Doctoral Dissertations

Norman Bores

Date of Award

5-1999

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Chemistry

Major Professor

J. R. Peterson

Committee Members

M. J. Sepaniak, J. L. Adcock, C. D. Cox

Abstract

Radiobioassay laboratories analyze urine samples from personnel at nuclear facilities to ensure that no accidental intakes/uptakes have occurred and to provide radiation dose estimates in the event of an emergency. Quality control programs have, until this study, consisted of the analyses of test samples created within the facility itself or have been recognized test samples in a synthetic urine matrix from an external organization.The Intercomparison Studies Program at the Oak Ridge National Laboratory Is the first and largest International provider of radiobioassay quality control samples in a natural urine matrix on a monthly basis.This dissertation presents the results of radiobioassay intercomparison studies of selected alpha emitters (natural U, PU-238, Pu-239, and Am-241) that have been in progress over a period of six years. Because the laboratories involved in the study were unaware, in many cases, of the presence of test samples, this study gives a more accurate representation of the state of day-to-day operations in the participating radiobioassay facilities.It has been discovered that several participating laboratories have significantly improved over the course of this study. Increases in accuracy, as well as decreases in the number of severely biased samples, have been observed.It is shown that the analysis of natural uranium in urine by participating laboratories using Kinetic Phosphorescence Analysis (KPA) contains a significant source of negative bias, most likely the result of inhomogeneous sampling. The Analysis of Am-241 seems to contain a greater source of negative bias than that of the other actinide nuclides studied, possibly the result of spectral overlap of Am-243and Am-241.This work has shown, for the first time, that many radiobioassay laboratories intermittently produce results that are consistent with switching a routine (blank)sample with a QA/QC (non-blank) sample. The radiobioassay community is now realizing that this is possible, and that CWQC samples may be incorporated into the process at any time.This work describes a method of data treatment which gives participating laboratories an estimate of their analytical accuracy, while removing the effects of the so-called outliers. The outlier-free results appear reasonably Gaussian,indicating that the underlying processes are sound, although marred by severe,intermittent biases.

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