Nuclear power basically comes down to two issues: Safety and cost. Nobody denies that mass nuclear has the raw production capacity to provide for our energy needs through the remotely foreseeable future, but some argue that doing so would either bankrupt us, sicken us, or both. While this is certainly a disputed interpretation, it’s one that has been gathering support in the wake of the Fukushima disaster and a prolonged PR campaign from coal, natural gas, and certain wings of the environmentalist movement. As a result, the conventional nuclear industry, floundering due to widespread public unease and growing legislative opposition, seems to be begging for a revolution.
MIT and Transatomic’s Russ Wilcox certainly thought so last year, when he told Forbes that the coming years would be “a fabulous time to do a leapfrog move”. It was a strident statement at the time, even for a company boasting the former CTO of the nuclear pioneer Westinghouse, and the head of nuclear engineering at MIT. This week, though, Transatomic finally co-localized its money and its mouth, announcing a potential leapfrog technology that they claim could re-energize the energy industry: they claim to know how to make nuclear reactors smaller.
That’s an old idea, of course, and one that preoccupies most modern nuclear researchers. It has been generally accepted that the costs of continually scaling up nuclear reactors of any type will never be ameliorated by the associated increase in energy production. Large modern reactors don’t tend to produce much more than 1000 megawatts, despite grand increases in the technology. For the purpose of efficiency, it seems that the only solution is to build more and smaller reactors, but such mini-plants have only produced 200 megawatts or so; their energy production doesn’t approach the inflection point that marks the greatest possible efficiency, and the beginning of diminishing returns.
Enter Transatomic’s molten salt reactor (MSR). Researchers have actually had working models of the MSRs since the ’60s, but they’ve never been used for commercial purposes. One reason is that much of nuclear’s research capital comes from the military, and bulky MSR technology has traditionally been less desirable for submarines and aircraft carriers than their relatively slim light-water cousins. Another is that the plants require a separate facility to filter their core mixture. Still, for the purposes of mass land power production, the MSR design has some serious advantages, most importantly with respect to our two key issues: safety and cost.
The safety advantages of this project are mostly features of molten salt reactors in general. Using high boiling-point coolants like fluoride or chloride salts in place of light or heavy water negates the need to pressurize the system and instantly reduces the dangers associated with super-heated, pressurized liquids. Keeping the fuel-coolant mixture at a reasonable pressure also allows the mixture to expand — if the system overheats, the medium expands and holds fuel atoms too far apart for continuation of the nuclear reaction. This is called a passive safety system, and in a post-Fukushima industry such disaster-proof measures simply must be the future of nuclear power.
In the same vein, Transatomic’s proposed reactor would also have a so-called freeze plug — an actively cooled barrier that melts in the event of a power failure, leading all nuclear material to automatically drain into a reinforced holding tank. These reactors are “walk away safe,” meaning that a power failure, a runaway heat cascade, and a general worker’s strike could all happen on the same day — and the worst we’d suffer is loss of service. Fukushima’s problems stemmed (mostly) from the fact that the tsunami knocked out its diesel coolant pumps. MSR reactors replace such delicate systems with rugged ones: gravity, heat, and the most basic chemical properties of their materials.
Then, there are the costs. Transatomic claims their reactor will be capable of pumping out 500 megawatts for a total initial cost of about $1.7 billion. By comparison, the super-advanced light water Westinghouse AP1000 pumps out a little over 1000 megawatts for an estimated $7 billion. That’s about half the cost per megawatt, at least on paper. The new reactor would also be small enough to be built in a central factory and then shipped to its destination, rather than requiring that the plant’s eventual location be made into an expensive, multi-year construction site.
Transatomic is not hedging its bets: the researchers claim their design is production-ready, and stand behind their numbers. “I wish someone would build this thing,” said one early investor. The project has raised about $1 million, so far.