[Masslessxphoton]

I KNOW the difference between fission and fusion. What I want to know is: is nuclear fusion better than fission? Is it cleaner? Why should we invest in fusion?
I WOULD LOVE SOME LINKS TO WEBSITES ON THIS!
Thanks
To view links or images in this forum your post count must be 2 or greater. You currently have 0 posts.

[Project 2501]

In fission unstable radioactive elements are concentrated beyond normal concentrations and brought together, they randomly decay and release neutrons.

If a random radioactive element decays and releases more than one neutron as it decays and those collide with the nucleus of another unstable radioactive atom which releases two or more neutrons it sets off a chain reaction like a snowball effect. Other atoms of the same or similar elements absorb a neutron and release two or more neutrons each setting off two or more and so forth.

The element is transmuted into another element and in doing so release a lot of energy in the form of heat which can be used to turn turbines to make energy with generators.

The problem with most fission reactions is that transuranic elements are left behind as waste and are highly radioactive for tens of thousands of years and require careful storage in areas like salt mines to avoid contamination with the soil and water.


Fusion on the other hand would be nearly perfect.

In the sun under extreme pressure hydrogen atoms (protons) collide and forum helium 3, and in doing so release tons of energy.

The idea is to use magnetic fields like in a tokamak


To view links or images in this forum your post count must be 2 or greater. You currently have 0 posts.


to squeeze together light elements like special forms of hydrogen to fuse together into helium.

It does release a LOT of energy currently, but it still takes way more to start up the reactor so it's a waste.

There is some interesting progress with inertial confinement fusion they are about to reach break even point at the national ignition facility They are using 200 super powerful lasers all focused on one fuel pellet to achieve fusion as x-rays are emitted and crunch the contents forcing fusion.

There is another method using electrostatic confinement I believe it's called Buzzard polywell fusion that the navy is interested in.


More interesting than all that though, is the fact in the 50's and 60's
the head of oak-ridge national labs Alvin Weinberg and the inventor of the type of nuclear reactor we use today (the light water reactor) spent the rest of his career there campaigning the powers that be to switch to a new type of fission power called a Liquid Fluoride Thorium Reactor that promised many of the advantages of fusion but in a proven and tested design.
They told him to shut up and he didn't so they fired him.


The LFTR was a type of molten salt reactor and was passively safe in that it could not melt down under any circumstance, and that it generated almost no transuranic waste, also it burned abundant thorium 232 which is thousands of times more plentiful than uranium 235 which we currently use, and that it can completely burn all the thorium fuel wasting almost nothing, literally there were thousands of years worth of proven thorium reserves in the USA alone and we throw away enough thorium each year from US mines to power the earth completely including transportation.

We could use the dirt cheap electricity to generate synthetic liquid fuel alternatives to gasoline, and diesel from ocean water, atmospheric C02 and electricity and it could be used to generate ammonia for fertilizer in the same manner.

We didn't choose that route though as the LFTR could not be used to generate weapons grade material, which is very sad as we would all have unimaginably higher qualities of life now had we built them in the 50's.

If you want to learn more on thorium power go to :

To view links or images in this forum your post count must be 2 or greater. You currently have 0 posts.

[Vogon Poet]

The Molten Salt Reactor (MSR) is still a fission reactor burning U233 in Uranium Tetraflouride (UF4) as its fuel. The U233 is a fission product of Thorium 232 plus a moderated neutron, after it goes through Protactinium 233. Here's the problem with the MSR. In general, to get any nuclear fission fuel to work you have to get the fuel to absorb neutrons which trigger the decay cycle. So you need an abundance of neutrons to begin with, and they need to be moderated (slowed down) so they have a better chance of hitting some fissile material.

All fission produces what are called "prompt neutrons", which are traveling at extremely high speeds. The faster a particle travels through a substance, the lower the chance it has of hitting something (hitting is good, escaping is bad). So what reactors do is surround the fuel in some moderator (usually water, or graphite). A neutron hits a hydrogen atom in water and it's like a cue ball hitting another pool ball. The cue ball slows down and gives energy to the object ball (this is heat). But the important part is, the neutron is now slowed down, and can bounce back into the fuel with a much better chance of being absorbed, starting a new chain reaction.

OK, another thing reactors use are poison control rods. These are rods made of something that can absorb a lot of neutrons (usually halfnium), so when you stick the rod into the fuel process it can slow down the reaction (control/poison it).

