What are the waste products from a deuterium and tritium fusion reaction?

[Morbius]

Quite right. But I was thinking more of the efficiency. Neutrons bouncing off heavy nuclei would not impart much energy per collision so one would need many more collisions to absorb that energy

Andrew,

So then you need 0.0001 sec to absorb the energy instead of 0.00001 sec to absorb the energy.

What's the problem?

Dr. Gregory Greenman
Physicist

 

[Morbius]

Perhaps one could put a thick shield of depleted uranium around the core to absorb the fast neutrons - at least then the neutron capture could produce useable plutonium fuel for a fission reactor.

Andrew,

Or you could do what the LIFE program at Lawrence Livermore National Laboratory proposes; you put
a layer of fuel pebbles - the same pebbles that are used in a pebble bed reactor. The layer of fuel pebbles
is a sub-critical assembly; but it is driven by the high energy neutrons from the fusion reaction. Rather
than just absorbing the energy of the fast neutrons; you use those neutrons to trigger more fissions so
that you MULTIPLY the production of energy by the sub-critical multiplication factor of the sub-critical
assembly of fuel pebbles:

https://lasers.llnl.gov/missions/energy_for_the_future/life/

https://lasers.llnl.gov/missions/energy_for_the_future/life/how_life_works.php

Dr. Gregory Greenman
Physicist

 

[Morbius]

The major selling points of fusion over fission include nearly eliminating radioactive waste and little or no weapons proliferation risk.

mheslep,

Actually, if a nation wants to develop nuclear weapons; they can use neutrons from a fusion reactor
to make plutonium every bit as effectively as with a fission reactor.

It is a MYTH that fusion is inherently more proliferation resistant, or waste resistant than fission.

That myth comes from people that look at the byproducts of a fusion reaction and see, for example;
a He-4 and a neutron. They stop thinking right there and say - Helium-4 and neutrons are not long
lived waste nor useful for weapons - therefore fusion is waste-resistant and proliferation-resistant.

However, if you think one more step; whatever that neutron hits will most likely be activated and hence
constitute a radioactive material that needs to be dealt with. Additionally, that neutron can be used to
breed plutonium and hence can be used for nuclear weapons proliferation.

Dr. Gregory Greenman
Physicist

 

[mheslep]

mheslep,

Actually, if a nation wants to develop nuclear weapons; they can use neutrons from a fusion reactor
to make plutonium every bit as effectively as with a fission reactor.

It is a MYTH that fusion is inherently more proliferation resistant, or waste resistant than fission.

That myth comes from people that look at the byproducts of a fusion reaction and see, for example;
a He-4 and a neutron. They stop thinking right there and say - Helium-4 and neutrons are not long
lived waste nor useful for weapons - therefore fusion is waste-resistant and proliferation-resistant.

However, if you think one more step; whatever that neutron hits will most likely be activated and hence
constitute a radioactive material that needs to be dealt with.

IIRC in comparison to spent fuel rods D-T fusion waste from high Z first wall materials is still low rad, short half life material.

Additionally, that neutron can be used to
breed plutonium and hence can be used for nuclear weapons proliferation.

Dr. Gregory Greenman
Physicist

An argument for more aneutronic fusion research? IRC that was Lidsky's argument in the 'The Trouble with Fusion'.

I don't agree the two, fission and fusion, are equivalent in proliferation risk. Granted one can make Pu by inserting U into a neutron producing fusion reactor (though the practicality is not clear to me). The point is practical weapons production regardless of the process still requires U up front. Fusion power completely eliminates the need for U; thus a country attempting to acquire U is unmistakably stating "I am making a weapon" and can be dealt with accordingly. More importantly it robs the enablers, like a Russia or China, from pretending otherwise when they sell fission technology and materials to want to be weapons states.

 

[Morbius]

I
I don't agree the two, fission and fusion, are equivalent in proliferation risk. Granted one can make Pu by inserting U into a neutron producing fusion reactor (though the practicality is not clear to me). The point is practical weapons production regardless of the process still requires U up front. Fusion power completely eliminates the need for U; thus a country attempting to acquire U is unmistakably stating "I am making a weapon" and can be dealt with accordingly.

mheslep,

If you think they are not an equivalent risk - then you are not up on the studies that labs such as LLNL
have conducted. Besides, the proliferation concern is really a "red herring". The number of nuclear armed
nations that got to be nuclear armed by co-opting a commercial nuclear power program is exactly ZERO!
When nations decide they want to have nuclear weapons - they build purpose-built facilities like production
reactors to produce bomb fuel. Getting bomb fuel out of a commercial power program is just too expensive
and technically demanding.

