RADON MIGRATION MODEL FOR COVERING U MINE AND ORE PROCESSING TAILINGS

Several radioactive and radiation dose limit values should be kept for the remediation of waste rock piles and tailings ponds of former uranium mining. Using some 1m order of magnitude thick inactive cover on the tailings, the requirements for ambient gamma dose rate and for radioactive aerosol generation are fulfilled automatically. Keeping the limits for radon concentration in air and for radon exhalation rate from soil surface is more difficult task due to the high mobility of radon. Construction of suitable radon barrier on the emission sources (first of all: tailings ponds) is one of the basic points of remediation planning. A radon transport model has been developed to study the cover options and the acceptable versions of the available cover layer materials were experimentally surveyed in practice. In the present state the model deals one-dimensional, stationary and single cover layer situations only. The basic soil-physical parameters are involved into the model and their role in radon exhalation rate is particularly analysed. Both the model calculations and the field experiments supported that the official requirements for radon exhalation rate are fulfilled well in the case of applied versions of cover.