Clean Fusion Bombs: Possibility of "Clean" Explosions

[SkepticJ]

Could it be possible to one day create fusion bombs that are "clean"(not create radioactive isotopes and other nasty stuff that lingers for years)? The only thing it'd do is create thermal energy and the bast when it goes off?

 

[mathman]

To trigger a fusion bomb you need intense pressure and high temperature. At present using a fission bomb is the only practical method. Maybe in the distant future a laser trigger might be possible. At the moment they are simply trying to get something for a fusion reactor, using lasers.

 

[Morbius]

To trigger a fusion bomb you need intense pressure and high temperature. At present using a fission bomb is the only practical method. Maybe in the distant future a laser trigger might be possible. At the moment they are simply trying to get something for a fusion reactor, using lasers.

mathman,

That's correct.

Additionally, saying that the fusion reaction is "clean" because it doesn't
create any radioactive species [ at least not directly ] is short-sighted.

The main fusion reaction under consideration is "D-T" fusion:

D + T --> He4 + n + 17.6 MeV

The product isotope He4 is stable - so it is often said that fusion is
"clean" and doesn't produce radioactive species.

However, that neutron; the "n" ; receives 14.1 MeV worth of energy and
the next atom it hits will most likely become radioactive.

So D-T fusion is only "clean" if you look at just the first generation of
products. If you look one generation removed from the initial products -
then you are going to have radioactive species and fusion is not "clean".

In fact, fission gives you about 2 radioactive atoms per reaction, which
releases about 200 MeV worth of energy. Fusion gives you 1 radioactive
atom per reaction that releases 17.6 MeV of energy.

So in effect, on a per energy released basis; fusion is more than 5 times
more "dirty" than fission.

Dr. Gregory Greenman
Physicist

 

[hitssquad]

Clean fusion bombs via tungsten or lead jacketing

in effect, on a per energy released basis; fusion is more than 5 times more "dirty" than fission.

But can't the neutrons be stopped with lead?
http://www.cartage.org.lb/en/themes/Sciences/Chemistry/NuclearChemistry/NuclearWeapons/FirstChainReaction/TypesofNuclear/CombinedFission.htm

--
By jacketing the third stage with non-fissionable material, three stage devices can produce high yield clean weapons. Both Zuni and Tsar Bomba were in fact very clean devices - Zuni was 85% fusion and Tsar Bomba was 97% fusion. Both designs permitted replacing the lead or tungsten third stage jacket with U-238 however.
--

 

[Morbius]

But can't the neutrons be stopped with lead?

Yes - but you get radioactive lead - albeit a relatively short lived isotope.

http://www.cartage.org.lb/en/themes/Sciences/Chemistry/NuclearChemistry/NuclearWeapons/FirstChainReaction/TypesofNuclear/CombinedFission.htm

--
By jacketing the third stage with non-fissionable material, three stage devices can produce high yield clean weapons. Both Zuni and Tsar Bomba were in fact very clean devices - Zuni was 85% fusion and Tsar Bomba was 97% fusion. Both designs permitted replacing the lead or tungsten third stage jacket with U-238 however.
--

The "clean" Tsar bomb had a yield of 58 Megatonnes, or 58,000 kilotons.
If it was 97% fusion, then it was 3% fission. Thus the fission yield was
1740 kilotons - so Tsar was 116 times as "dirty" as Little Boy.

The last line above tells the story on this. The lead jacket is used in lieu
of a jacket of U-238. Under the flood of fast neutrons, the U-238 would
fission thus creating lots of radioactive fission products.

The fully configured Tsar bomb, with the U-238 jacket, was supposed to
have a yield of 100 Megatonnes. Since the fusion yield was 97% of the
tested 58 MT yield; or 56.26 MT - the fully configured device would have
a fission yield of 43.74 MT. So the never tested "full-up" version would be
56.25% fusion and 43.74 % fission. The "as tested" device, although having
a yield that was 97% fusion - there was still very substantial fission yield.

So the lead jacket case is only relatively clean in that you are not
letting the neutrons cause extra fissions. You aren't escaping the
fact that the neutrons are going to induce radioactivity; no matter
what you do.

