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Science & Technology |
Economist: A modern philosopher's stone - Radioactive waste disposal |
2006-05-01 |
It may be possible to destroy much of the world's long-lived radioactive waste, if a new experiment in Japan proves successful TRANSMUTATION of the elements was the goal of the medieval alchemists. They dreamed of the riches to be won by the man who could find the philosopher's stone—a substance that, among other wonderful properties, would convert base metals such as lead into gold. Actual transmutation, though, had to await those modern alchemists, the atomic physicists. Nuclear reactors transmute elements routinely. They break uranium atoms, which are heavy, into lighter so-called fission products, such as technetium. This releases energy, along with sub-atomic particles called neutrons. Some of these neutrons go on to hit further uranium nuclei so hard that they, too, shatter and release yet further neutrons. It is this chain reaction that sustains the process. Other neutrons, however, are captured by uranium nuclei. That makes those nuclei heavier still, converting them into neptunium, plutonium, americium and curium. All these by-products of nuclear fission are radioactive, and many will remain so for thousands—sometimes millions—of years. They are thus difficult to dispose of; the most practical idea being to bury them deep underground in stable rock formations and just wait. On top of that, the plutonium could, in principle, be extracted to make nuclear bombs. But the organisers of the Kumatori Accelerator-driven Reactor Test Facility (KART), at Kyoto University in Japan, which starts up this month, have dusted off an old scheme that might help overcome the problems of nuclear waste. This is to transmute the by-products still further, into something that can be disposed of safely. Analysis in another blog... are heavy, into lighter so-called fission products, such as technetium. This releases energy, along with sub-atomic particles called neutrons. Some of these neutrons go on to hit further uranium nuclei so hard that they, too, shatter and release yet further neutrons. It is this chain reaction that sustains the process. Other neutrons, however, are captured by uranium nuclei. That makes those nuclei heavier still, converting them into neptunium, plutonium, americium and curium. |
Posted by:3dc |
#1 *sigh* This idea has been around for ages. It's called nuclear incineration. This takes advantage of the strange fact that the amount of radioactive waste in a nuclear power reactor is a function of reactor power, not megawatts generated. This seems counterintuitive: it's as if pollution from cars is a function of how FAST you drive them, not how FAR you drive them. Surprising, yes. counterintuitive, yes. and absolutely true. Theoretically, you can take the waste from 6 reactors, dump it into one reactor, cook it for a full fuel cycle, and have the waste from 1 reactor come out at the end. oh, AND the electricity generated is a bonus. Practically speaking, nobody wants to handle fuel that already has the waste products embedded in it: too radioactive to ship around. |
Posted by: Ptah 2006-05-01 21:57 |