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PostPosted: Jan 13, 2008 5:24 pm 
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STG wrote:
Am I mistaken perhaps?


I just don't think that fusion will ever be a large consumer of tritium. If one believes that controlled, affordable nuclear fusion is some sort of inevitability (an attitude that I often see in future energy discussions) then it would be logical to assume that someday fusion will consume lots of tritium.

But I really don't see the evidence to support that. Fifty years ago fusion was really hard, and impossible to make economic. Twenty years ago fusion was really hard and impossible to make economic. The situation is the same today. I see little reason to think that the laws of physics are going to be changing.

Contrast that with thorium, where there is no question about the physical feasibility of its energy release. All questions are engineering, economic, and political.


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PostPosted: Jan 14, 2008 2:22 pm 
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fusion reactions are working, look at the JET experiments. It is only hard to sustain the reaction. But that is due to some physics related to the primary transformer of the tokamak reactor.

But with new means to create the plasma current the reaction can be sustained. The only thing to prove then is that this can be done while fuelling (with T-cubes, gas puffing and neutral beam injectors) and while removing He-ashes, and this will probably be demonstrated at ITER. There are already designs done by CEA and JRC Karlsruhe to extract the energy of the 14MeV neutron while creating tritium. It goes without saying that the energy created will be greater when less tritium has to be bred.

And indeed it is hard to sustain a fusion reaction, that's what makes it so safe (in the mind of the public). And the laws of physics have nothing to do with the economics of a fusion plant. It is true that over the long years of fusion research not much has been realised in practical point of view, but the exploration of the physics behind the process has been realised. Now we know the laws, let's use them.

And by the way, it's the US their fault that the International fusion program caught up some delay. And let's be honest, the budget that fusion receives are peanuts, just like the budgets some other interesting technologies recieve.

So again the matter is just like for thorium: engineering, economics and politics.

And of course I know that commercial fusion will only be available after GEN-IV. But in the lectures in Belgium and Europe in general, LFRs are placed on an equal time scale. Furthermore there are currently a lot of articles being published about fusion-fission breeders (see articles by Mannheimer), which show more potential on the short term in my opinion.


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PostPosted: Jan 14, 2008 4:37 pm 
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You're comparing a working reactor that has run for years at a time to some proof of concept engineering? I'm sure we'll get there someday over the next ten centuries, but its not a likely technology for the next hundred years unless Bussards electrostatic confinement or something like it really did work, which I honestly think just isn't likely.

Sure we could make a fusion reactor work that would produce lots of energy with engineering from 40 years ago also. All you have to have is flowing molten salt caverns and mass produced teller-ulam h-bombs making putt-putt fusion power. Sure, you have to make a grid that can suck up terrawatts from a single point and have a heat exchanger that boils a spot of the ocean, but these are just engineering and economics details. Its technically viable.

Back on topic... the isotopic purity of the noble metals for sale on the spot market isn't that important. There are numerous demands for catalysts in the petrochemical industry where the metals wouldn't be mobile in the environment at all. The lowest hanging fruit is the xenon, being automatically sparged out, easy to separate, and having no long lived isotopes while having a nice hefty market value.


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PostPosted: Jan 14, 2008 4:49 pm 
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Would the technetium-99 be of value as a catalyst?

I've also wondered about the value of the iodine-131 for thyroid therapy. In a fluid-fueled reactor iodine would be a lot easier to get.


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PostPosted: Jan 14, 2008 9:13 pm 
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Kirk Sorensen wrote:
I've also wondered about the value of the iodine-131 for thyroid therapy.

Well, there's certainly a "market" for I-131 (http://www.mds.nordion.com/products/medical-isotopes-iodine-131.htm), but, again, I'm not going to gurantee that there's more demand than there is supply. I suspect that it is pretty much fully supplied.

-Gary


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PostPosted: Jan 14, 2008 9:24 pm 
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Gary wrote:
Kirk Sorensen wrote:
I've also wondered about the value of the iodine-131 for thyroid therapy.

Well, there's certainly a "market" for I-131 (http://www.mds.nordion.com/products/medical-isotopes-iodine-131.htm), but, again, I'm not going to gurantee that there's more demand than there is supply. I suspect that it is pretty much fully supplied.


Gary, that's a very interesting link. I had no idea this was the production method for I-131:

130Te (n,gamma) -> 131Te -> 131I

and then it states that the radioiodine is separated from the tellurium target by dry distillation into an alkaline solution.

So such a process is probably only done at dedicated isotope production reactors with "rabbit" access to the high-flux regions of the core?

With an 8.02-day half-life, it's easy to see that I-131 runs out pretty quickly, whether you use it or not.


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PostPosted: Jan 14, 2008 10:59 pm 
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Kirk Sorensen wrote:
Gary, that's a very interesting link. I had no idea this was the production method for I-131:

130Te (n,gamma) -> 131Te -> 131I

I think that's some kind of screw-up -- I'm pretty sure we make it from fission targets, just like the Belgian sources, also listed on the Nordion page.

Maybe MNR uses the (n,g) method ?

.


