Self‐Irradiation Damage of a Curium‐Doped Titanate Ceramic Containing Sodium‐Rich High‐Level Nuclear Waste

The polyphase titanate ceramic containing sodium‐rich simulated high‐level nuclear waste was doped with 0.69 wt% of ²⁴⁴Cm to accelerate long‐term self‐irradiation due to α decays. α autoradiography showed that α emissions were almost uniformaly distributed throughout the curium‐doped samples on a >20‐μm scale although micropore surfaces and titanium oxide agglomerates were free of α‐emitting nuclides. The phase assemblage of the curium‐doped titanate ceramic included freudenbergite and loveringite in addition to the more abundant oxide phases: hollandite, perovskite, and zirconolite. Accumulation of α decays was accompanied by a gradual decrease in density. The increment of density was – 1% after an equivalent age of 5000 yr. Leach tests showed a slight trend toward higher total release of curium with equivalent age. The release of soluble nonradioactive elements (e.g., Na, Cs, Sr, and Ca) in the oldest specimens (equivalent age, 2000 yr) varied from specimen to specimen but, on average, were higher than specimens that had suffered a lower radiation dose.