China ICBM/SLBM, nuclear arms thread

[Index]

Atomic weapons have around a thousand times more destructive power than chemical explosives of the same weight. And that is for fission weapons. Fusion weapons have even more destructive power than fission ones.

The tactical nuclear weapon imparts all that energy into just 1 point and is delivered by a single vehicle that is much easier to intercept than 50 different conventional missiles. The 50 conventional vehicles can strike 50 different targets, with enough force to destroy all of them and their close surroundings.

To achieve the same result, a tactical nuke would have to pray that 50 high value targets are clustered in a small enough area.

 

[bustead]

Hopping into this thread again. Just here to talk about U-235 (the useful uranium) in Chinese warheads with less jargon to help newcomers.

Uranium cannot be used as is in nuclear weapon construction. You will need to separate the useful U-235 out from the U-238. The products of this process are useful HEU full of U-235, and "useless" DU full of U-238.

China's HEU stockpile is around 14 tonnes. It is highly likely that the 506 warhead (the 4.4Mt warhead used on DF-5A) uses a HEU core and DU tamper, meaning that it takes maybe 10-15 kilos of HEU to build. Doing some math, it is clear that China can build around 1000 uranium warheads with its current stockpile.

HEU based tactical nuclear weapons can also be built. A small 1 kiloton weapon can be built with 3-4 kilos of HEU. So it is totally possible for China to build thousands of tactical weapons if needed.

 

[CMP]

Hopping into this thread again. Just here to talk about U-235 (the useful uranium) in Chinese warheads with less jargon to help newcomers.

Uranium cannot be used as is in nuclear weapon construction. You will need to separate the useful U-235 out from the U-238. The products of this process are useful HEU full of U-235, and "useless" DU full of U-238.

China's HEU stockpile is around 14 tonnes. It is highly likely that the 506 warhead (the 4.4Mt warhead used on DF-5A) uses a HEU core and DU tamper, meaning that it takes maybe 10-15 kilos of HEU to build. Doing some math, it is clear that China can build around 1000 uranium warheads with its current stockpile.

HEU based tactical nuclear weapons can also be built. A small 1 kiloton weapon can be built with 3-4 kilos of HEU. So it is totally possible for China to build thousands of tactical weapons if needed.

So that bit about depleted uranium you mentioned does not seem to be totally correct.

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A thermonuclear weapon, fusion weapon or hydrogen bomb (H bomb) is a second-generation

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. Its greater sophistication affords it vastly greater destructive power than first-generation

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, a more compact size, a lower mass, or a combination of these benefits. Characteristics of

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reactions make possible the use of non-fissile

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as the weapon's main fuel, thus allowing more efficient use of scarce fissile material such as

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(235 U) or

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(239 Pu).

 

[ZeEa5KPul]

So that bit about depleted uranium you mentioned does not seem to be totally correct.

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A thermonuclear weapon, fusion weapon or hydrogen bomb (H bomb) is a second-generation

Please, Log in or Register to view URLs content!

. Its greater sophistication affords it vastly greater destructive power than first-generation

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, a more compact size, a lower mass, or a combination of these benefits. Characteristics of

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reactions make possible the use of non-fissile

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as the weapon's main fuel, thus allowing more efficient use of scarce fissile material such as

Please, Log in or Register to view URLs content!

(235 U) or

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(239 Pu).

What @bustead is talking about is the primary stage of the weapon. The depleted uranium is used in the tamper in the secondary. You need a small fission (fusion-boosted fission, to complicate matters further) bomb to set off a much larger fusion bomb. The neutrons given off by the fusion reactions are energetic enough to fission U-238, which increases the bomb's yield. A lot of the yield comes from fission of this tamper by neutrons from the fusion.

1) A chemical explosive implodes a hollow sphere, called a pit (modern designs use other geometries like ellipsoids) of fissile material (U235 or Pu239) filled with deuterium-tritium gas. This causes a nuclear chain reaction which releases enough heat to fuse the DT gas. Neutrons released from this fusion improve the fission in the pit.
2) X-rays and gamma rays from this nuclear explosion are channeled by the interstage into the hohlraum, the radiation cavity housing the secondary stage.
3) The secondary stage is another spheroid with a tamper (an outer shell made of depleted uranium), an outer core of lithium deuteride, and an inner core of fissile material (called a spark plug). The channeled X-rays/gamma rays heat the tamper to such a degree that material ablates from it in jets, the reactive force of which implodes the secondary.
4) The imploding secondary crushes the fissile material at the core, which starts a fission chain reaction. Neutrons from this reaction fission the lithium in the outer core, and the heat and pressure start fusion reactions in the fusion fuel.
5) Very fast neutrons released by the fusion reaction fission the depleted uranium tamper. Note that this isn't a chain reaction, this is a massive flux of very energetic neutrons fissioning a material that can't sustain a chain reaction.