So with the MSR, you have this Protactinium product that sits around for 27 days half-life before finally becoming usable Uranium233. A Protactinium233 atom can actually absorb 2 neutrons before decaying. Those neutrons are supposed to be smacking into more Th232 or U233 to keep the reaction going, so the Protactinium acts like a built-in poison within the fuel. This is no small obstacle, but other than this a thorium reactor would be great.

Oh, I have to mention that while commercial light water reactors do have a positive thermal coefficient of reactivity [R(t)], changing fuel purity and density will easily give it a negative thermal coefficient of reactivity which prevents the "china syndrome" problem people worry about. All military nuclear propulsion systems have a negative R(t), meaning an overheating core will naturally shut itself down as long as it hasn't gone prompt critical.

Fusion is cool, but safe reactors are not on the near horizon though. So to the OP question, fission is better for now. Invest in fusion for space travel possibilities.

[Uber10]

	Originally Posted by Project 2501 To view links or images in this forum your post count must be 2 or greater. You currently have 0 posts.
	The idea is to use magnetic fields like in a tokamak

The tokamak is a dead end. Try a fusor


To view links or images in this forum your post count must be 2 or greater. You currently have 0 posts.

[Masslessxphoton]

WOW THANKS! You guys helped A LOT!

[Project 2501]

I didn't say it wasn't fission, only that it was safer than what we had, and we have thousands of times more Th232 than we do U235, so it makes a lot more sense to burn plentiful thorium than it does uranium 235 which is very rare on on par with platinum or gold.

The protactinium as I understand stays in the blanket salt and gives off 100% of it's decay heat.

The real magic happens in the core salt.

They fluoridate the blanket salt to remove U233 as it is produced and introduce that into the core salt where all the fission happens.

As I understand it there is no technical reason other than the funding and basic research needed to start construction on one tomorrow.

Originally Posted by Vogon Poet To view links or images in this forum your post count must be 2 or greater. You currently have 0 posts.

The Molten Salt Reactor (MSR) is still a fission reactor burning U233 in Uranium Tetraflouride (UF4) as its fuel. The U233 is a fission product of Thorium 232 plus a moderated neutron, after it goes through Protactinium 233. Here's the problem with the MSR. In general, to get any nuclear fission fuel to work you have to get the fuel to absorb neutrons which trigger the decay cycle. So you need an abundance of neutrons to begin with, and they need to be moderated (slowed down) so they have a better chance of hitting some fissile material. All fission produces what are called "prompt neutrons", which are traveling at extremely high speeds. The faster a particle travels through a substance, the lower the chance it has of hitting something (hitting is good, escaping is bad). So what reactors do is surround the fuel in some moderator (usually water, or graphite). A neutron hits a hydrogen atom in water and it's like a cue ball hitting another pool ball. The cue ball slows down and gives energy to the object ball (this is heat). But the important part is, the neutron is now slowed down, and can bounce back into the fuel with a much better chance of being absorbed, starting a new chain reaction. OK, another thing reactors use are poison control rods. These are rods made of something that can absorb a lot of neutrons (usually halfnium), so when you stick the rod into the fuel process it can slow down the reaction (control/poison it). So with the MSR, you have this Protactinium product that sits around for 27 days half-life before finally becoming usable Uranium233. A Protactinium233 atom can actually absorb 2 neutrons before decaying. Those neutrons are supposed to be smacking into more Th232 or U233 to keep the reaction going, so the Protactinium acts like a built-in poison within the fuel. This is no small obstacle, but other than this a thorium reactor would be great. Oh, I have to mention that while commercial light water reactors do have a positive thermal coefficient of reactivity [R(t)], changing fuel purity and density will easily give it a negative thermal coefficient of reactivity which prevents the "china syndrome" problem people worry about. All military nuclear propulsion systems have a negative R(t), meaning an overheating core will naturally shut itself down as long as it hasn't gone prompt critical. Fusion is cool, but safe reactors are not on the near horizon though. So to the OP question, fission is better for now. Invest in fusion for space travel possibilities.

[ummon]

Fusion is cleaner and more efficient than fission.

The only problem we haven't managed to actually make fusion workable as a source of energy. And we won't be able to for at least a few decades.

One of the interesting things though is that a fusion-fission hybrid reactor that could burn 99% of waste created through fission is feasible today. Basically the fusion reactor is used as a source of neutrons which will cause the radioactive waste to decay and this decay actually produces more energy than is needed to drive the fusion reactor.

---------- Post added 04-05-2012 at 01:25 PM ----------

Originally Posted by Project 2501 To view links or images in this forum your post count must be 2 or greater. You currently have 0 posts.

