Why are fission uranium bombs more used than fusion hydrogen bombs?

[Jarfi]

I keeps seeing news about iran making uranium and everybody is using nuclear fission bombs instead of nuclear fusion. Hydrogen bombs are much more powerful because they use fusion, but still all countries that have nuclear weapons use uranium fission bombs, Why?

What advantage does fission have over hydrogen fusion bombs?
Why isn't everybody making hydrogen bombs?

 

[JaredJames]

Well they all operate using primarily fission looking at this: http://en.wikipedia.org/wiki/Nuclear_weapon

The second basic type of nuclear weapon produces a large amount of its energy through nuclear fusion reactions. Such fusion weapons are generally referred to as thermonuclear weapons or more colloquially as hydrogen bombs (abbreviated as H-bombs), as they rely on fusion reactions between isotopes of hydrogen (deuterium and tritium). However, all such weapons derive a significant portion, and sometimes a majority, of their energy from fission (including fission induced by neutrons from fusion reactions).

 

[Pengwuino]

If I'm not mistaken, building a hydrogen bomb is orders of magnitude more complicated than building a fission bomb.

 

[russ_watters]

To say what jardenjames said in a different way: in order to build a fusion bomb, you have to first build a fission bomb to use as detonator for the fusion part...so you have to perfect that first.

 

[Drakkith]

If I'm not mistaken, building a hydrogen bomb is orders of magnitude more complicated than building a fission bomb.

I don't think so. You simply must have a fission bomb as the primary stage of the warhead. This provides the required power to detonate the fusion stage.

 

[cjl]

Also, most countries with a significant nuclear arsenal do use hydrogen bombs pretty much exclusively. The fission bombs are discussed more in the context of countries which are attempting to create bombs, or have very few of them. As stated above, a fusion (hydrogen) bomb requires a fission bomb in order to operate, so you have to be able to make a fission bomb before you can make a fusion device.

 

[Drakkith]

Yep. Also, fusion bombs are capable of being variable yield fairly easily. Want a big boom? Allow the 2nd stage, the fusion stage, to go off. Dont want a big boom? Dont let the 2nd stage go off.

 

[sophiecentaur]

I think it will be partly due to the different strategic (?) reasons for having Nuclear Weapons. If you are a 'super power' you will want to have the capability of annihiating your enemy so you would want a lot of Bang and can afford it. If you are a 'developing nation' you can't expect to be part of a global war. You just hope (?) that a low tech, probably dirty bomb will provide a disincentive for another 'developing nation' to attack you with a bomb. OR, you may just want to prove a point and target a super power - just before your whole country fries.

 

[Jarfi]

If I'm not mistaken, building a hydrogen bomb is orders of magnitude more complicated than building a fission bomb.

Yes but we had them in the 50's and usa should be able to easily produce high tech hydrogen fusion bombs way stronger than atom bombs that everybody is using

 

[JaredJames]

Yes but we had them in the 50's and usa should be able to easily produce high tech hydrogen fusion bombs way stronger than atom bombs that everybody is using

It's not always about "strength".

You don't want to set of a 50Mt Tsar bomb if your objective doesn't require that level of devastation.

The concept of "I've got bigger bombs than you" results in MAD (mutually assured destruction - aka the cold war) and isn't employed any more.

 

[Drakkith]

Yes but we had them in the 50's and usa should be able to easily produce high tech hydrogen fusion bombs way stronger than atom bombs that everybody is using

Actually the standard design for a thermonuclear warhead hasn't changed in about 40 years. Its not really that high tech. Look up thermonuclear warhead on wikipedia for more.

 

[swoymyoinrye]

Large amounts of very precise test data and a large and expensive body of research are required to produce reliable fusion weapons. While the development of genuinely novel nuclear weapons has presumably stalled since the 1980's, saying the technology has not advanced in 40 years is just false. Vast sums of money are presently spent on technology related to nuclear weapons testing and development in the US. To assume that none of this is directed at technological advancement of warheads is just silly. Look at wikipedia alone and you will realize that the United States is believed to possesses nuclear weapons of a fundamentally more advanced nature than any other deployed fusion weapons system.

No emerging power would attempt to build fusion weapons because the political and economic(sanctions) cost of extensive testing would overwhelmingly negate any perceived gain in military/political power from fusion weapons.

 

[Drakkith]

Large amounts of very precise test data and a large and expensive body of research are required to produce reliable fusion weapons. While the development of genuinely novel nuclear weapons has presumably stalled since the 1980's, saying the technology has not advanced in 40 years is just false. Vast sums of money are presently spent on technology related to nuclear weapons testing and development in the US. To assume that none of this is directed at technological advancement of warheads is just silly. Look at wikipedia alone and you will realize that the United States is believed to possesses nuclear weapons of a fundamentally more advanced nature than any other deployed fusion weapons system.

No emerging power would attempt to build fusion weapons because the political and economic(sanctions) cost of extensive testing would overwhelmingly negate any perceived gain in military/political power from fusion weapons.

What I meant was that the basic design, the Teller-Ulam design, has not changed much. From what I have read that is still the design of choice in all thermonuclear weapons. Sure the basic technology has improved, which could improve the performance of the warheads, but as far as I know the basic design is still the same.

 

[swoymyoinrye]

The open source description of the Teller-Ulam design is a very general description of a primary and secondary. I do not agree that the supposed arrangement of the W88 belongs to that design. The W88 is believed to possesses a reversed arrangement and be constructed with a prolate primary. This is believed to be unique amongst all weapons ever successfully tested. The supposed functioning of plasma-generating plastics in modern weapons is also novel. The fabrication methods for these plastics are so sensitive that the USG recently discovered that it was unable to manufacture the chemical anymore because the successful production relied on undocumented contaminants that led to proper functioning via serendipity. Something like 40 million dollars was immediately spent in a crash program to maintain production capability when it was detected that the new product did not meet specifications.

