What would make nuclear fusion viable?

TxCoatl1970

IMO, the US completely flushed whatever chance it had to develop fusion in the 1990's when it dumped the SSC. I know we still have Fermilab, SLAC, and other accelerators operational, but for me, it was a statement that high-energy physics was not something that had full federal support. Private funding AFAIK of fusion is miniscule.

What technical and theoretical issues stand in the way of a sustainable fusion reaction and obtaining electrical power from it that makes it worthwhile?
 

dgharis

The problem is containment; controlled fusion requires operating temperatures in the tens of millions of degrees and there is no physical material that can withstand that. Magnetic confinement might be possible, but no one knows how to make a stable magnetic field that large.

There is also the problem of safety; a failure of the containment field would be catastrophic, in the sense of a titanic explosion levelling the facility and the surrounding area, followed by a firestorm.

(Cold fusion, BTW, probably violates the laws of physics as we understand them; the energy necessary to start a hydrogen fusion reaction is immense, far exceeding that used in the experiments so far. All such experiments to date have been either failures or fundamentally flawed.)
 

stewacide

Nuclear fusion seems like a solution in search of a problem, given fission energy, affordably and intelligently deployed at scale, could power the planet pretty much indefinitely, and requires orders-of-magnitude less advanced technology. It's not as if nuclear fuel is expensive or in short supply, so designing it out of the equation (with fusion) seems pointless.
 

dgharis

stewacide said:
Nuclear fusion seems like a solution in search of a problem, given fission energy, affordably and intelligently deployed at scale, could power the planet pretty much indefinitely, and requires orders-of-magnitude less advanced technology. It's not as if nuclear fuel is expensive or in short supply, so designing it out of the equation (with fusion) seems pointless.
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Not indefinitely; given current and projected future consumption uranium reserves are sufficient for between fifty and one hundred years. The uncertainty is due to the uncertainty of projections of future usage and possible technological improvements.

This:

http://www.world-nuclear.org/info/inf75.html

gives current reserves at 5.4 million metric tons and current usage at 68,000 metric tons/yr, which is about eighty years' supply assuming usage remains constant, which will almost certainly not be the case.

Although it is in theory possible to extract uranium from seawater the cost of doing so makes the process economically unviable.
 
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RamscoopRaider

Donor
dgharis said:
Not indefinitely; given current and projected future consumption uranium reserves are sufficient for between fifty and one hundred years. The uncertainty is due to the uncertainty of projections of future usage and possible technological improvements.

This:

http://www.world-nuclear.org/info/inf75.html

gives current reserves at 5.4 million metric tons and current usage at 68,000 metric tons/yr, which is about eighty years' supply assuming usage remains constant, which will almost certainly not be the case.

Although it is in theory possible to extract uranium from seawater the cost of doing so makes the process economically unviable.
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This is assuming the current process of just throwing away spent fuel continues. If we decide to reprocess it for reuse properly with breeder reactors I have seen estimates ranging from 5,000 years to when the sun goes red giant
 

Johnrankins

RamscoopRaider said:
This is assuming the current process of just throwing away spent fuel continues. If we decide to reprocess it for reuse properly with breeder reactors I have seen estimates ranging from 5,000 years to when the sun goes red giant
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Better yet use thorium salt reators which will last somewhere from now until Hell freezes over as thorium is as common as lead.
 

Tusky

Banned
Alternate hot fusion

For those interested, there are half-a-dozen schemes under development to achieve commmercially viable fusion. IMHO, the one with the best chance of success is Focus Fusion. Their web site is quite informative.

Their goal is Boron-Hydrogen fusion, as the products are only four alpha particles and some x-rays. The alphas leave the site as a beam, so you have charged particles heading off in one direction, and if they pass through a coil you can thus make a current in the wire. No rotating machinery, eh?

IMHO, again, ITER and Tokamak are unlikely to be successful, and even then they may not compete against schemes like Focus Fusion.