Dr. Gregory Greenman
Physicist

 

[kapton]

wow!

Are you blind,

the energy that is emmited from Deutrerium and Tritium fusion on the order of 17.6 meV is radioative - a stream of photons of a 10^-14 gamma wavelength.

 

[SkepticJ]

Well if fusion won't work what about anti-matter-matter bombs? IIRC anti-matter reactions only give off gamma and thermal energy. How would one shield the gamma from getting out but still have the huge explosion?

 

[mathman]

There are at least two obvious problems using anti-matter (in spite of Star Trek). First, how to make it in sufficient quantities for a bomb? Second, what sort of container can you use to hold it until you want the bomb to go off?

 

[sid_galt]

There are at least two obvious problems using anti-matter (in spite of Star Trek). First, how to make it in sufficient quantities for a bomb? Second, what sort of container can you use to hold it until you want the bomb to go off?

Third, If accidentally the container gets broken or the bomb is hit with a nuclear missile, the whole bomb explodes. You don't want a 100,000 kiloton explosion in your own country.

 

[Pengwuino]

lol i think this proves how people actually do care about the environment. We want the weapons that are made to kill hundreds of millions of people to be as harmless to the environment as possible lol.

 

[Pyrovus]

Well if fusion won't work what about anti-matter-matter bombs? IIRC anti-matter reactions only give off gamma and thermal energy.

The only problem there is that the gamma rays produced are extremely high energy. As soon as they hit a nucleus, these rays would easily be able to knock several nucleons out, possibly even splitting the atom altogether. And these nucleons would likely have high kinetic energies, and thus be capable of causing further radioactivity upon impact with other nuclei.

 

[Astronuc]

Well if fusion won't work what about anti-matter-matter bombs? IIRC anti-matter reactions only give off gamma and thermal energy. How would one shield the gamma from getting out but still have the huge explosion?

Thermal energy implies particles other than photons, i.e. thermal energy is the manifestation of particle kinetic energy. A proton-anti-proton reaction generally causes pions or Kaons, which then decay muons and pions/muons respectively (see table on decay modes), and muons ultimately decay into electrons and neutrinos.

Photo-nucleon reactions have a threshold, the binding energy of the nucleons. The gamma-rays are much more likely to scatter off-electrons.

One does not keep gamma-rays from getting out - they scatter and each subequent photon has less energy.

 

[theCandyman]

Going back to the inital topic for a second, why make something like fusion a weapon!? I want to go into research on fusion when I graduate and I do not want to make it into something that is a weapon. I know that is far too idealistic, but I would feel better thinking that I am helping the world, not working towards its destruction.

 

[Morbius]

Going back to the inital topic for a second, why make something like fusion a weapon!? I want to go into research on fusion when I graduate and I do not want to make it into something that is a weapon. I know that is far too idealistic, but I would feel better thinking that I am helping the world, not working towards its destruction.

Candyman,

Although it is counterintuitive; nuclear weapons, in the opinion of many,
are responsible for keeping the peace.

There is an old expression from "Epitoma Rei Militaris" by Vegetius -
"Igitur qui desiderat pacem, praeparet bellum." or "If you want peace,
prepare for war".

Owing principally to both World War I and World War II; during the
first half of the 20th century - about 1 million people per year were
killed in war.

After 1945, that number dropped precipitously. What happened in
1945 to cause that? The dropping of the bombs on Hiroshima and
Nagasaki is what!

Due to the existence of nuclear weapons - all out war, like humankind
experienced twice in the first half of the 20th century, is no longer an
option.

The deterence to war afforded by the existence of nuclear weapons
has arguably saved many, many lives. In that matter; those that
work on nuclear weapons are helping to save the world - not destroy it.

Dr. Gregory Greenman
Physicist

 

[arivero]

The deterence to war afforded by the existence of nuclear weapons
has arguably saved many, many lives. In that matter; those that
work on nuclear weapons are helping to save the world - not destroy it.

Ir is regrettable that this people lost time "saving the world" instead of, for instance, decoding the origin of the spin-orbit coupling at magic numbers.

 

[SkepticJ]

lol i think this proves how people actually do care about the environment. We want the weapons that are made to kill hundreds of millions of people to be as harmless to the environment as possible lol.

