# Fourth Generation Nuclear Weapons

Staff Emeritus
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Dearly Missed
See http://www.arxiv.org/abs/physics/0510071" [Broken] excellent paper on the latest technology research on using tiny pellets of DT to yield explosions in the 100 ton range. Also includes brief but illuminating discussion of earlier nuclear weapons, from an international standpoint.

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theCandyman
What is the Independent Scientific Research Institute? The paper seems like an intresting read, but I do not like the idea of research into more powerful nuclear weapons. The current ones are already so powerful, there is not a need to get greedy and make sommething that has the probability of having an effect on something other than a target if a bomb absolutely has to be used, earth is a confined space after all.

Lapin Dormant
100 ton range is less then the KILOtonnes of an A bomb, and less moreso then the MEGAtonnes of the H bomb.

If I have the inference of "100 tons range" read properly. Smaller weapons of destrucive force from Nuclear sourcing.

Staff Emeritus
Gold Member
Dearly Missed
Lapin Dormant said:
100 ton range is less then the KILOtonnes of an A bomb, and less moreso then the MEGAtonnes of the H bomb.
If I have the inference of "100 tons range" read properly. Smaller weapons of destrucive force from Nuclear sourcing.

Yes. And with only a tiny, very thin shell of actinide, so minimal radiation signature. DT is a clean reaction, and they only need milligrams of it per weapon, so "safe for battlefield use"!:surprised

with [...] a [...] thin shell of actinide
What are you referring to? I only skimmed the article, but it seemed to be saying that the trigger would be non-fission. Are you referring to a U-238 blanket? I didn't see the article mention a U-238 blanket.

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sharmans
wow...Great

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Dearly Missed
What are you referring to? I only skimmed the article, but it seemed to be saying that the trigger would be non-fission. Are you referring to a U-238 blanket? I didn't see the article mention a U-238 blanket.

I thought I saw a reference to a thin shell of Uranium or Plutonium surrounding the pellet, but maybe this was in the "sparkplug" pellets used in H-bombs.

I thought I saw a reference to a thin shell of Uranium or Plutonium surrounding the pellet, but maybe this was in the "sparkplug" pellets used in H-bombs.
I think that was part of the section discussing older-generation devices:

2.2 Two-stage thermonuclear weapons

In two-stage thermonuclear weapons, the fusion material(i.e., lithium-deuteride, LiD) is generally packaged as a cylindrical or spherical shell sandwiched between an outer-shell of heavy material (the pusher/tamper) and an inner-shell of fissile material. This inner-shell (the spark-plug) is generally boosted with some DT gas. As suggested by its name, the purpose of the spark-plug is to ignite the fusion material at the appropriate time, i.e, once it has been sufficiently compressed. This whole package is called the "secondary" of the thermonuclear weapon, and is enclosed together with the "primary" in a thick and heavy "radiation case" which is designed to contain the soft-X-rays from the primary as long as possible.

theCandyman
Lapin Dormant said:
100 ton range is less then the KILOtonnes of an A bomb, and less moreso then the MEGAtonnes of the H bomb.

I did read it wrongly. I still do not agree with it, using smaller weapons like this would only encourage using larger ones.

Gold Member
theCandyman said:
I did read it wrongly. I still do not agree with it, using smaller weapons like this would only encourage using larger ones.

That is if we actually ever use the smaller ones. Maybe there are actual applications for something like that (mining for example) although I wonder what kind fo radiation levels it creates. And I also believe the belief that using smaller will result in bigger is as baseless as when they started saying the cheaper/cleaner you can make them, the more people will start using them.

theCandyman
The machine gun comes to mind, the inventor wanted to make something so horrible that war would no longer be something humanity wanted. In the present, they are common place and unlike defending trenches in the world wars, they are mounted onto helicopters and vehicles.

Of course there are other applications for this, but they are looking into the "military effectiveness".

Gold Member
I never really liked his reasoning for the machine gun. I don't see how he could have thought "humanity wants war" at the time and that the machine gun would have made people "not want it".

sid_galt
There is one weapon so horrible that humanity does not engage in major wars - the nuclear bomb.

Anyway, it's a pretty cool idea. I wonder how large they'll be. Could one for instance fit in a small UAV?

