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    Material Characterization for Aqueous Processing

    Production efforts at Plutonium Facility 4 (PF-4) at Los Alamos National Laboratory (LANL) generate large amounts of byproducts and waste.

    By John Ahern | February 1, 2022

    Aqueous.processing

    Production efforts at Plutonium Facility 4 (PF-4) at Los Alamos National Laboratory (LANL) generate large amounts of byproducts and waste. Storage space for these byproducts and waste is limited and very expensive. Continued production relies on having enough space for these materials. Reducing the volume of material sent to these storage locations by consolidating the byproducts and minimizing waste is therefore essential.

    For over 40 years, special nuclear material (SNM) has been processed using aqueous methods at PF-4 in part to help reduce the volume of material in the vault and material sent for waste disposition. Aqueous processing supports a variety of efforts including recovery of plutonium (Pu) and americium (Am) from pit production byproducts, stabilization of oxides for long-term storage, and production of americium dioxide (AmO2) for sales via the DOE Office of Science Isotope Sales Program. Aqueous processing takes production byproducts as feed and separates the special nuclear material in a form that will occupy less space in the vault. The aqueous teams then safely consolidate and dispose of the remaining material as waste in cement drums for disposition at the Waste Isolation Pilot Plant (WIPP) and liquid sent to the Radioactive Liquid Waste Treatment Facility (RLWTF). Aqueous processing can be divided into two categories based on different acid media: nitric or hydrochloric acid. Aqueous chloride processing alone is capable of removing 800 drums worth of material from the pit production waste stream per year (mainly by removing americium from the feed). 

    Separating the flowsheet into nitrate and chloride halves allows for the optimal handling of the greatest variety of feedstocks (Figs. 1a,b). Trace actinides, such as americium, naturally grow into aging feedstock. The material in these processes requires monitoring at various stages to ensure each segment is performing as expected, to track inventory and to identify trace elements. Material is analyzed between each identified operation. 

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