Abstract: Faced with the problem of radon exhalation from fractures in soil overburden layer of uranium tailing pond, a simulation experiment of radon exhalation from fractures in soil overburden layer of uranium tailing pond was carried out with a self-made test device, and the effects of different fracture parameters (depth, number and dip angle) on radon exhalation from overburden layer were studied. The results show that the radon exhalation is mainly affected by the pore-fracture migration path, and the radon exhalation rate has a positive linear correlation with the fracture depth. The shortest pore migration distance is shortened with the increase of fracture inclination angle, and the radon exhalation rate for slope angle of 60° increases by 0.164 Bq·m^-2·s^-1 than that of 45°. The pore-fracture path has an influence boundary on radon exhalation on tailing pond surface, and the increase of radon exhalation decreases greatly after the overlap of the fracture affected area. The shortest pore path proportion ζ is introduced, and there is a good correlation between ζ and radon precipitation J. The research results can provide a theoretical reference for radon control of tailing pond surface.

Key words: uranium tailing pond surface, soil overburden layer, prefabricated fracture, pore-fracture migration, radon exhalation rate