Isotopic ratios of uranium on uranium salts and pitchblende Urban, David

An investigation was conducted to ascertain if high resolution alpha spectrometry could be used to effectively determine the isotopic ratios (²³⁴U/²³⁸U and ²³⁵U/²³⁸U) of a group of uranium salt samples. The aim of this characterisation was to use the ratios as a means of discriminating between these samples. A sample of pitchblende was analysed and used for quality control purposes. The determined uranium mass percentages and ratios in the pitchblende sample were in agreement, within experimental uncertainty, with published values. However, it was found that the experimental uncertainty for ²³⁵U was significantly higher than that for ²³⁴U and ²³⁸U. The pitchblende sample could be easily discriminated from the salt samples by using both the ²³⁴U/²³⁸U and ²³⁵U/²³⁸U ratios. When attempting to distinguish between the salt samples, the ²³⁴U/²³⁸U ratio was more reliable than the ²³⁵U/²³⁸U ratio. This was because the difference between salt samples for the ²³⁵U/²³⁸U ratio was not sufficiently large enough to overcome the higher experimental uncertainty. Statistical analysis showed that there was no difference between the ratios within some of the salt samples so discrimination was not possible. During the course of the pitchblende analysis, different digestion procedures were evaluated in order to determine the best recovery of the uranium within the ore. It was found that microwave digestion techniques were successful in attaining near to or total recovery of the uranium within the ore and would be the most appropriate method of quantitative analysis.