New Reactor May Make Nuclear Power Safer and Cheaper: Technology Review India
New Delhi, February 25
A new way of fueling reactors could make nuclear power safer and less expensive as it needs only a small amount of uranium and doesn’t need to be opened from time to time.
A group of researchers at Intellectual Ventures, an invention and investment company in Bellevue, WA has come up with a preliminary design for a reactor called a traveling-wave reactor, which can generate power from uranium without damaging the environment and at a lower cost. This would reduce use of fossil fuels, reports the inaugural issue of the Indian edition of Technology Review, a 109-year magazine from Massachusetts Institute of Technology (MIT).
As it runs, the core in a traveling-wave reactor gradually converts nonfissile material into the fuel it needs. Nuclear reactors based on such designs theoretically could run for a couple of hundred years without refueling, says John Gilleland, manager of nuclear programs at Intellectual Ventures.
Enriching the uranium for reactor fuel and opening the reactor periodically to refuel it are among the most cumbersome and expensive steps in running a nuclear plant. And after spent fuel is removed from the reactor, reprocessing it to recover usable materials has the same drawbacks, plus two more: the risks of nuclear-weapons proliferation and environmental pollution.
Gilleland’s aim is to run a nuclear reactor on what is now waste. Conventional reactors use uranium-235, which splits easily to carry on a chain reaction but is scarce and expensive; it must be separated from the more common, nonfissile uranium-238 in special enrichment plants. Every 18 to 24 months, the reactor must be opened, hundreds of fuel bundles removed, hundreds added, and the remainder reshuffled to supply all the fissile uranium needed for the next run.
This raises proliferation concerns, since an enrichment plant designed to make low-enriched uranium for a power reactor differs trivially from one that makes highly enriched material or a bomb. But the traveling-wave reactor needs only a thin layer of enriched U-235. Most of the core is U-238, millions of pounds of which are stockpiled around the world as leftovers from natural uranium after the U-235 has been scavenged. The design provides “the simplest possible fuel cycle”, says Charles W. Forsberg, executive director of the Nuclear Fuel Cycle Project at MIT, “and it requires only one uranium enrichment plant per planet.”
The trick is that the reactor itself will convert the uranium-238 into a usable fuel, plutonium-239. Conventional reactors also produce P-239, but using it requires removing the spent fuel, chopping it up, and chemically extracting the plutonium—a dirty, expensive process that is also a major step toward building an atomic bomb. The traveling-wave reactor produces plutonium and uses it at once, eliminating the possibility of its being diverted for weapons.
Intellectual Ventures has patented the technology; the company says it is in licensing discussions with reactor manufacturers but won’t name them. Although there are still some basic design issues to be worked out—for instance, precise models of how the reactor would behave under accident conditions—Gilleland thinks a commercial unit could be running by the early 2020s.
 |