It was the winter of “Snowmaggedon” in Boston, and MIT grad students Leslie Dewan and Mark Massie had just passed their qualifying exams in nuclear engineering. Suddenly, after months of nonstop test-prep work, they had the luxury of time. “We said, we’re no longer studying 16 hours a day,” Dewan recalled, “Let’s do something new and exciting!”
As February rolled by, the two began looking at ways to bring to market different types of nuclear reactors that could solve some of the problems—especially safety and waste issues—that have dogged the traditional light-water reactors that produce nearly all of the world’s nuclear power today. “We both considered ourselves to be environmentalists, and we felt that nuclear power is the best way to shift away from fossil fuels—and from coal in particular,” Dewan said.
It’s an increasingly common perspective. “Nuclear is a non-carbon-emitting resource and it has a contribution to play in greenhouse gas emissions avoidance,” said Dan Lipman, executive director of policy development and supplier programs for the Nuclear Energy Institute, an industry lobbyist group. He echoes the sentiments of many across the nuclear industry who are hoping that a growing sense of urgency on climate issues could reinvigorate the market for their technology.
Critics are quick to refute these claims, citing cost, safety, waste management, and time-to-market as major barriers to the large-scale adoption of nuclear energy for baseload grid power. But are these truly insurmountable challenges? If nuclear is to play a significant role in a low-carbon energy future what will it take to make that happen?Some climate scientists and high-profile nonprofits are beginning to agree. Renewable energy is gaining ground, but it still makes up just over 13 percent of the total U.S. electric power mix. Concerns about resource intermittency, immature storage technologies, grid reliability, and land use haunt faster growth scenarios. As a result, achieving even the moderate carbon emissions reductions—pegged to a 30 percent reduction over 2005 levels by 2030—outlined by the EPA’s proposed Clean Power Plan [pdf] is expected to require both the development of new nuclear plants and extended lifespans for those that were built as far back as the 1970s.
The Promise: Innovation
These were the kinds of questions that Dewan and Massie asked themselves as well, and by summer 2010, they had decided that the “new and exciting” thing that would make nuclear a truly viable part of a low-carbon future wasn’t new at all. It was a molten salt reactor, developed and tested at the Oak Ridge National Laboratory (ORNL) in the 1950s and ’60s. Molten salt reactors (or MSRs, as they’re known in the acronym-heavy jargon of the nuclear industry) were just one of several proposed reactor designs emerging at the time. They were also one of the most promising.
In a 1964 progress report that laid the groundwork for ORNL’s Molten Salt Reactor Experiment (MSRE), program director R. Beecher Briggs extolled specific virtues of the system’s liquid-fuel design. Among them were low operating pressure, passive cooling design, continuous operation during refueling, and low fuel and operating costs, all of which translated into both lower capital costs and the need for less complex control and safety systems. Traditional light-water reactors can claim almost none of these benefits.
In short, molten salt reactors promised cheaper, safer nuclear energy.
Dewan and Massie spent several months examining the ORNL program’s research findings, studying the science, and concluded that although there were hard problems left to solve, the MSR branch of nuclear technology hadn’t been pruned because of insurmountable technical challenges. In 1973, when the program was defunded, it was (as ORNL put it) “in spite of the technical success of the MSRE.”
One of the main reasons funding for the project was stopped, according to Dewan and other supporters, is that the breeder reactor wasn’t a good source of plutonium, which was needed for use in a nuclear weapons program. Today, the lack of a weaponization potential is a selling point, not a showstopper. So, Dewan and Massie formed Transatomic Power in April 2011 and set out to solve some of the remaining challenges, tapping into about $1 million in angel investment to fund the work.
“[We] changed around some of the materials to make it a lot more compact, power dense, and cheaper,” Dewan says. Furthermore, they identified another big opportunity: the proposed design can be powered by the nuclear waste produced by traditional reactors. In traditional nuclear reactors, just 4-5 percent of the energy is extracted from the solid fuel rods used to power them. “That is why nuclear waste is so dangerous; it has a lot of energy left in it,” says Dewan.
Transatomic Power intends to use spent fuel from other plants and recover the remaining energy (simultaneously reducing the amount and intensity of radioactivity in the final waste stream). Their vision has attracted plenty of attention, landing Dewan, as its eloquent spokeswoman, on three separate lists of young innovators in big-name publications.
For now, however, the potential is still just that: potential. Transatomic Power’s MSR is only in the initial design stage, which is done almost exclusively through computer modeling and simulation. The company’s Series A funding, which is likely to be announced later this summer, will move its ideas from the simulation stage into the lab.