| The study of radon release and migration is the basic theoretical issue for radon measurement, which has close relationship with extensive applications in geoscience, environmental science and so on. In this thesis, the laws of the release and migration of radon and its daughters have been studied in laboratory conditions using the accumulative radon-measurement method in a static state with high sensitivity. The mechanism of release and migration of radon and its daughters has been studied by experimentation and theory. According to our experiments we find: The release of radon from uranium mineral is characterized by erratic and spontaneous features and is related to the uranium mineral's category, granularity and so on. Because of the variety of porosity in uranium mineral's interior, the radon and helium, which are brought by the emission of α-particles of radium, cannot flood out of mineral body until they accumulate in mineral's interior and the air pressure goes beyond the limit. This is the inherent cause for the release of radon from uranium mineral characterized by erratic and spontaneous features. The migration of radon and its daughters is directional, and contravenes the law of the diffusion. On the condition that upwardness, downwardness and horizontalness reach respectively 4m, the ability of radon and its daughters to move vertically is much greater than its ability to move horizontally, while its ability to rise is obviously greater than its ability to fall. As far as upwardness, downwardness and horizontalness are concerned, the percentages of migration measurements results for each end point are respectively 66%, 31% and 3%; The average percentages are respectively 54%, 35% and 11%; The percentages of total volume of migration are respectively 54%, 34% and 12%; The migration coefficients are respectively 0.184cm2s-1, 0.094cm2s-1 and 0.015cm2s-1; The migration velocities are respectively 220.4× 10-6cm/s, 181.3×10-6cm/s and 58.3×10-6cm/s. Radon and its daughters possess the ability to rise although the specific gravity of radon and its daughters is high. The mechanism is: after α-particles emitted by radon and its daughters decelerate, they become He nucleus. The He nuclei can combine with radon and its daughters and form clusters. Because He is very light, it can make the specific gravity of the clusters lower than their buoyancy in the medium. As a result, the clusters will rise of their own accord. The mechanism of radon-helium cluster migration is further verified by the difference of quantity of 4He emitted from uranium ore and liquid radium source in the course they release radon. The theoretical distribution equation is established to describe radon migration and the results of calculation with the equation are satisfactory.
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