An intensive exploration on structure transformation of talc under gamma-ray irradiation at 0-1000 kGy

摘要

To have a clear cognition on whether clay could be used for disposal of high level radioactive waste efficiently or not, in this work, talc was irradiated by Co-60 gamma ray in air at a dose rate of 54 Gy/min with doses up to 1000 kGy. Then, variations in chemical/crystalline structure and intrinsic mechanism were explored. Main results show talc occurred dehydroxylation and lattice shrink. Under 0-1000 kGy irradiation, shrink range in (002) lattice plane was near 1.5% close to 0.14 angstrom. Main mechanisms involve framework/Mg-OH bond break and H2O radiolysis. Framework break seems more important, Mg-OH bond break and H2O radiolysis are secondary. It seems talc exhibits poor stability to radiation. Clay matrix mightn't ensure the effectiveness of disposal project, the effect of nuclear accident to environment can be serious.