Performance of alpha spectrometry in the analysis of uranium isotopes in environmental and nuclear materials

The accuracy of alpha spectrometry in the determination of uranium isotopes at various concentrations levels and with various isotope ratios was tested in a round robin international intercomparison exercise. Results of isotope activity/mass and isotope mass ratios obtained by alpha spectrometry were accurate in a wide range of uranium masses and in isotopic ratios typical of depleted, natural, and low enriched uranium samples. Determinations by alpha spectrometry compared very satisfactorily in accuracy with those by mass spectrometry. For example, determination of U isotopes in natural uranium by alpha spectrometry agreed with mass spectrometry determinations at within ±1%. However, the ²³⁶U isotope, particularly if present in activities much lower than ²³⁵U, might not be determined accurately due to overlap in the alpha particle energies of these two uranium isotopes.