Conceptual Site Model - Argonne National Laboratory

WVDP Phase 1 CSAPEnergy Radiation (FIDLER) will be used. A 2 in. × 2 in. NaI detector may also be used toenhance the detectability of Cs-137 at CG w levels, if necessary. To evaluate FIDLER detectorperformance and to determine whether a 2×2 or 3×3 NaI detector is necessary, the following datacollection activities will be performed:• A reference area will be established with a portion (100 m 2 ) used for detector evaluation(see Section 8 for more details). Each gross gamma activity detector used in support ofPhase 1 activities for logged surveys will be evaluated by surveying and logging the datafor this area. Key parameters will include average response of the detector and thevariability in data results observed. Data density will be at least one reading per squaremeter; data will be collected in a manner that results in relatively uniform coverage forthe area.• At least 20 locations will be selected from the WVDP premises for comparative samplecollection. The key characteristics desired for each location are as follows: indications ofelevated surface activity at levels that would likely be near or above CG w requirementsfor Cs-137, an area likely affected primarily by Cs-137 impacts, an absence of any shineconcerns, no surface cover (e.g., pavement, gravel, asphalt, and the like), relative constantgross activity readings over a small area (2 to 3 m 2 ), and an area that will unlikely beimmediately affected by Phase 1 remediation activities. WMAs most likely to have theseconditions are the northern portion of WMA 10, the northern portions of WMA 5, and thewestern portions of WMA 4. Under ideal conditions, the 20 locations would span grossactivity levels ranging from slightly above background through approximately three timesbackground gross activity levels.• Each location selected will be flagged and marked in a manner that allows it to berecovered exactly. Each detector type (e.g., FIDLER, 2×2, 3×3) planned for use as part ofPhase 1 activities will have, at minimum, a static 30-second reading obtained at a heightof 15 cm above the location prior to soil sampling. Detector measurements will not takeplace if soil moisture conditions may adversely affect results (i.e., immediately afterheavy rains or in the presence of saturated or near-saturated surface soil conditions).• After detector measurements have been made, each location will be sampled. Sampleswill be representative of a 0-to 15-cm soil depth.Rev. 1 47