Skip to main content

The Traveling-Wave Reactor

Traveling Wave Nuclear ReactorIntellectual Ventures, an invention company, believes they've developed a "new reactor design [that] could make nuclear power safer and cheaper." Published by MIT's Technology Review magazine:
a traveling-wave reactor requires very little enriched uranium, reducing the risk of weapons proliferation. (Click here for a larger diagram). The reactor uses depleted-uranium fuel packed inside hundreds of hexagonal pillars (shown in black and green). In a “wave” that moves through the core at only a centimeter per year, this fuel is transformed (or bred) into plutonium, which then undergoes fission. The reaction requires a small amount of enriched uranium (not shown) to get started and could run for decades without refueling. The reactor uses liquid sodium as a coolant; core temperatures are extremely hot--about 550 ºC, versus the 330 ºC typical of conventional reactors.

...

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.

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 for 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. An active region less than a meter thick moves along the reactor core, breeding new plutonium in front of it.

The traveling-wave idea dates to the early 1990s. However, Gilleland's team is the first to develop a practical design. 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.

While Intellectual Ventures has caught the attention of academics, the commercial industry--hoping to stimulate interest in an energy source that doesn't contribute to global warming--is focused on selling its first reactors in the U.S. in 30 years. The designs it's proposing, however, are essentially updates on the models operating today. Intellectual Ventures thinks that the traveling-wave design will have more appeal a bit further down the road, when a nuclear renaissance is fully under way and fuel supplies look tight.

"We need a little excitement in the nuclear field," says Forsber­g. "We have too many people working on 1/10th of 1 percent change."
Sounds very promising! Be sure to watch the animated video as well.

Hat tip to FuturePundit.

Comments

Anonymous said…
Sounds a lot like a candle-type reactor. I just hope the fuel containment won't fail after a few decades. These reactor types always push mechanical fatigue to their limits on paper...
Anonymous said…
give it time. hopefully with a few more innovations in storage/containment ability this will become a viable solution in the days to come.
Anonymous said…
I see a serious problem with this design, which is the neutron balance. Once the wave has traveled a bit through the bloc, something like half of the neutrons will be directed into the burned-up part and not contribute to the chain reaction, nor contribute to the breeding, and I don't see how you can keep this going. After all, a breeder needs 2 useful neutrons per fission (one for the chain, and one for the breeding), and with plutonium, you get at most 2.9 or so, so you can permit to loose overall at most 0.9 neutrons. But if you loose half of them (by geometry) you've already lost 1.4 or so.
Gunnar said…
Maybe the core innovation is a kind of Maxwell's demon who is able to direct the neutron's deflector shields effective axis towards the wave front.
Anonymous said…
make a sphere of fuel and start fission in the centre. what's the problem?

Popular posts from this blog

An Ohio School Board Is Working to Save Nuclear Plants

Ohio faces a decision soon about its two nuclear reactors, Davis-Besse and Perry, and on Wednesday, neighbors of one of those plants issued a cry for help. The reactors’ problem is that the price of electricity they sell on the high-voltage grid is depressed, mostly because of a surplus of natural gas. And the reactors do not get any revenue for the other benefits they provide. Some of those benefits are regional – emissions-free electricity, reliability with months of fuel on-site, and diversity in case of problems or price spikes with gas or coal, state and federal payroll taxes, and national economic stimulus as the plants buy fuel, supplies and services. Some of the benefits are highly localized, including employment and property taxes. One locality is already feeling the pinch: Oak Harbor on Lake Erie, home to Davis-Besse. The town has a middle school in a building that is 106 years old, and an elementary school from the 1950s, and on May 2 was scheduled to have a referendu

Why Ex-Im Bank Board Nominations Will Turn the Page on a Dysfunctional Chapter in Washington

In our present era of political discord, could Washington agree to support an agency that creates thousands of American jobs by enabling U.S. companies of all sizes to compete in foreign markets? What if that agency generated nearly billions of dollars more in revenue than the cost of its operations and returned that money – $7 billion over the past two decades – to U.S. taxpayers? In fact, that agency, the Export-Import Bank of the United States (Ex-Im Bank), was reauthorized by a large majority of Congress in 2015. To be sure, the matter was not without controversy. A bipartisan House coalition resorted to a rarely-used parliamentary maneuver in order to force a vote. But when Congress voted, Ex-Im Bank won a supermajority in the House and a large majority in the Senate. For almost two years, however, Ex-Im Bank has been unable to function fully because a single Senate committee chairman prevented the confirmation of nominees to its Board of Directors. Without a quorum

NEI Praises Connecticut Action in Support of Nuclear Energy

Earlier this week, Connecticut Gov. Dannel P. Malloy signed SB-1501 into law, legislation that puts nuclear energy on an equal footing with other non-emitting sources of energy in the state’s electricity marketplace. “Gov. Malloy and the state legislature deserve praise for their decision to support Dominion’s Millstone Power Station and the 1,500 Connecticut residents who work there," said NEI President and CEO Maria Korsnick. "By opening the door to Millstone having equal access to auctions open to other non-emitting sources of electricity, the state will help preserve $1.5 billion in economic activity, grid resiliency and reliability, and clean air that all residents of the state can enjoy," Korsnick said. Millstone Power Station Korsnick continued, "Connecticut is the third state to re-balance its electricity marketplace, joining New York and Illinois, which took their own legislative paths to preserving nuclear power plants in 2016. Now attention should