Traveling-Wave Nuclear Reactor

[n2doc]

A new reactor design could make nuclear power safer and cheaper, says John Gilleland.
By Matt Wald

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.

These problems are mostly accepted as a given, but not by a group of researcher s at Intellectual Ventures, an invention and investment company in Bellevue, WA. The scientists there have come up with a preliminary design for a reactor that requires only a small amount of enriched fuel--that is, the kind whose atoms can easily be split in a chain reaction. It's called a traveling -wave reactor. And while government researchers intermittently bring out new reactor designs, the traveling-wave reactor is noteworthy for having come from something that barely exists in the nuclear industry: a privately funded research company.

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.

more:

http://www.technologyreview.com/energy/22114/page1/


A. Coolant pumps

B. Expansion area for fission gases

C. Fuel (depleted uranium) inside the hexagonal pillars; green represents unused fuel, black spent fuel

D. Fission wave (red)

E. Breeding wave (yellow)

F. Liquid sodium coolant

[Greyskye]

1. Looks good in theory.

Have to watch out for the hype though. The quote above talks about not needing refueling for '200 years', while the associated video http://www.technologyreview.com/video/?vid=266 gives a 60 year timeframe without refueling.

[struggle4progress]

2. How exciting. Yet another still nonexistent nuclear device that's going to solve all our problems

It seems like only yesterday we were hearing of the glorious future that pebble-bed reactors would bring

Proposed pebble-bed reactor ‘not feasible’
Shanthini Naidoo Published:May 30, 2007

A damning report doubting the feasibility of the pebble-bed nuclear reactor project was given to the government four years ago — yet the country is pressing ahead with plans to build one. The government has already invested R2-billion, and the report has been kept under wraps ... One of the authors of the report, British nuclear expert Steve Thomas, describes the entire process as bizarre, saying the researchers were sworn to secrecy and not allowed to discuss their findings publicly or with each other ... “It has all gone very badly since 2002,” said Thomas. “The government has invested a lot of prestige and backing into this. The more money they invest, the more difficult it is to pull out ... http://www.thetimes.co.za/TheVault/Article.aspx?id=304816

[bananas]

3. A "new" design that's 20 years old

"The traveling wave reactor (TWR) was first suggested in the 1990s by Manhattan Project member Edward Teller"
http://en.wikipedia.org/wiki/Traveling_wave_reactor

and it's been rejected for 20 years for good reason.

[phantom power]

4. I wonder...

if they require active moderation of the wave progression, or if it's all passive and accomplished with the fuel mixture design.

[Greyskye]

5. Linked article and video implies that it's passive

My interpretation. :shrug:

[phantom power]

6. Passive would be the elegant (and safest) solution.

Puts more burden on the fuel mixture, but maybe not more so than usual.