Results on re-verification tests of spent fuel casks with muon tomography: MUTOMCA project

The MUTOMCA (MUon TOMography for shielding CAsks) international project explores the suitability of cosmic muon tomography, a non-invasive and non-destructive imaging method, for the re-verification of loaded spent fuel casks. Such casks are stored in dedicated interim storage facilities under continuous containment and surveillance by international safeguards authorities using unattended monitoring equipment. In the hypothetical case of a temporary failure of these instruments, resulting in a loss of continuity of knowledge, a re-verification of the spent fuel to fulfill international safeguard obligations would be required. The project aims to demonstrate the ability of muon tomography, a non-invasive and non-destructive imaging method, to distinguish between dummy elements and spent fuel assemblies based on their different densities. For this purpose, an experimental detector system based on drift tube technology was designed, developed, constructed, and installed for a field test at a dry storage facility in Germany (Grafenrheinfeld, operated by BGZ). The test examined two CASTOR® V/19 casks: one loaded with a mixed configuration of dummy elements and spent fuel assemblies and the other exclusively with spent fuel assemblies. This was the first real data reconstruction with muon tomography performed in an interim storage facility.