Coulometry for the determination of uranium and plutonium: past and present

Precise and accurate determination of uranium (U) and plutonium (Pu) in nuclear fuels is an essential requirement in nuclear fuel cycle for chemical quality assurance of these materials. The redox based electroanalytical methods viz. Potentiometry and Biamperometry are capable of meeting the requirements of high accuracy and precision using milligram amounts of the analyte. However, use of chemical reagents to perform redox reactions in these methods, generates radioactive liquid waste which needs to be processed to recover plutonium. The analytical waste generated by the controlled-potential coulometric (CPC) method is clean as the change in the oxidation state of the analyte is done by the electrolytic reaction. Therefore, the determination of U and Pu in nuclear fuel materials by controlled-potential coulometry is an attractive option instead of biamperometry and potentiometry. In this report, the work carried out to develop CPC employing indigenous coulometers is discussed. The coulometric results for both U and Pu using indigenous coulometers agreed within ± 0.2% with the biamperometric values. The results indicate that indigenous coulometers are suitable for U and Pu determination in nuclear fuel materials and the CPC method can be employed for nuclear fuel samples. (author)