Were did I say weapon? I didn't. The point of having non radioactive isotope creating bombs is you could use them for stuff without hurting biology for decades afterwards. Using nukes for blasting out huge amounts of rock in pit mines is one use I can think of, or that pesky mountain you want gone.

 

[SkepticJ]

There are at least two obvious problems using anti-matter (in spite of Star Trek). First, how to make it in sufficient quantities for a bomb? Second, what sort of container can you use to hold it until you want the bomb to go off?

Particle accelerators designed to make it in high amounts, they are powered by fusion power plants.

Magnetic bottles, like we already use to hold small amounts of anti-matter. Or the ones that keep plasma from touching matter in plasma rockets.<-- These things already exist; they just need improving before NASA uses them.
Or out in the realm of still speculation, thin tanks of monopolium .

 

[mathman]

Particle accelerators designed to make it in high amounts, they are powered by fusion power plants.

How high is high amounts - thousands of anti-protons? For bomb purposes, it may not be enough. There are no fusion power plants!

 

[Pengwuino]

Were did I say weapon? I didn't. The point of having non radioactive isotope creating bombs is you could use them for stuff without hurting biology for decades afterwards. Using nukes for blasting out huge amounts of rock in pit mines is one use I can think of, or that pesky mountain you want gone.

you guys get offended so easily lol. Its a weapon against mountains!

 

[Pengwuino]

Going back to the inital topic for a second, why make something like fusion a weapon!? I want to go into research on fusion when I graduate and I do not want to make it into something that is a weapon. I know that is far too idealistic, but I would feel better thinking that I am helping the world, not working towards its destruction.

... fusion bombs already exist. They are banned by international treaty though but Russia and the US most likely still have half a dozen or so sitting around. At least that's how i think it is... not sure. Can anyone clarify?

And whoever said the whole, nukes have stopped war... man... isn't that the greatest irony this worlds ever realized lol. The real question though is having the threat of a small accident causing the human race's exstinction vs the practical guarantee of no massive wars killing tens of millions ever happening again. And i hate when people think its bad to have nukes because there 'full of hate' or some other hippie slogan like that. I mean come on, look at Russia now and look at it the past 50 years. Take nukes outta the equation and we'd be doing WW5 right about now. We learned nothing from WW1 and WW2 (typical human nature) and would probably have gone into ww3 the second another nation got back to military strength. So yes, totally, peace = threat of annihilation!

 

[theCandyman]

I think the hydrogen bomb relies on fusion, I am not completely sure. I see the point of Morbius' comment, but I still see that a fusion bomb is a weapon and the point of a weapon is to kill.

 

[Pengwuino]

Yah... a hydrogen bomb can't be a fission bomb... that would make no sense

 

[Huckleberry]

I was under the impression the hydrogen bomb was a fission/fusion bomb. Please don't ask me to explain that. I was doing some research on fusion bombs and was looking at something called Red Mercury. Supposedly it is a pure fusion weapon, using deuterium and tritium to fuel the fusion reaction.

As far as nuclear weapons keeping the peace. Yeah, that may work for a time, but it seems inevitable that something that is built will eventually be used. I would rather see WW3-5 over the span of the last half a century or so than see the end of humanity in the next.

What was the question?
Huck

 

[Astronuc]

I was under the impression the hydrogen bomb was a fission/fusion bomb.

That was explained by Mathman and Morbius at the top of page 1 of this thread. The fission (Pu) trigger provides the high temperature required for the fusion reaction.

As for the US arsenal - The Trident II D5 missile can be fitted with the W88/Mk5 mini-thermonuclear warhead (~475 kT each (from FAS.org)). There are more than a few dozen.

 

[Morbius]

I was under the impression the hydrogen bomb was a fission/fusion bomb. Please don't ask me to explain that. I was doing some research on fusion bombs and was looking at something called Red Mercury. Supposedly it is a pure fusion weapon, using deuterium and tritium to fuel the fusion reaction.

Red Mercury is a bunch of nonsense.

Hydrogen bombs have to be triggered by atom bombs.

You have both fission and fusion going on in an H-bomb.

