Transfer of Ruthenium from a Simulated Reprocessing Solution to Gas Phase during a Continuous Distillation
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A continuous evaporation experiment was carried out, in order to verify the ruthenium (Ru) volatilization mechanism, for a simulated high-level liquid waste (HLLW). The feed solution contained 2.65M (10<SUP>3</SUP> mol/m<SUP>3</SUP>) of nitric acid and 0.097M fission product compounds (FPs) including 0.008M RuNO3+. The operation pressure was 12, 700±200 Pa and the operation was continued for 44 h. The total volume of the feed solution was 13.0×10<SUP>-3</SUP>m<SUP>3</SUP> and the volume of the final evaporator solution was 0.90×10<SUP>-3</SUP>m<SUP>3</SUP>. The concentration ratios of elements in distillate to concentrate initially decreased with the evaporator operation. Then the ratios reached plateau for Cs and Ce, with values of about 7×10<SUP>-7</SUP>. The ratio for Ru was 200% of those for Cs and Ce at 15 h after the operation began, and decreased to 110% toward the end of operation. The difference in ratios was quantitatively explained by the formation rate of volatile Ru in simulated HLLW solution taking into account the changes of activity and concentration of nitric acid caused by salting out effect of FPs.
- Journal of Nuclear Science and Technology
Journal of Nuclear Science and Technology 33(10), p.753-757, 1996-10-25
Atomic Energy Society of Japan