(from ~7-8 years ago)
Safe Nukes — No, Really!
By Wil McCarthy
One great thing about science fiction is that there are so many cool futures to choose from. You've got your robots future, your biotech future, your hardscrabble colonies out in the planets and asteroids. ... Of course, the real world of yet-to-come probably includes all of these and more; it's as complex a place as the world of today, and never loses the ability to surprise us. One thing all hopeful futures have in common, though, is clean, abundant energy. Without that, some people imagine we could sink back into a pleasant sort ofLittle House on the Prairie world, only with better medical care, longer lifespans and picturesque windmills dotting the landscape. But considering the population growth since 1880 (6.5 billion people now vs. about 1.5 billion then), and the difficulty of growing food without machines and energy-rich fertilizers, we're more likely to descend into a retro-dystopian Road Warrior-ville of bad haircuts and short, violent lives.
But that's a long way off, right? We don't really need to worry about it, right? Even when the oil runs out, the world has abundant supplies of coal, natural gas, crop waste and garbage to cushion us while wind and solar technologies become efficient enough to fill all our needs. Well, hopefully. One thing the world could really use, though, is a clean, efficient source of nuclear power. Fusion—the power source of the sun, which bangs hydrogen atoms together to produce helium and carbon and eventually iron—is by far the best of the alternatives, since it produces huge amounts of energy from tiny amounts of fuel, and leaves almost no waste behind. But we've been working on that for 50 years, with no real progress toward useful energy output. The physics work out just fine—hence sunburn, the H-bomb and lingering questions about cold fusion—but the engineering somehow eludes us. No matter what we do, our fusion reactors take in more power than they put out. C'est la vie.
That leaves fission, the nuclear power that works by breaking big atoms into little ones. These reactions are a lot easier to control, putting their abundant energy within easy grasp. Unfortunately, they produce high-level radioactive waste, which is immediately lethal and lasts for months or years, and also low-level waste, which is slow poison that can last for millennia. By itself this might be a tractable problem—the Earth's interior is a red-hot, radioactive hell, and there's no particular reason why we can't just sink the wastes in "subduction zones" where the movement of tectonic plates will carry them back down into the mantle whence they came. This may not be a politically viable solution, but it's a sensible one that would certainly work.
Alas, there are other problems with fission: meltdown and the Bomb. Uranium-235 breaks down in a chain reaction that feeds on itself, in the same way that fire feeds on itself. And like fire, it can occasionally run out of control if we aren't careful (think Chernobyl). Also, thanks to the same factors that make uranium power plants easier to build than helium ones, uranium bombs are also pretty simple. If you had access to the right materials and instructions, you could just about build one in your garage. And that's a huge problem, which forces governments to keep track of every gram of nuclear material running loose in the world. No one wants to live in a police state, but when the alternative is the sudden vaporization of random cities, strict measures may in fact be the lesser evil.
There's no fuel like a new fuel
This Promethean triple whammy has made nuclear power understandably unpopular in North America, with a popular sentiment that the world is simply better off without it. And that may be. But energy-rich countries like the United States and Canada can afford an opinion like that—at least for now. But with the Kyoto accords forcing Europe and Russia away from fossil fuels, the equation is not quite so simple, and in Third World countries, where ambitions run high and energy resources run low, it isn't even the same equation. Think of places like Nigeria, where a wealth of precious uranium lies waiting in the ground; it's no joke when people come around telling you not to dig it up. What else are you supposed to do for light and heat and money? But the poorest countries are also the least stable, and often the most corrupt. It's a bitter irony indeed, that nuclear power is needed most in the places we trust the least. That's bound to cause resentment all the way around.
But what if nuclear fuel were as common as lead, as nonpolluting as wind, as safe to handle as coal, and as terror-useless as ordinary concrete? Science fiction, you ask? Nope. Just science—soon to be everyday business.
At the bottom of the periodic table, eight steps over from lead and two back from uranium, sits thorium, a heavy metal used in gas lamp mantles and as an additive for alloys, glasses and ceramics. Named for the Norse god Thor (bringer of thunder and lightning), it's mildly toxic and even more mildly radioactive, but considered generally safe. About as safe as lead, anyway, and certainly much less dangerous than sunlight, which after all can cause radiation burns in under an hour and kill an unprotected human in a few days. Thorium is a much more common material than uranium, being found in most rocks and soils throughout the world. It's a component of ordinary granite and concrete, for example, and its slow breakdown is the reason those materials emit small amounts of radon gas, which can slowly build up in our cellars. (Radon is radioactive and contributes to lung cancer, so, on a completely tangential note, it's good to have your basement checked every now and then.)
