SUMMARY

Despite their importance, there is a dearth of post-detonation nuclear forensics Standard Reference Materials (SRMs) suitable for analysis traceable back to a national standard. Accordingly, the nuclear forensics community has requested SRMs be produced that mimic post-detonation fallout debris that include actinides, urban materials, fission products, and activation products. The National Institute of Standards and Technology (NIST) developed two Surrogate Post-Detonation Urban Debris (SPUD) SRMs to mimic the “rubble” of a city after an Improvised Nuclear Device detonation. NIST SPUD samples were irradiated at The University of Texas TRIGA reactor, then analyzed via gamma ray spectroscopy for short-lived, medium-lived, and long-lived fission and activation products. MCNP was used to model the efficiency of a High Purity Germanium (HPGe) detector as a function of source material density and gamma ray energy.