Radon concentration and radiation hazard of a rare earth waste dump in China
The 222Rn activity concentration and air absorbed dose rate of a rare earth waste slag heap in China were measured by radon and air absorbed dose rate instruments. A total of 34 monitoring points including waste residue heaps were selected. The 222Rn activity concentration and absorbed dose rate measurement ranges are 51.0-246.9 Bq/m3 and 0.071-0.110 μGy/h. Other radiation hazard indicators: outdoor annual effective dose (Eout), annual effective dose from radon (Eradon)), excess lifetime cancer risk for outdoor (ELCRout), excess lifetime cancer risk for radon (ELCRradon), and excess lifetime cancer risk for total (ELCRtot) were calculated. They were 0.087-0.135 mSv/y, 0.409-1.640 mSv/y, 0.305-0.472×10-3, 1.577-6.314×10-3, and 1.959-6.787×10-3. The results show that the radiation hazard indicators at all monitoring sites were within the international level. The annual effective dose at 33 monitoring sites in the human activity areas was lower than 1 mSv/y recommended by ICRP for public exposure. Data obtained in this study can be used to treat waste residue heaps and develop and utilize surrounding areas.