The Use of a National Nuclear Forensic Library in Order to Identify Unknown Seized Nuclear Material Brazils Participation in the Galaxy Serpent Exercise, Brazils Participation in the Galaxy Serpent

The process of nuclear fission is governed by well-understoodphysical laws that may cause specific and predictable changesin the nuclear fuels resulting from, for instance, the type ofnuclear reactor, fuel type and its irradiation history, or aspectsassociated with energy production through the buildup of fissionproducts and the transmutation of heavy metals.All such information, compiled in a national nuclear forensiclibrary (NNFL), can be an important tool during the identificationof a seized unknown sample, allowing linking of informationconcerning its irradiation history, the type of reactor oreven the origin of the sample.The usefulness of an NNFL depends on not only the quantityor quality of the available data, but also on the capacity ofthe investigators to identify, correlate, and interpret the maincharacteristics identified, or measured, in the seized sample.This paper describes the strategy adopted by the Brazilian teamduring the virtual, web-based Galaxy Serpent Exercise,1 coordinatedby the Nuclear Forensics International Technical WorkingGroup, where an NNFL was developed and used to identify ahypothetical unknown sample. Our experience demonstratedthe importance of knowledge of nuclear reactions in order toidentify parameters that are most relevant during the technicalevaluation. Then, using these, the importance of simple isotopiccorrelations can be used to verify the consistency of theavailable information before invoking more complex multivariatestatistical techniques. Based on our investigation the hypotheticalseizure, which was determined to come from a boilingwater reactor, was conclusively found not to have originatedfrom a reactor in our model NNFL.