A system for the analysis of urine bioassay samples for
the purpose of inversely investigating an unknown exposure to
uranium has been developed. This technique involves the use of a
thin flow electrochemical cell in conjunction with an anodized
glassy carbon electrode to selectively separate uranium atoms out
of solution for later analysis on an inductively coupled plasma
mass spectrometer. A series of uranium urinalysis bioassay sample
results can be used to investigate the time frame and type of
exposure. This analysis uses an exposure database and regression
analysis to best fit urinalysis uranium excretion data to expected
profiles using commercially available mathematics software. The
least number of data points to determine an acceptable confidence
interval is ten bioassay samples taken at least a week apart. The
system was benchmarked using a random sampling of urinary excretion
samples from a known case at the Y-12 plant in the 1960's. The
electrochemical system was characterized using U.S. Department of
Energy synthetic urine quality assurance standards from an
inter-laboratory exercise in 2012. The separation apparatus was
able to consistently separate uranium from the synthetic urine
solutions with a consistent recovery between ten and fifteen
percent and up to fifty percent. The method is isotope independent
and maintains the enrichment of any excreted material. This allows
for the material to be compared to operational logbooks at
facilities using multiple enrichments in the nuclear fuel cycle.
This methodology is recommended for spot estimation in support of a
traditional bioassay program.
- J. Miller, W. Charlton, and R. Steiner,
"Investigation of Trace Uranium in Biological Matrices,"
INMM 54th Annual Meeting, 14-18 July 2013, Palm Desert, California, USA.
- J. Miller and W. Charlton,
"Measurement of Uranium in Bio Matrices for Nuclear Forensic Purposes,"
Proceedings of the 51st Annual Meeting for the Institute of Nuclear Materials Management, Baltimore, Maryland, July 11-15, 2010. See Document