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

 

[cjl]

Yes but we had them in the 50's and usa should be able to easily produce high tech hydrogen fusion bombs way stronger than atom bombs that everybody is using

The US (and Russia, and France, and Britain, etc...) pretty much exclusively do use hydrogen bombs. Yes, they're smaller than the enormous, multi-megaton bombs that were tested in the 60s, but that's because the modern designs are optimized to be relatively small, light, and efficient. Most are still around 10 times the explosive yield of the early fission bombs, while being much, much smaller and lighter. You seem to be under the impression that most of the bombs currently in service are fission devices, and that definitely is not the case.

Consider: the Little Boy bomb from WWII weighed nearly 10,000 pounds and had a yield of around 18 kilotons. The W80 thermonuclear warhead (designed in the late 70s) weighs 290 pounds, and has a yield of up to 150 kilotons. Yes, we could make them bigger, but in many cases, it's more useful to make them smaller and lighter.

 

[swoymyoinrye]

ICBM's are deployed with large fusion warheads because treaties prevent installation of MIRV packages onto them, so they are equipped with one smaller warhead with PENAIDS or one large warhead with chaff or something simpler. SLBM's are permitted to deploy MIRV packages and presumably do so, to increase weapon effects against both hard and soft targets.

The production and deployment of modern MIRV'd ICBM's threatened to destabilize the current state of MAD, and were decommisioned, so now we only have the older minuteman system. Same reason why the russians won't deploy HGV or FOBS, any new weapons that favor first strike are a no-no.

 

[SteamKing]

The START II treaty between the US and Russia, which outlawed MIRV installations, was never ratified and never went into effect. MIRVs are still deployed in the US arsenal.

 

[swoymyoinrye]

Start II did not outlaw MIRVs on SLBMs.
According to OSI, the USA only deploys MIRVs on SLBMs.
Can you cite a source that states the SERV Minuteman rockets are currently loaded with more than one RV? SORT may not restrict MIRV installation but the restrictions on launchers alters the battlescape such that MIRV configuration may reduce reliability of the arsenal to an unacceptable degree.

 

[Drakkith]

Also remember that the ICBM's in the US were manufactured between the 1950's and 1970's and only have a few options to use for warheads because of designs. The Minuteman III ICBM uses a W62 Warhead with a yield of 170 kilotons, compared to the W56 warhead's yield of 1.2 megatons that was used in the I and II versions. This was because the Mark III was the first minuteman to use the MIRV's, and as such didn't need such a large warhead. (Not to mention that it probably couldn't hold 3 W56's due to size and weight constraints)

To design and build new warheads AND modify the missiles would be very expensive and is something that most of the public is against anyways, making it difficult if not impossible to achieve. So we are stuck with the same stuff we've had for about 30 years or more. (Which isn't that uncommon. I work in the air force on 30+ year old missiles that are loaded onto B-52 bombers which are themselves at LEAST 40+ years old, as the last one produced was manufactured in 1962.)

 

[cjl]

Also remember that the ICBM's in the US were manufactured between the 1950's and 1970's and only have a few options to use for warheads because of designs. The Minuteman III ICBM uses a W62 Warhead with a yield of 170 kilotons, compared to the W56 warhead's yield of 1.2 megatons that was used in the I and II versions. This was because the Mark III was the first minuteman to use the MIRV's, and as such didn't need such a large warhead. (Not to mention that it probably couldn't hold 3 W56's due to size and weight constraints)

To design and build new warheads AND modify the missiles would be very expensive and is something that most of the public is against anyways, making it difficult if not impossible to achieve. So we are stuck with the same stuff we've had for about 30 years or more. (Which isn't that uncommon. I work in the air force on 30+ year old missiles that are loaded onto B-52 bombers which are themselves at LEAST 40+ years old, as the last one produced was manufactured in 1962.)

The other factor is that a very large (multi-megaton) warhead is never needed to destroy a target. The reason for the very large warheads was because of relatively inaccurate delivery systems. If you can only hit within two miles of your target, but you use a bomb that makes a three mile radius fireball, then you're fine. With the updated guidance systems, the ICBMs became more accurate, and therefore a smaller, lighter warhead became practical to use.

 

[swoymyoinrye]

To design and build new warheads AND modify the missiles would be very expensive and is something that most of the public is against anyways, making it difficult if not impossible to achieve. So we are stuck with the same stuff we've had for about 30 years or more. (Which isn't that uncommon. I work in the air force on 30+ year old missiles that are loaded onto B-52 bombers which are themselves at LEAST 40+ years old, as the last one produced was manufactured in 1962.)

New warheads and new missiles were designed, manufactured, and deployed after minuteman. You may work on old ALCMs but ACMs are deployed with new warheads, and there are delivery systems much more survivable and effective than the B-52. We deploy older, less capable systems to maintain detente, not because we didn't develop and deploy better weapons at some point.

Also the USG did spent over $100 million over the last several years developing a new nuclear warhead based on W89.

 

[Drakkith]

New warheads and new missiles were designed, manufactured, and deployed after minuteman. You may work on old ALCMs but ACMs are deployed with new warheads, and there are delivery systems much more survivable and effective than the B-52. We deploy older, less capable systems to maintain detente, not because we didn't develop and deploy better weapons at some point.

Also the USG did spent over $100 million over the last several years developing a new nuclear warhead based on W89.

Good point. Also, we still use older stuff because, frankly, it's too expensive to upgrade them, or there isn't a big need to.