Ceramic Matrix Composites Based on Lanthanum Orthophosphate for Disposal of High-Level Radioactive Waste

摘要

Ceramic matrix composites for solidification and disposal of actinide-rare-earth fraction of high-level waste (HLW) were prepared by sintering of nanosized powders of 0.8LaPO(4)-0.2Al(2)O(3), 0.8LaPO(4)-0.2Y(2)O(3) and 0.8LaPO(4)-0.2ZrO(2) obtained from 0.8LaPO(4) center dot nH(2)O-0.2Al(OH)(3), 0.8LaPO(4) center dot nH(2)O-0.2Y(OH)(3) and 0.8L-aPO(4) center dot nH(2)O-0.2ZrO(OH)(2) precursors. These powders-precursors were synthesized via sol-gel technique. After heat treatment at 850 degrees C powders of 0.8LaPO(4)-0.2Al(2)O(3), 0.8LaPO(4)-0.2Y(2)O(3) and 0.8LaPO(4)-0.2ZrO(2) were obtained. Further powdered compositions were stepwise sintered to prepare ceramic composites which were supposed to be used as matrices for storage of HLW. Rate of La3+, Al3+, Y3+ and Zr4+ leaching from ceramic matrix composites in strength aqueous solutions of NaCl and Na2SO4 simulating underground brine typical for proposed location of HLW geological repository was estimated.