R. S. HERBST, Idaho National Laboratory, USA, P. BARON, CEA, France and M. NILSSON, University of California Irvine, USA

Abstract: The PUREX process for separating uranium and plutonium from irradiated nuclear fuels has been extensively studied and successfully operated industrially over the preceding five plus decades. It is anticipated that PUREX will play an important role in upcoming and advanced future nuclear fuel cycles. The first objective of this chapter is to provide the background information required to status the present state of the art as currently practiced at the industrial scale. The second objective is to examine the modifications ready, or nearly so, for implementation into the next generation of PUREX reprocessing facilities, thereby further expanding the utility and operation of the process for use in nuclear fuel cycles of the future.

Key words: PUREX, tributyl phosphate, uranium separation, plutonium separation, solvent extraction, nuclear separations, nuclear fuel cycle.

5.2 Introduction

The PUREX (Plutonium, Uranium, Reduction, EXtraction) process was first reported in 1949 and subsequently operated with irradiated nuclear fuel at the large scale in 1954 (Lanham 1949). In the ensuring 50+ years, it has been widely described, publicized, and reviewed in the open literature, and remains the only technology internationally practiced on an industrial scale to reprocess (recover U and Pu) from used nuclear fuels. A major objective of this chapter is then, not to provide an in depth review of PUREX technology (that has already been eloquently accomplished in a plethora of previous reports, articles, and treatises), but rather to provide the necessary background information to logically status the current state of the art, as practiced today, at the industrial scale. The second, and perhaps more timely objective is to provide insight into the modifications ready or near-ready to be implemented into the next generation of PUREX repro­cessing facilities, thereby further expanding the utility and operation of the process in the ever-changing climate of technical, political, and environmen­tal considerations.

It should be noted that initially, PUREX was developed and applied primarily to produce a pure Pu stream for military (weapons) applications and was consequently cloaked in great secrecy under the auspices of “national security.” Those countries that have produced substantial amounts of Pu for military purposes have done so by means of the PUREX process. Today, the Pu and U products are commercially recovered from used fuels from civilian nuclear power plants (NPP) and fabricated into fresh fuel for recycle back to NPPs for electricity production. Interestingly, many of the intricate details associated with present-day commercial reprocessing facili­ties are considered “propriety information” and are therefore often pro­tected as well as (or better than) what were formerly considered to be national secrets.