Uranium is EVERYWHERE! Uranium is one of the most UNIFORMLY distributed elements in the
Earths crust. Dig up a football field sized area to a depth of about 6 feet practically anywhere and you
can can get a few kilograms of Uranium.

No country would have ANY problem obtaining natural uranium - which is what can be transmuted into
weapons grade material. Practically ANY country has enough uranium within its own borders for bombs.

The only reason countries need Russia or China is to get enriched uranium - either slightly enriched for
power reactors or something of higher enrichment for research reactors.

Dr. Gregory Greenman
Physicist

 

[Morbius]

IIRC in comparison to spent fuel rods D-T fusion waste from high Z first wall materials is still low rad, short half life material..

mheslep,

Evidently you don't understand the inverse relationship between specific radioactivity and half-life.

Short half-life isotopes give you high levels of specific radioactivity. Long half-life isotopes give
you low specific radioactivity. Therefore you don't get "low rad short half life" material anywhere.

If you reprocess / recycle spent fission reactor fuel; then you get short lived high specific activity
waste analogous to what one gets with fusion.

The low specific radioactivity, but long half-life waste such as actinides; are what are recycled back
to the reactor - so they don't appear in the waste stream.

Dr. Gregory Greenman
Physicist

 

[Morbius]

I don't agree the two, fission and fusion, are equivalent in proliferation risk. Granted one can make Pu by inserting U into a neutron producing fusion reactor (though the practicality is not clear to me). The point is practical weapons production regardless of the process still requires U up front. Fusion power completely eliminates the need for U;

mheslep,

If you really want to use fusion for a powerplant in an efficient manner; then you are going to have to
go to one of the fusion-fission hybrid designs like LLNL's LIFE concept:

https://lasers.llnl.gov/missions/energy_for_the_future/life/

A fusion / fission hybrid has so much more going for it over a fusion only reactor. We've studied the
economics and operation of pure fusion concepts; and concluded fusion / fission hybrids are the most
promising. However, that means that you aren't going to eliminate the need for uranium.

Dr. Gregory Greenman
Physicist

 

[mheslep]

The only reason countries need Russia or China is to get enriched uranium - either slightly enriched for power reactors or something of higher enrichment for research reactors.

They also sell reactors, as was the case with Bathist Iraq and the French for instance. The French sold the Osiriq 'materials test reactor' to them (in addition to the 23 lbs of HEU). The Bathists also made the cover statement that the reactor was intended for research and electricity production.
http://www.fas.org/nuke/guide/iraq/facility/osiraq.htm
Then we have the reactor that Canada supplied to India in 1955, which aided India's path to a weapon.
http://nuclearweaponarchive.org/India/IndiaOrigin.html

 

[Morbius]

They also sell reactors, as was the case with Bathist Iraq and the French for instance. The French sold the Osiriq 'materials test reactor' to them (in addition to the 23 lbs of HEU). The Bathists also made the cover statement that the reactor was intended for research and electricity production.
http://www.fas.org/nuke/guide/iraq/facility/osiraq.htm
Then we have the reactor that Canada supplied to India in 1955, which aided India's path to a weapon.
http://nuclearweaponarchive.org/India/IndiaOrigin.html

mheslep,

Yes - and the Israeli Air Force took care of that reactor back in 1981.

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

However, the REAL THREAT came not from a French built reactor; but from Iraq's own
"home grown" enrichment facilities. They made electromagnetic enrichment facilities EMIS,
also known as "Calutrons":

http://nuclearweaponarchive.org/Iraq/Calutron.html

http://www.fas.org/nuke/guide/iraq/nuke/program.htm

Besides, if your goal is to be able to design a nuclear weapon; then you should be able to
design a nuclear reactor - the reactor is easier to design than the weapon. [ I've done both. ]
So if you are going to design / build your own nuclear weapon - you shouldn't be dependent
on someone for a reactor.

