Conceptual Site Model - Argonne National Laboratory

WVDP Phase 1 CSAPFor field or on-site methods deployed as part of Phase 1 CSAP data collection, the following arethe minimum generic performance verification requirements:• Precision. Precision is a measure of the degree of variability or “error” in a method’sresults. Precision is usually expressed either as a standard deviation or as a relativepercentage error. Precision is typically a function of contaminant concentration. Theprecision of field and on-site laboratory methods will be established for contaminantlevels that are of significance from a decision-making perspective.• Accuracy. Accuracy refers to how close a reported result from a method is to the truevalue. Accurate methods are methods with acceptable precision and an absence of bias.Bias is evaluated by comparing average reported results with known values for repeatedmeasurements of standard reference materials.• Reproducibility. Reproducible results refer to results that can be replicated, typicallywithin a specified percentage of the original value. Acceptable percentages aretechnology/application-specific. In the case of detectors, reproducibility is demonstratedby replicate measurements. For analytical methods, reproducibility is demonstrated bysplit sample analyses.• Completeness. Completeness is a measure of how often data are rejected or lost due tomethod problems and/or data quality issues. Methods must be shown to produce useable(i.e., satisfying data quality requirements) data sets at least 80% of the time.Method performance can also be evaluated by the level of decision-making error associated witha method’s data sets. For example, if the decision was whether contamination was present orabsent at a location, errors would include falsely identifying contamination when it was notpresent at levels of concern or missing contamination when, in fact, it was present at levels ofconcern.6.11.1 NaI Gamma Walkover Survey Detector PerformanceThere are a variety of NaI detector geometries that can potentially be used for GWS. Because oflow-energy gamma emitting radionuclides that are ROI, a Field Instrument for Detection of LowRev. 1 46