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Lasers point to the future of uranium enrichment


November 5, 2013

Laser enrichment of isotopes has major potential to reduce the cost of nuclear power (Phot...

Laser enrichment of isotopes has major potential to reduce the cost of nuclear power (Photo: Shutterstock)

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With the world’s first laser enrichment plant having received a construction and operating license from the US Nuclear Regulatory Commission in 2012, the stage has been set for a radical change in the industry. So how does laser enrichment work, and what commercial benefits, along with proliferation concerns, does this new process present compared to current methods?

Nuclear power plants generally benefit from uranium enrichment. By increasing the abundance of U-235 in uranium fuel rods from the natural abundance of 0.71 percent to 3 percent or greater, fewer compromises need be made to reach gigawatt power levels. A few reactors use uranium enriched to about 20 percent U-235, and at the extreme, some nuclear submarines use fuel enriched to about 93 percent.

Nuclear weapon designs based on uranium fission always benefit from uranium enrichment. Few proliferation concerns arose when the expensive and technically demanding method of gaseous diffusion was the only practical approach to enrichment, as only nation-states with enormous resources were likely to be able to use that process to obtain weapons-grade fuel. Given centrifuge and now laser-based enrichment technologies, this is no longer the case.

Three general types of uranium enrichment have been developed into large-scale processes: gaseous diffusion, centrifuge cascades and now laser-based enrichment. Of these, gaseous diffusion facilities have been considered to be too large, expensive, and technically demanding to represent a significant proliferation hazard. Such facilities are now obsolete and currently the dominant technology for uranium enrichment is the high-speed centrifuge cascade. Now that laser-based enrichment methods have arrived, will highly enriched uranium become significantly more accessible to rogue nations and terrorist groups? Let's take a look at this new approach in comparison to centrifuges in an effort to answer this question.


A gas centrifuge is a hollow cylindrical tube that is rapidly rotating around its long axis. The rotation produces a centrifugal force on a uranium hexafluoride gas in the cylinder, which acts to force the gas toward the wall of the centrifuge.

This force is stronger on uranium hexafluoride containing U-238 than on the same material that contains U-235. As a result, the gas near the centrifuge wall is enriched in U-238, while the gas near the axis of rotation is enriched in U-235. The largest centrifuges used in uranium enrichment hold only about 15 grams of uranium, so an enrichment plant must include many parallel paths to produce commercially viable quantities of enriched uranium.

Cascade of gas centrifuges used at Piketon, Ohio to produce enriched uranium (Photo: USDOE...

Typically, an enrichment cascade would require about seven stages to produce uranium enriched to five percent U-235, and about 20 stages to produce weapons-grade U-235. Centrifuge cascades have been the main route toward nuclear proliferation, most notably in Pakistan, Iraq, Iran, Libya, and North Korea.

Laser isotope separation

The new player in the game is enrichment techniques that depend on laser excitation to separate isotopes. The basis for all laser-based enrichment schemes is that the amount of energy required to put a uranium hexafluoride molecule containing an atom of U-235 into an excited state is slightly smaller (by about 0.1 percent) than the energy required when the uranium atom is U-238.

It turns out that carefully tuned photons from a 16 micron laser will excite the U-235 containing molecules, but not the U-238 containing molecules. As only molecules containing U-235 are in an excited state, this gives a handle with which to differentiate, and eventually to separate, the two isotopes.

To be built by GE and Hitachi, the first commercial-scale U-235 laser enrichment facility licensed for production will use an Australian-developed laser enrichment technology known as Separation of Isotopes by Laser Excitation (SILEX). Currently Silex has completed its phase I test loop program at GE-Hitachi Global Laser Enrichment’s (GLE) facility in North Carolina. When the commercial plant is built, its target enrichment level will be 8 percent, which puts it on the upper end of low-enriched uranium.

SILEX is only one of a number of new approaches that have been investigated for uranium enrichment. The SILEX process [PDF] was developed by Dr. Michael Goldsworthy and Dr. Horst Struve.

As part of licensing the technology to the United States Enrichment Corporation, details of the SILEX are classified under the provisions of the US Atomic Energy Act. So while we don't have the whole story on the details of the process, it's reasonable to assume that only about three stages of enrichment are needed to produce five percent enriched uranium from ore, and only about seven stages to produce fully weapons-grade enriched uranium. Estimates suggest that a laser-based uranium enrichment plant would have an initial cost, size, and power requirement about one-fifth that of an equivalent centrifuge-based enrichment plant. The operating cost would also be expected to be far smaller.

Simpler, smaller, and less costly are characteristics that give laser enrichment of isotopes major potential to reduce the cost of nuclear power. However, these same characteristics also make such processes pose a substantial danger for widespread proliferation. Time will tell which potential future will win out, or if both hopes and concerns are valid.

Source: US Nuclear Regulatory Commission

About the Author
Brian Dodson From an early age Brian wanted to become a scientist. He did, earning a Ph.D. in physics and embarking on an R&D career which has recently broken the 40th anniversary. What he didn't expect was that along the way he would become a patent agent, a rocket scientist, a gourmet cook, a biotech entrepreneur, an opera tenor and a science writer.   All articles by Brian Dodson

There is no future in Uranium enrichment that does not cause more harm than good. By the time all the waste has decayed, and the cancers and mutations buried, we will have had a net loss in energy production from the whole disaster. Fukushima is what we warned our parents about. Renewables are already far cheaper - imagine if they had had the subsidies instead!

