Conceptual Site Model - Argonne National Laboratory

WVDP Phase 1 CSAPthe lower bound of the gray region (LBGR) and variability observed. If contamination above thecleanup standards is found in the sloped soil walls of the excavation in WMA 1, the impermeablesheet piling will limit the extent to which this contamination can be pursued laterally.In the case of WMA 1, approximately 476 foundation pilings will be present that extend into thetill (and in some cases through the till). According to the Phase 1 DP, these pilings will be cut justbelow the final excavation surface. If scans identify elevated activity of potential CG exceedancesin the till material adjacent to the pilings, excavation will continue until CG exceedance concernsare no longer present. Biased soil samples with rapid Sr-90 turnaround results may be used tofurther interpret scan readings for these piles. Remedial action surveys combined with quickturnaroundSr-90 sample results will be used to segregate pilings into two groups: those thatclearly have contamination present in soils above them and those that do not. These groupingswill be used to implement Phase 1 FSS data collection protocols as described in the FSSP.7.2 HLW Transfer Trench Contamination StatusThe planned Phase 1 decommissioning activities in WMA 3 will remove the HLW transfer linesand leave behind the concrete HLW transfer trench. The assumption is that the exterior of thetrench has not been affected. Remedial action surveys will be conducted inside the empty HLWtransfer trench to establish the radiological status of the trench after removal of the transfer line.The trench is approximately 500 ft long, 6 to 20 ft wide, with a height of 6 to 9 ft.Before data collection is initiated within the trench, radiological safety surveys conducted duringthe removal of the transfer lines will be reviewed to determine whether there is any immediateevidence of elevated areas.Data collection for the trench will include two types of scans: one using an appropriately shieldedNaI detector to evaluate the potential for volumetric contamination within the concrete, and theother with a zinc sulfide (ZnS) scintillation or gas proportional detector to evaluate for thepresence of surface beta contamination. In the case of an NaI detector, shielding may be requiredto limit the field of view of the detector to the area of concrete of interest and to mitigate potentialshine effects from other portions of the trench. In both cases, surveys will be conducted toprovide 100% coverage of the trench floor and 25% coverage of the trench sides. If appropriatecoordinate/measurement logging systems are combined with the detectors, digitally recordedRev. 1 57