Radioanalytical Detection Status in Environmental Samples

Data Quality, Management, and Review
Oral Presentation

Presented by C. White
Prepared by S. Sandborgh1, P. Mark2, R. Cowan2, S. Marczak3, J. Garrett1, J. Patureau1
1 - N3B-Los Alamos, 1200 Trinity Drive, Suite 150, Los Alamos, NM, 87544, United States
2 - Adelante Consulting, Inc., 3483 Corrales Road, Corrales, NM, 87048, United States
3 - Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM, 87545, United States

Contact Information: [email protected]; 505-309-1178


Radionuclide detection status is an important factor when determining the success of environmental remediation efforts. To determine if a radionuclide has actually been detected, the common practice at the Department of Energy’s (DOE’s) legacy cleanup sites has been to use the minimum detectable concentration (MDC) as the decision point for determining the detection status of a radionuclide. This practice does not align with guidance found in the Multi-Agency Radiological Laboratory Analytical Protocols (MARLAP) Manual and American National Standards Institute (ANSI) 41-5, Verification and Validation of Radiological Data for Use in Waste Management and Environmental Remediation. Both of these documents recommend using the critical level (Lc) to determine the detection status of a radionuclide.

As remediation work has commenced under the Los Alamos Legacy Cleanup Contract (LLCC), the Sample and Data Management (SDM) team at Newport News Nuclear BWXT-Los Alamos, LLC (N3B) has reassessed the historical use of the MDC as the decision point for radionuclide detection status. The objective is to align N3B practices with the guidance documents, and provide transparency in the evaluation of low-level radiological data. Through the analysis of radiological data down to the Lc, the risk of a false negative result is reduced significantly.

The N3B SDM team created a hybrid approach that incorporated both ANSI and MARLAP guidance, as well as the LLCC site historical use of the MDC. In this hybrid approach, data that are in the range of Lc and MDC are assigned validation qualifiers and reason codes that alert the end user to the possibility of low levels of radioactivity below the MDC, which historically is considered a non-detect at LANL. Although still a non-detect, flagging allows for easy data trending to determine if there is the potential for widespread low-level activity that may have previously been overlooked.