Conceptual Site Model - Argonne National Laboratory

Conceptual Site Model - Argonne National Laboratory Conceptual Site Model - Argonne National Laboratory

10.07.2015 Views

WVDP Phase 1 CSAPperformance for the analytical methods that will be used to support Phase 1 decommissioningdata collection activities.Sampling and analysis will proceed as follows:1. The reference area will be divided into ten 200-m 2 areas. Two sets of ten soil sampleswill be collected, with two samples from each 200-m 2 area. One set of samples will berepresentative of soils from the surface to a depth of 15 cm. The second set will berepresentative of soils from 15 cm to a depth of 1 m. Sufficient soil mass will be collectedto allow analysis of all 18 ROIs and the 12 potential ROIs. Each sample will be fieldhomogenized, containerized, and labeled in a manner that clearly identifies the area fromwhich it was taken and the depth profile it represents.2. The resulting 20 samples (10 samples representing a 15 cm surface soil depth and 10samples representing the 15 cm – 1 m surface soil depth) will be submitted for analysis ofall 18 ROI and the 12 radionuclides of potential interest.Four soil cores will be obtained from within the reference area to a depth of at least 1 m into theLavery Till. The locations of the soil cores will be selected so that they are representative of fourquadrants within the reference area. The soil cores will be retrieved in a manner that allowsretrieval of intact cores and down-hole gamma scans by using a suitable detector. Down-holegamma scans will be conducted by taking a 30-second static reading at 15-cm intervals downhole.Data will be recorded in electronic spreadsheets in a fashion that clearly identifies thedetector type and identifier, the location of the core, the depth of the reading, and gross counts incounts per minute. Soil cores will also be scanned ex situ with a suitable detector. As part of thiswork, the soil type will be recorded for the length of the soil core along with soil moistureestimates.8.3 Radionuclide-Specific Background Activity ConcentrationsIn many instances, the CSAP pre-remediation decision-making process described in the attachedappendices requires a determination of whether soil sample results are consistent withbackground conditions or not. The Phase 1 DP provides an analysis of background activityconcentrations for ROIs in Section 4.2.2 and Appendix B based on historical data for surface soilsRev. 1 62

WVDP Phase 1 CSAPand sediments, and based on a combination of historical data and more recent sampling results forsubsurface soils. As part of the analysis, average and maximum results were presented.For CSAP pre-remediation decision-making, background comparisons will be based on resultsfrom the reference area surface soil sampling. The 95% UTL will be estimated for eachradionuclide that could be expected to be present in measurable quantities in background soils(i.e., naturally occurring radionuclides and those anthropogenic radionuclides present inbackground surface soils due to historical fallout) based on the 0- to 15-cm-deep sample resultsand the 15-cm to 1-m-deep sample results. The raw sample results will be used to perform thiscalculation regardless of whether sample results are considered detections or not.Background comparisons will be based on depth (i.e., 15-cm to 1-m-deep samples to 15-cm to 1-m-deep reference area sample results, 15 cm deep samples to 15 cm deep reference area sampleresults). For surface soils, a sample result will be considered inconsistent with background if theactivity concentration of one or more radionuclides exceeds its respective 95% UTL. Forsubsurface soils, the point of comparison will be to 15 cm to 1 m deep reference area sampleresults. The same rule for surface soils will apply for those radionuclides that are naturallyoccurring. In the case of the Pu-239, measurement error is expected to be significant with respectto measurable background activity concentrations. If the application of the rule described aboveresults in an unacceptably high rate of false positive “hits” for Pu-239, the comparison processmay be modified with NYSERDA concurrence to also account for measurement uncertainty.For those radionuclides that are anthropogenic and site-related, a surface or subsurface soilsample result greater than three times its reported uncertainty will be considered inconsistent withbackground conditions.For samples that fail either the 95% UTL or the three-times-uncertainty rule (whichever isapplicable), re-analyses may take place to verify that the observed result is not a product ofanalytical error alone.Sediment sample results will be compared to 15 cm deep surface soil sample results, using thesame protocol as described above for surface soils.Rev. 1 63

WVDP Phase 1 CSAPand sediments, and based on a combination of historical data and more recent sampling results forsubsurface soils. As part of the analysis, average and maximum results were presented.For CSAP pre-remediation decision-making, background comparisons will be based on resultsfrom the reference area surface soil sampling. The 95% UTL will be estimated for eachradionuclide that could be expected to be present in measurable quantities in background soils(i.e., naturally occurring radionuclides and those anthropogenic radionuclides present inbackground surface soils due to historical fallout) based on the 0- to 15-cm-deep sample resultsand the 15-cm to 1-m-deep sample results. The raw sample results will be used to perform thiscalculation regardless of whether sample results are considered detections or not.Background comparisons will be based on depth (i.e., 15-cm to 1-m-deep samples to 15-cm to 1-m-deep reference area sample results, 15 cm deep samples to 15 cm deep reference area sampleresults). For surface soils, a sample result will be considered inconsistent with background if theactivity concentration of one or more radionuclides exceeds its respective 95% UTL. Forsubsurface soils, the point of comparison will be to 15 cm to 1 m deep reference area sampleresults. The same rule for surface soils will apply for those radionuclides that are naturallyoccurring. In the case of the Pu-239, measurement error is expected to be significant with respectto measurable background activity concentrations. If the application of the rule described aboveresults in an unacceptably high rate of false positive “hits” for Pu-239, the comparison processmay be modified with NYSERDA concurrence to also account for measurement uncertainty.For those radionuclides that are anthropogenic and site-related, a surface or subsurface soilsample result greater than three times its reported uncertainty will be considered inconsistent withbackground conditions.For samples that fail either the 95% UTL or the three-times-uncertainty rule (whichever isapplicable), re-analyses may take place to verify that the observed result is not a product ofanalytical error alone.Sediment sample results will be compared to 15 cm deep surface soil sample results, using thesame protocol as described above for surface soils.Rev. 1 63

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