Lessons and Methodologies from the Galaxy Serpent Exercise on National Nuclear Forensics Libraries

Key lessons learned and methodologies used in Galaxy Serpent, a first-of-a-kind, virtual, web-based international tabletop exercise utilizing the concept of a national nuclear forensics library (NNFL), are presented. The two phase exercise involved teams of scientists from twenty-four countries, eighteen of which actively participated. Teams were provided public domain spent fuel compositions used to compile a model NNFL, which served as a comparative instrument to assess whether hypothetically seized spent nuclear fuel was or was not consistent with their NNFL. This tabletop exercise was conducted under the auspices of the Nuclear Forensics International Technical Working Group (ITWG) and funded and organized by the U.S. Department of State with technical expertise provided by the U.S. Department of Homeland Security and Department of Energy. Teams reported similar analytic conclusions while employing different analytical techniques, including statistical analysis, more complex multivariate analysis including principal component analysis (PCA) and Fisher linear discriminant analysis (FLDA), and isotopic correlations. Galaxy Serpent served to mature to the concept of NNFLs by providing a vehicle for participants to 1) gather key technical expertise to create an NNFL comprised of existing data and information; 2) use International Atomic Energy Agency (IAEA) documents; and 3) continues to illustrate the potential probative benefits offered by creating such a library. During the play of Galaxy Serpent, many teams also involved other areas of expertise, such as nuclear reactor engineers and fuel experts, helping to mature the range of expertise of the nuclear forensics international community. Several Galaxy Serpent teams have used this tabletop exercise experience to inform their efforts at home to develop or refine their own NNFLs. The exercise has yielded insightful lessons regarding the vital role NNFLs can provide, and how they, in concert with traditional forensics, may expand the suite of tools for investigating nuclear or other radioactive materials encountered outside of regulatory control. The success and efficacy of the exercise has initiated the development of a follow-on exercise, similar in scope and intent, which uses data pertaining to radioactive sealed sources.