Quantification Study of ²³⁸U in Uranium Oxides

The accurate quantification of ²³⁸U in uranium oxides is of great importance for measurements of fission yield. The study for the method of ²³⁸U quantification has significance to lots of experiments involving absolute measurement of ²³⁸U. The reaction (n, γ) in the triuranium octoxide samples was induced by T(p,n)³He quasi-monoenergetic neutrons provided by the 2.5 MeV proton electrostatic accelerator in Sichuan University. The 277.6 keV characteristic γ ray of ²³⁹Np that comes from β-decay of the activation product ²³⁹U was detected by a HPGe detector. With the known (n, γ) cross section, the mass percentage of ²³⁸U in samples was determined to be 79.1%, with the uncertainty of 6.2%. ICP-MS was also used in the quantification of ²³⁸U in samples, its result was 59.2%. Meanwhile, the samples were analyzed by other several methods and the results showed that less than 2.2% H₂O, no nitrogen, and no other impurity elements above Al were contained in the samples. EPBS was used to measure the atomic ratio of U and O and it was found that the mass percentage of ²³⁸U in samples was about 80%, verifying the result 79.1% of INAA.