Use Of Controlled Potential Coulometry System For Plutonium Analysis At The IAEA Nuclear Material Laboratory

Controlled Potential Coulometry (CPC) is routinely used by the International Atomic Energy Agency’s Nuclear Material Laboratory (NML) to validate Plutonium in-house controls and Plutonium pure solutions used to prepare mixed U-Pu large-sized dried (LSD) spikes. However, CPC often requires costly and expensive maintenance as well as being particularly sensitive to interferences from certain elements. As such, many laboratories have opted for alternative methodologies (such as the Isotopic Dilution Mass Spectrometry method) for Pu amount content determination, and today there are only a few laboratories having the expertise, instrumentation and software operational for CPC method. With the aim of promoting the advantages of CPC as a primary analytical method, investigations were conducted with the IAEA Network Analytical Laboratories (NWAL) to study the potential of extending the application of CPC for the analysis of Pu content to samples of smaller size and more complex composition. Pu samples were prepared by the IAEA/NML and analysed by laboratories in France and the USA. The results confirmed that, with an adequate sample preparation protocol, CPC is applicable to small size samples. Furthermore, tests conducted by the IAEA/NML confirmed that CPC is applicable to synthetic samples containing U and Pu at a low molar U, Pu ratio but cannot be directly used for inspection samples without proper bias correction from Uranium and Iron interferences.