Much has been written about the problems incurred while the folks at the Y-12 nuclear weapons plant try to bring microwave casting into the production units at the 9212 complex, where highly enriched uranium is processed.
Not nearly as much has been written about why the use of microwaves is useful, desirable and what’s being achieved with this technology at Y-12. In an unusual sort of post, the staff of the Defense Nuclear Facilities Safety Board essentially provided a primer of sorts on microwave casting in its June 21 weekly report to board headquarters in Washington.
Here’s the text of that report:
Microwave Casting: Carbon is the one of the primary impurities of concern in cast uranium parts because it contributes to the formation of uranium carbide agglomerates that prevent the part from being machined to required specifications. The vacuum induction melting casters currently used in Building 9212 typically increase the carbon content of the item being cast. This is primarily due to the graphite crucible and mold, which provide a source of carbon that can diffuse into the molten charge. To counteract this phenomenon, personnel add highly purified uranium metal during batch makeup to ensure that parts will remain within specification once the run has been completed. One of the anticipated benefits of microwave casting technology is its ability to reduce the carbon content in the item being cast. The reasons for this phenomenon are not fully understood, though experts believe that the materials used for the crucible and mold, the environment in the furnace, and the nature of the mixing induced by microwave frequencies are all contributors. The chemical analyses of the first consolidation logs cast in the production microwave caster were recently completed. The results showed a reduction in carbon content of approximately 15 percent. The microwave casters used by the technology development organization and the prototype unit in Building 9212 had also produced these results on more than 100 runs. Microwave casting technology would reduce the future demand for highly purified uranium metal if it can produce these results consistently.