662. ゼオライトによる放射性廃液の処理,(IV)

ゼオライトの高温焼成時におけるCsの揮発

抄録

Volatilization of Cs from Zeolites at High Temperature By Hitoshi MIMURA and Takuji KANNO Volatilization of Cs from Cs type zeolites and calcined zeolites were studied at high temperature. Synthetic zeolites A, X, Y, synthetic mordenite (Zeolon), natural mordenite and clinoptilolite saturated with Cs were used in this study.
Volatilized Cs from CsX was largest in quantity and from Cs type natural zedlites smallest. Volatilization of Cs was observed at about 800°C and increased as the calcining temperature rose. Volatilized Cs from CsA was smallest in synthetic zeolites. CsA recryStallized to nepheline and pollucite with the ratio of about 1:1 above 1, 000°C and it seemed that the volatilization of Cs from pollucite was suppressde with the nepheline phase surrounded them.
The rate of volatilization was very fast within the initial 10min and very slow after 60min except for CsX. This behavior suggested that the rate was very fast before structural transformation.
The mean volatilization rate of Cs in 3hr from calcined CsX (pollucite) was 1.1×10^-4mg/cmcm²·min and the others were 10^-5-10^-6mg/cmcm²·min. The amount of volatilized Cs in Ar flow was decreased 20-90% of that in air flow. Volatilized species was identified with Cs₂O by mass spectrometry.