Transmutation of nuclear waste in accelerator-driven systems: Thermal spectrum

The TRIGA accelerator-driven experiment is a milestone in the roadmap towards the demonstration of the transmutation of nuclear waste in accelerator-driven systems (ADSs). It is designed in such a way as to couple the different components of an ADS in a realistic environment by using an existing critical reactor adapted to the experiment's objectives, at significant power levels. This paper summarises the neutronic characterisation of the system, an essential step in the design and licensing process. The feasibility of the experiment is demonstrated, establishing the sub-criticality levels of operation and fuel rod configurations. The analyses of the neutron distribution in space, energy and time detail the behaviour of a real-power thermal ADS and identify the extent and limitations for the experimental programme. Studies investigating the potential of such a system to transmute transuranics and long-lived fission fragments demonstrate the need to move to fast neutron systems in order to efficiently transmute these major components of nuclear waste