As you can see, the only places fissile material is used is in the pit and the spark plug. This is why modern devices that leverage all these principles and techniques can use relatively little fissile material (a few kilograms is sufficient for hundreds of kilotons yield). There are other tricks that can be used, like surrounding the pit with beryllium, a material that reflects neutrons, so less fissile material is needed to sustain a chain reaction.

 

[bustead]

So that bit about depleted uranium you mentioned does not seem to be totally correct.

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A thermonuclear weapon, fusion weapon or hydrogen bomb (H bomb) is a second-generation

Please, Log in or Register to view URLs content!

. Its greater sophistication affords it vastly greater destructive power than first-generation

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, a more compact size, a lower mass, or a combination of these benefits. Characteristics of

Please, Log in or Register to view URLs content!

reactions make possible the use of non-fissile

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as the weapon's main fuel, thus allowing more efficient use of scarce fissile material such as

Please, Log in or Register to view URLs content!

(235 U) or

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(239 Pu).

DU is fissionable, not fissile. This means that it can undergo fission and generate lots of energy, but it cannot sustain a chain reaction. So in order to generate energy from DU, you will need a lot of neutrons. Luckily, a nuclear fusion reaction can generate a lot of neutrons. This means that DU can undergo fission and contribute to the final yield in a thermonuclear weapon.
And that is what happened in early thermonuclear weapons, like Ivy Mike.
The main issue with this approach is that you will still need to kickstart a nuclear fusion reaction. And that can only be done with a fission "primary". Basically a atomic bomb. This will have to be loaded with fissile materials like HEU, or else it would not explode. No explosion means that there will be no nuclear fusion.
In short, DU is useful in contributing to the final yield. But you cannot build a nuclear weapon with DU only.

 

[CMP]

What @bustead is talking about is the primary stage of the weapon. The depleted uranium is used in the tamper in the secondary. You need a small fission (fusion-boosted fission, to complicate matters further) bomb to set off a much larger fusion bomb. The neutrons given off by the fusion reactions are energetic enough to fission U-238, which increases the bomb's yield. A lot of the yield comes from fission of this tamper by neutrons from the fusion.

1) A chemical explosive implodes a hollow sphere, called a pit (modern designs use other geometries like ellipsoids) of fissile material (U235 or Pu239) filled with deuterium-tritium gas. This causes a nuclear chain reaction which releases enough heat to fuse the DT gas. Neutrons released from this fusion improve the fission in the pit.
2) X-rays and gamma rays from this nuclear explosion are channeled by the interstage into the hohlraum, the radiation cavity housing the secondary stage.
3) The secondary stage is another spheroid with a tamper (an outer shell made of depleted uranium), an outer core of lithium deuteride, and an inner core of fissile material (called a spark plug). The channeled X-rays/gamma rays heat the tamper to such a degree that material ablates from it in jets, the reactive force of which implodes the secondary.
4) The imploding secondary crushes the fissile material at the core, which starts a fission chain reaction. Neutrons from this reaction fission the lithium in the outer core, and the heat and pressure start fusion reactions in the fusion fuel.
5) Very fast neutrons released by the fusion reaction fission the depleted uranium tamper. Note that this isn't a chain reaction, this is a massive flux of very energetic neutrons fissioning a material that can't sustain a chain reaction.

As you can see, the only places fissile material is used is in the pit and the spark plug. This is why modern devices that leverage all these principles and techniques can use relatively little fissile material (a few kilograms is sufficient for hundreds of kilotons yield). There are other tricks that can be used, like surrounding the pit with beryllium, a material that reflects neutrons, so less fissile material is needed to sustain a chain reaction.

DU is fissionable, not fissile. This means that it can undergo fission and generate lots of energy, but it cannot sustain a chain reaction. So in order to generate energy from DU, you will need a lot of neutrons. Luckily, a nuclear fusion reaction can generate a lot of neutrons. This means that DU can undergo fission and contribute to the final yield in a thermonuclear weapon.
And that is what happened in early thermonuclear weapons, like Ivy Mike.
The main issue with this approach is that you will still need to kickstart a nuclear fusion reaction. And that can only be done with a fission "primary". Basically a atomic bomb. This will have to be loaded with fissile materials like HEU, or else it would not explode. No explosion means that there will be no nuclear fusion.
In short, DU is useful in contributing to the final yield. But you cannot build a nuclear weapon with DU only.