Dr. Gregory Greenman
Physicist

 

[Andrew Mason]

mheslep,


Uranium is EVERYWHERE! Uranium is one of the most UNIFORMLY distributed elements in the Earths crust. Dig up a football field sized area to a depth of about 6 feet practically anywhere and you can can get a few kilograms of Uranium.

No country would have ANY problem obtaining natural uranium - which is what can be transmuted into weapons grade material. Practically ANY country has enough uranium within its own borders for bombs.

The only reason countries need Russia or China is to get enriched uranium - either slightly enriched for power reactors or something of higher enrichment for research reactors.

Morbius makes a very good point. There may be a looming shortage of uranium in economically mineable deposits. But if money is not a concern, which would be the case if you were interested in making a bomb, there is plenty of uranium. You can get about 4 grams of uranium from a tonne of coal.

AM

 

[mheslep]

Morbius makes a very good point. There may be a looming shortage of uranium in economically mineable deposits. But if money is not a concern, which would be the case if you were interested in making a bomb, there is plenty of uranium. You can get about 4 grams of uranium from a tonne of coal.

AM

Sure its doable, but refining raw oar down from 4ppm likely means taking an extraordinary amount time to obtain concentrate, digging up half the countryside, and a great deal of oar, or rather dirt, processing equipment. All these again sum to a rather noticeable declaration of "Im making a bomb", given no fission electrical excuse.

 

[Morbius]

Sure its doable, but refining raw oar down from 4ppm likely means taking an extraordinary amount time to obtain concentrate, digging up half the countryside, and a great deal of oar, or rather dirt, processing equipment. All these again sum to a rather noticeable declaration of "Im making a bomb", given no fission electrical excuse.

mheslep,

ARE YOU KIDDING?

What do you think this operation looks like? We couldn't tell the difference between the
needed operations and the operations of a gravel pit.

For heaven's sake - do some ARITHMETIC - you don't need to "dig up half the country-side",
The amount of dirt that would need to be processed could be diverted from a road building
project and we'd never know it.

Look - I'm not just making this stuff up! We've STUDIED this!

Iraq got all the Uranium it needed for its Calutrons from its own "phosphate mines" back during
the 1980s and early '90s; and the IAEA and the USA never knew it.

We both had reason to be wary of Iraq - after all the Israelis had demolished their reactor in 1981.

However, under the inspections of the IAEA; the IAEA stated that Iraq was in full compliance with
the Nuclear Non-Proliferation Treaty.

Get the History Channel DVD "Saddam's Weapons". They cover this. They state that the IAEA gave
Iraq an "A+" [ that's a quote ] for compliance with the NPT; when all the while they were enriching
uranium in their EMIS "Calutrons".

We nor the IAEA NEVER SAW that because the amount is so SMALL! Just a few football fields.

Dr. Gregory Greenman
Physicist

 

[Morbius]

All these again sum to a rather noticeable declaration of "Im making a bomb", given no fission electrical excuse.

mheslep,

Just what do you think a nuclear weapon making operation "looks like"?

Every time someone says that we can keep an eye on a country and watch for them making
nuclear weapons; and that we will be able to SEE the proliferation - I always show them the following:

http://en.wikipedia.org/wiki/File:LLNL_Aerial_View.jpg

That's an aerial view of Lawrence Livermore National Laboratory - one of the USA's own nuclear
weapons facilities. However, LLNL is a multi-purpose laboratory - the whole lab is not devoted
to nuclear weapons - only a portion is.

Looking at the above picture - can you pick out the portion of the lab that works on nuclear weapons?

Of course not! So many think that there is a "tell-tale" look - and there really isn't. It's what makes
monitoring nuclear weapons proliferation so difficult.

Dr. Gregory Greenman
Physicist

 

[menergyam]

I would like to add on to the question about the concern of the amount of helium produced.

Suppose that we replace all the fossil fuel power plants and nuclear fission power plants with nuclear fusion power plants in the world. The amount of helium still might not be a problem, but what do we do with the helium? Do we just let the helium escape Earth's atmosphere into space? If so, won't the sun's gravity eventually pull the helium towards itself and use it to continue it's reaction? What else can we do with the helium besides cool it to near 0 K and study it's properties or to fill weather balloons or to use them to fill balloons for parties?

