M. C. REGALBUTO, Argonne National Laboratory, USA

Abstract: The separations strategy for the UREX+ type processes is based on an optimization approach for which key objectives for a closed or partially closed fuel cycle are pre-determined. The overall process is composed of a sequence of separation steps or modules linked to generate a desired set of outputs, whether products or intermediates. Processing options are shown for the case of LWR recycle, where incentives exist to separate and recycle the actinides, and separate and manage fission products. The UREX+ approach was successfully tested for the recycle of LWR SNF for a number of different product and waste forms configurations and the results from these tests are given.

Key words: LWR recycle, UREX+, GNEP, AMUSE, FPEX, NPEX, TALSPEAK, TRUEX, CCD-PEG.

7.1 Introduction

The original goal of actinide separations research in the US, which dates back to the 1940s, was the recovery of plutonium for defense purposes. The ultimate result was the development of large-scale chemical processes for the separation of plutonium from irradiated uranium. A number of chemi­cal processes were tested (US Nuclear Regulatory Commission, 2008, p. 13) at the Hanford and Savannah River sites. By far the most successful was the PUREX process, which has now been developed commercially to treat spent power reactor fuel. By the mid 1950s, advancements in nuclear power technology, the then-perceived scarcity of uranium-bearing ore, and the high energy requirements of gaseous diffusion for uranium enrichment, resulted in the belief that there would be a shortage of uranium fuel sup­plies if nuclear power expanded significantly. In response, efforts were begun to develop reactors that could breed plutonium to serve as the fissile component in fuel, along with reprocessing facilities to recover the bred plutonium.

Although the plutonium was intended for use in commercial power reac­tors (rather than defense applications), the goal remained the isolation of plutonium from the other components of spent fuel, as it was the product of interest. Uranium was also collected as a product in PUREX but required re-enrichment to serve as a fuel for light water reactors. Because of this early development work, PUREX is the only current industrial process for recovery of plutonium (and uranium) from commercial spent fuel. In the early 2000s, the reprocessing of spent fuel re-emerged as an area of interest driven by the forecasted growth in nuclear power (MIT, 2003) and the need to develop sustainable, environmentally acceptable and economic closed fuel cycles (Williamson et al., 2004). The separations goal this time had changed from recovery of plutonium to management of all minor actinides and fission products not only for reuse of material as fuel but also to help address the waste management challenges still facing nuclear power gen­eration (Wigeland et al., 2006).