Americium process, flowsheet

Treatment of Waste Solutions containing Americium. The process flowsheets developed to treat Masurca waste and the solution from recycling of Pu02 scrap are presented in Figure 6. Treatment of the Masurca whste is complex and requires the following steps. 

Figure 3 shows a flowsheet for plutonium processing at Rocky Flats. Impure plutonium metal is sent through a molten salt extraction (MSE) process to remove americium. The purified plutonium metal is sent to the foundry. Plutonium metal that does not meet foundry requirements is processed further, either through an aqueous or electrorefining process. The waste chloride salt from MSE is dissolved then the actinides are precipitated with carbonate and redissolved in 7f1 HN03 and finally, the plutonium is recovered by an anion exchange process. 

After a few years of storage, the main radioactive heat emitters in HLW are 90Sr and 137Cs. In addition, extremely long-lived actinides—neptunium, plutonium, americium, and curium—should be collected for transmutation in the future. Therefore, different flowsheets can be proposed for waste processing. It is possible to extract each radionuclide in the special extraction (sorption) cycle, for example, uranium and plutonium in the PUREX process, and after that, minor actinides (MAs) by the TRUEX process,4 strontium by the SREX process,5,6 and cesium by sorption7 or extraction.8... 

These studies resulted in the proposed solvent extraction recovery process for Am as given in the flowsheet of Figure 14. Solvent clean-up and recycle are included. The Am product stream is to enter the present Am02 production line either before or behind the ion exchange step (Figure 3) depending upon the concentration of Pu in the extracted americium. 

Each of these elements may be used for production of nuclear fuel or other purposes. The recovery efficiency for uranium is reported as 99.87% and for plutonium 99.36%-99.51% (NEA 2012). The extended PUREX includes separation of neptunium and technetium as well as recovery of americium and curium that are also separated from each other by additional extraction stages as given in detail in the flowsheet (NEA 2012). The advanced UREX-i-3 process generates six streams after separation uranium for re-enrichment Pu-U-Np for mixed oxide fuel c for managed disposal Am-Cm to be used as burnable poisons and for transmutation high-heat-generating products (Cs and Sr) and a composite vitrified waste with all other fission products. Some fuel types may require preliminary steps like grinding to enable their dissolution. 

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