Overview of initial work on spent-fuel verification at MYRRHAfuel verification at MYRRHA

The MYRRHA facility, which is under development at SCK CEN in Mol, Belgium, will be a multi-purpose research facility centred around an accelerator-driven reactor cooled by lead-bismuth eutectic. The MYRRHA core will contain MOX fuel with an initial plutonium content of 30%, and the lead-bismuth coolant will result in a fast neutron spectrum in the reactor. Due to reasons such as these, the radionuclide composition of spent fuel from MYRRHA can be considerably different from that of spent fuel from typical light water reactors. These differences will affect the choice of non-destructive verification techniques to safeguard the spent fuel. Further practical considerations, for example considering spent-fuel storage in lead-bismuth eutectic, will affect the choice of measurement technique. In a project led by Uppsala University, first studies of the requirements on gamma-ray and neutron measurements of spent fuel from MYRRHA have been performed using depletion calculations and Monte Carlo simulations. These studies have included i) an investigation into the radionuclide composition and gamma-ray and neutron emission in spent fuel from MYRRHA, ii) an analysis of the possibilities to discriminate between spent MYRRHA fuel and spent light-water reactor fuels using gamma-ray and neutron signatures and machine learning, iii) a feasibility study of using gamma-ray spectroscopic measurement for assaying a MYRRHA fuel assembly stored in lead-bismuth eutectic, and iv) a feasibility study of using neutron measurements under similar conditions. In the paper, new results connecting these studies will be summarised to highlight some important consequences for future safeguards verification at fast reactor systems.