Purification at Los Alamos

The production of plutonium metal by both fluoride and oxide reduction is well established at Los Alamos. The subsequent purification of this metal by electrorefining is now being performed in production on a 6-kg batch scale. The objective is the production of high-purity plutonium metal. 

In liquid separation, hollow fiber membranes based on PBI have shown excellent performance for pervaporation dehydration of organic liquids. For example, a dual layer PEI-PBI hollow fiber membrane with an outer selective layer of PBI showed better performance than most other polymeric membranes in pervaporation dehydration of ethylene glycol. Sulfonation modifications of PBI membranes have demonstrated excellent separation efficacies in the dehydration of acetic acid. Studies have shown that PBI hollow fiber membranes were effective in separating chromates from solutions. Also, PBI nanofiltration hollow fiber membranes are promising candidates as forward osmosis membranes. In gas separation, recent studies sponsored by the Department of Energy at Los Alamos National Laboratories and SRI International demonstrated potential applications of PBI membranes in carbon capture and Hj purification from synthesis gas streams at elevated temperatures. H2/CO2 selectivity > 40 has been achieved at H2 permeability of 200 GPU at 250°C. ... 

An overview is given of plutonium process chemistry used at the U. S. Department of Energy Hanford, Los Alamos National Laboratory, Rocky Flats, and Savannah River sites, with particular emphasis on solution chemistry involved in recovery, purification, and waste treatment operations. By extrapolating from the present system of processes, this paper also attempts to chart the future direction of plutonium process development and operation. Areas where a better understanding of basic plutonium chemistry will contribute to development of improved processing are indicated. 

The original plutonium recovery and purification processes were adopted from Los Alamos processes in 1950. The processes at Rocky Flats are still similar today, in many respects, to the Los Alamos processes. 

Status of Americium-241 Recovery and Purification at the Los Alamos National Laboratory... 

A two-stage, countercurrent molten-salt extraction process is used to extract Am from many kilograms of aged plutonium metal in which Am has grown-in by beta decay of Pu. The purification scheme, based partly on molten-halide/molten-metal studies at the Los Alamos Scientific Laboratory and Argonne National Laboratory, ronoves about 90% of the americium from plutonium metal, typically containing 200 2000 ppm Am [16]. 

Thiocyanate anion-exchange systems have been used to purify americium from rare earths until recently supplanted, a plant-scale thiocyanate ion-exchange process was in long use at the Rocky Flats plant (1960-75) for routine purification of Am recovered from aged plutonium metal [16], This purification scheme was developed at the Los Alamos Scientific Laboratory by Coleman et al. [59]. 

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