A RADIATION ANNEALING MODEL FOR MAINTENANCE OF CRYSTALLINITY IN SELF-DAMAGED ACTINIDE DIOXIDES

摘要

It is proposed that radiation annealing, an athermal process driven by mechanical and electrostatic instabilities, causes prompt substantial lattice recovery in radiation-damaged actinide dioxides, and thereby assures the stability of the crystal structure, even at high cumulative densities of damage events. Radiation annealing involves the recombination of randomly-occurring closely-spaced interstitial-vacancy pairs. In growth kinetics of defects in self-damaged actinide dioxides are modeled as event-by-event production of local defect zones and simultaneous recovery by radiation annealing and by diffusion of thermally-activated defect species. Comparison with experiments on self-damaged PuO{sub}2, AmO{sub}2 and CmO{sub}2 at ≤ 300 K suggests a damaged region of 3150 ± 700 unit cells per α-decay event and an average critical Frenkel-pair annihilation distance of a cell length.