Chemical characteristics of leachate in low-level radioactive waste disposal facilities

摘要

Leachate data from four low-level radioactive waste and mixed waste disposal facilities operated by the U.S. DOE for environmental restoration programs are presented and analyzed. Constituents in the leachates are categorized into four groups: inorganic macrocomponents, metals and metalloids (e.g., Cu, Fe, and Zn), radionuclides, and organic compounds. The leachates are circumneutral (pH from 5.7 to 9.1) and generally oxidizing (redox potential, Eh, ranging from -193 to 344 mV, averaging from 72 to 144.5 mV at each of the four facilities). Ionic strength of the leachate ranges from 2.15 to 135.86 mM. Marcocomponents include Ca~(2+) (0.77-24.90 mM), Mg~(2+) (0.86-30.20 mM), Na~+ (0.19-38.1 mM), K~+ (0.04-1.94 mM), Cl~- (0.33-19.27 mM), SO~(2-) _4 (0.39-29.60 mM), and NO~- _2 or NO~- _3 (0.00021-38.30 mM). Metals and metalloids in the leachates include Al (0.18-87 μM), As (0.033-1.89 μM), Ba (0.16-3.3 μM), Cu (0.0047-5.4 μM), Fe (0.022-43 μM), Li (0.090-139 μM), Mn (0.016-132 μM), Ni (0.010-1.86 μM), Sr (0.92-55 μM), and Zn (0.0082-2.6 μM). Uranium (6.4-3,060 μg=L), ~(99)Tc (0.15-47.9 Bq=L), ~(90)Sr (0.03-12.4 Bq=L), and ~3H (0.74-4,625 Bq=L) are the common radionuclides.