Americium oxide product, impurities

The flowsheet for the FFTF Pu02 production is shown in Figure 2. Briefly, the plutonium metal is converted to an impure oxide by burning the metal in air. This is followed by dissolution of the impure oxide in a 15.6 M HN03 - 0.5 M HF solution. The americium is separated from the plutonium by precipitation of the plutonium as the peroxide. Americium does not form an insoluble peroxide and stays in the filtrate with other cationic impurities. The active peroxide filtrate is slowly dripped into 9 M NaOH. The combination of strong alkali and heat destroys the peroxides and precipitates the americium as the hydroxide. Any residual plutonium in the filtrate, along with other cations, is precipitated also as the hydroxide. The flowsheet for the americium oxide production is shown in Figure 3. 

The analysis of the composite sample from the same series of curium-americium oxide production runs is presented in Table II. The content of carbon, the major impurity, is inferred rather than directly analyzed. The analyses of curium-americium oxide products generally reflect the purity of the feed, except for carbon and sulfur from the resin and a few potential corrosion products. 

The plutonium metal feed stock contained about 5 ppm natural lead which was not removed by the process. Recovery of americium in the finishing process (oxalate precipitation and calcination) averaged 98.5%. Most of the residual chromium contaminant was removed from the oxalate in decanted supernate and washes. The finished oxide product purity exceeded specifications i.e., >95% Am02 By selective blending, impurities in the shipped product, predominantly lead and nickel, were kept below 2%. 

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