Radiological characterization for future fusion reactor decommissioning: balancing accuracy, time, and radiation protection

Future fusion reactors will produce radioactive waste, primarily neutron activation products and tritium, necessitating robust decommissioning strategies. This study compares radiological characterization techniques for fusion waste management, focusing on destructive versus non-destructive methods, and evaluates the advantages and disadvantages of both by applying them to two case studies of nuclear fusion plant decommissioning, namely the ENEA Frascati Tokamak Upgrade (FTU) and the planned ITER, the International Thermonuclear Experimental Reactor. Gamma emitters can be readily quantified using solid-state detectors, while almost pure beta emitters like Fe-55 and Ni-59 traditionally require destructive methods. However, for ITER-scale inventories, Cadmium Telluride (CdTe)-based X-ray spectrometry offers a viable non-destructive alternative, combining good energy resolution, compactness, and potential reduced secondary waste. In contrast, the FTU decommissioning, which is a peculiar case due to its stringent clearance levels for material reuse and recycling (below 1E+03 Bq/kg), necessitates destructive methods for nuclides such as Fe-55 and Ni-59 because non-destructive X-ray spectrometry would require impractically long measurement times. This comparative analysis highlights the importance of tailored characterization approaches, balancing accuracy, efficiency, and radiation protection, and provides insights applicable to decommissioning in different nuclear facilities.