Candidate materials for actinide immobilization are subject to alpha-decay event doses that accumulate to values of more than 1020 alpha-decays per gram (tens displacements per atom, dpa) over the extended periods of geologic disposal. To evaluate the radiation-response of actinide-bearing materials, two experimental techniques have been used to accelerate the damage accumulation process: ion-beam irradiations and 244Cm-doping experiments. Based on modern characterization techniques, such as high-resolution transmission electron microscopy, and experimental results that involve ion-beam irradiation and chemical doping with highly active actinides, crystalline ceramics for the immobilization of actinides can be divided into three groups on the basis of their critical doses, D
c, i.e., the dose required for amorphization at 300 K: (i) low resistance to radiation damage accumulation (D
c ∼ 0.2 dpa) – murataite, Ti-perovskite, Fe-garnet; (ii) resistant (0.4 < D
c < 0.6 dpa) – Al-garnet, Ti–Zr-pyrochlore, Al-perovskite; and (iii) highly resistant (D
c > 0.8 dpa) – Zr-, Zr–Ti-, and Sn-pyrochlores. Phases with low critical temperatures (T
c below 600 K) will not become amorphous in a deep geologic repository, as long as the temperature remains between 300 and 550 K, but rather, they will remain crystalline. Only Zr-rich pyrochlore is fully resistant to radiation damage and will remain crystalline over the entire period of its disposal.