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Grogs
Pengwuino said:
That is if we actually ever use the smaller ones. Maybe there are actual applications for something like that (mining for example) although I wonder what kind fo radiation levels it creates. And I also believe the belief that using smaller will result in bigger is as baseless as when they started saying the cheaper/cleaner you can make them, the more people will start using them.

I think it's just the opposite really. I think most sane (ok, at least a little bit sane) world leaders realize that tossing ICBM's around will cause serious fallout in the international community. These seem to be an attempt to subvert that. It's seems like sort of an 'if we use a bunch of smaller nukes, maybe they won't mind so much' theory.

As for the long-term radiation effects on the landscape, it doesn't look like they'd be too bad. Of course the immediate effects for those near the weapon would be pretty horrible. The LD50/30 range for a 1-ton device would be about 300m and for a 100-ton one it would be around 1000m. This means that a person standing 1000m from a 100-ton detonation would have a 50% chance of dying (painfully!) from acute radiation sickness in the next 30 days. Of course people farther out still have a chance of dying either from ARS or from a cancer induced by the radiation. Closer in, people would literally drop dead in their tracks.

Lapin Dormant
What about the simplistic idea that the main reason is a manner of disposing of all {of some} of that nuclear waste, as this is seen as a Practical application for it's disposal?

Personally I don't think we need any more explosive devices as we already have enough to 'face off' the planet.

Grogs
Lapin Dormant said:
What about the simplistic idea that the main reason is a manner of disposing of all {of some} of that nuclear waste, as this is seen as a Practical application for it's disposal?

I'm not sure I follow you. Was this something discussed in the paper? I don't see how these weapons could in any way help with waste disposal. The only radioactive isotope it would contain would be tritium (H-3). As radioactive substances go, Tritium is pretty benign, releasing only an 18.6 keV electron and no gammas whatsoever when it decays. We're also only talking about a few grams, so even if tritium *were* a serious disposal problem, it would take a *lot* of these bombs to make even a sizable dent in our inventory.

Lapin Dormant
Probably my error, as I did NOT read the paper, but in the manufacture of tritium, isn't that done by nuclear bombardment using radioactive isotopes?
Hence a 'use' for some of the waste?

Grogs
Lapin Dormant said:
Probably my error, as I did NOT read the paper, but in the manufacture of tritium, isn't that done by nuclear bombardment using radioactive isotopes?
Hence a 'use' for some of the waste?

To the best of my knowledge, the easiest way to produce Tritium is to put some Li-6 inside of a reactor. The high-neutron flux in the reactor will produce Tritium using the reaction: Li-6 + n -> He4 + H-3. In spent fuel rods, there will be some residual neutron flux, but it's going to be considerably less than what you'd get inside of a reactor.

In an operating nuclear reactor, only about 0.7% of the neutron flux come from sources other than the fissions (we call these delayed neutrons and they're actually critical to our ability to control fission reactors.) Most of these delayed neutron sources have quite short half-lives though, typically less than 1 minute, so in spent fuel the neutron flux would fall off significantly after only a short period of time.

This isn't to say there aren't uses for nuclear waste though. We could pull about 99% of the material from spent fuel rods (the Uranium and Plutonium) plus a few other select isotopes which are useful for medical or commercial purposes (radioisotopic tracing and food irradiation for example.) Unfortunately, in order to do that we'd have to reprocess the waste and our current policy in the U.S. is that we don't recycle our fuel.

Back to the initial article, I noticed one item that I missed on my first initial skim. It completely ignores the problems associated with storing tritium-deuterium gas in a warhead. First, by it's very nature tritium is difficult to store as a pure gas. It tends to escape through the walls of most common storage materials (glass, steel) over a period of time. It's also radioactive, with a half-life of 12.3 years. The result is that after a period of time, your weapon will have considerably less yield than it did when it was first produced, giving it a fairly short shelf-life.

In the earliest thermonuclear weapons, they had to periodically disassemble the warhead, remove the pit, and refill it with tritium. This was less than desirable, so a solution was devised to use Li-D, which is stable, in the pit instead of D-T. When the first-stage (fission) trigger was ignited, it would provide the neutron flux to produce tritium from the Li to be used in the reaction. In the case of a conventional trigger, like the FGNW's, you wouldn't have the neutron flux so you'd have to use D-T gas in the pit. Has our technology improved enough that this is no longer a significant obstacle?

