Electrometallurgical separation

Electrometallurgical separation (also known as pyroprocessing) distills away any volatile elements and leaves behind high-purity fuel material. A typical fuel rod is pictured in Figure 6.17 with indication of active fuel region, bottom reflector, and top plenum. 

The PRISM NFRC uses an established electrometallurgical separations process employed by the aluminum industry for separating aluminum from alumina. This electrometallurgical process has been proven and deployed on a laboratory and engineering scale for nuclear materials by both ANL and Idaho National Laboratory [23]. Separations are accomplished in a molten salt bath that uses an electrical potential in the solution to separate used fuel. The uranium and TRUs plate out on an anode and are subsequently removed from the solution. 

Several processes for the extraction of copper by electrometallurgical methods have been devised. The Marchese patent2 aimed at the decomposition of copper matte and deposition of the copper simultaneously in a sulphuric-acid electrolyte with a copper-matte anode and a copper cathode. In Siemens and Halske s patent3 the copper of the ore was oxidized to the cupric state by an acid solution of ferric sulphate, and the copper deposited electrolytically in a second vessel with a diaphragm separating the cathode and the anode. Neither process has been commercially successful. 

NAS (1994) Management and disposal of excess weapons plutonium. National Academy of Sdences. Committee on International Security and Arms Control, National Academy Press, Washington DC, p 34 NAS (1996) Nudear wastes, technologies for separations and transmutation. National Academy Press NAS (2000) Electrometallurgical techniques for DOE spent fiid — final report. National Academy Press OCED/NEA (1999) Actinide and fission product... 

With the NFRC process, nonproliferation concerns are alleviated by the intrinsic diversion resistance of tihe electrometallurgical process [11,24]. All TRUs (Np, Pu, Am, Cm) are separated en masse in one step of the electrometallurgical process the combined constituents are not usable for military purposes without complex additional processes. These TRUs are continually recycled in the PRISM until they are fissioned completely [25,26], which localizes the material on-site thereby avoiding risks of theft or diversion during transport. 

The electrometallurgical recycle technology does not involve separation of plutonium. The plutonium product is inherently commingled together with minor actinides (i.e. americium, curium, and neptunium), uranium, and fission products. The minor actinides contribute substantial decay heat and contamination with alpha, beta, gamma, and neutron radiation emitters. The fresh fuel product is highly radioactive, which complicates thefts and diversion. 

In electrometallurgy, electrolysis is used to produce metals from their compounds. For example, the Hall process is an electrometallurgical process crucial to aluminum production. The main source of aluminum is bauxite, AI2O3 n H2O. A hydrometallurgi-cal process, the Bayer process, separates bauxite from the irou aud silicon dioxide with which it is usually found. In this process, the bauxite is heated in a concentrated aqueous NaOH solution under high pressure. The aluminum oxide dissolves, leaving the other oxides behind in solid form. 

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