Anyway, it turns out that if you bombard thorium with low-energy neutrons, it turns into an isotope of uranium which rapidly decays, releasing energy. This is not a chain reaction, so in special power plants called subcritical energy amplifiers, the breakdown can be controlled precisely, in a process that simply can't run away or melt down the way ordinary reactors have been known to. Even better, the decay of thorium produces no weapons-grade materials of any kind. The worst you could do is make a radioactive "dirty bomb" from the reactor waste. But even here you'd run into problems, because thorium waste—while highly radioactive—doesn't last nearly as long as uranium waste. You still want to be careful with it, but it loses the worst of its punch within 10 to 20 years, and after just 500—the blink of an eye, in geological terms—it's as harmless as coal ash.
In fact, energy amplifiers can be used to break down normal reactor waste, and even bomb-grade materials like plutonium, making them more radioactive but much shorter-lived. (If that sounds paradoxical, just remember a simple rule: Isotopes with a short half-life emit more radiation because they break down faster. The ones with long half-lives emit fewer particles. Stable, nonradioactive atoms have infinite half-lives. The hardest wastes to store are actually the ones in the middle, which are radioactive enough to be dangerous but long-lived enough to outlast any reasonable disposal method.) So in one fell swoop, thorium addresses all three of nuclear power's main weaknesses, and offers a number of interesting benefits on the side, including cheap, abundant energy that could easily dwarf the output of uranium and fossil fuels combined. It's like discovering you can heat your house with sand!
Nuclear power to the people
The next question to ask here is why we aren't building thorium-based power plants on every street corner. It's a good question, with no definitive answer. The basic design has been around since 1993, when Italian physicist and Nobel laureate Carlo Rubbia published a report at CERN, the European Center for Nuclear Research. The underlying physics have actually been known for decades, and confirmed by experiments all over the world. A few commercial nuclear plants have even used thorium as an adjunct fuel in standard U-235 reactions. But pro-nuclear countries have little incentive to switch away from uranium, while the anti-nuclear ones have no interest in developing new reactors, and of course poor countries couldn't build an energy amplifier even if they wanted to.
Nestled in the middle, though, are a handful of countries with the courage, cheap labor and freewheeling spirit of the Third World, but the education and capital resources of the First World. India in particular has positioned itself as the next likely superpower, with a capable military, a number of rapidly growing cash industries and a burgeoning appetite for energy of all kinds. No strangers to nuclear power (they got the bomb in '74), the Indians are drawn to its luminous promise and little dissuaded by the problems and accidents of the 20th century. And as luck would have it, they're also sitting on some of the richest deposits of thorium in the world—a coincidence that isn't lost on their scientists.
At the Bhaba Atomic Research Center near Kalpakkam, nuclear eggheads like Anil Kakodkar have been noodling with thorium since 1995, and are currently building a pilot plant to work the bugs out of Carlo Rubbia's design. If all goes well, the reactor should begin producing continuous power by the end of the decade, and should pave the way for nine commercial workhorses due to come online between 2010 and 2020. If the scheme works—and there's no scientific reason why it shouldn't—it could well pave the way for a global migration to fission technology safe enough for urban areas and Third World dictatorships. So, far from ignoring the problem or playing the politics of half-measures, India is positioning itself for the realities of Kyoto and the decline of fossil fuels, and plans to be a leader in 21st century energy technology. I say, more power to 'em!
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Sources used for writing are:
"The Periodic Table in Earth and Sky," 3rd edition, Jenner Scientific LLC, 2005
Wikipedia: ("thorium","Carlo Rubbia","energy amplifier", "overpopulation"):
www.wikipedia.org www.webelements.com ("thorium")
"The Energy Amplifier: Carlo Rubbia's solution to world energy demand": CERN Courier, April/May 1995
"Kalpakkam to get next generation fast reactor", The Hindu 09 March 2003
"A mission at Kalpakkam," Frontline, Volume 17 - Issue 26, Dec. 23, 2000
The Encyclopedia Britannica, 2004 Edition ("thorium," "thorium processing")
