Accurate quantification of high-purity uranium in coatings by small solid angle method

Aiming at quantifying high-purity uranium (²³⁵U/²³⁶U/²³⁸U) in coatings, a series of experiments were carried out by a dedicated small solid angle device. The physical design of the device and the small solid angle method were here in described, focus in particular on the analysis of detection efficiency, the effect of the isotope impurity in the coatings and the correction for the non-uniform distribution of the uranium samples. The results show that the weight of ²³⁵U in the coatings is 5.2-5.6 mg, while 4.7-5.0 mg for ²³⁸U and 2.2 mg for ²³⁶U in the corresponding coatings, with relative experimental uncertainties of 1.0%--1.2%.