332. LASER ALCHEMY
Here's an interesting technology I ran across while researching something else.
From the Oct. 6, 2003 CERN Courier:
Laser alchemy could burn nuclear waste
A new approach to disposing of radioactive waste without using intense sources of neutrons is based on nuclear alchemy by laser. Ken Ledingham and colleagues from Strathclyde University, Glasgow University, Imperial College, and the Rutherford Appleton Laboratory (RAL) in the UK and the Institute for Transuranium Elements in Karlsruhe, Germany, have harnessed the ability of intense laser-plasma interactions to produce gamma rays that can be used for nuclear transmutation.
Working with the petawatt facility of the VULCAN glass laser at RAL, the team used a 0.7 ps pulse of 360 J to focus on a gold target with an intensity of about 5 x 10^20 W cm^-2. Electrons from the plasma formed in this way reached relativistic energies and emitted bremsstrahlung gamma rays as they stopped in the gold. The team used these gamma rays to irradiate a sample prepared with waste solution from a fuel processing plant. They found that the irradiation changed iodine-129 into iodine-128. While both these isotopes are radioactive, the change is important because it corresponds to swapping a half-life of 15.7 million years for one of 25 minutes.
by JD
posted by JD @ 2:10 AM
7 comments
7 Comments:
I'm not sure I would like to change something from a half-life of millions of years to a few minutes.
Something with a half-life of millions of years probably radiates so little that it's insignificant.
What I would like to see is how the deacay chain changes?
Anyway, the only two really problematic elements in nuclear waste are plutonium and americium.
Plutonium is dealt with today on an industrial scale and is not a problem from a radioactivity point of view.
Research is progressing on americium, but don't hold your breath. It might well take decades, and even if it's developed it probably will be more expensive than the deep burial developed today.
Something with a half-life of more than hundreds of thousands of years has pretty insignificant activity. Something with a half-life of less than a few years is nearly gone from the waste even before it's disposed of. The most worrysome isotopes are the medium length isotopes in the window between those extremes.
I somewhat doubt the utility of this. Obviously you can interact with nuclei with electromagnetic radiation, but the cost of building the laser and the rate at which you transmute the nuclei I suspect are less than glorious. We allready have ways of dealing with inconvenient isotopes anyways: Neutron radiation. If we have any reactor with a neutron surplus, we can allways use this to change the decay rate to something more desirable if its worth the effort.
The thing is, it almost never is worth the effort when you can pursue a prudent cost effective solution such as dry cask storage.
and how much uranium is there left in the world? that's a non-renewable resource..
"I'm not sure I would like to change something from a half-life of millions of years to a few minutes."
Actually it's enormously useful. Wait a few days and the material with 25 minutes half life will have lost its radioactivity.
"Anyway, the only two really problematic elements in nuclear waste are plutonium and americium."
Not really. Both of those are useful for reprocessing. The ugly radioactive stuff in nuclear used fuel aka 'waste' that's the worst are that partial products like strontium and cesium, which have half lives measured in years. This stuff can be radioactive for about 300 years, although the use fuel loses about 99% of its radioactivity in the first 10years
After 300 years, the only readioactive components are the actinides.
"and how much uranium is there left in the world? that's a non-renewable resource.." Actually,saying its non-renewable is about as relevant as saying sand is non-renewable. uranium resources are abundant relative to need and we will never run out of uranium and there is also plenty of thorium-233 as well. our once-through nuclear life cycle only uses about 3% of the useful Ur-235 energy, but even sticking with that wasteful course, we have centuries of resources. OTOH, a breeder-based processing system with nuclear power can last for about 1 million years at current use rates.
"The thing is, it almost never is worth the effort when you can pursue a prudent cost effective solution such as dry cask storage."
That's true. if its not going to be re-used, nothing is cheaper than just sticking it in a cement/steel cylinder and leaving it there.
OTOH, if you wanted to reprocess nuclear fuel, this might be a useful way to transmute undesireable products.
What we need to do is rethink Yucca mountain from being a 10,000 year repository to being a 100 year one: Store the stuff for 100 years, so the radiocativity cools off, and after 100 years you have a high-quality source of actinides ready for re-use as fuel.
I'll look for more information on this study currently but if you can repost any new info on this experiment that would be great.
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