Use of the 1001 keV peak of 234mPa daughter of 238U in measurement of uranium concentration by HPGe gamma-ray spectrometry

For the direct gamma-ray spectrometric measurements of uranium concentrations in the samples, the use of 1001 keV peak of 234mPa, second daughter of 238U is emphasized. This “clean” peak is well resolved by HPGe detectors and gives accurate indication of uranium concentration in the samples without any self-absorption correction. The 1001 keV peak of 234mPa in the 238U chain is selected because it does not include any contribution from any other gamma emissions and does not have any interference with other peaks in the high-energy region even if the samples contain high amounts of thorium. The activity of 234mPa is determined by calibrating a HpGe detector with uranium standards. The measurement of 1001 keV gamma-ray emission from 234mPa by high-resolution gamma-ray spectrometry provides the basis for a reliable determination of 238U in the samples. The results obtained from the 63.3 keV peak of 234Th and those of the 1001 keV peak from 234mPa in the 238U chain for the uranium standards are compared with the certified values of the same samples. The results obtained from the measurements of 1001 keV peak from 234mPa agreed to within 2–5% with the certified activity values of 238U in the samples with uranium content ranging from 0.014 to 1.02 wt%. The results indicate that the uranium concentrations in the samples can be determined to within 5% error by about 14 h counting in a HpGe detector system.