As for fission, the commenter who mettioned thorium-fuelled molten salt reactors is on the right track. Google "LFTR" for loads of information. In addition to operational economy, LFTR runs at temps high enough to economically decompose water. Cheap hydrogen is the immediate key to converting coal to liquid fuels at an acceptable cost.

This bit of forecasting Black Swans is, of course, perilous!


Tusky
 

BlondieBC

Banned
dgharis said:
Not indefinitely; given current and projected future consumption uranium reserves are sufficient for between fifty and one hundred years. The uncertainty is due to the uncertainty of projections of future usage and possible technological improvements.

This:

http://www.world-nuclear.org/info/inf75.html

gives current reserves at 5.4 million metric tons and current usage at 68,000 metric tons/yr, which is about eighty years' supply assuming usage remains constant, which will almost certainly not be the case.

Although it is in theory possible to extract uranium from seawater the cost of doing so makes the process economically unviable.
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1) Breeder Reactors

2) Thorium Fission cycle.

Either one works, and either one gets the supply to last for many generations. Also be careful with reserves in mining, reserves are by definition economical reserves, so when price goes up, reserves go up.

For example crude oil, at $10 per barrel: Canadian Oil Sands, Venzuala Tar, and Fracking of Shale are not reserves. At $100 per barrel, the worlds crude oil reserves double. If one goes to $250 per barrel, then the Oil Shale in Colorado is economical.
 

Maur

Banned
dgharis said:
Not indefinitely; given current and projected future consumption uranium reserves are sufficient for between fifty and one hundred years. The uncertainty is due to the uncertainty of projections of future usage and possible technological improvements.

This:

http://www.world-nuclear.org/info/inf75.html

gives current reserves at 5.4 million metric tons and current usage at 68,000 metric tons/yr, which is about eighty years' supply assuming usage remains constant, which will almost certainly not be the case.

Although it is in theory possible to extract uranium from seawater the cost of doing so makes the process economically unviable.
Click to expand...
And there's the possibility of breeder reactors, which make supply non-issue.

And make non-proliferation impossible, so take your pick. Fusion has the advantage of proliferation being non-issue, otoh.
 

Maur

Banned
Tusky said:
For those interested, there are half-a-dozen schemes under development to achieve commmercially viable fusion. IMHO, the one with the best chance of success is Focus Fusion. Their web site is quite informative.

Their goal is Boron-Hydrogen fusion, as the products are only four alpha particles and some x-rays. The alphas leave the site as a beam, so you have charged particles heading off in one direction, and if they pass through a coil you can thus make a current in the wire. No rotating machinery, eh?

IMHO, again, ITER and Tokamak are unlikely to be successful, and even then they may not compete against schemes like Focus Fusion.

As for fission, the commenter who mettioned thorium-fuelled molten salt reactors is on the right track. Google "LFTR" for loads of information. In addition to operational economy, LFTR runs at temps high enough to economically decompose water. Cheap hydrogen is the immediate key to converting coal to liquid fuels at an acceptable cost.

This bit of forecasting Black Swans is, of course, perilous!


Tusky
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So, do you have an opinion why ITER is pursued, then?
 

Tusky

Banned
ITER

Maur said:
So, do you have an opinion why ITER is pursued, then?
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It's all speculation but I've seen bureaucratic inertia before. Cozy relationships between funding entities and the funded investigators/companies are common enough. Even so, it is my understanding that ITER is not quite so lavishly funded as in past. They must produce some results! And if not it will all end up as a glorified garage sale.

Take a second look at Focus Fusion and consider how cleverly they bypass the Carnot cycle. The other fusion projects harvest heat from the rx, and so have all sorts of materials limitations as well as the nasty Carnot limitations.

FoFu does actually manage to fuse atoms, just not to breakeven. But they make progress.
 

Maur

Banned
Tusky said:
It's all speculation but I've seen bureaucratic inertia before. Cozy relationships between funding entities and the funded investigators/companies are common enough. Even so, it is my understanding that ITER is not quite so lavishly funded as in past. They must produce some results! And if not it will all end up as a glorified garage sale.

