On-line bulk composition analysis of steel scrap using PGNAA (SCRAP PROBE) : final report

The principal aims of this project were to develop PGNAA-based system technology for the on-line bulk composition analysis of steel scrap, its full chemical characterisation and the implementation of a scrap composition analyser in a field trial. Monte Carlo neutronics modelling and simulation were performed for the design of the analyser, and gamma spectroscopy methods for the application of PGNAA and PFTNA techniques to bulk metal-scrap units were developed. New linear shaped high intensity neutron generators emitting 2.5 MeV and 14 MeV neutrons, respectively were developed and tested. Well established LIBS technology was adapted to make available a standard technique for inter-comparison and validation of the Scrap Probe analyser. Spectroscopic characteristics of several gamma detectors were evaluated. Different prototypes of the analyser were constructed, extensive trial measurements were performed and improvement suggestions proposed. Synthetic and industrial steel scrap have been analysed in different geometries to characterise various elements. Due to inadequacies of the gamma detectors used as well as other major electronics problems, the targeted accuracies have not been achieved yet. In the case of 800 kg scrap in a 1 m3 container, a detection limit of <2 % was achieved for copper when PGNAA was applied using NaI(Tl) detectors. The full capabilities of PFTNA could improve the limits for certain elements. Standardisation could not be accomplished. Preliminary validation has been done. A tremendous amount of knowledge has been acquired and needs more effort to bring it fully into practice. Though expensive, high resolution Ge-detectors are necessary for achieving targeted detection limits and accuracies.