The COEX process
Under GNEP, various reprocessing and recycling options have been proposed for separating UNF constituents into several product streams. Hanson stated that AREVA has proposed a recycling strategy based on a new integrated co-extraction (COEX) process (Figure 3).
3. Once is not enough. In the AREVA COEX recycling process the used nuclear fuel is separated into three major streams: uranium-plutonium, uranium, and fission products and minor actinides. The COEX process does not separate out pure plutonium, which reduces the risk of its being used to build nuclear weapons. Source: AREVA
Whereas the PUREX process was originally designed to purify plutonium for weapons purposes, the COEX process does not separate pure plutonium at any point in the recycling plant. COEX consists of two colocated processes: the treatment process and the mixed oxide (MOX) fuel fabrication process. One additional attraction of MOX fuel is that it provides a way to dispose of surplus weapons-grade plutonium in the current U.S. fleet of conventional light-water reactors (LWRs).
In the COEX treatment process, UNF is separated into three major streams:
- Uranium-plutonium, extracted together and then turned into MOX fuel.
- Uranium, which is sent to external facilities for purification, conversion and reenrichment, and fabrication of additional recycled fuel.
- Fission products and minor actinides, which are vitrified into glass logs, stored on site as HLW, and eventually disposed of in a licensed repository.
In the COEX process, the uranium-plutonium mix is turned into MOX fuel for use in LWRs. Hanson commented that “The uranium-plutonium output stream is precipitated and co-precipitated and never, either as a product or in the piping in the facility, is pure plutonium. In that regard, COEX meets the nonproliferation requirements of GNEP by not producing pure separated plutonium, and the output product is one step further away from being usable for weapons purposes.”
The next generation of reprocessing and recycling plants in France that will ultimately replace the La Hague facility will use the COEX process.
Here in the U.S., AREVA announced in May 2008 that Shaw AREVA MOX Services LLC and the DOE had signed an agreement implementing construction of the Mixed Oxide (MOX) Fuel Fabrication Facility at the Savannah River Site in Aiken, South Carolina. The facility will remove impurities from surplus weapons-grade plutonium and mix it with uranium oxide to form MOX fuel pellets for reactor fuel assemblies. The assemblies then will be used in commercial nuclear power reactors. The facility’s design is based on AREVA’s La Hague and Melox fuel treatment facilities in France. From a physical protection perspective, the self-protecting, highly radioactive nature of the used MOX fuel will prevent direct handling of the assemblies, which will deter diversion of the residual plutonium.
Email
Comments
Print
Reuse