Take a second look at Focus Fusion and consider how cleverly they bypass the Carnot cycle. The other fusion projects harvest heat from the rx, and so have all sorts of materials limitations as well as the nasty Carnot limitations.

FoFu does actually manage to fuse atoms, just not to breakeven. But they make progress.
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I have lifetime worth of important links to read (thanks to the wider range of my interests), adding another scares me ;)

I glanced over FF site, and unfortunately clicked on the link to the forum and "BBNH" book. That was disappointing.
 

ANTIcarrot

TxCoatl1970

Good thoughts all.

I appreciate everyone's responses. As a casually interested observer since the 1980's I always felt nuclear fusion was tantalizingly close but needed a lot more precise control- tokamaks seemed to get enough power but were sloppy in containment. LHT, control, but not enough power to get a sustainable reaction.

I felt SSC would (A) give us better ideas about particle and plasma physics, and (B) with superconducting collider, we'd get a much better idea how to control the reactions after a few thousand runs.
LHC might get us that data over the next decade or so but IIRC hey seem a lot more interested in filling in the blanks about "dark matter" though.

It makes sense form a physics-geek perspective to finally resolve the three-cornered debate between relativity, quantum mechanics, and superstrings as explanations for how things work. In the long-view, far more important to figure that out far more thoroughly than we do now.

Of course, I agree with folks up thread, for probably 5% of the capital investment in fusion, we could get thorium-cycle and breeder-reactors going that provide the power for centuries and process the waste fuel rods down the decay ladder to much shorter-lived, harmless isotopes, removing the nuclear fission waste and proliferation issues.

It's a very good point about reserves vs cost of current technology/usage.
If the relative price goes up for whatever commodity to the point that marginal reserves become viable, you've got all kinds of options but I digress.
Anyhow, as a semi-Greenie environmental scientist, I'm amazed at how spastic my colleagues are about nuclear risks vs the ongoing mess coal makes of things.

I like fusion because it doesn't require really scary isotopes to be mined, (what do you do to detoxify uranium tailings?) refined, enriched, and reprocessed as the fission cycle should be but isn't.
 

RazeByFire

What was that guy in Canada working on? His reactor looked like something diesel punk, something about massive compression waves?
 

Tusky

Banned
Reply Anti Carrot

Well, I wish I knew what Anti Carrot stood for!

At any rate, it's sure that the US Navy continues to support Polywell, though also true that Dr. Richard Nebel left the project. Nebel appeared to be very level headed and didn't mislead the public. The Navy would surely love to have small fusion rx in ships, they could run forty kt across oceans and let half the crew water ski for exercise!

Cold Fusion is also supported by the Navy, they have an investigator at SPAWAR who has produced some very nice papers showing stout evidence. Anyone interested lately should google "Rossi" or "LENR" or "Lattice Fusion". These are typical buzz words used to discuss the topic. We are beginning to see good evidence of transmutation, a strong piece of evidence.

Polywell, however, uses fusion to generate heat, and so leads direct to the Carnot cycle inefficiencies. If my favorite Alien Space Bat comes to roost it will be the Focus Fusion, and part of this is because it will release less waste heat to the environment...all sorts of favorable consequences to this effect.

As far as the effect on electric costs, must realize that about half the cost is gen and half is transmission.

Tusky
 

dgharis

Thorium fission:

http://en.wikipedia.org/wiki/Thorium_fuel_cycle

Thorium reactors are in fact breeder reactors, using small quantities of U233 or other neutron sources to breed U233 from Th232. The technical challenges of building such reactors are not small.

If solid fuel is used then the problem is that U232 is also produced by the breeding process. U232 decay products emit gamma radiation and therefore the fuel requires remote handling and processing, increasing fuel and disposal costs. If liquid fuel is used then the solutions are corrosive, which increases the cost of building the reactor vessel by an order of magnitude or more, and increases both the likelihood and severity of nuclear accidents.

U233 can be weaponized, leading to proliferation problems, although the cost of doing so makes U235 and Pu239 the preferred materials for the purpose.