As far as nuclear weapons keeping the peace. Yeah, that may work for a time, but it seems inevitable that something that is built will eventually be used. I would rather see WW3-5 over the span of the last half a century or so than see the end of humanity in the next.

Why do you think a nuclear war is inevitable?

The history of the last half century is that war - both nuclear and
conventional is restrained. I wouldn't accept the millions of deaths
that WW3 - WW5 would represent so easily.

Nuclear weapopns represent such a large quantitative increase
in destructive power, that they are a qualitative difference - a difference
in kind. A typical 2000 lb. bomb as can be dropped from many of our
aircraft represents an ~ 1 tonne yield. A hydrogen bomb can be a
Megatonne - a million times greater. That's what I mean by a difference
in kind. I don't think you can extrapolate from past experience that since
every other weapon has been used that, of necessity, that means the
hydrogen bomb will eventually be used - not when it represents a jump
of 1 Million. Past experience with lesser weapons doesn't speak to the
use of thermonuclear weapons.

In our quest to avoid some imaginary nuclear war, we would be unwise
to eliminate nuclear weapons and once again make the world safe for
all out conventional war.

Dr. Gregory Greenman
Physicist

 

[Huckleberry]

In our quest to avoid some imaginary nuclear war, we would be unwise
to eliminate nuclear weapons and once again make the world safe for
all out conventional war.

Have you ever played poker? In order to keep peace through the use of nuclear weapons there must be the threat that they will actually be used. If nobody believes that they will be used then they lose their effectiveness in forcing nations to be peaceful. Eventually someone will call the bluff intentionally because they have nothing to lose and the potential for much to gain afterwards. The person with the fewest chips is most likely to make that call.

What was the question?
Huck

 

[NEOclassic]

Recalling Candyman's 1st post in this String:

Going back to the inital topic for a second, why make something like fusion a weapon!? I want to go into research on fusion when I graduate and I do not want to make it into something that is a weapon. I know that is far too idealistic, but I would feel better thinking that I am helping the world, not working towards its destruction.

Hi Candyman,
I seriously applaud your didication to the development of a sustained fusion reactor which will be more an engineering feat than a physics one. Be not deceived by the current fusion technology where tritium, as now used in relatively small applications, has become a sort of a poster-boy that could be reckoned as a kind of catalyst to fusion reactor success. And well it might be at the beginning of such a project, but its availability on a one to one demand basis could become an onerous problem for anyone of a few reasons, it would be wise to go for DD fusion rather than DT fusion. Recall what Morbius has mentioned often is that the neutron energy from the DT fusion is about 14 MeV compared to that of the DD fusion of about 2.5 MeV. Before making a point on the relative size of the reactor let's consider a modelling as follows: Centered in a large extremely heavy walled spherical shell is a smaller spherical shell made of some hydrogen sieve material, such as palladium, that contains the reaction zone where the neutrons that carry off so much of the fusion energy are created. These neutrons radiate isotropically and lose energy to the deuterated fuel that fills the gap between the two shells.
[The deuterated fuel could be water or lithium-D or dodecaborane etc because it is these light materials that most effectively absorb the kinetic energy transfers and so it becomes important that the thickness of the fuelgap be large enough that most of the neutron energy is retained. One reason why I would chose to go with DD is that the outer shell would be much smaller with DD than with the 14 MeV neutrons of the DT.]
Now then the absorbed energy of the fuel results in a temperature gradient of some sort but it should be possible to have, in onion layered fashion, bimetalic thermocouple porous shells whose voltages are to be amplified such that at say 200 KeV directed from the inner surface of the palladium shell to the dead centered pod/anvil that holds deuterons that have been shared from the Pd source can produce a continuum of sustained reaction. Don't you think? Its just a thought from one dedicated contrarian. Cheers, Jim

 

[Morbius]

In our quest to avoid some imaginary nuclear war, we would be unwise
to eliminate nuclear weapons and once again make the world safe for
all out conventional war.

Have you ever played poker? In order to keep peace through the use of nuclear weapons there must be the threat that they will actually be used. If nobody believes that they will be used then they lose their effectiveness in forcing nations to be peaceful. Eventually someone will call the bluff intentionally because they have nothing to lose and the potential for much to gain afterwards.

