Aqueous reprocessing methods, spent

Aqueous reprocessing methods have been developed to effect an efficient and thorough separation of fissile elements from the contaminating fission products in spent fuel( l). While these processes may be altered to yield a proliferations-resistant product by coprocessing or by the addition of radioactive material that will contaminate the clean fissile material, it still is necessary to safeguard some of the process steps to ensure that material useful in nuclear weapons will not be diverted (3). The safeguard requirements and the ease of subversion of such provisions make many versions of the conventional processes subject to unacceptable proliferation risks. 

The pyrochemical coprocessing of spent nuclear fuel by the Salt Transport Process appears to be a potentially viable reprocessing method, not only as an "exportable proliferation resistant technology," but as a domestic reprocessing operation. All operations are nonaqueous and waste generation is in solid form, thus requiring no conversion from aqueous solutions to solids. 

Some part of the spent fuel of atomic reactors is reprocessed separating uranium, plutonium, and the fission products, in order to produce new fissionable fuel or to collect some part of the valuable fission products. While several reprocessing methods have been proposed, the Purex process is the most widely used all over the world. The process uses 30% tributyl phosphate, TBP, as extractant in dodecane or kerosene solvent that is used to decrease the viscosity and the density of the liquid. The mixture is easily separated from water. The spent fuel is dissolved in concentrated nitric acid and the aqueous solution is mixed with the organic extractant. U and Pu present in the aqueous phase in the forms U02 and Pu are extracted to the organic phase, the fission products remain in the aqueous solution. After reduction of Pu by chemical or electrochemical method, Pu goes back to the aqueous phase, while the uranium remains in the organic phase (Benndict et al., 1981 Choppin et al. 1995 Katsumura 2004). 

The use of non-aqueous methods is assumed for reprocessing of spent RBEC-M fuel ... 

In the non-aqueous reprocessing process of spent nuclear fuels by pyrometallurgical and electrowinning methods [1, 2], a spent fuel is dissolved into molten LiCl-KCl or NaCl-CsCI eutectic melt and dissolved uranium and plutonium ions are recovered as metal or oxide. 

Fuel cycle option, basic - Closed fuel cycle (U, TRUs, and some fission products will be recovered from the spent fuel and recycled) an option of on-line refuelling is being considered U-Pu-Zr ternary fuel - For a start-up core, the fresh fuel is composed of recovered LWR transuranics and depleted uranium in subsequent cycles, where the discharged TRU become available for manufacturing new fuel feeds, the fissile make-up of a core load will be based on recycled Pu - Pyro-processing of metallic fuel will be apphed the fuel cycle facilities (fabrication and reprocessing) will be co-located with the reactor at the same site - Closed fuel cycle (U, Pu) - Flexibility in fuel oxide, nitride or metallic fuel options - Non-aqueous methods of fuel reprocessing... 

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