Isotope ratios determination of uranium in soil samples affected due to Chernobyl accident using thermal ionisation mass spectrometer

Abstract

A rapid and highly precise method was developed for the separation of uranium from soil samples for thermal ionisation mass spectrometry. The chemical separation procedure is based on the use of anion exchange resin and UTEVA extraction chromatography column. The isotope ratios of uranium, 234 U/ 238 U, 235 U/ 238 U and 236 U/ 238 U were measured by using a VG Sector 54 TIMS equipped with a Wide Aperture Retardation Potential (WARP) energy filter with a precision of better than 0.2% at two standard deviations (sd). The use of a WARP energy filter improves abundance sensitivity by an order of magnitude over a conventional VG Sector TIMS. Replicates of standard reference materials showed excellent analytical agreement with established values, supporting the reliability and accuracy of the method. Uranium isotopic compositions have been determined in soil samples in the exclusion zone of Chernobyl nuclear power plant. The isotopic composition of Chernobyl soil samples showed significant deviation from the natural uranium and the 236 U/ 238 U ratio varied from 105 to 10 4.