Muon Tomography for Reverification of Spent Fuel Casks (the MUTOMCA Project)

Abstract

The MUTOMCA (MUon TOMography for shielding CAsks) project investigates the suitability of muon
tomography for the reverification of spent fuel casks. Spent fuel casks are stored, for decades, in dedicated
locations and are under constant surveillance by international agencies through unattended monitoring
equipment. In the hypothetical case that these instruments would temporarily fail, thus leading to a loss
of Continuity of Knowledge (CoK), a reverification of the spent fuel enclosed in self-shielding casks would
be required. The reverification is particularly challenging for conventional nondestructive assay (NDA)
methods since thick-walled spent fuel casks considerably attenuate the radiation emitted by the spent fuel.
On the other hand, inspectorates need a high degree of assurance on the amounts of nuclear material
stored in those casks. With the aim of proving the ability of muon tomography to detect a diversion of fuel
assemblies in closed spent fuel casks, an experimental apparatus was designed, developed, constructed,
and commissioned. The detectors were used during the first months of 2023, in a field trial at a dry storage
facility in Germany to examine CASTOR®V/19 casks. Preliminary results are presented along with the
potentials and drawbacks of the experimental apparatus.