Grogs said:
tritium [...] tends to escape through the walls of most common storage materials (glass
Glass is tritium-permeable?

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Grogs
Glass is tritium-permeable?

No, actually that should be plastic, not glass.

Lapin Dormant

Had some experience at this have you?

(it shows)

Grogs
Lapin Dormant said:
Had some experience at this have you?
(it shows)

Thanks. It's education rather than experience actually. My minor as an undergrad was nuclear engineering and I'm getting ready to start on a Master's degree in NE this spring. Sometimes what you learn in the classroom is quite a bit different than how things are actually done though, so it's nice to have folks like Astronuc and Morbius who have years of experience working in the field for sanity checking.

Lapin Dormant
Fooled me you did

Grogs said:
Thanks. It's education rather than experience actually. My minor as an undergrad was nuclear engineering and I'm getting ready to start on a Master's degree in NE this spring. Sometimes what you learn in the classroom is quite a bit different than how things are actually done though, so it's nice to have folks like Astronuc and Morbius who have years of experience working in the field for sanity checking.
It is probably the usage of the "We" thing cause you make it sound like you have done it.

Fun stuff itsn't it, complex, yet simple, yet mightly Complex.

Potent.

Dearly Missed
sid_galt said:
There is one weapon so horrible that humanity does not engage in major wars - the nuclear bomb.
Anyway, it's a pretty cool idea. I wonder how large they'll be. Could one for instance fit in a small UAV?

sid_galt,

We have had nuclear artillery shells!!!

No secret there.

Dr. Gregory Greenman
Physicist

NavyMan
Gotta love atomic annie.

Dearly Missed
NavyMan said:
Gotta love atomic annie.
NavyMan,
Yes - but what I actually had in mind were regular 8" and 155mm shells.
For example, the W-79 was an 8 inch projectile:
http://nuclearweaponarchive.org/Usa/Weapons/W79.jpg
and the W-48 was a 155mm [ 6.1 inch ] projectile:
http://nuclearweaponarchive.org/Usa/Weapons/Mk48.jpg
"Atomic Annie" was the W-9 and was a 280 mm shell:
http://nuclearweaponarchive.org/Usa/Weapons/Mk9.jpg
Later designs like the W-48 were almost half the diameter of "Atomic Annie"
Dr. Gregory Greenman
Physicist

theCandyman
Morbius said:
Yes - but what I actually had in mind were regular 8" and 155mm shells.
For example, the W-79 was an 8 inch projectile:
http://nuclearweaponarchive.org/Usa/Weapons/W79.jpg

I thought the bombs were big because a critical mass is needed, so what are the dimensions of the smallest critical mass?

Staff Emeritus
theCandyman said:
I thought the bombs were big because a critical mass is needed, so what are the dimensions of the smallest critical mass?
That's a secret.

The smallest critical mass depends on how well one can compress a mass of fissile material (i.e. depends on max density achieveable) and on the purity of the fissile material. One certainly needs less Pu239 than U235.

NavyMan
I read recently it was possible to get the critical mass documents due to the freedom of information act, they are supposedly available from the National Archives and cost about $20. Scary thought Gold Member NavyMan said: I read recently it was possible to get the critical mass documents due to the freedom of information act, they are supposedly available from the National Archives and cost about$20. Scary thought

Well then go buy it :P

You'd think thatd be one of the things that were exempt from FOIA.... unless the information is less useful then it seems.

Staff Emeritus
NavyMan said:
I read recently it was possible to get the critical mass documents due to the freedom of information act, they are supposedly available from the National Archives and cost about $20. Scary thought Unless they have been declassified, I doubt that key critical mass calculations are available. The details of nuclear weapons are not in the public domain, and are not available under FOIA. There was a move during the Clinton administration to declassify some DOE records. IIRC, that program was suspended. Science Advisor Dearly Missed NavyMan said: I read recently it was possible to get the critical mass documents due to the freedom of information act, they are supposedly available from the National Archives and cost about$20. Scary thought
NavyMan,

NO - anything that is classified by the Atomic Energy Act of 1954 is IMMUNE from the
Freedom of Information Act.

