Assessing field-scale migration of radionuclides at the Nevada Test Site: 'mobile' species
| Autor: | David K. Smith, Mavrik Zavarin, Jean E. Moran, Qinhong Hu, T P Rose, P. Zhao |
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| Rok vydání: | 2008 |
| Předmět: |
Water Pollutants
Radioactive Health Toxicology and Mutagenesis Carbonate minerals Fresh Water Aquifer Tritium Natural (archaeology) Iodine Radioisotopes Water Movements Environmental Chemistry Carbon Radioisotopes Water pollution Waste Management and Disposal Radioisotopes Hydrology geography Radionuclide geography.geographical_feature_category Technetium Radioactive waste General Medicine Pollution Environmental chemistry Chlorine Groundwater Geology Nevada Water well |
| Zdroj: | Journal of Environmental Radioactivity. 99:1617-1630 |
| ISSN: | 0265-931X |
| DOI: | 10.1016/j.jenvrad.2008.06.007 |
| Popis: | Many long-lived radionuclides are present in groundwater at the Nevada Test Site (NTS) as a result of 828 underground nuclear weapons tests conducted between 1951 and 1992. In conjunction with a comprehensive geochemical review of radionuclides (3H, 14C, 36Cl, 99Tc and 129I) that are presumably mobile in the subsurface, we synthesized a body of radionuclide activity data measured from groundwater samples collected at 18 monitoring wells, to qualitatively assess their migration at the NTS over distances of hundreds of meters and over timescales of decades. Tritium and 36Cl showed little evidence of retardation, while the transport of 14C may have been retarded by its isotopic exchange with carbonate minerals in the aquifer. Observed local reducing conditions (either natural or test-induced) will impact the mobility of certain redox-sensitive radionuclides (especially 99Tc) that were otherwise soluble and readily transported under oxidizing conditions. Conversely, strongly oxidizing conditions may impact the mobility of 129I which is mobile under reducing conditions. The effect of iodine speciation on its transport deserves further attention. Indication of delayed transport of some “mobile” radionuclides (especially 99Tc) in the groundwater at the NTS suggested the importance of redox conditions of the natural system in controlling the fate and transport of radionuclides, which has implications in the enhanced performance of the potential Yucca Mountain repository, located adjacent to the NTS, to store high-level nuclear wastes as well as management of radionuclide contamination in legacy nuclear operations facilities. |
| Databáze: | OpenAIRE |
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