determined. Further validation of RASE was undertaken using two different radionuclide identification algorithms.