(510c) Development of Electrochemical Process Models for Treatment of Used Nuclear Fuel

Chemical process models that simulate the unit operations within an electrochemical metallic used-fuel treatment facility are being developed to inform the design and implementation of process monitoring systems for material accountancy. The Argonne Model for Pyrochemical Recycling (AMPYRE) calculates the mass balance of a complete electrochemical reprocessing facility. The code consists of a series of interdependent unit operations models. Calculations enable prediction of the batch-wise evolution of salt and product compositions. The code follows all of the fuel components (U, TRU, rare earth and active metal fission products), plus Li, K, from the salt and Na from the fuel bond. The anode and cathode subunits use thermodynamic parameter values obtained from the open literature or supplied by the user. All major material movements are captured, including salt recycle from cathode processing and waste treatment. As a comprehensive representation, the code can be used to design flowsheets or to study operational effects on output. The Dynamic Electrorefiner (DyER) code simulates the major components of an electrorefiner: the anode, U cathode, U/TRU cathode, and molten salt electrolyte. Built in Mathworks MATLAB®, it is a time-dependent code that uses an ODE solver to predict the compositional evolution of these various components. It can be run as either standalone software, or interfaced with a facility or sensor model to provide a more rigorous representation of electrorefiner operations. DyER follows the same species as the AMPYRE code. As a fully dynamic model, DyER can be used to explore transient conditions in the electrorefiner and to predict the outcomes arising from time-variant or off-normal inputs or conditions. These codes predict the evolution of the distribution of uranium and the transuranics (TRU), as well as key fission products, in a facility when direct measurement is not practical during process operations, or when a fully integrated set of processes is not available. The calculation of the in-process inventory serves as part of an integrated approach to safeguards by informing the design and selection of measurement techniques, sensor arrangement, and the development of specialized analysis tools.

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