Application of HRGS for forensic characterization of uranium oxides, pure uranium metals and uranium alloys

A nondestructive iterative method for uranium-bearing material characterization with HRGS developed earlier in Burdeinyi et al. (2020) is applied to determine matrix densities, uranium mass fraction and uranium isotope masses of uranium ore, UO₂ and U₃O₈ powders, fuel elements in the form of UO₂ microspheres, uranium metal and uranium alloys. It is shown that U₃O₈ powders with uranium mass fraction of about 84% can be distinguished from the powders of UO₂ with uranium mass fraction of about 87%; uranium products in the form of liquid or loose powder with matrix density of 0.5-2.0g/cm³ can be distinguished from uranium products in the form of compacted fuel elements with matrix density of 6.0-10.0g/cm³ and from pure metal uranium and uranium alloys with matrix density of 14.0-19.0g/cm³. In fuel microspheres based on UO₂ the uranium mass fraction 88.02% measured by HRGS is consistent, within the measurement uncertainties, with the results of isotope dilution mass spectrometry 87.76±0.64% and also is confirmed by X-ray diffraction technique. The uranium mass fraction of the uranium ore estimated as 0.08% by HRGS is consistent, within the measurement uncertainties, with the value 0.09±0.01% determined with WDXRF. Densities of two different uranium metal samples, estimated as 18.42g/cm³ and 19.33g/cm³ by HRGS are consistent with values 18.24±0.55g/cm³ and 18.86±0.59g/cm³, respectively, obtained by the gas pycnometry technique.