Laser fusion?

[Porsche-O-Phile]

Real potential for fusion power or is this just another "cold fusion" or "gererator" buncha' B.S.?

It does sound awfully promising though... Boy it'd be nice to see something like this come along to help curtail our dependency on fossil fuels. Even if it's legit I suspect it'd be at least a couple decades from being viable/available for commercial use. Faster if they use sharks with the lasers on their heads to accelerate the reactions.

Lasers may enable fusion – SciTechBlog - CNN.com Blogs

[mjohnson]

I like the comment "...National Ignition of Funds".

Tritium is one of the more rare and expensive things around. I'm not sure if it exists in any quantity in nature, but we make the stuff we use now in fission reactors.

So we use fission reactors to make fuel to run fusion machines?

I've been in the thing - whether it works or not, it's a damn impressive widget!

[red-beard]

Almost all of the energy coming out of the Fusion reaction is in the neutrons. This makes it tough to collect the energy in a manner to keep the reaction going.

[mjohnson]

Those neutrons will make all sorts of radioactive stuff when they hit something. Maybe eventually we'll cut the thing up and burn it in a fission reactor?

Wouldn't the neutrons' energy partly (the energy that's not doing further nuclear reactions) become heat as they're slowed and absorbed?

Even if they don't break even, there's some useful stuff we can use the machine for. That's hard for me to say out loud, sitting here in Los Alamos. We're almost required as a condition of employment to dis everything that happens in Livermore.

[red-beard]

The point of Fusion is it is supposed to be cleaner, not producing the radioactive particles that fission produces. This is not actually the case.

Now, what would happen if you put U238 in the area around the laser? Great way to make plutonium.

We have tons, and I do mean tons, of Plutonium. We need to design reactors to use Plutonium and get rid of all the stuff we've been making all of these years. We really should build and operate breeder reactors, so that we turn all of the "useless" U238 into Plutonium. This extends our nuclear supply by a factor of almost 30.

[kach22i]

I recently rented a Discovery Channel DVD from the local public library on "the future". Some people in the UK were doing what the article described (laser fusion), but the Brits said they were still 20 years away.

[m21sniper]

Originally Posted by mjohnson

I like the comment "...National Ignition of Funds".

Tritium is one of the more rare and expensive things around. I'm not sure if it exists in any quantity in nature, but we make the stuff we use now in fission reactors.

So we use fission reactors to make fuel to run fusion machines?

I've been in the thing - whether it works or not, it's a damn impressive widget!

Tritium is not really rare. I have 2 firearms with tritium illuminated sights. They're not even expensive. You can get the capsules for just a couple bucks.

[m21sniper]

Originally Posted by red-beard

The point of Fusion is it is supposed to be cleaner, not producing the radioactive particles that fission produces. This is not actually the case.

Now, what would happen if you put U238 in the area around the laser? Great way to make plutonium.

We have tons, and I do mean tons, of Plutonium. We need to design reactors to use Plutonium and get rid of all the stuff we've been making all of these years. We really should build and operate breeder reactors, so that we turn all of the "useless" U238 into Plutonium. This extends our nuclear supply by a factor of almost 30.

U238 has great military value as both armor and penetrator material.

[mjohnson]

Originally Posted by m21sniper

Tritium is not really rare. I have 2 firearms with tritium illuminated sights. They're not even expensive. You can get the capsules for just a couple bucks.

Yes, your sights aren't too expensive. Neither were the tubes I just had replaced on the hands of one of my watches. Neither contain much H3, though. Trijicon claims 0.018 curies in each tube, so that works out to about 180 nanograms of tritium.

One reference states that the DOE used to sell it for $10k/gram and Canada sold it for $30k/g. Same source estimates the cost of new production to be ~$100k/g, or roughly $50 million a pound.

Dat's some pricey stuff!

[mjohnson]

Originally Posted by red-beard

The point of Fusion is it is supposed to be cleaner, not producing the radioactive particles that fission produces. This is not actually the case.

Now, what would happen if you put U238 in the area around the laser? Great way to make plutonium...

With the right neutron energies, U238 will burn just fine.

Fusion reactors, if they ever exist, won't be some cuddly benign thing that anybody will want in their back yard.

[m21sniper]

Originally Posted by mjohnson

Yes, your sights aren't too expensive. Neither were the tubes I just had replaced on the hands of one of my watches. Neither contain much H3, though. Trijicon claims 0.018 curies in each tube, so that works out to about 180 nanograms of tritium.

One reference states that the DOE used to sell it for $10k/gram and Canada sold it for $30k/g. Same source estimates the cost of new production to be ~$100k/g, or roughly $50 million a pound.

