Year
2011
Abstract
To support the demonstration of a more proliferation-resistant fuel processing plant, techniques and instrumentation to allow the real-time, online determination of special nuclear material concentrations in-process must be developed. The primary goal of this project is to understand fundamental UREX and PUREX reprocessing chemistry and corresponding UV-Visible spectroscopy for application in process monitoring for safeguards. Due to the impact of process chemistry on the molar absorbtivity of uranium, the potential application of UV-Visible spectroscopy as an online technique for materials accountability must be examined separately for every set of conditions. An ideal materials accountability technique for proliferation resistance should be able to provide real-time, on-line measurements of the actinide elements in the process streams at a separations facility. UV-Visible spectroscopy can be adapted for this precise purpose - materials accountability and process monitoring, even in high radiation fields. The secondary goal of the project is to simulate a diversion scenario in UREX (a change to PUREX conditions) and successfully detect changes in metal concentration and solution chemistry in a counter current contactor system with a UV-Visible spectroscopic process monitor. UREX uses the same basic solvent extraction flowsheet as PUREX, but has a lower acid concentration throughout and adds a complexant/reductant (AHA) to the feed solution to prevent the extraction of plutonium. By examining a full spectrum, the objective is to detect the conversion of a recycling plant from the UREX process, which does not separate plutonium, to the PUREX process, which yields a purified plutonium product. The change in process chemistry can detected in the feed solution, aqueous product or in the raffinate stream by identifying the acid concentration, plutonium distribution and the presence or absence of AHA. This milestone is a demonstration of the potential of this technique, which lies in the ability to simultaneously and directly monitor the chemical process conditions in the plan, providing inspectors with another tool to detect nuclear material diversion attempts.