Discriminating Between Irradiated MYRRHA Fuel And Light Water Reactor Fuels Using Gamma Rays And Neutrons

MYRRHA is an accelerator-driven system featuring a MOX-fuelled core cooled by lead-bismuth eutectic, which is under development at SCK CEN in Mol, Belgium. An initial plutonium content of 30% in the fuel is foreseen, which together with the fast neutron spectrum in the core results in considerably different spent-fuel properties compared to spent fuel from typical light water reactors. These differences have been studied through depletion simulations, and include how radionuclide densities depend on burnup, which radionuclides contribute to the gamma-ray and neutron emission, and the intensity of the emitted radiation. As a consequence, current techniques for safeguards verification of spent fuel via non-destructive assay may need to be updated, or new techniques developed, for use in safeguarding of spent MYRRHA fuel. To some extent, these differences may have consequences in the wider context of nuclear safeguards for Generation IV systems. The focus of this paper is to what extent the gamma-ray and neutron signatures could be used to differentiate irradiated MYRRHA fuel from irradiated MOX and UO2 fuels from a light water reactor. The ability to discriminate between light-water-reactor MOX and UO2 has been recognised as an important task in safeguards verification today, and this work extends this objective to a future nuclear energy system.