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Nuclear Security

ORNL creates focused tools on emerging, difficult radiological questions in support of US government agencies. Tools in the nuclear security area are generally made available within select communities at the discretion of sponsoring agencies.

Recently developed tools include the Defense Land Fallout Interpretive Code (DELFIC) Airborne Planning Tool that predicts the sample characteristics of debris collected from the air after a nuclear detonation. This tool is based on DELFIC and builds on the success of a previous tool, the DELFIC Fallout Planning Tool, which was used by the interagency nuclear forensics community since 2009. Our Inverse Depletion Theory (INDEPTH) tool is being applied to international safeguards efforts to predict and confirm declarations of spent fuel characteristics such as burnup, initial enrichment, and cooling time. This tool uses the ORIGEN code and numerical methods to minimize the difference between spent fuel measurements and model predictions to infer reactor parameters. Another recently developed tool is the INVERSE GUI, which was created in partnership with Los Alamos National Laboratory. The INVERSE GUI uses advanced uncertainty quantification and various computer speedup techniques to infer shielded source characteristics from first responders’ measurements of radioactive material. Major analysis projects include an ORNL-led multilaboratory venture for the NNSA to improve prediction of plutonium production in reactors of concern using modeling and simulation capabilities. ORNL also plays a major role in another NNSA venture project to apply modeling and simulation to urban searches for radioactive sources where the confounding signals of background are being considered in detail. These capabilities are also being used to predict and calculate experimental observables such as the optical properties of uranium oxides, fluorides, oxyfluorides, and related compounds. Modeling and simulation capabilities are also being developed to help gain understanding of the solid state chemistry, structure, and dynamics of actinide compounds. Genetic algorithms are being used to predict crystal structure of novel uranium oxide phases. The fundamental chemistry of actinide materials is also being investigated using density functional theory and ab initio molecular dynamics codes employed on HPC clusters. Software for nuclear material holdup characterizing is also being developed. The SNAPSHOT software uses generalized geometry to characterize material left in a glovebox or other handling facility. Research is also being performed to develop transformative image reconstruction capabilities for radiological source characterization.