Conceptual Site Model - Argonne National Laboratory

WVDP Phase 1 CSAPA.4 Known and Suspected ReleasesA.4.1Cesium ProngPotentially Affected Media:Potentially Affected WMAs:surface soil, subsurface soil, sediments1, 2, 3, 4, 5, 6, 10, 12 NorthIn 1968, a ventilation system filter in the Process Building failed, releasing contaminatedparticulate up the Process Building stack. A mixture of radionuclides was released, with Cs-137predominant. Approximately 0.33 Ci particulate gross beta radioactivity was released. Thecontaminated particulate was deposited on surface soils, resulting in a large area of contaminationaround the Process Building and to the north-northwest. Detectable deposits extend several miles,including beyond the WVDP premises. WMAs 1, 2, 3, 4, 5, 6, 10, and 12 North likely areaffected. Because Cs-137 is predominant, this area of contamination is known as “the cesiumprong” (DOE 2009 Table 2-17, DOE 2010 Section 3.11.5).As originally deposited, surface soil activity concentrations should have decreased towards thenorth, away from WMA 1. However, the surface features of many areas within the WVDPpremises have been reworked significantly since the release; as a result, the current spatial anddepth distribution of soil contamination may be significantly different than the original footprint.In addition, the surface soil contamination likely has been naturally spread by erosion and runoffinto surface drainage features; this phenomenon may have enlarged the area impacted bydeposition, although detailed data regarding this effect are not available (DOE 2010 Section3.11.5).Finally, other releases from the Process Building stack may have produced minor impacts. Theseother releases include the 1968 failure of a dissolver off-gas system filter, resulting in 0.28 Ci ofparticulate activity, and the 1968 failure of a vessel off-gas system filter, resulting in the March1968 releases to exceed the monthly allowance by 15 percent (DOE 2010 Section 3.11.5).Rev. 1 A-4