Science Nuclear Power
posted by June 7 at 14:10 PMon
With oil prices spiking again—I say from both real increases in global demand and speculation piggybacking on the market conditions, you may disagree—and global energy supplies at some of the tightest margins ever, is it any surprise that…
Nuclear power, long reviled as a dangerous source of energy, is on the verge of a comeback. That’s because a growing body of scientists, politicians and environmental activists see atomic energy as part of the solution for global warming and our ever-growing dependence on foreign oil, much of it from nations that, if not downright hostile toward us, certainly don’t share our values.
Well, what of nuclear power? On the Dear Science blog, I’ve just completed a six post series on nuclear power, covering…
Every nuclear power plant in operation today works by capturing the energy release when a really unhappy large nucleus breaks up into two smaller and more successful get-togethers–atomic fissioning. When these cranky huge parties break up, a few neutrons typically get flung out at high speeds–think of these as a few type-B’s from the party screaming away in tears. If these neutrons hit another large nucleus, teetering towards breaking up already, they can smash the party to pieces, sending yet more neutrons out.
So, you can imagine a game where you place enough of these large nuclei next to one another, such that the neutrons from one breaking up shortly cause a neighboring large nucleus to break up, sending more neutrons out to break up more nuclei… creating a chain reaction.
… how almost all current nuclear power reactors work…
The goal? A controlled fissioning of large nuclei. You’ll need fuel, moderation, coolant, and some control…
Hey, something nifty! Water is both a good coolant and moderator! No moderator, no chain reaction, right? So, if you use water as your coolant and moderator, your reactor has an intrinsic safety feature. If you lose coolant, you lose moderation and the chain reaction stops. We all live! Thus, almost all nuclear reactors in operation today use water as a coolant and moderator.
Alpha particles, the cannon balls, can be stopped by a single sheet of paper. Smash! Likewise, the dead outer layer of skin does a damn good job of protecting your living cells from alpha particles. Beta particles, the bullets, go right through paper. A thin sheet of aluminum, or something of similar density and substance, will gobble these up.
Gamma radiation is trickier. Gamma radiation is just a freakishly high energy version of light, with almost no substance. Just like light can pass right through your hand, gamma radiation can pass through all but the heaviest and densest of metals, wreaking havoc deep into the body.
… nuclear waste …
When we loaded our reactor, the fuel was chemically fairly pure. Recall, however, that nuclear decay typically results in new chemicals being created–whether by alpha or beta decay or by fissioning. As our reactor operates, these new atoms build up. Most are radioactive themselves, also undergoing various decays. Most of these atoms are neutron hoarders–gleefully absorbing our precious neutrons, while offering up few when they themselves decay. So, as these new atoms build up, we lose more and more neutrons. Eventually there are too few free neutrons left to keep the chain reaction going, even if we completely remove the control rods. Such fuel, still containing a bunch of Uranium but now contaminated various highly radioactive but non-chain reacting atoms, is called spent. It’s hideously radioactive, more radioactive than when we put the fuel in the reactor, but useless as fuel.
Welcome to the trickiest problem of nuclear power, the waste. What can we do?
… the two most famous disasters at nuclear power plants …
I’d like to imagine the following exchange, between a middle manager in the Soviet Union and us, some plucky nuclear engineers, when planning these plants:
Middle manager: “You have my plant design?”
Us: “Yes, but it is incredibly dangerous!”
MM: “But it will work without any Plutonium, enriched Uranium or heavy water?”
Us: “Yes. In fact, it produces Plutonium as a waste product!”
MM: (Claps hands) “Excellent. We shall have such nice dachas when I tell everyone of this plan.”
Us: “It is far to dangerous to build. I refuse to do it!”
MM: (Laughs. Then pauses.) “Oh. You’re serious.”
MM: (Considers his boss, probably some one-eyed, one-armed veteran of Zhukov’s Berlin campaign in the Great Patriotic War, who won’t be sympathetic to concerns about hoards of irradiated civilians after asking why his reactor isn’t operating yet.)
MM: (Points to us.) “Guards, shoot this man.”
Us: (Shot in the head)
MM: (Turns to our assistant) “So, ready to build the reactors?”
Assistant: “Let’s just pick some places in Ukraine, Romania and other shitholes to build ‘em, yes?”
… and finally what future reactor designs will be like.
The designs are, individually, brilliant. The lead-cooled variant is designed to be modular. The reactor is small, easily installed and removed and works for about fifteen to twenty years without having to be opened or refueled. Perfect for countries or remote areas with no interest in or infrastructure for refining nuclear fuels. The gas-cooled variant can operate safely at huge temperatures and is incredibly efficient at minimizing waste products in a relatively simple manner. The sodium-cooled design is the dreamiest to me. Such a reactor complex could not only operate at tremendous efficiencies, but also eat up the waste of the older pressurized water reactors. Keen!
2030 is too far away. If we were smart, we would throw resources at these fourth generation technologies, pushing to have the pilot reactors and designs finalized within ten years. None of these are perfect. No source of power is without risk or environmental injury. None. Our planet hosts nearly seven billion people. Fossil fuel reserves are dwindling. The atmosphere and oceans are buckling under the carbon strain. Nuclear power, particularly responsibly applied with standardized plant designs and a real plan for dealing with the waste, remains our best hope. The physics and technology is available. We just need to do it. Now.
It’s time we talked about nukes. For most, the opinions run deeper than knowledge. Read my series, or pick up a good book on the subject. Educate yourself. Get an informed opinion and then go out and win some arguments.