In addition to my job as a physicist, I am also an Authorized Derivative Classifier. That
is, with published guidance from DOE, I decide if a document is classified or not.

In that capacity, I also handle Freedom of Information Act requests. There is a check
box on the FOIA form which states that the information is covered by the Atomic Energy
Act. If I check that box, then the FOIA request is automatically DENIED.

Dr. Gregory Greenman
Physicist

D_M_Wayne
Dearly Missed
Astronuc said:
Unless they have been declassified, I doubt that key critical mass calculations are available. The details of nuclear weapons are not in the public domain, and are not available under FOIA.
There was a move during the Clinton administration to declassify some DOE records. IIRC, that program was suspended.
Astronuc,

The Clinton Administration did seek to declassify a lot of information. Most classified
information is defined by an Executive Order - so the President has a lot of latitude in
the determination of classified information.

http://www.fas.org/sgp/clinton/eo12958.html

However, nuclear information is classified by the Atomic Energy Act of 1954 - which is
an Act of Congress - i.e. a Law. It takes another Act of Congress to change its provisions.

https://www.osti.gov/opennet/forms.jsp?formurl=od/rdfrdhtm.html

Specifically, the Clinton Administration stated that for "borderline" cases, the
determination should favor a finding that the information is unclassified.
However, the Atomic Energy Act, with its "born secret" provisions, states that the
determination should favor classified, not unclassified in borderline cases.

In order to overule the "born secret" provisions, it would take an Act of Congress, as I
stated above; which the Clinton Administration did not pursue.

Dr. Gregory Greenman
Physicist

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James Essig
Hi Folks;

I can imagine the potential for shaped charged nuclear devices able to produce enough heat and pressure to induce fusion in a limited subset of or throughout entire body of water. Note that shaped charge nuclear devices may be able to produce a concentrated jet of plasma and thermalized gamma rays with a blackbody temperature of about 10 EXP 14 K to 10 EXP 15K and pressures of perhaps 100,000,000 million atmospheres based on the estimate that the device could concentrate the reaction energy/plasma as much as 6 orders of magnitude above that of a spherically symmetric nuclear explosion. Nested shaped charges wherein a shape charge jet would be formed from a multitude of primary shaped charge jets could probably best this figure by several orders of magnitude.

Such a device might be detonated in a small pond or lake in an enemies territory thus roasting the enemies whole country in one feld-swoop. The danger is that it could be detonated in the ocean causing a chain fusion reaction to propagate through the entire Earth's ocean in a fraction of a second thus vaporizing the Earth with an effective 10 EXP 18.5 metric ton fusion bomb.

At a temperature of 10 EXP 15 K, it might be possible to create a macroscopic aggregate of Higg's Bosons thus causing a type of energy release that might be associated with such a large concentration of Higg's Bosons. Perhaps such a device could be used to alter the zero point energy state of the space within with the device is set off perhaps leading to a Higg's field imbalance and a limited release of zero point energy which is estimated by some physics theories to have a density 120 orders of magnitude greater than that of the average mattergy density of the obsevable universe. One cubic meter of space might have the latent energy of 10 EXP 41 times that of the mattergy within the observable within the universe. The danger here obviously is that a runaway phase change might ensue to envelope the whole universe. The worst possible scenario would be that the phase change might effect the whole multiverse or omniverse if such exist or the entire fractal verse proposed to exist within the theory of chaotic inflation due to any weak causal coupling between our Big Bang and any others in any form of causal coupling with our universe.

The message is that we had better be careful with our nuclear weapons experiments. No doubt, improvements in our ability to produce ever greater amount of liberated energy will continue, but lets be careful.

Regards;

Jim

GammaScanner
Hi Folks;

... thermalized gamma rays ...

All mine sort of fade out once they've been comptonized a bit and then photoelectronized.

A particular spectrum of gamma rays?
Photoneutron production maybe?
Gamma rays produced by thermal sources? (not just really high energy x-rays)

I've not thought of gamma rays being in equilibrium, they just go down in energy.
Inverse Compton scattering?

Are we talking such density of gamma rays, the most likely thing they might collide with is each other? That would have to be like 10 EXP zillion or so, at which point my puzzler gets sore and goes to sleep.

Interesting to think of though, Thanks!

- Ed