抄録
A study was made on the decontamination of F.P. from irradiated UO2 fuel by means of a sorption-desorption process using BaCl2 bed. A very high degree of decontamination was obtained.
Irradiated UO2 pellets were pulverized through a repeated oxidation-reduction process, and then chlorinated with CCl4 vapor at 580°C. The gas containing the vapor of the chlorides formed thereupon was passed through the BaCl2 bed whose temperature varied along its length from 500° to 100°C. The vapor of the chlorides was sorbed on the bed. From this bed, zirconium and niobium chlorides were selectively desorbed by maintaining the bed at between 460° and 480°C in a mixed gas stream of Ar and CC14 vapor. The uranium chlorides, remaining on the bed, were then desorbed by maintaining the bed at 500°C in a mixed gas stream of Ar, Cl2 and CCl4 vapor. Cesium chloride accompanied the uranium chlorides in this process. Cerium and ruthenium chlorides remained undesorbed on the bed after both desorption processes. The vapor of uranium chlorides desorbed was trapped to recover the U. The γ-decontamination factor of the U recovered after 1, 2 and 3 cycles of the sorption-desorption process was of the order of 102, 103 and 104, respectively.
