DUF6 Process

DUF6 Autoclaves.jpg
The DUF6 conversion process has five interrelated systems which result in two products: uranium oxide (UOx) and hydrofluoric acid (HF). The UOx is stored for eventual disposal or reuse, and the HF is sold for use in industrial applications. The five systems consist of vaporization, conversion, oxide powder handling, HF recovery, and cylinder reuse. Operating the five systems of the process is quite complex and calls for the integration of multiple mechanical, chemical, temperature, scrubbing, recycling and storage systems. It also calls for well-trained staff to run and maintain the various process systems 24/7.

  1. Vaporization

    DUF6 cylinders are moved from the cylinder storage yards to the DUF6 conversion facility. The cylinder is placed in an autoclave and heated to turn the DUF6 from a solid to a gas. Cylinder weight, line pressure, temperature and flows are monitored by a process control system. This process is called vaporization, and it occurs at a temperature slightly below boiling water. Each production line consists of autoclaves and conversion units. All the connected elements are heated to prevent the gas from cooling (desublimation) and creating material processing problems. Monitoring for DUF6 reaction leaks is continuous during this process.

  2. Conversion

    The conversion unit separates the DUF6 into UOx and HF. Steam and hydrogen separate the two in an exothermic (release of heat) chemical reaction. The conversion reactions are a two-step process occurring in the conversion unit. The UOx oxide powder is removed out of the bottom of the conversion unit and the HF vapor flows out the top through filters.

  3. Oxide Powder Handling

    The oxide powder goes through a cooler and then is transferred to hoppers. The hoppers drop the oxide through roller-compactors. The compacted oxide is dropped into reused cylinders. Reused cylinders are cylinders that formerly held DUF6 which are chemically stabilized and modified with a flange on one end. The modified cylinders are filled with uranium oxide and used as the shipping container.

  4. HF Recovery System

    Once the HF passes out the top of the conversion unit, it goes through a condensers and changes into a liquid. The gases are processed through scrubbing systems to be converted to liquid. The acid is stored in tanks. The storage tanks serve as the loading station for transfer to a railcar or truck to remove the material from the site. There are multiple industrial uses for the processed HF.

  5. Cylinder Reuse

    Cylinders are moved from the yards by various vehicles and brought into the Conversion Building, where they are heated in the vaporization system. The cylinder is then cooled down and disconnected and moved to a station where the interior is neutralized with potassium hydroxide. The cylinder goes into storage and is then modified so it can be filled with UOx material using a gravity feeding method. This allows the cylinder to be re-used as a UOx container. The cylinder is upended, filled and UOx cylinder is returned to the storage yard where it will be stored for future disposal or shipped for reuse of the uranium oxide.