Dat's some pricey stuff!

Indeed. But a tiny bit goes quite a long way, thankfully.

[red-beard]

Originally Posted by mjohnson

With the right neutron energies, U238 will burn just fine.

Fusion reactors, if they ever exist, won't be some cuddly benign thing that anybody will want in their back yard.

U238 will burn, beacause you're converting it into Plutonium.

I've always wondered if a reactor design could be made that breeds and then burns Plutonium without having to reprocess. It would be quite an interesting concept. Fuel could potentially be 1/30th the price, depending on how much work it is to create the newer type of fuel rod/reactor.

[red-beard]

ON the topic of Fusion, I've also wondered if we're going after the wrong reaction. Oxygen-16 is the most stable element. Why don't we try to fuse Nitrogen-15 and Hydrogen or Nitrogen 14 and Duterium together?

[mjohnson]

I think the real future for the US is:

1 - Join the rest of the world and start fuel reprocessing
2 - Modify the incoming fission fuel to tailor the spent fuel's makeup to ease reprocessing (much of the hassle isn't from the U fission products)
3 - Like Redbeard said, start burning up Pu

Oh, yeah, START REPROCESSING!

[nota]

Originally Posted by red-beard

ON the topic of Fusion, I've also wondered if we're going after the wrong reaction. Oxygen-16 is the most stable element. Why don't we try to fuse Nitrogen-15 and Hydrogen or Nitrogen 14 and Duterium together?

bigger bits take more input energy to fuse
and I think give off less energy in return too
or a double problem for cheap energy
also I think most fusion joins two like mass same elements
as there maybe a energy penalty both in put and out to a unlike mass reaction

most stars take a long time to fuse H to He

but once the H is used up the process takes less time
for each mass increase

btw the most stable is iron it only fuses in a supernova

[nota]

Originally Posted by mjohnson

I think the real future for the US is:

1 - Join the rest of the world and start fuel reprocessing
2 - Modify the incoming fission fuel to tailor the spent fuel's makeup to ease reprocessing (much of the hassle isn't from the U fission products)
3 - Like Redbeard said, start burning up Pu

Oh, yeah, START REPROCESSING!

Pu is nasty stuff and letting it out is NOT a good idea

I would wait a few years to let the religious nuts calm down or die out
and let the tec to do the reprocessing clean up
we donot need more slikwood type cases or worse

[red-beard]

Originally Posted by nota

bigger bits take more input energy to fuse
and I think give off less energy in return too
or a double problem for cheap energy
also I think most fusion joins two like mass same elements
as there maybe a energy penalty both in put and out to a unlike mass reaction

most stars take a long time to fuse H to He

but once the H is used up the process takes less time
for each mass increase

btw the most stable is iron it only fuses in a supernova

They don't have to be the same. The standard fusion reaction is Dueterium-Tritium.

Heavier particles have more momentum, which might give them a better chance to stick. This is why we do H(2) and H(3) instead of just 2x H(2).

As I've pointed out before, in my nuke-e classes, the professor asked us what the size of a critical mass of Uranium was, and he'd hold his hands a few inches apart like he was holding a small sphere. He then asked what the size of a critical mass for Hydrogen Fusion. He then pointed out the window at the sun.

IF fusion were easy, we'd alreayd be there.

And I think you're right about Iron being the most stable.

And Plutonium is no worse than a lot of other substances we use. And it is much harder to make a Pu bomb than a U235 bomb.

[nota]

they can't fuse pure H1 as they need neutrons to get He to stick together
He is two protons and two neutrons
H2 and H3 are 2&3 because of the extra 1 or two neutrons
there is no way to get H1 to stick together in to He

all heavier element fusions produce less power and need more input power
or a double hit to cheap power production

yes a Pu -bomb is more complex then a U-bomb
but Pu is very nasty stuff and is eazy to use in a dirty bomb
and a dirty bonb is very low tec

[beepbeep]

My money is on magnetically-suspended Tokamak design, like ITER. Fortunately, most of research money is going in that direction as well. Burning Pu or reprocessing will work, but is very messy. Spent fuel must be stored for a looong time...100000 years or so.

Fusion is so much cleaner. Yes, fast neutrons hitting the walls will make them low-active but much less so than spent fuel from fission reactor. Unfortunately, capturing neutron flux and actually turning it into energy is the biggest problem. Making fusion happen is already possible in Tokamak's, the trick is to make net energy profit out of it. Neutrons make chamber very brittle...at least that's what a scientist I spoke with said to me.

[Superman]

Which brings us back to the conventional perception and research that harnessing fusion is really a matter of containment.