IMPUREX cycle: recent advances

Full text: We are currently studying the IMPUREX (IMproved PUREX) process as an advanced process for the joint decontamination of uranium and plutonium that excludes their separation. This approach reduces the danger of nuclear proliferation. Its application in our country would be advantageous for the implementation of synergic cycles, like the reuse of spent enriched uranium fuel in natural uranium reactors. The development of this process includes three stages: a) Inactive tests; b) Development with radiotracers; c) Hot test (in hot cells). As a part of the first stage, recently the development of a mini mixer-settler battery has been completed. This equipment was built using innovative materials such as high density polyethylene and glass, which are adequate options for hot cell operation. The operating features of the device are, among others: independence of the aqueous phase circulation between stages achieved by the use of little air-lift pumps, and air pulse mixing with tubes of different height. An automatic control loop governs the position of the uranium 'front', a fundamental characteristic of the IMPUREX process. The control software was especially developed for this task. The loop acts in response to the continuous uranium concentration measurement by molecular absorption spectrometry, possible by means of an ad hoc optic fiber arrangement. Results have been satisfactory so far with respect to the operation of the equipment (taking into account variables such as watertightness, efficiency and stability). The control loop also performed well with regard to ease of configuration change, stability and other characteristics