Voloxidation

Tritium differs from the noble gases. Tritium is very reactive and readily combines to form water. The voloxidation process, which controls the point at which the oxidation occurs and recovers the resulting tritiated water, has been developed. As of this writing it has not yet been used. 

Voloxidation A process for removing volatile fission products and tritium from irradiated nuclear fuel in advance of other processing. Being developed from 2004 at the Argonne National Laboratory. 

The behavior of volatile fission products is largely unknown. Brief literature references to iodine and ruthenium are contradictory. It is likely that elemental iodine is the stable species in the melt (16 ), and that some will be volatilized. Possible process modifications to guarantee a unique path for ruthenium have not been considered. The rare gases should escape because of the elevated temperature crystal modification. However, experience with the voloxidation process suggests that this release may not be complete. The behavior of both Kr-85 and tritium must thus be investigated. 

Although promising data have been acquired for the fluoride volatility process, the technical feasibility has not been demonstrated yet. Aside from chemical problems, many technological problems such as process stability due to powder handling and remote maintenance, are still remained unsolved. In order to solve these problems, head-end process studies as voloxidation have been started. Here, stress is put on the environmental protection of... 

In preparation for dissolution, step 1, cladding is opened to permit subsequent dissolution of the oxide fuel. For steel or zircaloy this is done by mechanical shearing or sawing. Off-gases from decladding contain up to 10 percent of the radiokrypton and xenon in the fuel and some of the 002," tritium, and other volatile fission products. If voloxidation (Sec. 4.3) is used after decladding to remove tritium, more of the other volatile radionuclides will then be evolved also. 

In voloxidation, stainless steel-clad UO2 is oxidized with flowing air or oxygen at 575 to 650°C. With zircaloy-clad fuel, these gases may be unsafe because of the danger of a zirconium fire. Less reactive N2O4 has been proposed as an oxidant for such fuel. 

Voloxidation of mixed U02-Pu0j fuel of high PUO2 content... 

Another approach is a suitable head-end process in the reprocessing plant, such as voloxidation (Chap. 10, Sec. 4.3). However, such a head-end process is not yet available technology but requires several more years of development. 

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