I didn't say it wasn't fission, only that it was safer than what we had, and we have thousands of times more Th232 than we do U235, so it makes a lot more sense to burn plentiful thorium than it does uranium 235 which is very rare on on par with platinum or gold. The protactinium as I understand stays in the blanket salt and gives off 100% of it's decay heat. The real magic happens in the core salt. They fluoridate the blanket salt to remove U233 as it is produced and introduce that into the core salt where all the fission happens. As I understand it there is no technical reason other than the funding and basic research needed to start construction on one tomorrow.

And therein lies the catch. As Admiral Rickover said:

An academic reactor or reactor plant almost always has the following basic characteristics: (1) It is simple. (2) It is small. (3) It is cheap. (4) It is light. (5) It can be built very quickly. (6) It is very flexible in purpose. (7) Very little development will be required. It will use off-the-shelf components. (8) The reactor is in the study phase. It is not being built now. On the other hand a practical reactor can be distinguished by the following characteristics: (1) It is being built now. (2) It is behind schedule. (3) It requires an immense amount of development on apparently trivial items. (4) It is very expensive. (5) It takes a long time to build because of its engineering development problems. (6) It is large. (7) It is heavy. (8) It is complicated.

[Project 2501]

Liquid Fluoride Thorium Reactors (MSR) technology may not be fusion but for all intents and purposes it is almost as good.

We have thousands of years worth of fuel here in the usa alone, including energy to generate synthetic transportation fuels, and account for projected increases in consumption.

World wide reserves are at almost 10,000 years for the entire earths needs.

LFTRs cannot under any circumstances melt down, they are passively safe, worst case scenerio is that the salt is dumped into an underground passively cooled holding tank.

LFTR is a proven technology we built and tested the reactors in the 50's and 60's.

LFTR produces thousands of times less transuranic waste than a conventional light water reactor.

LFTR burns almost 100% of the thorium fuel, and releases almost 100% of it's potential energy.

What waste it does make is desperately needed by both NASA and the medical communities, so it is highly valuable.

LFTR can be used to burn existing waste stockpiles as fuel instead of burying it, which is a much better solution.

The man who invented the light water reactor that we use today, previous head of oakridge national labs Alvin Weinberg was fired for his LFTR advocacy.

The real reason we aren't using it today is the fact it makes U233 which is extremely hard to use for weapons.

Check out thorium remix 2011 the video if you think I am misrepresenting the facts.

Originally Posted by ummon To view links or images in this forum your post count must be 2 or greater. You currently have 0 posts.

Fusion is cleaner and more efficient than fission. The only problem we haven't managed to actually make fusion workable as a source of energy. And we won't be able to for at least a few decades. One of the interesting things though is that a fusion-fission hybrid reactor that could burn 99% of waste created through fission is feasible today. Basically the fusion reactor is used as a source of neutrons which will cause the radioactive waste to decay and this decay actually produces more energy than is needed to drive the fusion reactor. ---------- Post added 04-05-2012 at 01:25 PM ---------- And therein lies the catch. As Admiral Rickover said:

[Vogon Poet]

Originally Posted by Project 2501 To view links or images in this forum your post count must be 2 or greater. You currently have 0 posts.

Liquid Fluoride Thorium Reactors (MSR) technology may not be fusion but for all intents and purposes it is almost as good. LFTRs cannot under any circumstances melt down, they are passively safe, worst case scenerio is that the salt is dumped into an underground passively cooled holding tank. The real reason we aren't using it today is the fact it makes U233 which is extremely hard to use for weapons.

Actually any reactor can go prompt critical if you overmoderate the fuel. A prompt critical core produces what we had at Chernobyl, which is probably still burning today under the tons of cement poured over it. I'd like to see specifically how they can prevent this in a U233 fission chain.

Also, U233 is HIGHLY usable in weapons, even more potent than plutonium 239. It's critical mass is 50% larger than Pu239 however it is also much more radioactive and can't be handled with gloves like Ploutonium. U233 is very hard to work with, which is why as a fuel it must be bred from Thorium. There is a large political concern having commercial reactors which create extremely volitile and highly toxic weapons-ready U233. If these see production it will probably be in military reactors first.

[Uber10]

	Originally Posted by Vogon Poet To view links or images in this forum your post count must be 2 or greater. You currently have 0 posts.
	There is a large political concern having commercial reactors which create extremely volitile and highly toxic weapons-ready U233.

Politics exactly. It's not a good idea at this time to have cheap and easy to build breeders.