Also, we would now have a lot more energy than before from what we considered, so, this leads to my next set of questions. "How much energy does it take to fuse helium nuclei together?" and "What new machinery or modifications to existing fusion machines need to be made to fuse helium nuclei? and "Why not stop there?" "What does it take to continually fuse the by-products until you get to Iron?"

 

[Astronuc]

The sun's mass is about 333,000 Earth masses, to the putting the entire Earth into the sun isn't going to change the sun's energy output.

He from Earth will simply drift on the solar wind out of the solar system. Some of the He might end up on Jupiter and Saturn.


As for He fusion, it is impractical and unfeasible in Earth bound systems. The conditions are well above what is now going on in the sun.

http://hyperphysics.phy-astr.gsu.edu/hbase/Astro/helfus.html
http://hyperphysics.phy-astr.gsu.edu/hbase/Astro/astfus.html#c2

http://csep10.phys.utk.edu/astr162/lect/energy/ppchain.html
http://csep10.phys.utk.edu/astr162/lect/energy/cno.html
http://csep10.phys.utk.edu/astr162/lect/energy/cno-pp.html
http://csep10.phys.utk.edu/astr162/lect/energy/triplealph.html

 

[Yor_on]

Just some questions.
If I understand you guys (don't count on it though:) rightly.

You are saying that we through fusion will be able to reuse the wastes we already have from fission? And after that, what kind of new radioactive materials will we see as the new wastes from fusion? I read "short lived high specific activity waste" which then would be of what 'half time'? Would we be able to use it again? And the power plant in itself? Would it be as difficult to demolish as a fission plant is, or would it be even more difficult?

What would the halftime be of those fusion wastes?
And how much of it would be produced as compared to a fission plant of the same energy output?
Would we be able to reprocess the waste into new fuel?
If so, how?

Is there any studies done on how many of those fusion plants that would be needed for f ex. USA, or similar power output, and then what the total waste could be?
As for Helium, how high would the concentration in the air need to be before we would see it as a health hazard, and what would the output of those plants need to be to produce that concentration?

I understand that it may not be possible to give any definite answers here but a 'educated guess' is ok with me :)
I do like the idea of reusing nuclear waste, As for weapons, there is no way any country can stop a sovereign government from creating a nuclear weapon if they have the material and the know how. For myself I believe the best way of avoiding that lays in cooperation, education and a decent standard of living. Then people will understand (hopefully) what nuclear armament leads too.

 

[Morbius]

Just some questions.
If I understand you guys (don't count on it though:) rightly.

You are saying that we through fusion will be able to reuse the wastes we already have from fission? And after that, what kind of new radioactive materials will we see as the new wastes from fusion? I read "short lived high specific activity waste" which then would be of what 'half time'? Would we be able to use it again? And the power plant in itself? Would it be as difficult to demolish as a fission plant is, or would it be even more difficult?

Yor_on,

Actually most of the schemes for reusing nuclear waste are ones in which we have a fission / fusion
hybrid reactor. The fusion part is driving a subcritical fission part.

Because of that; the wastes from this hybrid scheme is the SAME as if we used fission reactors; in
particular fast fission reactors to do the same thing.

The longest lived waste product in such a scheme is the same as the longest lived waste product
in an all fission fuel cycle with reprocessing / recycle - namely Cesium-137 with a 30 year half life.

Dismantling the plant is NOT a big problem. We have already completely dismantled and disposed
of a number of nuclear power plants; from the original Shippingport plant, to Elk River, to Trojan...

I know the anti-nukes like to claim that the dismantle / disposal of the plant at the end of its life is some
big unsolved hurdle - but it is not. We've done it already, and for costs that are within that set aside
in the decommissioning escrow fund that the plant operators are required to contribute to during the life
of the plant.

Dr. Gregory Greenman
Physicist

 

[Yor_on]

Thanks for your answers Gregory.
In Sweden I believe us to have around 5000 tons of nuclear waste from fission.
And we don't really have any safe place yet to put them.
So if the fusion scheme would be shown to work that would be a relief I believe.

You write "The longest lived waste product in such a scheme is the same as the longest lived waste product in an all fission fuel cycle with reprocessing / recycle - namely Cesium-137 with a 30 year half life."

