Update on Establishing the Feasibility of Lead Slowing Down Spectroscopy for Direct Measurement of Plutonium in Used Fuel

Developing a method for the accurate, direct, and independent assay of the fissile isotopes in bulk materials (such as used fuel) of next-generation domestic nuclear fuel cycles is a goal of the Office of Nuclear Energy, Fuel Cycle R&D, Material Protection and Control Technology (MPACT) Campaign. To meet this goal, MPACT supports a multi-institutional collaboration to address the feasibility of Lead Slowing Down Spectroscopy (LSDS) as an active, nondestructive assay method. LSDS has the potential to provide independent, direct measurement of Pu and U isotopic masses in used fuel with an uncertainty considerably lower than today’s confirmatory assay methods, for which typical uncertainties are approximately 10%. LSDS techniques are sensitive to the fission resonances in the energy range of ~0.1-1000 eV, enabling their use to determine the mass content of the fissile isotopes in used fuel. This paper will present an update with regard to applying LSDS for used fuel assay and the development of algorithms to extract fissile isotopic masses from the used fuel.