Nuclear Technology / Volume 173 / Number 3 / March 2011 / Pages 289-299
Technical Paper / Chemical Reprocessing
Advanced designs of nuclear fuel recycling and radioactive waste treatment plants are expected to include more ambitious goals for solvent extraction-based separations, including higher separation efficiency, high-level-waste minimization, and a greater focus on continuous processes to minimize cost and footprint. Therefore, annular centrifugal contactors (ACCs) are destined to play a more important role for such future processing schemes. Previous efforts defined and characterized the performance of commercial 5-cm, model V-02; and 12.5-cm, model V-05, single-stage ACCs in a nonradioactive environment. The next logical step, the design and initial evaluation of remote-capable, pilot-scale ACCs for use in a "hot" or radioactive environment has been completed. This work continues the development of remote designs for ACCs that can process the large throughputs needed for future nuclear fuel recycling and radioactive waste treatment plants. Novel designs were developed for the remote interconnection of contactor units, clean-in-place (CIP) and drain connections, and a new solids removal collection chamber. A three-stage, 12.5-cm-diam rotor module has been constructed and is being evaluated for use in highly radioactive environments. This prototype assembly employs three standard CINC V-05 CIP units modified for remote service and replacement via new methods of connection for solution inlets, outlets, drain, and CIP. Hydraulic testing and functional checks were successfully conducted, and then the prototype was evaluated for remote handling and maintenance. Removal and replacement of the center position V-05R contactor in the three-stage assembly was demonstrated using an overhead rail mounted PaR manipulator. Initial evaluation indicates a viable new design for interconnecting and cleaning individual stages while retaining the benefits of commercially reliable ACC equipment. Replacement of a single stage via remote manipulators and tools is estimated to take [approximately]30 min, perhaps fast enough to support a contactor change without loss of process steady-state equilibrium. The design presented in this work is scalable to commercial ACC models from V-05 to V-20 with total throughput rates ranging from 20 to 650 l/min.