Unlike Russia, Japan and several European countries, the United States does not recycle its used nuclear fuel. But new, advanced drivers are reviving the possibility of recycling the nation’s spent nuclear fuel. What will influence this decision and what conditions will need to be met first?
Used nuclear fuel (UNF) has long been reprocessed to extract fissile materials for recycling to provide fresh fuel for existing and future nuclear power plants. Entire spent fuel is not waste, as plutonium and uranium – which can be recycled – contribute to about 98% of the spent fuel, and thus only the remaining two to three per cent of spent fuel is waste.
Over the past five decades, the main reason for reprocessing UNF has been to recover unused uranium and plutonium in the used fuel elements and thereby close the fuel cycle. This approach captures the vast amount of energy still remaining in the UNF.
“The primary driver for the recycling of UNF is to increase utilisation of available natural resources for energy generation. Waste management benefits are secondary and advanced fuel cycle technologies are not needed for the safe disposal of used fuel and high-level waste,” Andrew Sowder, senior project manager in EPRI’s Used Fuel and High-Level Waste Management Program, tells Nuclear Energy Insider.
After being used once in the reactor, UNF is typically removed for ultimate disposal in a repository, in what is called an open fuel cycle. On the other hand, the recycling and reuse of nuclear fuel takes place in a closed cycle; an approach that captures the vast amount of energy still remaining in the UNF.
“While the recycling of plutonium in light water reactors is a mature commercial technology, the associated improvements in resource utilization are modest. Single-pass recycling, for example, only provides uranium savings on the order of 12 per cent to 15 per cent.
“The full promise of recycling – that is natural uranium savings on the order of 95 per cent - can only be realized with the commercial-scale deployment of fast reactor technology,” explains Sowder, who helped launch EPRI’s Extended Storage Collaboration Program which serves as a focal point for international R&D on very long-term dry and wet storage of UNF.
A game-changing technology?
The Integral Fast Reactor (IFR), or Generation 4 Reactor, was developed at Argonne National Laboratory in the US, but was cancelled in 1994 for political reasons, just as demonstrations were being prepared after a decade of successful development. Since then, interest has grown in recovering all long-lived actinides together - with plutonium – to recycle them in the IFR so that they end up as short-lived fission products.
As can be deduced from the word “fast” in its name, the IFR is a type of reactor that allows neutrons to move at higher speeds by eliminating the moderating materials used in thermal reactors. “The greater velocity of the neutrons results in a more energetic splitting, and thus a greater number of neutrons being liberated from the collisions. The result is that the fuel is utilized much more efficiently,” explains Tom Blees in his book Prescription for the Planet (http://www.filegarden.com/tomblees/Misc/Chapter5.pdf).
Whereas, a normal reactor utilises less than 1 per cent of the fissionable material that was in the original ore, with the rest being treated as waste, a fast reactor can burn up virtually all of the uranium in the ore. In addition, the fuel can be recycled on site in a process that removes the fission byproducts and incorporates the actinides from the UNF into new fuel rods, which are then reloaded into the reactor. They can then be stabilized by vitrification, and stored for thousands of years without fear of significant air or groundwater contamination.
It is argued that the waste coming from an IFR does not have to be stabilised for anywhere that long, unlike the waste from the thermal reactors used today, waste elements from IFRs have much shorter half-lives than the actinides that have been retained in the reprocessing and subsequently reloaded into the IFR’s core for further fissioning. With the actinides removed from the UNF, dealing with this new type of nuclear waste becomes fairly manageable.
The Science Council for Global Initiatives (SCGI), an international NGO aiming to get the first commercial-demonstration IFR, claims that more than 99 per cent of the energy is left in the spent fuel and can provide all the energy the world needs for many centuries.
“The IFR can be the solution to virtually all of the problems humanity faces today that are in any way connected to energy. Instead of recovering less than 0.6% of the energy in uranium, IFRs can utilize 100% of it, making them about 160 times more efficient than conventional reactors. They leave behind no long-lived waste products, and the small amount left can be easily and safely disposed of,” the SCGI states.
