Conceptual Site Model - Argonne National Laboratory

WVDP Phase 1 CSAPany stack monitoring alarms. The release was discovered during routine radiation surveysconducted in November 2001 when workers found fixed radioactivity in unexpected locationsnear the Process Building stack. Total releases were less than 0.5% of the administrative releaselimits. Measurements of 4.8E-04 uCi gross beta were recorded. The fallout was confined to thearea several hundred feet from the Process Building, in WMA 1 and WMA 3. Accessible abovebackgroundspots were decontaminated (DOE 2009 Table 2-18; DOE 2010 Section 3.11.5).A.5 Existing DataExisting data sets for this area include:• In 1982, static direct exposure readings were collected across the WVDP premises(WVNSCO 1982). A portion of WMA 1 was covered by these measurements on a 10-mgrid. Figure A.12 shows these results color-coded by the exposure readings encountered.These data indicated the potential for significant surface contamination within the WMA1 boundary; their interpretation, however, is complicated by potential shine from theProcess Building.• In 1990 and 1991, a second static direct exposure measurement program was conductedacross the WVDP premises, including the accessible portions of WMA 1(WVNSCO 1992). This data collection used different instrumentation and protocols thanthe 1982 study, so the results are not quantitatively comparable. Figure A.13 shows theseresults. These data show a significant change for the western and southern portions ofWMA 1, with significantly lower measured gross activity than the 1982 study. There area couple of possible explanations for the decrease: (1) this could reflect the removal ofcontaminated surface soil associated with maintenance and construction activities aroundWMA 1; or (2) it could reflect the placement of surface material (e.g., gravel orpavement) on top of contaminated soils; or (3) it could be that the 1982 readings wereaffected by shine from Process Building and associated structures whose sources weremitigated by decommissioning activities in the intervening years.• There is some soil sampling data for WMA 1 available within ELIMS. Figure A.14shows the locations of soil cores with subsurface soil samples. There are no sediment orsurface soil results for WMA 1. The bulk of the data were collected either in 1993, 1994,Rev. 1 A-9