Advances in the field of solid-phase extraction, along with substantial improvements in automated control systems and on-line monitoring, suggest that the technology merits further consideration for nuclear fuel reprocess­ing applications. The technology is probably more suited to MA and Ln separations subsequent to the removal of U and Pu by other means, or for polishing applications in any number of processing and/or raffinate streams. Issues with high U loading will likely preclude the use of solid-phase extrac­tion materials for primary actinide separations, but this decision is ulti­mately a function of the stability of the given material and economics of the process under consideration. It is noteworthy that many researchers have recognized the need for more information regarding the robustness of the solid-phase extraction composites. This is evidenced by attempts to increase substrate stability via the addition of inorganic materials as well as bench-top studies to assess extractant losses and radiation effects. Still, more data is needed to evaluate the issues mentioned in the previous section. Future work should include comprehensive assessments of resin performance under the multiple cycles of loading and stripping correspond­ing to those typical of an actual process. Some testing at larger scales, and smaller tests using actual reprocessing solutions, will also be needed to accurately assess the viability of the technology. The added complexity of these studies will certainly drive up cost and likely require some type of programmatic support. This is typically the issue when transferring any technology from small scale to large scale applications. The information to be gained is, however, essential for performing adequate engineering and cost-benefit analyses of the technology.

13.5 Sources of further information and advice

The works by Cortina et al., (1994a, b), Braun and Ghersini (1975), and the numerous journal publications by E. P. Horwitz and coworkers are excellent sources for more detailed information on solid-phase extraction.

13.6 Acknowledgment

I would like to thank Mitchell Greenhalgh of the Idaho National Laboratory for fruitful discussions and immense help in gathering information for this work.