Area 11 case study of radionuclide movement by storm channel erosion: A baseline method and initial evaluation

摘要

At the Nevada Test Site (NTS), where radionuclide contamination is found in surface soils, there is potential for water erosion to move radionuclides beyond the boundaries of controlled areas and into channels cut by infrequent storms. This loss of control and the increased risk of further movement are issues which require the development of a method for the quantitative monitoring of contamination and calculation of the radionuclide-movement rate. In this report the authors develop a method which is used to measure the amount and rate of movement of americium-241 ((sup 241)Am) in a storm channel, and which offers special features for establishment of baseline concentrations. This method was applied to the standing problem of the erosion of the plutonium contaminated (open quotes)ground zero(close quotes) area of site (open quotes)11D(close quotes) in Area 11 of NTS. By establishing (sup 241)Am concentrations in the storm channel, the concentrations of (sup 239+240)Pu can also be calculated using a previously determined (sup 239+240)Pu/(sup 241)Am ratio from soil samples collected in Area 11. The method utilizes systematic field surveys with a field instrument for detection of low-energy radiation (FIDLER), and provides a computational method which, when validated, could become a standard procedure for monitoring radionuclide movement in the washes and storm channels throughout the NTS.