Huck,

Why do you think nobody believes they will be used?

The USA has its weapons laboratories maintaining these weapons so that
they will be ready to use. The U.S. Navy, for example, has its Trident
submarines practice launching nuclear missiles as part of their normal
operations.

It is quite clear that the USA will use nuclear weapons in response to a
nuclear attack.

You've bought into the questionable assumption proferred by many
anti-nukes that nuclear weapons are just too powerful to be used - so
they won't be used. They are wrong.

As an analogy, suppose a police officer mistook you for a dangerous
criminal and held you at gunpoint; ordered you to lie on the ground,
and not to approach him. Would you say, "Oh he's not going to shoot me;
he'd kill me - and that would be too strong a reaction. So the police
officer is just bluffing - and I can approach him"?

If you do approach inspite of the officer's admonitions not to - and the
officer feels threatened by the approach of someone he thinks [ albeit
mistakenly ] a dangerous criminal - he'll shoot and be well within his
rights to do so.

It would be STUPID for anyone to think that a large-scale attack on the
USA would not be met with a nuclear reprisal.

Look at President John Kennedy's handling of the Cuban Missile Crisis.
He put our nuclear forces on alert - and the USA was ready to release
a nuclear barrage against the Soviet Union. Kruschev was not dumb -
and did not assume that those missiles would not be fired.

Or look at the first Gulf War in 1991. Back then we knew [ as was later
confirmed by the post-war inspectors ] that Saddam Hussein actually
had chemical weapons at his disposal. His forces could very well have
used chemical weapons against coalition forces or Israel.

Yet the Iraqi military didn't use the one type of weapon that would
really have caused us some difficulty. Why not?

Because British Prime Minister Maggie Thatcher and then President
George H.W. Bush made it very clear to Saddam that use of chemical
weapons would meet a retaliation by tactical nuclear weapons.

To back that up, tactical nuclear weapons, AFAPs [ Artillery Fired
Atomic Projectiles ] were moved into the Iraqi theater, ready for use -
and they would have been used under the right circumstances.

NO - don't buy this propanganda that nuclear weapons can't be used.
The USA used them to end World War II, and will use them again if the
circumstances demand it.

Just as that police officer is ready, willing, and able to shoot you dead
if you don't comply properly - the USA will use its nuclear forces should
the need ever arise.

And that, my friend, is what keeps the peace.

Dr. Gregory Greenman
Physicist

 

[Morbius]

Hi Candyman,
I seriously applaud your didication to the development of a sustained fusion reactor which will be more an engineering feat than a physics one. Be not deceived by the current fusion technology where tritium, as now used in relatively small applications, has become a sort of a poster-boy that could be reckoned as a kind of catalyst to fusion reactor success. And well it might be at the beginning of such a project, but its availability on a one to one demand basis could become an onerous problem for anyone of a few reasons, it would be wise to go for DD fusion rather than DT fusion. Recall what Morbius has mentioned often is that the neutron energy from the DT fusion is about 14 MeV compared to that of the DD fusion of about 2.5 MeV.

NEOClassic,

Given that the energy loss is logarithmic - the difference between a
2.5 MeV neutron and a 14.1 MeV neutron is absolutely TRIVIAL.

Let's express the neutron energy, as is commonly done when we are
doing neutron slowing down calculations, in terms of its "lethargy".
The lethargy is the common logarithm of the ratio of the neutron
thermal energy divided by the energy of the neutron.

With E_thermal = 0.025 eV; the lethargy difference of a 2.5 MeV neutron
is 8.0; while the difference in lethargy of the 14.1 MeV neutron is 8.75 -
a rather trivial difference. In fact, the fact that you have hydrogen
around - means that you need only about ~2 more collisions to slow down
the 14.1 MeV neutron on average, than you need for the 2.5 MeV neutron.

So the claimed advantage of D-D fusion over D-T fusion due to the
lower product neutron energy is INSIGNIFICANT.

