Nuclear Power: What’s Next.Jun 6th, 2008 | By Jonathan Golob | Category: Featured Articles, Nukes
Nuclear power plants were first proposed at the dawn of the cold war. It was assumed the best fuels–enriched the most for atoms releasing the most neutrons per fissioning–would forever be reserved for military use. We had bombs to build. Hundreds, thousands, millions–enough to scare the Soviets (and the Soviets to scare us.) Military first, commercial power second. So, the plants were designed around using minimally enriched fuels with moderators to keep the scant neutrons around. Hence the collection of plants in operation today, almost all based around mildly enriched Uranium, moderated and cooled by heavily pressurized water. By far not the safest or most efficient design, but doable, particularly if you are limited to mediocre quality fuel.
Two funny things happened along the way.
The development of the hydrogen bomb vastly increased the efficiency of atomic bombs. Effectively limitless amounts of explosive force can be created using relatively small amounts of highly enriched Uranium or Plutonium, some heavy hydrogen and lithium and a whole lotta unenriched Uranium. About the time the US and the Soviets could destroy the entire surface of the planet three times over, interest in building more bombs started to wane.
Then the US won the cold war. While more and more states can field nuclear bombs, most have realized all you need are a few–just enough to pose a solid deterrent. You can’t eat atomic bombs. Nor can you really use them in war. Atomic bombs have always been a sort of military-industrial masturbation, a show of prowess rather than a practical weapon, a solid way of saying “don’t mess with me.”
The result? Our present world is awash in enriched Uranium-235 and plutonium–fine for making bombs or much better nuclear power plants. With this sort of high quality fuel, we have neutrons to spare. Let’s do some interesting things with them.
The first thing we can chuck from our reactor? The moderator. If we have enough neutrons, we can keep the chain reaction going even if most are flying away before meeting another fuel atom–a fast neutron reactor. No more graphite or water. Now we can use something more forgiving as a coolant, like molten metal or an inert gas. Wait, wasn’t one of the safety features of the water-moderated, water-cooled reactor that the loss of water would shut down the chain reaction? Fine. We’ll load the fuel a matrix that physically expands as it gets hotter. If it gets hot enough, the fuel will get too far away to keep the chain reaction going. Great! We’re back to the lose-coolant, lose-chain reaction situation.
What can we do with all those extra neutrons? Why not use them to smash up all those pesky radioactive decay products! Now, instead of having to periodically remove the fuel rods and chemically remove all the neutron-absorbing, non-fissioning, and highly radioactive waste atoms, we’ll just burn them off right in our reactor.
A traditional pressurized water reactor can only fission about 3-5% of the Uranium in it’s fuel before it has to be removed an reprocessed. About 270,000 metric tons of radioactive waste are scattered around the world, predominantly stored in pools or casks right next to the power plants thanks to this inefficiency. If we use the extra neutrons in our fast neutron reactor to burn off the radioactive waste, we can boost this efficiency to above 90%. With some relatively simple fuel-reprocessing on site, we can boost this to 99%.
Nuclear waste is the overwhelmingly major problem with nuclear power plants today. There is no plan, no strategy beyond burying it someplace for at least a million years. No technology exists that matches the problem. Fast neutron plants, that eat their own waste and potentially the waste of others, are an overwhelmingly better solution than Yucca mountain.
Where are these plants? The ideas here aren’t new ones. A pilot project, the Integral Fast Reactor (IFR) was to build a liquid sodium metal cooled, plutonium and U-235 fueled fast neutron reactor with an on-site waste processing center. The project’s budget was cut in 1994 by President Clinton‘s energy secretary and thus languished before the project could be completed. The ideas from this project have been rejuvenated, with plans for a liquid sodium, liquid lead and gas cooled reactor variants based around the same general principles, called generation IV reactors, to be ready for commercial operation in 2030.
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.