FIXATION OF ACTINIDE ELEMENTS INTO ZEOLITES ZEOTYPES AND FLEXCRETE-CEMENT MATRIX

The leaching behavior of alpha-emitter radionuclides (uranium and americium) from zeolite-L and the zeotype (SAPO-34) in a Flexcrete-cement matrix were examined by static and dynamic methods using 0.005 M CaCl2 and synthetic ground water as leachants. The leaching rates of UO22+ were found to be higher by about ten orders of magnitude than those of Am3+ for both zeolite-L and SAPO-34 in the cement matrix. The static and dynamic leaching rates of UO22+ for SAPO-34 in CaCl2 and synthetic ground water were ten orders of magnitude lower than those for L. SAPO-34 showed good selectivity for uranium at pH 2-3.5 and L was usefully selective for Am3+. Distribution coefficients of Am3+ and UO22+ increased with equilibrium pH.