Breeder reactors (including the above thorium reactors):

http://en.wikipedia.org/wiki/Breeder_reactor

The other possibility is to use small quantities of Pu239 to breed Pu239 from U238. Since the Pu239 can easily be weaponized the proliferation problem with such reactors is great.

BTW, all reactors breed; the ratio of fuel produced to fuel consumed is roughly 0.55 in modern reactors. To achieve a true breeder reactor the ratio has to be equal to or greater than one.

There are two main difficulties. First, water cannot be used as a coolant because it absorbs neutrons; most breeders are cooled by liquid metal solutions, with corresponding increases in expense and complexity. Second, the reaction process produces neutron-absorbing isotopes as well, necessitating the removal and reproccessing of the fuel at regular intervals.

The point is that it's all well and good to say that by building breeder reactors we could make more efficient use of our uranium and thorium stocks and gain a few hundred years more for nuclear fission power generation, but doing so is not a simple or cheap process. There are numerous technical and political challenges to overcome before making that a reality.
 

Johnrankins

dgharis said:
Thorium fission:

http://en.wikipedia.org/wiki/Thorium_fuel_cycle

Thorium reactors are in fact breeder reactors, using small quantities of U233 or other neutron sources to breed U233 from Th232. The technical challenges of building such reactors are not small.

If solid fuel is used then the problem is that U232 is also produced by the breeding process. U232 decay products emit gamma radiation and therefore the fuel requires remote handling and processing, increasing fuel and disposal costs. If liquid fuel is used then the solutions are corrosive, which increases the cost of building the reactor vessel by an order of magnitude or more, and increases both the likelihood and severity of nuclear accidents.

U233 can be weaponized, leading to proliferation problems, although the cost of doing so makes U235 and Pu239 the preferred materials for the purpose.

Breeder reactors (including the above thorium reactors):

http://en.wikipedia.org/wiki/Breeder_reactor

The other possibility is to use small quantities of Pu239 to breed Pu239 from U238. Since the Pu239 can easily be weaponized the proliferation problem with such reactors is great.

BTW, all reactors breed; the ratio of fuel produced to fuel consumed is roughly 0.55 in modern reactors. To achieve a true breeder reactor the ratio has to be equal to or greater than one.

There are two main difficulties. First, water cannot be used as a coolant because it absorbs neutrons; most breeders are cooled by liquid metal solutions, with corresponding increases in expense and complexity. Second, the reaction process produces neutron-absorbing isotopes as well, necessitating the removal and reproccessing of the fuel at regular intervals.

The point is that it's all well and good to say that by building breeder reactors we could make more efficient use of our uranium and thorium stocks and gain a few hundred years more for nuclear fission power generation, but doing so is not a simple or cheap process. There are numerous technical and political challenges to overcome before making that a reality.
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You are going by wikipedia? Thorium reactors are MUCH safer than conventional ones Nuclear meldowns are impossible .
http://wordpress.mrreid.org/2010/07/22/uranium-233-and-the-thorium-future/
and here http://www.physicsforums.com/showthread.php?p=3565422 and
http://memagazine.asme.org/Articles/2010/May/Too_Good_Leave_Shelf.cfm
 

Anderman

Donor
Johnrankins said:
You are going by wikipedia? Thorium reactors are MUCH safer than conventional ones Nuclear meldowns are impossible .
http://wordpress.mrreid.org/2010/07/22/uranium-233-and-the-thorium-future/
and here http://www.physicsforums.com/showthread.php?p=3565422 and
http://memagazine.asme.org/Articles/2010/May/Too_Good_Leave_Shelf.cfm
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It´s a common misconception, it it not the Thorium itself that it saver. Thorium is not fissile but decays into Uranium 233 which is. To have a meltdown or runaway proof reactor you need a Molten Salt Reactor (MSR) the Thorium/Uranium is solved in molten salts whichhave a high melting point and a boiling point over 1000 degress celsius . So no need to put the stuff under pressure like in PWR. So if the Reactor vessel is damaged will only cause a leak but not a steam explosion.
 
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