Release Characteristics of Ruthenium from Highly Active Liquid Waste in Drying Step

Abstract

The release characteristics of Ru from highly active liquid waste （ HALW ） have been investigated under the condition of accidental evaporation to dryness by boiling of HALW. Using a laboratory-scale apparatus, the simulated HALW （ s - HALW ） was heated with an external heater to dryness to observe the release characteristics of Ru and gaseous nitrogen oxides. As a result, Ru was significantly released between 120 and 300 ℃ of the s - HALW. The cumulative release ratio of Ru was 0.088. It was also found that the partially released amount of Ru against the temperature of the s - HALW had two peaks at about 140 ℃ and about 240 ℃ . Referring to the results of the release rate of gaseous nitrogen oxides and the volume of condensate, which was a collection of the mixed vapors of steam and nitric acid released from the s - HALW, we discussed the causes of Ru release around these peaks.