Could you explain what you mean by "all fission fuel cycle with reprocessing / recycle"?
The wastes we have have must be safely stored for centuries and isolated from the living environment for hundreds of thousand years as I understands it?.

 

[Morbius]

Could you explain what you mean by "all fission fuel cycle with reprocessing / recycle"?
The wastes we have have must be safely stored for centuries and isolated from the living environment for hundreds of thousand years as I understands it?.

Yor_on,

Actually you DO NOT have to store waste for thousands of years IF you reprocess / recycle.

The reason for the storage time of many thousands of years is that some of the waste products -
the actinides like Plutonium - have very long half lives. Plutonium-239 has a half life of 24,000 years;
hence the long storage time.

However, Plutonium-239 is good as a reactor FUEL. You don't have to store the Plutonium-239 - you
can use it as FUEL in a reactor. In the reactor, the Plutonium-239 will fission and turn into short lived
fission products - the longest lived of which is Cesium-137 with a half life of 30 years.

Sweden should get France, or Britain, or Japan to reprocess their spent fuel so it can be recycled.

When you reprocess / recycle spent nuclear fuel - you don't have any more "many thousand year
disposal problem". ALL those long lived isotopes can be burned and turned into short lived problems
in the appropriate reactors - like Argonne's Integral Fast Reactor; the IFR:

http://www.pbs.org/wgbh/pages/frontline/shows/reaction/interviews/till.html

"Q: And you repeat the process.

A: Eventually, what happens is that you wind up with only fission products, that the waste is only fission
products that have, most have lives of hours, days, months, some a few tens of years. There are a few
very long-lived ones that are not very radioactive."

Dr. Gregory Greenman
Physicist

 

[wrexhamseadog]

Helium is a noble gas. How can it be an asphyxiant? If you breathe it, it just makes you talk funny. CO2, on the other hand, in sufficient concentration (eg. 5%) will interfere chemically with hemoglobin transport of oxygen in the blood. I don't see how Helium can do this. If you breathe nothing but He for long enough, of course, you will die from lack of oxygen.

AM

Argon is a noble gas, and that is a gas used to remove all oxygen. As has also been mentioned, you answered your own questions by saying it displaces the oxygen, and eventually asphyxiates you. Asphyxiation is lack of oxygen in the body, whether induced by a biological process or simply displacement of oxygen. ANY gas from a chemical element in the periodic table, as long as oxygen isn't present, is an asphyxiant! And just going back to a previous point, using argon. Argon is used to get rid of oxygen. For example, musems use argon gas to preserve old documents. Oxygen, ironically, erodes at things, which, if everything in our body lived forever, oxygen erosion would eventually kill us. Argon makes sure no oxygen is present in the atmosphere of, in this case, the document that is being protected. Also, all a noble gas is, is a chemical element, in gas form, with all the outer electron shell full, (i.e. He with 2 electrons in the outer shell, and every other noble gas with 8) This means that these take the most energy to react with anything, so, don't asphyxiate biologically, but displace oxygen, so your argument that noble gases don't asphyxiate is completely wrong. Being a noble gas has nothing to do with it, except that they are very un-reactive substances, but, with enough energy, still can react!
Sorry for the rant, not trying to look down at you, but that is some quite common knowledge, i learned that in college in the UK (at age 16)!

 

[GTrax]

@wrexhamseadog

Goodness - this thread is more than a year old!
Even so, I mention that in explanations given me by a doctor concerning my child's asthma; he said that the body urge to gasp a breath is driven more by the CO2 concentration in the lungs, and not by the need for oxygen. A full lungful of an inert gas (Argon, whatever) that does not take part in the exchange to increase the CO2 can leave one asphyxiating, unable to breath unassisted.

Thankfully, my child now grown up, no longer suffers asthma, having learned to not to inadvertently hyperventilate (ie. over-breathe) as a norm.

All inert gases are suffocants! The warnings MUST be heeded. They can cause loss of consciousness and death in confined areas. They must be used with caution!

 

[wrexhamseadog]

@wrexhamseadog

Goodness - this thread is more than a year old!
Even so, I mention that in explanations given me by a doctor concerning my child's asthma; he said that the body urge to gasp a breath is driven more by the CO2 concentration in the lungs, and not by the need for oxygen. A full lungful of an inert gas (Argon, whatever) that does not take part in the exchange to increase the CO2 can leave one asphyxiating, unable to breath unassisted.