[ActiveMeasures]

LFTR is the best way to go, to my knowledge. I have watched this video at least 4 times now and it still amazes me each time.


To view links or images in this forum your post count must be 2 or greater. You currently have 0 posts.

[Project 2501]

Dear VogonPoet,

I sincerely and honestly do not mean to upset you or bruise your ego.

Any Douglas Adams fan is a friend of mine.

That being said, I don't think you've researched the topic nearly as well as you think you have. LFTRs are completely alien concepts to most people who are familiar with the workings of traditional nuclear reactors. They burn nearly 100% of their fuel, unlike traditional reactors that burn 0.05% in a LWR or 0.07% in a CANDU. They aren't software controlled, they are analog devices, they self regulate their criticality in response to quickly changing increases and decreases in power load on demand on the fly, unless gravity fails they cannot melt down or go critical.

LFTR is totally safe, intrinsically safe, passively safe, cannot go critical unless gravity fails, it generates thousands of times less transuranics LWRs, can burn existing waste stock piles instead of burying them, we have thousands and thousands of years worth of known reserves for thorium, it is plentiful element unlike U-235 which is like burning platinum for fuel.

There is no way it can go critical, even if the reactor housing is blown to bits the salt would just drain into the holding tank which is sinks it's heat to the earth and is passively cooled. There is no way a LFTR version of Chernobyl or Fukushima Daiichi could possibly ever happen. Well that is unless gravity quits working, at which point we will have bigger problems.

For all intents and purposes, It is almost as good as fusion. Except we built prototype LFTR's in the 50's and 60's and we know it is a viable technology.

What it can't do well is generate weapons grade material, that is exactly and specifically the reason we don't have them today.

To view links or images in this forum your post count must be 2 or greater. You currently have 0 posts. Liquid Fluoride Thorium Reactors are intrinsically safe because overheating expands the fuel salt past criticality. Because Liquid Fluoride Thorium Reactor fuel is not pressurized and because total loss of power or control will allow a freeze-plug to melt, gravitationally draining all fuel salt into a dump tray, where it cools convectively.

	To view links or images in this forum your post count must be 2 or greater. You currently have 0 posts. A LFTR can react to load changes in less than 60 seconds (unlike "traditional" solid-fuel nuclear power plants), thus it can satisfy both base load and peak load power demands.

U-233 has no use in weapons and here is why.

U-233 is fissile, yes I absolutely concede this fact to you, however it is far from ideal for use in weapons.

There was one trial bomb which used U-233, and it fizzled.

Another practical problem with any weapon that uses U-233, is that it will also contain U-232 which will be easily detected by satellite sensors and people because it has high energy gamma emissions in it's decay chain.


U-233's critical mass is closer to 60% higher than Pu-239, and U-233 produces way more spontaneous fission neutrons that will rip the bomb apart before it can become dense enough to fission sufficiently.

U-233 will always be be contaminated with U-234 which is much worse for spontaneous fission neutrons which makes it nearly useless as a weapons grade material.

U-233 will also always be contaminated with U-232 which will destroy electronics, harm the builders even if they wear lead shielded suits, be detected easily by satellite gamma detectors.


Pu-239 is as good as it gets.


There was one Pu-239 / U-233 mixed core that I am aware of, and it's yield was less than half of that of a Pu-239 / U-235 mixed core.

Because of the large amount of Pu-239 used it suggests that U-233 cannot be used for weapons in any realistic manner.

The military grade U-233 was made in a special fast processing U-233/Pu-239 production reactor, and it had easy and fast removal of fuel plus lots of decontamination equipment.

LFTR is not even suited to generate military grade U-233

Absolute and totally pure U-233 with no U-232 or U-234 might be feasible for some crappy low yield weapon, but we don't have the technology to make 100% pure U-233 that I am aware of.

Originally Posted by Vogon Poet To view links or images in this forum your post count must be 2 or greater. You currently have 0 posts.

Actually any reactor can go prompt critical if you overmoderate the fuel. A prompt critical core produces what we had at Chernobyl, which is probably still burning today under the tons of cement poured over it. I'd like to see specifically how they can prevent this in a U233 fission chain. Also, U233 is HIGHLY usable in weapons, even more potent than plutonium 239. It's critical mass is 50% larger than Pu239 however it is also much more radioactive and can't be handled with gloves like Ploutonium. U233 is very hard to work with, which is why as a fuel it must be bred from Thorium. There is a large political concern having commercial reactors which create extremely volitile and highly toxic weapons-ready U233. If these see production it will probably be in military reactors first.