However, it is more difficult to achieve the D-D fusion conditions than
it is for the D-T fusion conditions. Therefore, by going to D-D fusion,
you increased the difficulty of achieving fusion - and the payback of
lower product neutron energy is TRIVIAL. So it makes for a very bad
tradeoff.

The scientists working on fusion aren't dumb - they've chosen to work on
D-T fusion for a reason.

Before making a point on the relative size of the reactor let's consider a modelling as follows: Centered in a large extremely heavy walled spherical shell is a smaller spherical shell made of some hydrogen sieve material, such as palladium, that contains the reaction zone where the neutrons that carry off so much of the fusion energy are created. These neutrons radiate isotropically and lose energy to the deuterated fuel that fills the gap between the two shells.

Just how big is your fusion reaction zone going to be? The mean free
path of high energy neutrons - be they 2.5 MeV or 14.1 MeV is measured
in 10s of centimeters. You are not going to be able to get much energy
transfer from the neutrons in order to sustain your fusion reactions.
Not unless your reaction zone is orders of magnitude greater in size
than anything that anybody is considering.

No - you sustain the fusion reaction itself by capturing the energy of
the other reaction product - the charged ion. The neutrons are captured
in a "blanket" outside the reaction zone. That's where they can be used
to breed additional Tritium [ by including Lithium-6 in the blanket
material ], as well as where you recover the bulk of the energy desired
for the power plant.

[The deuterated fuel could be water or lithium-D or dodecaborane etc because it is these light materials that most effectively absorb the kinetic energy transfers and so it becomes important that the thickness of the fuelgap be large enough that most of the neutron energy is retained. One reason why I would chose to go with DD is that the outer shell would be much smaller with DD than with the 14 MeV neutrons of the DT.

As above - the difference in shell thickness would be TRIVIAL.

Now then the absorbed energy of the fuel results in a temperature gradient of some sort but it should be possible to have, in onion layered fashion, bimetalic thermocouple porous shells whose voltages are to be amplified such that at say 200 KeV directed from the inner surface of the palladium shell to the dead centered pod/anvil that holds deuterons that have been shared from the Pd source can produce a continuum of sustained reaction. Don't you think?

My thoughts - not much.

Dr. Gregory Greenman
Physicist

 

[Huckleberry]

Morbius,

I personally do believe the threat of nuclear war is real and that they will some day be used. It seems you're attempting to confuse me with some weird logic.

Why do you think a nuclear war is inevitable?

Why do you think nobody believes they will be used?

It would be STUPID for anyone to think that a large-scale attack on the
USA would not be met with a nuclear reprisal.

This is essentially why I believe keeping peace with nuclear weapons will make nuclear war inevitable eventually. How many nations are there in the world that would like to see the downfall of the U.S.? How many terrorist organizations would be willing to use a nuclear weapon against the U.S.? Should we invade every third world nation on the planet that could potentially harbor resentment towards the U.S. looking for terrorists real or imaginary? Wouldn't that just accelerate other nations resentment against us and cause them to come together while we are separated from our allies?

Admittedly, there are a lot of what ifs, but this does seem to be a very plausible, natural progression to me. I have very little doubt that nuclear weapons will be used. I am not saying total human annihilation, just that they will eventually be used and that the more we rely on them for peace the sooner it will happen.

In your cop scenario only one person has a gun. Also, I'm not sure I like the inclusion of myself in your scenario.(please let me be my own puppet) Imagine if they both believed they had the proper authority (were both good guys from their own points of view) and they both had guns pointed at each other and came to an unresolvable conflict of interests. How would that scenario go then? All we need is the unresolvable conflict of interests such as freedom of government or availability of resources and then there will be people anxious to take advantage of the chaos that would result.

The reaction of the U.S. and the world to the 9/11 attack solidifies my opinion on the matter. That was the loss of a few major buildings and a few thousand lives. Law has changed arguably at the expense of freedom and constitutional rights, wars have been fought under apparently false pretenses, foreign relations strained somewhat, and a general increase in discontent in Arab nations. This is all bad for the U.S. and good for its enemies, but what should we do, nothing? There will always be a reaction. The masses will demand it. Aggression begets aggression (not every day you get to use the word beget ) Peace begets peace (Wow! twice in one day )

What was the question?
Huck