PNNL

Abstract

There is a renewed interest worldwide to promote the use of nuclear power. The long term successful use of nuclear power is critically dependent upon adequate and safe processing and disposition of the spent nuclear fuel. Liquid-liquid extraction is a separation technique commonly employed for the processing of the dissolved spent nuclear fuel. Our approach is based on the prerequisite that real time monitoring of the solvent extraction flowsheets provides unique capability to quickly detect unwanted manipulations with fissile isotopes present in the radiochemical streams during reprocessing activities. Our ability to identify material intentionally diverted from a liquid-liquid solvent extraction contactor system was successfully tested using on-line process monitoring. A chemical diversion and detection from a solvent extraction scheme was demonstrated using a centrifugal contactor system operating with the simulant PUREX extraction system of Nd(NO3)3/nitric acid aqueous phase and TBP/dodecane organic phase. A portion of the feed from a counter-current extraction system was diverted while a continuous extraction experiment was underway; the spectroscopic on-line process monitoring system was simultaneously measuring the feed, raffinate and organic products streams. The amount observed to be diverted by on-line spectroscopic process monitoring was in excellent agreement with values based from known mass of sample directly taken (diverted) from system feed solution. We conclude that real-time spectroscopic process monitoring would be a useful tool for the IAEA to detect the diversion of nuclear material in a timely manner. This poster summarizes our methodology of on-line process monitoring and shows recent results of specific examples.