Chairman of the Georgia Public Service Commission Tim Echols was recently heard saying that the mounting UNF being stored on the site of nuclear plants was like “constipation blocking the progress of the industry”, and that a better idea would be to recycle the fuel rods as the French do so that they can be used again. According to Echols, Nathan Deal, the governor of Georgia, has already given his support to a policy change and to locating a fuel-reprocessing plant in Georgia.
If France can do it
Through Areva, France has been at the forefront in UNF recycling and has reached an industrial maturity that lends itself well to use elsewhere. Areva has undertaken de-conversion of enrichment tails at Pierrelatte since the 1980s, and today, at its La Hague site, it operates the MELOX plant; a used-fuel recycling facility with capacity of 1,700 tons per year that has been working since 1995. It is also the world’s only operational large-capacity MOX fuel production plant.
Areva has proposed building a $20bn plant in the US with a similar technology to the one it uses in France, where 17 per cent of electricity is derived from recycled UNF. According to Areva, the group has joined with Duke Energy, one of America's largest nuclear power producers, to submit a proposal to the Department of Energy for the construction of an MOX-fuel fabrication plant to supply MOX fuel to reactors in the US.
“A common question raised during discussions on reprocessing is, ‘If the French are reprocessing used fuel, why isn’t the US?’. In many ways, the U.S. and France represent opposite ends of the spectrum,” notes Sowder.
“In France, the recycling of MOX in light-water reactors is a mature, ongoing commercial practice supported by an existing industrial, commercial, and regulatory infrastructure. This situation has resulted from a deliberate, multi-decade national energy policy prioritizing energy security for a country with limited domestic natural energy resources. Accordingly, there would need to be a compelling reason for France to abandon its recycling programme,” he explains.
In the US, initial plans for building a recycling programme were abandoned in the 1970s due to non-proliferation concerns, and the accompanying infrastructure was not developed or never completed. Therefore, a compelling case would need to be made for launching a recycling programme in the US, albeit not impossible.
In the nearer term, the overriding considerations for nuclear power are safety, reliability and affordability. “Current uranium projections indicate adequate fuel supplies for the remainder of the 21st century, and accordingly, departure from the once-through fuel cycle using current light water reactor technology will require a compelling business case,” Sowder points out.
Considering the capital intensive infrastructure required to bring commercial recycling to the US, a number of conditions would be required to shift from the current once-through fuel cycle based on light-water reactor technology. These include a stable national policy and strategic vision; maturity of the regulatory infrastructure; mature fuel cycle technology and designs; and cost and schedule estimates.
Furthermore, based on EPRI fuel-cycle assessments, several criteria will need to be met before transitioning from the current fuel cycle. “For high uranium prices, recycling of plutonium (as MOX) could become economically feasible as long as reprocessing costs are competitive, while the deployment of advanced reactors and fuel cycle technologies could extend fuel supply if uranium resources become limiting,” highlights Sowder, who will be speaking at the upcoming US Nuclear Used Fuel Strategy Conference (http://www.nuclearenergyinsider.com/used-fuel-strategy-conference/index.php).
“I always like to stress the importance of distinguishing between reprocessing and recycling and the paramount role that reactor technology plays in a fuel cycle worth developing and operating. While the two terms, reprocessing and recycling, are often used interchangeably, reprocessing represents just one element, albeit a very important one needed to support a recycling fuel cycle.
“Given that the primary objective of building and operating a nuclear fuel cycle is for energy generation, the primary focus on research, development, and demonstration (RD&D) programmes should be on the reactor as the key enabling technology, since that is the point of energy generation. All other technologies and infrastructures exist to support the safe, reliable, and economic operation of the reactor. This distinction speaks to prioritization of fuel cycle RD&D,” Sowder concludes.
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