Fabrication of radioactive and non-radioactive titanate and zirconate ceramics for immobilization of used nuclear fuel

•Titanate and zirconate ceramics may immobilize a whole used nuclear fuel assembly.•Radioactive (U and U/Pu) and non-radioactive ceramics (Ce and Gd) were fabricated.•Titanate phases included perovskite, rutile, zirconolite, pyrochlore, and fluorite.•Zirconate phases included pyrochlore, fluorite, apatite, and perovskite.•Overall, non-radioactive ceramics were more consolidated than radioactive ceramics.