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PostPosted: Jan 20, 2008 7:54 pm 
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I just remembered that Tritium has helion (He-3) as a decay product. If this helium could be sepated from the decaying tritium, this could be a valuable resource for cryogenic applications. And also for neutron gasdetectors this gas is used.


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PostPosted: Jan 23, 2008 9:35 pm 
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GE develops new superalloys to reduce use of rare rhenium
By Graham Warwick, Flightglobal.com, DATE:23/01/08

General Electric is about to begin engine testing of new nickel superalloys designed to reduce its use of rhenium, a rare metal that has increased 10-fold in price in recent years as demand has increased.
Engine testing is the final step towards approving the new materials for introduction into the GE90 and CFM56 turbofans later this year. Use in other commercial and military engines will follow, says GE Aviation.

Development of the new alloys is part of a two-pronged approach by GE to reduce its rhenium consumption. The other involves recycling high-pressure turbine blades made from nickel superalloys containing the element.

GE launched a scrap reclamation programme at its own service centres a year ago, reducing its need for new rhenium by 1% in 2007. The initiative is now being extended to customers, with Czech Republic Turkish Airlines the first to sign up.

First used in turbine blades 20 years ago, rhenium increases creep strength of superalloys, enabling them to withstand higher temperatures. The metal is a byproduct of copper production, and extremely rare.

"It's occurrence in the Earth's crust is two parts per billion. In association with copper it reaches hundreds of parts per billion," says GE's materials head Bob Schafrik. On average it takes 120t of copper ore to produce 30 grams (1oz) of rhenium, says GE. Prices are approaching $10,000/kg ($22,000/lb), up almost 10-fold from 2005 as demand has increased.

"There isn't a shortage at the moment, but as we look into the future we see engine production rates increasing and other uses coming on line," says Schafrik. Rhenium is used as a catalyst in the oil and gas industry, and also in rocket motors, he says.

The two new superalloys - one with half the rhenium of current materials and one with none, both with the same or better properties - is the result of a two-year effort. "We had a huge database of what is possible in superalloys, so we went back to that body of knowledge and combined it with our new design tools," says Schafrik.

The low-rhenium alloy is used for turbine blades, which must withstand high stress with high durability, while the rhenium-free alloy is used for static hardware such as nozzles and shrouds, says GE. Mechanical testing of properties and demonstration of manufacturing is complete and engine testing is the final qualification step.

The new alloys will be used first in the GE90-115B, which has the toughest thermal cycle, and also in the CFM56, which is GE's biggest user of rhenium, says Schafrik. They will be introduced into the GEnx and military engines in the future, he says.

The company's scrap-blade recycling programme, meanwhile, has reclaimed "hundreds of pounds" of superalloys at its seven service centres, says GE supply-chain "black belt" Larry Dening. This will increase to "thousands of pounds" this year, he says, as the programme is expanded to commercial and military customers.

Previously, scrapped blades were sold and recycled for use by the stainless steel industry, and the rare elements in superalloys were lost to aerospace. Now the material is cleaned and melted for re-use in manufacturing high-pressure turbine blades.

Schafrick says GE is looking at reclaiming other engine parts, and continues research into replacements for nickel superalloys in hot sections. These include ceramic matrix composites and high-temperature intermetallic materials such as niobium silicide.

.


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 Post subject: Rhenium
PostPosted: Jan 23, 2008 11:48 pm 
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Hi Jaro

Rhenium sits just below technetium in the periodic table, & rhenium is not produced by fission of actinides. Are you implying that technetium could be of value as a substitute for rhenium?

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PostPosted: Jan 24, 2008 5:10 am 
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I don't think so as there doesn't exist one stable isotope of technetium...

But as far as I know off, almost all elements are produced in a fission reaction. Also in those of the actinides, well minor actinides...


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PostPosted: Jan 31, 2008 10:55 pm 
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NNadir points out an interesting possible use for all the gamma emitting fission products.

http://www.dailykos.com/story/2008/1/27 ... 115/444308

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PostPosted: Feb 01, 2008 12:14 am 
Jim Baerg wrote:
NNadir points out an interesting possible use for all the gamma emitting fission products.

I couldn't tell from the article quite what he was on about. What kind of emitter would be used, and how would the process work?


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 Post subject: Re: Rhenium
PostPosted: Feb 03, 2008 7:22 pm 
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Jim Baerg wrote:
Rhenium sits just below technetium in the periodic table, & rhenium is not produced by fission of actinides.

You're quite right -- sorry about the obvious mistake.
Rhenium is well past the Lanthanides in mass, so the production rate would be close to nill.

.


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 Post subject: NNadir's suggestion
PostPosted: Feb 03, 2008 11:02 pm 
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He points out that almost the only thing that will destroy CFCs SF6 & many other halogenated compounds is ionizing radiation. These compounds when in the atmosphere contribute to global warming & destruction of the ozone layer.

Using ionizing radiation from such materials as Cs137 to sterilize water in sewage treatment would also destroy the trace quantities of CFCs etc. dissolved in the water.

Ie: we should regard gamma emitting fission products as a useful resource for pollution control.

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