65th Radiobioassay & Radiochemical Measurements Conference, Atlanta, GA, October 31 – November 4, 2022
The USTUR has drafted a quality assurance plan that applies MARLAP concepts and processes to measurements made at the USTUR’s laboratory. George Tabatadze and Thomas Rucker (Leidos) gave two presentations to discuss the development of the USTUR’s quality assurance plan, including aspects of the USTUR’s radiochemistry operations that are innovative or unique to the Registries.
Measurement and uncertainty challenges in bringing USTUR’s decades-old radiochemistry program into the 21st century – Part 1
George Tabatadze (USTUR), Daniel J. Strom (USTUR), Thomas L. Rucker (Leidos)
The United States Transuranium and Uranium Registries (USTUR; ustur.wsu.edu) is a U.S. Department of Energy funded research program at the Washington State University that studies deposition, biokinetics, dosimetry, and possible biological effects of actinides such as Pu, Am, and U. Other radionuclides of interest for analysis at the USTUR include Ra, Th, Np, and Cm. The USTUR radiochemical laboratory analyzes human tissues from deceased Registrants who have donated part or all their bodies for postmortem study. This presentation focuses on radiochemical measurements at very low levels by alpha spectrometry.
Plutonium measurements from as early as the 1940s appear in USTUR records. Radiochemical measurements have evolved and improved repeatedly since then, with new measurement technologies and new consensus standards. Understanding and expression of uncertainty have also evolved and improved. This presentation highlights the latest changes to align the USTUR Quality Assurance Program Plan with MARLAP concepts and processes, and also with ANSI ANS N41.5-2012. This talk presents those aspects of USTUR radiochemistry operation that are innovative or unique to the Registries, including implementation of MARLAP’s N+1 counting statistics, measurement quality objectives for tissue analysis, radiochemical measurement process, uncertainty propagation and management, and the unimportance of critical values when the analyte is known to be present. [USUR-0621-22A]
Measurement and uncertainty challenges in bringing USTUR’s decades-old radiochemistry program into the 21st century – Part 2
George Tabatadze (USTUR), Daniel J. Strom (USTUR), Thomas L. Rucker† (Leidos)
The United States Transuranium and Uranium Registries (USTUR; ustur.wsu.edu) is a U.S. Department of Energy funded research program at the Washington State University that studies deposition, biokinetics, dosimetry, and possible biological effects of actinides such as Pu, Am, and U. Other radionuclides of interest for analysis at the USTUR include Ra, Th, Np, and Cm. The USTUR radiochemical laboratory analyzes human tissues from deceased Registrants who have donated part or all their bodies for postmortem study. This presentation focuses on the development of Measurement Quality Objectives (MQOs) for radiochemical measurements based on the Data Quality Objectives identified in Part 1.
This presentation discusses the minimum detectable activity as a function of background, the quantized nature of statistical quantities at low numbers of counts, and minimum quantifiable activity (MQA) and its relationship to the minimal detectable activity (MDA) in routine measurements. The Registries characterizes the radiochemistry counting system using “expected activity on a planchet,” derived from a postulated 74 Bq uptake by the Registrant 50 years prior to counting as a function of isotope, route of intake, and chemical and physical form of the activity taken in. The resultant summary table indicates where there is technology shortfall, followed by a discussion of what, if any, measurement alternatives can be implemented. After determining what we might want in the best of all possible worlds in comparison to what we can logistically and financially achieve, we determined measurement quality objectives, control limits, and tolerance limits. [USTUR-0622-22A] †Presenter