Thanks for clarifying in detail. I was referring to the weapon as a whole rather than just the first stage. Even so, just based on the diagram alone (attached below), it looks like the 2nd stage tamper would be a much larger part of the total mass and volume compared to the 1st stage tamper. Meaning the use of DU in the second stage saves a LOT of what would otherwise be "wasted" U-235 or Pu-239 (or at least a very sub-optimal/unnecessary use of a scarce material in the 2nd stage). Lastly, the diagram seems to indicate that U-238 CAN be used for the 1st stage tamper. Doesn't that contradict what you implied in a previous post (not the one quoted here) about the U-238 not being useful?

 

[bustead]

What @bustead is talking about is the primary stage of the weapon. The depleted uranium is used in the tamper in the secondary. You need a small fission (fusion-boosted fission, to complicate matters further) bomb to set off a much larger fusion bomb. The neutrons given off by the fusion reactions are energetic enough to fission U-238, which increases the bomb's yield. A lot of the yield comes from fission of this tamper by neutrons from the fusion.

1) A chemical explosive implodes a hollow sphere, called a pit (modern designs use other geometries like ellipsoids) of fissile material (U235 or Pu239) filled with deuterium-tritium gas. This causes a nuclear chain reaction which releases enough heat to fuse the DT gas. Neutrons released from this fusion improve the fission in the pit.
2) X-rays and gamma rays from this nuclear explosion are channeled by the interstage into the hohlraum, the radiation cavity housing the secondary stage.
3) The secondary stage is another spheroid with a tamper (an outer shell made of depleted uranium), an outer core of lithium deuteride, and an inner core of fissile material (called a spark plug). The channeled X-rays/gamma rays heat the tamper to such a degree that material ablates from it in jets, the reactive force of which implodes the secondary.
4) The imploding secondary crushes the fissile material at the core, which starts a fission chain reaction. Neutrons from this reaction fission the lithium in the outer core, and the heat and pressure start fusion reactions in the fusion fuel.
5) Very fast neutrons released by the fusion reaction fission the depleted uranium tamper. Note that this isn't a chain reaction, this is a massive flux of very energetic neutrons fissioning a material that can't sustain a chain reaction.

As you can see, the only places fissile material is used is in the pit and the spark plug. This is why modern devices that leverage all these principles and techniques can use relatively little fissile material (a few kilograms is sufficient for hundreds of kilotons yield). There are other tricks that can be used, like surrounding the pit with beryllium, a material that reflects neutrons, so less fissile material is needed to sustain a chain reaction.

Well said. Just a side note, modern warheads like W88 make use of HEU tampers to further increase efficiency and yield.

 

[ZeEa5KPul]

@CMP, the primary uses a tamper as well. That's distinct from the pit. The tamper is a dense, heavy material that surrounds the stage so that it implodes smoothly and to confine the reactions for a few minute fractions of a second. Chain reactions are exponential processes: 1 fission causes 2 causes 4, 8, etc. Most of the energy is released in the last generations, so confining the reaction for as long as possible is very desirable. That's what the tamper is for.

The primary tamper doesn't really fission like the secondary's because the high energy neutron flux through it is low (only from the DT boosting gas, and most of that is absorbed by the pit, boosting its fission). The secondary's tamper is much bigger and fissions much more because the neutron flux from the lithium deuteride fusion is far greater.

The video by Matthew Bunn I linked earlier explains all of this in detail. I recommend you watch it.

 

[bustead]

Thanks for clarifying in detail. I was referring to the weapon as a whole rather than just the first stage. Even so, just based on the diagram alone (attached below), it looks like the 2nd stage tamper would be a much larger part of the total mass and volume compared to the 1st stage tamper. Meaning the use of DU in the second stage saves a LOT of what would otherwise be "wasted" U-235 or Pu-239 (or at least a very sub-optimal/unnecessary use of a scarce material in the 2nd stage). Lastly, the diagram seems to indicate that U-238 CAN be used for the 1st stage tamper. Doesn't that contradict what you implied in a previous post (not the one quoted here) about the U-238 not being useful?
View attachment 133113

I was saying that DU is not useful on its own. You can replace all the DU in a H-bomb with Tungsten or Lead, and the weapon will still detonate, albeit with a lower yield. If you are replacing the HEU in the primary with DU, the weapon will be a dud.
Also, it is possible to replace the DU tamper with HEU tamper for even higher yield. It is just more expensive.

 

[CMP]

I was saying that DU is not useful on its own. You can replace all the DU in a H-bomb with Tungsten or Lead, and the weapon will still detonate, albeit with a lower yield. If you are replacing the HEU in the primary with DU, the weapon will be a dud.
Also, it is possible to replace the DU tamper with HEU tamper for even higher yield. It is just more expensive.

Interesting. So do these additional smaller innovations you mention (such as swapping out DU for HEU) still all fall under the "2nd generation nuclear weapon" design? Do we have any evidence that any nation is currently and actively working on a 3rd generation design?