Discrimination of weapons-grade plutonium from thermal reactors in nuclear forensics

A simulated fingerprinting approach is demonstrated, aiming the discrimination of weapons-grade plutonium (WG-Pu) from different reactors. Light and heavy water and graphite moderated thermal reactors are considered, charged with fresh fuel assemblies of different enrichments. The plutonium isotopic composition is considered as the required characteristic fingerprints in the approach. Hence, plutonium isotopic ratios are used in 3D isotopic correlations for the discrimination purposes. The WG-Pu from the different reactors is well resolved between them. Within the light water moderated cases, the WG-Pu is resolved in groups according to their fresh fuel enrichment and the reactor and fuel assembly type. The fingerprinting approach is sensitive to a ‘Pu age’ beyond 0.5 years.