Plutonium fingerprinting in nuclear forensics of spent nuclear fuel

A fingerprinting procedure, based on the direct use of Pu isotopic ratios, is presented to discriminate spent fuels of different origin. Simulated and real spent fuels from PWR, BWR and LMFBR have been used, with different charge compositions in uranium, plutonium and minor actinides. The sensitivity of the procedure was sufficient to resolve the spent fuels from the same reactor type but of different enrichment and of the same enrichment from different reactor types. A dependence on the 234U and 236U charge composition is observed in the simulated fuels. The fingerprinting methodology is not influenced by the cooling time of the spent fuel and the Pu age. The discrimination of the actual spent fuel pins, although of the same enrichment and from the same assembly, indicates a dependence of the procedure on the pin location within the assembly.