For most people these days, "energy transition" means greater use of wind and solar power, or advances in electric vehicle and battery storage technology. But there's also increasing talk -- some of it perhaps a little overoptimistic -- of transition in the nuclear industry, via more widespread deployment of so-called fast neutron reactors, which offer a number of theoretical energy security and environmental benefits when compared with conventional reactors.
Visitors at the International Atomic Energy Agency's recent conference in Yekaterinburg, Russia, could be forgiven if they walked away with the impression that a new, glorious era of nuclear power is about to dawn. In one speech after another, conference participants from around the world lauded the potential of so-called fast neutron reactors, or "breeders," for producing abundant low-carbon energy, reducing high-level radioactive waste, and utilizing vast stockpiles of depleted uranium.
It is a matter of time, these scientists suggested, before governments and global markets realize that fast neutron technology, the successful use of which has proven elusive for the past 70 years, will be an inevitable next step in the energy revolution. But past experience suggests that the odds remain strongly stacked against fast reactors becoming a widespread energy source over the next generation.
At present, nearly all nuclear plants in operation worldwide produce power by splitting uranium atoms -- or to be more precise, by splitting U-235, a scarce isotope of natural uranium obtained in sufficient quantities for fuel through an enrichment process. This, however, wasn’t how nuclear power was conceived. The best way to achieve a sustainable nuclear chain reaction, physicists argued prior to World War II, is to bombard natural uranium, or U-238, with neutrons, which will create plutonium -- a man-made element that also fissions to produce energy. The trick is to place natural uranium in an environment of fast-moving, high-energy neutrons -- i.e., without the water-based moderator used in conventional reactors. In this way, a "fast" reactor can produce, or "breed," more nuclear fuel than it consumes, an obvious theoretical advantage for any government interested in improving its energy security -- or building an atomic bomb.
For better or worse, the construction of large-scale fast neutron reactors has turned out to be far more challenging than originally thought. The first stab at building one on a commercial basis took place in the 1960s in the US, on the coast of Lake Erie about 30 miles south of Detroit, and resulted in an accident and partial core meltdown in 1966. The reactor operated for a total of less than two years before being shut down in 1972. France built a large breeder, Superphenix, at enormous expense in the 1980s but decided to close it in 1996 due to public outcry and dismal operational performance. And the Japanese launched a fast reactor at the Monju plant in 1994, only to see it suffer an accident the following year -- one so serious that it took fully 15 years to resolve the safety and technical issues and receive regulatory approval for a restart. Having cost nearly $10 billion, the Monju fast reactor operated for less than a year before Tokyo decided to close it forever last October.
Only the Soviet Union, and by extension Russia, has managed to buck the disappointing trend. Through sheer perseverance -- and even, some would argue, insouciance with regard to safety -- Russia's nuclear industry has succeeded in mastering this notoriously difficult reactor technology. Today Russia operates the world's only two large commercial fast reactors, the second of which, the BN-800, sent its first power to the grid last year.
A Matter of Time?
The general consensus among experts in Yekaterinburg for the International Conference on Fast Reactors and Related Fuel Cycles, which is held every four years, was that it is a matter of time before fast reactor technology takes hold. They admit considerable research and development work remains to be done, but being scientists, they retain an unshakeable belief that solutions can eventually be found to any technical challenge. The one thing holding back fast reactors, they say, is dirt-cheap uranium. Why bother breeding plutonium and reprocessing it -- both costly undertakings -- when there is plenty of inexpensive uranium on global markets? As soon as uranium, however, grows scarce, then nuclear power-reliant countries worried about energy security will have little choice but to invest in a fast reactor that can effectively eke out 90 times more energy from the same amount of uranium. Furthermore, proponents argue, fast reactors are low-carbon and great incinerators for high-level nuclear waste.
While all this may be true, fast reactors' two central problems will remain -- costs and proliferation. As demonstrated so far, the technology is extremely expensive. Little data exists since so few large fast reactors have been built, but it is safe to say that a fast neutron reactor costs at least 50% more per megawatt of installed capacity than a conventional reactor, and maybe double. Since they work at very high temperatures and are susceptible to such things as power excursions and coolant leaks, these reactors require expensive metals, more pipes, and additional safety systems. One Russian scientist in Yekaterinburg presented a study showing that fast reactors could compete on a cost basis with conventional ones, an observation that foreign experts criticized as absurd. Oleg Saraev, an eminent Russian scientist who in the 1980-90s managed the country's other operational breeder, the BN-600, said he and others believed that fast reactors would always be more expensive than conventional units.
For these reasons, the private sector has been disinclined to get involved. A typical case in point is Russia's AKME Engineering, a private firm that backed out of a joint venture with state-owned Rosatom to develop a small, mobile fast reactor, the SVBR-100, due to exorbitant costs -- and this despite the technology's proven track record in Russian submarines. Granted, there are still a handful of intrepid efforts out there, such as US-based Terra Power, backed by Microsoft founder Bill Gates, which wants to build a fast reactor that skips the fuel reprocessing phase and burns plutonium in the core as it is bred. Another is LeadCold, a Swedish start-up looking to set up a series of small fast reactors in remote Canadian Arctic towns that can operate at a fraction of the cost of diesel-power generators.
Generally, however, large breeder projects are financed by the state -- i.e., the taxpayer. One could argue this is the way it should be, since where you have spent fuel reprocessing, you will get plutonium, which can be used for atomic weaponry. This is a key reason why India prioritized a breeder program over half a century ago, and indeed this country will soon join Russia in the elite club of large fast reactor operators when it launches the 500 megawatt PFBR, possibly this year. The US, in contrast, was terrified by the prospect of nuclear proliferation through plutonium-fueled reactors, and made a strategic decision in the 1970s not to develop the technology.
Yet the message from Yekaterinburg is that the future of nuclear energy lies with full uranium utilization in a fast neutron spectrum. Pioneers in this field should beware, however. While they try to advance safety and material issues, they will have to contend with other fast-developing energy technologies, where any number of breakthroughs -- in semiconductors, battery storage, nuclear fusion -- could conceivably bury fast neutron's hopes of competing on a level playing field.
Gary Peach is a reporter with Energy Intelligence based in Latvia, and an expert on the Russian nuclear power sector.