Bob Stuart
6th November, 2013 @ 01:22 am PST

Sometimes I wish things could be "un-invented" :-(. Perhaps the technique could be developed for more peaceful purposes.

Paul Adams
6th November, 2013 @ 02:21 am PST

Bob Stuart > Renewables are already far cheaper - imagine if they had had the subsidies instead!

Freyr Gunnar
6th November, 2013 @ 05:19 am PST

When you consider the biggest challenges we face this is a good news story. Nuclear is clearly the most important tool we have for GHG reduction and resource depletion. Hard to think of a technology that has saved more lives and all in costs of wind/solar are far greater than even older nuclear on a truly level field.

The big problem for nuclear now is the short term fracking induced gas glut. Wind and solar are not less expensive in most capacity factor situations but are riding on the gas binge to deal with dispatch ability issues.

6th November, 2013 @ 08:05 am PST

So much for Thorium reactors - guess nuclear bombs are still more sexy than ADS reactors

6th November, 2013 @ 08:19 am PST

We're not going to see renewables making any kind of impact for decades. Nuclear is the way to go. We'll eventually resolve the waste disposal problems. Unfortunately this new process makes for an even scarier Iran.

Jeff Michelson
6th November, 2013 @ 08:25 am PST

@Bob Stewart: "nuclear waste" has always disturbed me. If it's radioactive enough to be dangerous, it's radioactive enough to potentially be a source of MORE ENGERGY. Storage of nuclear "waste" is actually just storing low grade nuclear fuel stocks until we come up with a way to concentrate what's left.

Bryan Paschke
6th November, 2013 @ 09:41 am PST

Although I like renewal energy, no matter how much subsidies you put into it. It will NEVER be predictable enough to produce enough energy on a day to day basis to override all the energy needs.

Remember, AC power cannot be stored or saved for another time. Electricity is planned and created base on predictability what is needed 365/24/7. Renewal energy has a LONG way to go to reach predictability.

Until then, stop sticking your head in the sand...and deal with nucs.

Luan To
6th November, 2013 @ 10:08 am PST

There's no free lunch. Penalties to be paid with any energy source (wind power a hazard to wildlife, solar panel production waste toxic). Newer nuclear technologies are safer, and this sounds like it reduces the cost. Thorium even safer, if they can ever make it practical. Even the holy grail of fusion produces lots of neutron radiation, unless you use Boron, but even the "easiest" fusion fuels (deuterium, tritium) haven't been made to reach break even yet. Cheaper and cleaner in the long run to restructure society, getting away from big cities and centralized power, moving to a more distributed population living in low energy use housing and telecommuting as much as possible.

Pat Kelley
6th November, 2013 @ 10:24 am PST

More Fukushimas.

6th November, 2013 @ 10:55 am PST

Thorium provides and alternative basis for nuclear energy that solves all concerns revolving around Uranium. Thorium reactors do not melt down, because the chain reaction requires a controlled input to be sustained. For the same reason, you cannot build atomic bombs with Thorium. Thorium is much more plentiful (by an order of magnitude), so it is cleaner to mine. And Thorium reactors can be used to safely burn up spent Uranium fuel rods. Why are nations not clamoring toward Thorium? (Could the answer be sitting three sentences back?)

Carlos Ricci
6th November, 2013 @ 11:02 am PST

Google "fastest growing energy source" to end the discussion about what will be the future. The free market is answering that question already and the answer is not "nuclear". Surprise!

6th November, 2013 @ 04:25 pm PST

Laser enrichment can this be used for the start up fuel for LFTR, as no other fission concept even comes close to its inherent safety and awesome efficiency. The liquid fluoride thorium reactor can power the entire world with only about 5,000 tons of thorium, displaying MANY BILLIONS of tons of fossil fuels. Renewables can't yet provide the energy to even "make themselves" much less to power planetary civilizations.

Go LFTR, or The slightly less inherently safe (but still melt down proof) integral fast reactor aka PRISM!

Robert Bernal
6th November, 2013 @ 05:43 pm PST

If usable, mass produce & reuse over those spent fuel rods alone & refit onto idle N plants like San Onofere CA alone for Demo model


Stephen N Russell
6th November, 2013 @ 05:52 pm PST

Ummmmm..... NO. Thorium, not Uranium, is the fuel we need to be using.

Seth Miesters
7th November, 2013 @ 08:15 am PST

BeWalt, "fastest growing" means nothing. It's only the fastest growing because governments are forcing utilities to install wind and it won't go beyond a few percent of the total output because it's too expensive. They would not install it on their own because it makes no economic sense and cannot be more than a few percent of our total power because it's too variable. When you add the cost of gas or coal plants that must be built to back up the wind turbines it makes it even more expensive.

California's solar initiative is another joke on the consumer. Billions were spent that had it been spent on nuclear would have provided TWENTY TIMES the power output of the installed solar cells.

10th November, 2013 @ 02:01 am PST
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