For 28-year-old Leslie Dewan — and for a growing number of other young scientists interested in energy — nuclear energy isn’t about meltdowns and catastrophe. They see atomic power not as an existential threat to the planet but instead as the best way to save it, and they’re trying to revive the stalled industry with next-generation reactor designs that could change the way a skeptical public views atomic energy. Dewan just finished her doctorate* in nuclear engineering at MIT, and in her spare time she co-founded a start-up called Transatomic Power, which has plans to build a safer and cheaper nuclear reactor, one that couldn’t melt down like the older plants at Chernobyl or Fukushima. “I’ve always been concerned about global warming,” she says. “It seemed to me like working in nuclear power was a logical way to do something to help the environment.”
But the nuclear industry today faces major challenges. Yes, there are scores of nuclear reactors being built around the world — including in the U.S., where new construction ceased for more than three decades beginning in the mid-1970s. But existing nuclear plants are being shut down out of concern for safety and cost. Germany has already announced that it will be phasing out all of its atomic plants over the next decade, and the U.S. has seen plants close early — including the San Onofre nuclear plant in southern California, which is being decommissioned because of equipment failure. The Fukushima disaster — while unlikely to have a measurable health effect — could cost more than $100 billion to clean up. This past weekend brought news of a scandal in South Korea over faked safety tests and bribes at nuclear plants. Last week Duke Energy shelved a planned new plant in Florida because of licensing problems and concerns about cost recovery. With fracking keeping the cost of natural gas so low, any new nuclear plant faces both economic and safety headwinds.
So if nuclear is going to achieve what young engineers like Dewan are hoping for, the industry is going to need a new generation of reactors that are cheaper and safer. In the U.S., that will start with Southern Co.’s new Vogtle nuclear plants, which began construction in 2009 in northeastern Georgia. Southern is using a new reactor design: Westinghouse’s AP1000, the first Generation III+ reactor to be built in the U.S. (Generation I reactors were early prototypes; Generation II includes nearly all of the commercial reactors currently operating.) The AP1000 has passive-safety features — in the event of an accident, the plant is designed to automatically shut down, with no need for human intervention or outside power for up to 72 hours. As a result, the AP1000 requires significantly fewer components, reducing the redundancies that have driven up construction costs in the past. And large sections of the plant are being built off-site in prefabricated sections before being shipped to the plant and welded into place. “The passive-safety design allows you to get water to where it needs to be without an external power source,” says Tom Fanning, Southern Co.’s CEO. “That would have obviated a lot of the problems at Fukushima.”
Another new concept that’s grown popular is the small modular reactor (SMR). Designed to be about a third the size of traditional reactors, SMRs can shrink the multibillion-dollar up-front costs of a conventional nuclear plant. Less nuclear fuel means that even if something goes wrong, you won’t see the widespread radioactive contamination that can happen after a meltdown at a normal-size plant. Because they’re small and standardized, SMRs could be mass-produced and then shipped wherever they’re needed, which could mean an end to construction delays that can stretch to years. A number of small start-ups, like Hyperion and NuScale, have put forward SMR designs, and the U.S. Department of Energy agreed in June to provide $150 million to support the development of a Babcock & Wilcox subsidiary’s SMR design. Overcomplexity has always been the bane of nuclear technology — both in cost and safety. SMRs promise simplicity. “When you’re small, it just becomes a lot easier to manage everything,” says Jacob DeWitte, the CEO of the micro-nuclear-start-up UPower.
To really change the economics of nuclear, however, you need to fundamentally change how plants operate. That’s where Generation IV reactors come in. These designs — none of which has yet gotten to the prototype stage — alter the kinds of fuel and coolant that would be used, experimenting with mixes that potentially offer inherent safety, greater efficiency and less waste. Dewan’s company, Transatomic, is developing a molten-salt reactor. Instead of the familiar nuclear rods, it uses fuel dissolved in a salt mixture. At the bottom of the reactor vessel is a drainpipe plugged with solid salt, its temperature maintained with an electrical cooler. Should power be lost in a Fukushima-like accident, the plug would melt and the molten salt containing the fuel would drain into a storage area, where it would cool on its own. “You just coast to a stop,” says Dewan. The reactor would also be able to use the atomic fuel found in nuclear waste, which means more efficiency and less radioactive by-product.
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The challenge of nuclear waste — another factor that has held back new construction in the U.S., since no one can agree where to put it — is also at the heart of another atomic start-up. TerraPower is experimenting with a traveling-wave reactor design, which would largely eliminate the need for uranium enrichment. (Traveling wave refers to the fact that fission occurs bit by bit in the reactor core, as if a wave of energy were slowly spreading through it, rather than in the entire core all at once as in standard fission.) In conventional reactors, composition of the isotope uranium-235 has to be increased in the fuel before it becomes fissile. TerraPower’s reactor design could use the depleted uranium found in nuclear waste, burning it for decades without refueling. That revolutionary potential is what attracted Bill Gates, who is one of TerraPower’s main funders. “We think we could have a prototype by the early 2020s and become the commercial reactor of choice by the 2030s,” says John Gilleland, TerraPower’s CEO.
That’s the dream. The reality is that bringing any of these next-generation reactors to market would take billions of dollars and a lot of luck. Nuclear critics fear that any design that would significantly reduce costs would inevitably skimp on safety. “As a general rule, the more excess safety margins you build in, the more expensive it’s going to be,” says Edwin Lyman, senior scientist at the Union of Concerned Scientists’ global-security program. “It’s a hump you can’t get over.”
That won’t deter Dewan or the rest of the young engineers working on a nuclear renaissance, for whom climate change has changed the rules. “Everyone’s coming at this from an environmental perspective,” she says. “There’s a sense of possibility that we can invent new things in the realm of nuclear to save the world.” If a melting Arctic really is scarier than a meltdown, advanced nuclear might just have a chance.
[*Updated to note that Dewan completed her doctorate in June.]