Radioactive Level Survey Of Rare Earth Waste Residues In Jiangsu Province And Preliminary Investigation Of Hazard Reducing Measures

This paper is based on the programme "Research of safe disposal method suitable for low level radioactive residues in Jiangsu rare earth industry", which is sub-topic of "Projiects funded by Jiangsu Provincial Environmental Protection and Scientific Research Fund". The radioactive level of rare earth waste residues produced by rare earth smelting enterprises in Jiangsu Province are investigated deeply based on the programme, and some methods which can reduce environmental hazard are explored.The following conclusions are obtained by sampling, preparing, measuring and analysing of acid-soluble residues and neutralization slags produced by rare earth smelting enterprises in Jiangsu Province:1. Specific activity level of rare earth waste residues is lOBq/g, which is classified as low-level radioactive waste. At present, because specialized sites for rare earth waste residues disposal have not been built in Jiangsu Province, residues are temporary stored by residue repository, partial of which are even outdoor stacked, resulting in different degrees of radioactive contamination.2. Specific activity of nuclides in rare earth waste residues from different companies is different, which is due to the difference of raw materials, production processes and waste management methods.3. Specific activity of both total alpha and total beta in acid-soluble residues is much higher than that in neutralization slags, and specific activity of total alpha in both acid-soluble residues and neutralization slags is much higher than that of total beta.4. y radiation absorbed dose rate level of public areas in these enterprises remain within the natural background level of Jiangsu Province, and the level of superintendent districts is generally higher than that of public areas. This shows that the production environment of these enterprises has different degrees of radioactive contamination.Meanwhile, based on the current management status of rare earth waste residues in Jiangsu Province and the fact that radioactive hazard to the environment is getting worse, some countermeasures and suggestions are put forward:(1) The method of adding a quantity of calcium oxide before stacking or handling acid-soluble residues can reduce specific activity of leachate generated by the natural rainfall or other factors effectively, which has good persistence and economic value.(2) UF resin can adsorb thorium ions in rare earth smelting wastewater, thus reducing the specific activity of rare earth smelting wastewater and neutralization slags, and helping reduce their radiological hazard to the environment.(3) The comprehensive utilization of rare earth waste residues turns waste into treasure, which can not only increase income but also eliminate their hazard to the environment.(4) The competent authorities are recommended to strengthen the construction of the rare earth waste management regulations and standards, to make the exemption and clearance levels of rare earth waste residues clear, to carry out the post-assessment of rare earth smelting enterprises, to construct the provincial disposal sites for rare earth waste residues, to formulate temporary storage and management approach for residues from rare earth smelting enterprises in Jiangsu Province.