Fabrication of CeO2 ceramic spheres as a surrogate of nuclear fuel by an improved microwave-assisted rapid internal gelation process

Abstract

CeO2 is a surrogate of PuO2 in nuclear fuel development. Uniform sized ceramic CeO2 spheres were fabricated by an improved internal gelation process which combined the in-situ instant mixing of room-temperature precursor solutions with microwave-assisted internal gelation. Chemical kinetics investigations showed that the gelation process sped up as the [HMTA]/[Ce4+] ratio, [OH-]/[Ce4+] ratio and temperature increased. However, to avoid cracking during the sintering process, the [HMTA]/[Ce4+] ratio should be limited at low value while [OH-]/[Ce4+] ratio should be sufficiently high. Besides, pressured water treatment was adopted to wipe off impurities in the gelled spheres before sintering. The microstructure and morphology of the prepared ceramic CeO2 spheres were also investigated. The improved microwave-assisted internal gelation process greatly simplifies the conventional sol-gel process and avoids secondary organic radioactive waste. It will be a potential method for the fabrication of MAs and Pu-containing ceramic nuclear fuel spheres in glove-box in future.