Nuclear Fuel Recycling: Getting Down to Business
Although the United States has chosen to focus on a throw-away fuel cycle, many of our allies have decided that recycling nuclear fuel fits their national interests. France and Great Britain, have built large, modern, and very expensive facilities to extract useful metals from used fuel rods to provide raw material for new fuel assemblies. Entities from other nations contract for their services of reprocessing and temporary nuclear fuel storage.
The final product of the plants is a fuel known as MOX (mixed oxide) that has a mixture of plutonium and uranium oxides designed to give it characteristics similar to fuel made from virgin uranium. This MOX fuel can generally be used to replace up to 30 percent of the fuel elements in existing reactors without any modifications.
With some modifications to the control systems to account for the slightly higher reactivity of MOX, existing reactors can be configured to use it for 100 percent of the fuel load.
MOX fuel takes the first step in making better use of nuclear fuels while at the same time reducing the long-lived component of waste material. In the separated waste stream from reprocessing plants, the majority of the radioactive isotopes completely decay in less than 300 years instead of the tens of thousands of years needed for waste streams that include plutonium.
Recycling Obstacles
As is common in recycling programs, there are some difficulties associated with recycled material that are not present with virgin raw material. With newspapers and office materials, the difficulty is removing ink without producing a toxic sludge, with nuclear fuel it is the fact that irradiated fuels have more associated radiation hazards than virgin material.
It is safe to handle virgin uranium with virtually no protective measures as long as workers do not ingest the material. Workers can pick up fuel rods and move them about without worrying about their whole body dose. With irradiated fuels, people need far more protection from radiation hazards.
The reprocessing and fuel fabrication plants are designed with thick concrete shields and remote handling systems. For fuels that have experienced high burn-ups, the chemicals currently used in the process can undergo radiolytic decomposition. Any maintenance or handling needed must be done with remotely operated manipulators.
The market for MOX is just starting to develop as more experience is gained in manufacture and as more product is made available at a cost competitive with virgin materials. The current world capacity for MOX fabrication is approximately 225 metric tonnes of heavy metal per year, and requires only about nine metric tonnes of plutonium. The total contribution of MOX is rather small in comparison to the entire nuclear fuel business, but there are plans for expansion.
It Just Makes Sense
For utilities and countries that are concerned about disposal costs and long term availability of uranium fuels, it makes sense to begin the process of learning how to make the best use of this relatively new energy source.
Scientists and engineers in the United States invented most of the basic technology and chemistry associated with nuclear reprocessing. However, we have been out of the business for nearly 20 years; our industrial capabilities for fuel recycling are not even close to those of our former customers.
It appears likely that the British and the French will dominate this industry for many years based on the proven performance of their plants and the fact that transportation costs are not a dominant consideration when moving concentrated materials. A single shipment might provide Japan’s reprocessing needs for a whole year. When more capacity is needed, the logical place for construction will be in places with the installed base of knowledge and expertise.
