USE OF THE 1001 KEV PEAK OF PA-234M DAUGHTER OF U-238 IN MEASUREMENT OF URANIUM CONCENTRATION BY HPGE GAMMA-RAY SPECTROMETRY

For the direct gamma-ray spectrometric measurements of uranium concent rations in the samples, the use of 1001 keV peak of Pa-234m, second da ughter of U-238 is emphasized. This ''clean'' peak is well resolved bg HPGe detectors and gives accurate indication of uranium concentration in the samples without any self-absorption correction. The 1001 keV p eak of Pa-234m the U-238 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 s amples contain high amounts of thorium. The activity of Pa-234m is det ermined by calibrating a HpGe detector with uranium standards. The mea surement of 1001 keV gamma-ray emission from Pa-234m by high-resolutio n gamma-ray spectrometry provides the basis for a reliable determinati on of U-238 in the samples. The results obtained from the 63.3 keV pea k of Th-234 and those of the 1001 keV peak from Pa-234m in the U-238 c hain for the uranium standards are compared with the certified values of the same samples. The results obtained from the measurements of 100 1 keV peak from Pa-234m agreed to within 2-5% with the certified activ ity values of U-238 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 cou nting in a HpGe detector system. (C) 1998 Elsevier Science B.V. All ri ghts reserved.