Electrometallurgical Techniques for DOE Spent Fuel Treatment: Status Report on Argonne National Laboratory's R & D Activity Through Spring 1997 (1997)

an acceptable uranium ingot. (Since there is no cadmium involved in the operation of the Mark V electrorefiner, the operation of the cathode processor is simplified.)

Collection efficiencies for uranium deposits in the Mark IV range from 42 to 78 percent. They are stated to be less than 100 percent because of loss of uranium that falls from the cathode during deposition. (This uranium is not actually lost but falls into the cadmium cathode, from which it may be recovered by subsequent anodization into the molten process salt and then deposited onto the cathode mandrel.)

Material for the cathode processor crucible is still being evaluated to minimize the uranium loss (more than the design specification of 1 percent) to the crucible itself. When process salt and cadmium salt are present in addition to the uranium, graphite crucibles are attacked, with changes in the quality of the uranium ingot, formation of loose dross, appearance of a heavy surface scale, and poor release of the ingot from the crucible. Beryllia crucibles were stated in a presentation to the committee to “look favorable,” but it is not clear from data so far in evidence that beryllia is the answer. Large beryllia crucibles were found to be subject to thermal stress failure, and small crucibles exhibited poor ingot release. Since the Mark V will not have one of the troublesome elements—cadmium—it is not clear whether the crucible failure problems will persist with that unit.⁴

As indicated in the Spent Fuel Treatment Project Schedules supplied by ANL, blanket assembly treatment will not start until March 1998 at the earliest, although installation of the Mark V unit at ANL-W was scheduled to begin in the summer of 1997. Heretofore it has not been clear to the committee whether both of these electrorefiners are to operate at the same time during the EBR-II fuel treatment demonstration. Further, it was not clear what effect, if any, the EA-mandated reduced scale of the demonstration would have on the operation of the equipment. Based on presentations to the committee, it now appears that there will be no adverse effect, either in electrorefiner operation or in demonstrating the success of the process. In any event, both electrorefiners are needed to complete the demonstration on the projected schedule.

In the March 1997 report (NRC, 1997a), the committee noted the benefits to be gained by formalizing the organizational arrangements of the demonstration project, both at ANL-E and ANL-W and