Baseline Radionuclide and Nonradionuclide Concentrations in Soils, Vegetation, and Small Mammals at the Proposed Expansion Area at TA-54 Area G

Abstract

Area G is a 25.5-hectare (63-acre), fenced, low-level radioactive solid waste processing and disposal area located on the east end of Mesa del Buey at Technical Area 54 at Los Alamos National Laboratory. This disposal area has been in existence since 1957 and is expected to be filled by the year 2015. Thus, a new area, located adjacent to Area G on the west side, has been proposed for the expansion of disposal activities. Since 1994 to the present, baseline levels of several radionuclides and nonradionuclides have been collected in soils, vegetation, and small mammals (field mice and rock squirrels). These data will be used to assess potential impacts, if any, at the expanded site once operations begin. Baseline statistical reference levels (BSRLs) (mean plus three standard deviations = 99% confidence level) of radionuclides and nonradionuclides in these media were calculated and compared with regional statistical reference levels (RSRLs). RSRLs are calculated from regional areas away from the influence of the Laboratory and represent natural and worldwide fallout sources. BSRLs in most media, with the exception of field mice (mostly Peromyscus spp.), compare very well with RSRLs. Field mice, probably because they are mobile and may have spent time within the active disposal area, appeared to be impacted by Area G operations as they contained higher concentrations of 3 H, 238 Pu, 239,240 Pu, and 241 Am as compared to RSRLs. Overall, however, the preoperational data from the other media show that the proposed expansion area has been impacted very little by Area G operations. ______________________________