U.S. Department of Energy

Pacific Northwest National Laboratory

Outcomes: Phase Field Modeling of Microstructure Development in Plutonium (IV) Oxalate Precipitation

Principal Investigator: David Abrecht

Project was transitioned to new funding in FY18

Outcomes: More information is needed about microstructural evolution of precipitating solid materials--including the ways crystal shapes and structures form--to improve nuclear forensics capabilities. The focus of the project was on development of phase field models (in which the solid-liquid interface is treated as a continuous mathematical field) aimed at capturing, in plutonium oxalate, the correlation between the precipitating conditions and final structures, and then translating this information into a predictive capability.   

The project's progress included development of the physical constants for the plutonium oxalate system needed to describe crystallization behavior in phase field models, and establishment of thermodynamic properties of the solutions from which plutonium oxalate is normally precipitated. In fiscal year 2018, the project's results gained the attention of, and funding from, the Department of Homeland Security, and the project was transitioned out of NPSI.

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