By Nancy Spring, Senior Editor
For economic and national security reasons, the United States does not recycle used nuclear fuel. After it is used once in the reactor, it is stored at the reactor site, bound for ultimate disposal in a repository.
 Storage for vitrified waste at La Hague, France. Courtesy Areva. |
There are two main problems with the current once-through fuel cycle. First, storing nuclear waste at the Yucca Mountain repository is no longer an option. Money for the project has been cut and U.S. Energy Secretary Steven Chu has made it clear that the repository is “off the table.” Second, by not recycling, the volume of final waste that must be stored is greater than it would be with a reprocessing program.
In ballpark figures, it takes around 30 metric tons of fuel each year to power a 1,000 MW nuclear power plant. That creates 20 tons of waste. Because 96 percent of each fuel assembly is re-useable, with recycling the volume of waste is reduced by a factor of five. Radiotoxicity is reduced by a factor of 10 because the lower the volume of waste, the lower its toxicity. Plus, plutonium is removed from the final waste stream.
The federal government plans to evaluate both the once-through or “open” cycle and closed fuel cycles that include recycling. Chu said a blue-ribbon panel will be convened to study the issue.
A nuclear program with decades of experience could also provide valuable insights for the U.S. decision-making process. French nuclear company Areva operates the largest nuclear fuel reprocessing/recycling plant in the world. At the La Hague facility in northwest France, spent fuel from 90 to 100 nuclear reactors can be recycled each year, separated into uranium, plutonium and fission products, each one bound for the next use or final storage.
The cycle begins with the nuclear fuel assemblies. After powering nuclear reactors for three to five years, the fuel assemblies are stored at the reactor site for about a year and then shipped to La Hague. There they are put into an interim storage pool for another cooling-down period of three to five years.
After the second cool-down, the spent fuel assemblies are cut into 35-mm chunks and the plutonium and uranium are separated from the fission products. The uranium is used for UOX fuel and the plutonium is shipped to Areva’s Melox plant to be made into mixed oxide (MOX) fuel. Fission products, which are highly radioactive and thermally charged, account for 4 percent of the total. They are vitrified and poured into stainless steel containers, ready for waste storage in ventilated pits.
Forty years of France’s nuclear waste is stored in three storage halls at La Hague—9,500 containers containing vitrified nuclear waste in pits 20 meters deep. The containers can be stored there for 100 years and will then be moved to a final repository.
The Nuclear Future
Should the U.S. modify its stance on recycling used nuclear fuel? Rémi Coulon, Areva’s back-end sector, strategy and international projects director addressed that question. Coulon oversees downstream decommissioning and recycling for the company. “People have the wrong image (of reprocessing),” he said. “Maybe the burden is on us to educate them.”
In an exclusive interview with Power Engineering, Coulon talked about the nuclear future and the evolutionary recycling option.
P.E.: What kind of research and development is needed for nuclear fuel recycling?
Coulon: In the U.S., there hasn’t been much R&D in the past on recycling. It is only since 2004/2005 that we are seeing R&D resuming in this area in the U.S. national labs and this is a very good thing. I’ve heard that this year’s Department of Energy (DOE) budget will continue to show a strong push for recycling R&D and we are all for it.
We know from our experience in building and operating the La Hague and Melox plants that we need strong R&D support. In the early ’90s, when we were building our latest generation of plants, we had more than 500 people from CEA (France’s National Lab) on those projects. Even today as the plants are operated we still have about 200 R&D people to help us ensure we will continue operating our plants safely, for instance with analyses on the impact of increasing fuel burnup.
Even if you were contemplating building a recycling plant today in the U.S., which really means starting operations in 2025 with an evolutionary design, it wouldn’t be a copy/paste of La Hague/Melox. There will likely be new constraints in effluent releases, for instance, and selected new processes to implement, so R&D would still be needed to support such an industry-led evolutionary plant.
Where DOE’s R&D has a crucial lead role to play is the longer-term demonstration and improvements on issues such as advanced fast neutron reactors and advanced recycling technologies in order to handle actinides transmutation. We don’t have today the separations technologies to separate those actinides (such as Americium or curium) and we don’t have the reactors and appropriate fuel design in order to “digest” those actinides and transmute them. This will be a longer-term endeavor, but we are convinced that such technologies are part of the nuclear future and that in order to prepare for their arrival at a significant scale by mid-century, we need to start and push R&D now.
The key then becomes what to do now. Some propose to interim-store used fuel and wait for Gen IV revolutionary recycling, while others—and that includes Areva and a growing number of utilities—advocate that we can start now with Gen III evolutionary recycling including LWR recycling through MOX fuel and reprocessed uranium-based fuel while in parallel continuing to prepare Gen IV.
It is our strong belief that indeed this phased approach can be successful and that the evolutionary recycling option can indeed be deployed quickly in the U.S. as a best value complement to direct disposal. To summarize the role of R&D, we view it as two-fold: support in an evolutionary recycling plant project and lead in the preparation of the Gen IV framework.
P.E.: What kind of funding or business model would come into play?
Coulon: Studies have shown that commercial recycling facilities can indeed be developed and funded by the private sector with appropriate conditions provided by state and federal authorities; enhancing long-term guarantees and security, for example. The key of course for industry to invest and take its share of the risks is that the recycling plant has to be evolutionary compared to today’s plants, otherwise the risks are far too large and no one will be willing to take them.
P.E.: What needs to change in the U.S. for recycling to be adopted?
Coulon: We actively worked over the past three years with a number of utilities on this issue. We thought that the key would be to establish the framework that will lead to securing the interest of industry to further engage and invest and that includes the policy/legislative framework and the licensing framework.
On the policy/legislative side, our conclusion was that a government-owned used fuel management entity (UFME) should be formed to manage the back-end of the fuel cycle, including interim storage at a centralized location, transportation, recycling and the repository program. Such an entity would need full access to the nuclear waste fund including all annual revenues and corpus and broad authority to enter into contractual relationships with service providers. As a key consequence, it would be unplugged from the annual appropriations funding cycles.
Several organizational models are possible for such an entity and the government-owned corporation (a federal corporation such as TVA) looks like the preferred model. This entity would be responsible for evaluating and implementing the used fuel management integrated strategy, using of course the results of the blue-ribbon panel to be set on used fuel management. The utilities would be engaged in the management of the UFME.
On the licensing side, our conclusion was that a number of changes had to be implemented in order for the licensing framework for recycling plants to be more conducive to private investment; roughly similar to the changes the National Regulatory Commission (NRC) went through with the combined license application process for new nuclear plants. Through industry groups, the NRC has actually been engaged and discussions are proceeding, though of course it will take a few years to see this action come to fruition.
The fundamental conclusion behind this is that the long-term R&D actions should squarely rest with DOE and the national labs and be actively pursued, while a public-private model would be best fitted to handle the strong involvement—and commensurate risk-taking—of industry for the industrial implementation of a shorter-term evolutionary recycling stage. Those two tracks, long-term and short-term, should not be opposed, but they are truly complementary.
As you see, this won’t happen overnight, but we are honestly convinced that this is a sustainable path worth pursuing. Under appropriate conditions, the industry believes it is possible to privately finance such a project with the right guarantees. This project will fuel the economy for decades with recycled fuel, while contributing to solving a long-lasting national commitment regarding nuclear waste.