Thankfully, my child now grown up, no longer suffers asthma, having learned to not to inadvertently hyperventilate (ie. over-breathe) as a norm.

All inert gases are suffocants! The warnings MUST be heeded. They can cause loss of consciousness and death in confined areas. They must be used with caution!

Yes, the urge to breathe is determined by the Conc. of CO2 in the lungs, that is the 'URGE'
to take a breath. But what I am merely stating, is that, one does not need an urge to breathe to asphyxiate. One can breathe in pure nitrogen, and the eventual high saturation of which, sends the person into a sleep due to lack of oxygen and eventually, the major organs shut down. The asphyxiation can be caused by any gas, inert or reactive. All I am saying is really, that inert gases just take the place of the oxygen to asphyxiate, the more reactive gases actually make biological changes to the bodily functions, which can cause distress and pain, however, I previously mentioned Nitrogen, which isn't inert, but is very unreactive!There was actually a campaign to use nitrogen as a gas for execution in the US! It is the lack of oxygen that causes us to asphyxiate, as we, as well as virtually every other life form (that we know of) need oxygen to survive.
In the bloodstream, Oxygen combines with the haemoglobin. As the Conc. of CO2 in the persons lungs increases, so, naturally, does the Conc. in the bloodstream. The CO2 binds differently to the haemoglobin, and takes the place of oxygen, hence the asphyxiation, however, any other gas, e.g. helium (trying to get back to the original thread topic here!) simply displaces the oxygen. If we breathed in pure helium, we would asphyxiate, because we are breathing no oxygen. But when the helium is introduced into the atmosphere, helium is a very light particle, and floats above the air we breath, so, overall, there is nothing to worry about with releasing this 'waste' gas into the air! (helium is lighter than air, hence why we talk in a high-pitched 'squeak'. It is because the gas is less dense than air and the vibrations speed up from your vocal chords, making it sound higher)

 

[GTrax]

Interesting - about the urge to breath, and that using nitrogen only would leave one comfortably breathing, but still drifting off into unconsciousness.

But when the helium is introduced into the atmosphere, helium is a very light particle, and floats above the air we breath, so, overall, there is nothing to worry about with releasing this 'waste' gas into the air! (helium is lighter than air, hence why we talk in a high-pitched 'squeak'. It is because the gas is less dense than air and the vibrations speed up from your vocal chords, making it sound higher)

One thing about helium. It is only "lighter" than air when collected in a balloon or similar so as to be able to displace the air around it. Released loose, the atoms just ping around with astonishing speed. To test for leaks in a vacuum chamber, I released just a few seconds of puff almost too gentle to feel on a hand. Almost immediately, the detector responded from a considerable distance in the next industrial unit. After I had released less helium than would fill a party balloon, we had to wait about 30 minutes to let it disperse because we had "contaminated" the 2 units, and the car park outside all the way up to the road with detectable helium.

The "squeak voice" is primarily about the speed of sound in helium. I am not sure how much that speed is directly related to density - you are probably right about the relationship.

On the main theme of the thread, I think most of the available helium on the planet was/is ultimately derived from radioactive decay of Radon. Recently it has been pointed out that Helium in quantity is non-renewable, and is only available at the present price because of US Government policy to sell off its stock to pay for the storage and projects associated with the remainder. http://amarillo.com/news/local-news/2010-09-13/helium-prices-jump-curb-debt"
http://www.mnn.com/earth-matters/wilderness-resources/stories/helium-crisis-spreads-around-the-world"

Of course, should nuclear fusion become a major part of our energy resource, we should not expect that the helium "waste product" would amount to much - I think?

 

[mheslep]

Released loose, the atoms just ping around with astonishing speed. To test for leaks in a vacuum chamber, I released just a few seconds of puff almost too gentle to feel on a hand. Almost immediately, the detector responded from a considerable distance in the next industrial unit. After I had released less helium than would fill a party balloon, we had to wait about 30 minutes to let it disperse because we had "contaminated" the 2 units, and the car park outside all the way up to the road with detectable helium.

Yes, apparently molecular or atomic detectors will start pinging to show first arrivals progressing at an appreciable fraction of the speed of sound.