Centrifuge May Be Superseded by Laser Enrichment

An anonymous reader writes "Australian scientists have discovered, after a decade of tests, a new way to enrich uranium for use in power plants." From the article: "There are at present only two methods for sifting uranium atoms, or isotopes, to create the right mix. One, called diffusion, involves forcing uranium through filters. Being lighter, U-235 passes through more easily and is thus separated from its heavier counterpart. The second method, widely adopted in the 1970s, uses centrifuges to spin the heavier and lighter atoms apart. Both, said Dr Goldsworthy, are 'very crude. You have to repeat the process over and over,' consuming enormous amounts of electricity. The spinning method requires 'thousands and thousands of centrifuges'."

Comments

Re:True cost of nuclear...?

[DemoLiter3]

No problem : here you have an emissions comparison for all widespread methods and various pollutants

http://www.nei.org/index.asp?catnum=2&catid=260

This is hardly a new technology

[Trestop]

According to Mordechai Vanunu, the Israeli nuclear whistle blower - as quoted by the Sunday Times - Israel had laser enrichment technology, in actual production use, at the early 1980s.
http://en.wikipedia.org/wiki/Mordechai_Vanunu

So - nothing new here, move along, move along.

Women And Warheads

[cybrpnk2]

I'm one of the "500 scientists" who worked on the ""failed" US efforts in the early 1980s, and I'd take this whole report with a grain of salt. First of all, just how far the US got with our effort is classified and having the media calling it a "failure" doesn't mean that we never accomplished in our labs 20 years ago what these Austrians did in theirs last month. The US lab effort was HUGE and not just aimed at uranium enrichment. There was a seperate program for seperating plutonium isotopes via laser enrichment to fine-tune and further miniturize nuclear weapons to an amazingly small package. These were the Reagan Star Wars years, after all.

However, it's a LONG way from lab benchtop enrichment experiments to a functioning enrichment plant. And once you get to that functioning enrichment plant, there's the question of whether or not it was economically justifiable to build in the first place. This is where the American effort "failed" - even on paper, it never made sense to pursue this technology because it was just too expensive. Sure, you need thousands of high-precision centrifuges to run an enrichment cascade. This was still cheaper than building a laser enrichment plant.

The designs for a uranium laser enrichment plant ON AN INDUSTRIAL SCALE are not for the fainthearted. YOu've got to have the uranium in a gaseous state. That means heating it so hot that not only do you have a pool of molten uranium, but it's BOILING. The laser is going through the HOT uranium "steam". The only material that can stand up to these temperatures is pure graphite. The design becomes like a series of rain gutters on a house that carries "more enriched" and "less enriched" streams of molten uranium back for reboiling. Somehow you've got to figure out a way of putting optical ports into this hellhole to fire the laser beams in. The laser beams themselves are a weird wavelength (green) and takes some really expensive gear to generate at all, much less with intense enough power to penetrate deeply into a fog of molten uranium. Doing all of this cheaply? Good luck.

And in the background overshadowing enrichment plant economics was and is the fact that nuclear power plants are still just too expensive a way to generate electricity (primarily due to regulatory costs) compared to coal and natural gas turbine plants. The expected boom in nuclear power plant construction forcast in the 1970s and early 1980s never materialized, mainly due to Thre Mile Island and Chernobyl, and so the need for new-fangled enrichment technology as a support industry never materialized with it either.

Right now the cheapest way to come up with fuel for a nuclear power plant is not laser enrichment or even centrifuge enrichment. It's diluting old Russian warheads, all 30,000 of them, down from 93% enriched uranium back to 3% uranium. This, along with all those Russian brides American men now have access to, are the REAL spoils of winning the Cold War.

Fun with lasers

[Deadstick]

That trick of selective absorption of laser light has some pretty neat applications...you can actually cool a gas by shining a laser into it.

If a photon of precisely the right frequency (and therefore energy) hits an atom, two things happen:

(1) It gets absorbed, and transfers its momentum to the atom -- i.e., gives it a little push.

(2) One electron in the atom absorbs the photon's energy, exciting it to a higher energy level.

Then, after a random time interval, two more things happen:

(3) The electron drops back down to its old energy level.

(4) The atom emits a photon, carrying the energy given up by the electron, and the photon's momentum delivers another push to the atom.

But while the first push was in the direction of the laser beam, the second one is in a random direction -- so the affected atoms, statistically speaking, wind up with a net gain of momentum in the direction of the laser beam.

So far, the laser is basically just stirring the gas. Now you tune the frequency of the laser a little bit lower. The "average" atom sees the photons at the wrong frequency, and the photons just truck on by. But atoms that happen to be moving toward the laser see the photons Doppler-shifted up to just the right frequency and they receive a push away from it -- so their average speed is reduced. Ba-bing, ba-boom, the gas is colder.

Laser cooling, along with a couple of other techniques, made it possible to get the super-low temperature needed to isolate the Bose-Einstein Condensate which got the 2001 Nobel.

rj