Performance Evaluation of Natural Radioactivity of Mine Wastes Using Various Shielding System

Abstract

The objective of this study is to evaluate covering system for natural radioactivity in mine wastes from the Boeun(jeil) mine underlain by the Okcheon black shale using various radiation shielding materials including bentonite, lime(pozzolan), steel slag, thickness of covering materials and particle size of the materials. Concentrations of uranium in the wastes were 174.8 mg/kg, and the average natural radioactivity of the wastes was 15.5 mSv/year. A large scaled in situ column system with 0.3 m 3 in volume was adapted. In the column, a 80 kg of the mine waste and a 0.6 m thickness of various covering materials were filled. Among the shielding materials, a column shielded with bentonite reduced up to 80% of natural radioactivity. In addition, the radioactivities were decreased with increasing thickness of covering materials irrespective of particle size and compaction ratio of the materials. Therefore, natural radioactivity from mine waste can be controlled by covering system with over 0.6 m thickness of covering materials, particularly the efficiency of the covering system filled with mixture of gravels and covering materials will be enhanced.