My Grandfather spoke these exact words not too long ago, and I am inclined to agree:

"Va fa en culo Enrico Fermi e quella sfaciema de bomba nuclear!"

< subtitle>f**k Enrico Fermi and that God damn nuclear bomb!< /subtitle>

Uhoh.. A technical discussion! I have a grave weakness: I can't resist kibitzing on things like this...

I'm not taking issue with anything you said on the technical side, but I feel an irresistible urge to expand a bit on a few points, so on with the kibitzing..

Ummm, no. A fusion bomb is called a staged thermonuclear weapon. It uses a plutonium trigger to ignite a fusion reaction. The yield of the weapon is adjusted by manipulating the amount of deuterium injected into the weapons core milliseconds before the trigger is set off. It is in reality a fission bomb augmented with fusible hydrogen.

 

Fission bombs typically yield in the kilo-ton range. They produce fallout of radioactive decay products (radioactive strontium, iodine, etc) and unspent plutonium. They also create what is known as an electro-magnetic pulse which is deadly to computers and electronics.

A "Fusion" bomb, also known as a hydrogen bomb, is a design that utilizes fusion in some way, through the actual definition is rather vague in practice. The US began using fusion-boosting in fission weapons in the 1950's, basically a standard plutonium implosion core with some fusion from deuterium injected into the pit, mainly to increase the levels of high-energy neutrons to enhance the fission reaction. This allowed the use of less plutonium and also boosted the yield.

A "true" hydrogen bomb is actually a three-stage device. A plutonium fission (usually fusion-boosted) primary, a fusion secondary, and a fission third stage. The fusion reaction releases the majority of it's energy in the form of high-energy (10 MeV or higher) neutrons. Those Neutrons can cause fission in Uranium 238 (also called depleted uranium) and therefore the bomb casing on a three-stage device is usually made of that material. That's why, although it is a difficult metal to work with, all US ICBM and SLBM launched warheads use U-238 for the warhead case. The interesting thing is that in a "Hydrogen" bomb, up to 80% of the energy yield is actually fission, not fusion.

Deuterium is not, so far as I know, used in the current US inventory for pragmatic reasons: It's use requires frequent and costly servicing of the warheads. Deuterium has a half-life of about 12 years, and it's primary decay product is an isotope of Helium (I can't recall which one offhand, and I'm too lazy to look it up). Helium is very fusion unfriendly, so helium contamination of the deuterium is a big problem. Therefor, Lithium 6 is often used instead, as it in part converts to Deuterium under neutron flux and serves a similar role.

Edit: I goofed. For some reason (although I do know the difference) I referred to Deuterium where I meant Tritium. It's Tritium, not deuterium, that has the half-life of 12 years. Only very early experimental US hydrogen bombs used Deuterium, though both Deuterium and Tritium are in a sense used in more modern multi-stage devices: The Lithium 6 converts to some of both. I have no idea why I mixed up Deuterium and Tritium throughout this post, but it only occurred to that i had done so while typing an utterly unrelated post. Duh! Well, I could edit this post and just correct it, but I think it's better to leave it alone and let everyone have a laugh at my expense. I sure did when I realized what I'd done!

IMHO, the main reason the "Neutron bombs" were retired from the US inventory was their maintenance issues (they needed Deuterium, as they relied upon a massive initial boost to the fission reaction).

As for the EMP, it's actually more a function of altitude than yield. I'll be happy to get into the physics if anyone is interested, but the short version is that at very high altitude, more of the energy from the bomb yield is converted to an electron cascade in the atmosphere, and from there it propagates down. It's only a factor at long range (outside of the direct effects zone) when a detonation occurs in the far upper atmosphere. That's why some of the Soviet warplans were based upon a FOBS (Fractional Orbital Bombardment System) with the first detonations occurring in the troposphere inland from the US East and West coasts. That would effectively blind and cripple the US (even most hardened communications and radar systems would be impaired), opening the way for the main strike.

If a terrorist or enemy really wanted to do the most damage to the US, a single device in the 100kt range (boosted fission would suffice for that yield) detonated about 100 miles up over the central US could fry around 90% of the electronics in the country. Vehicles (anything with electronic ignition) wouldn't work, as indeed very little else would. This would be vastly more damaging than taking out a single city, as it would cripple the entire country and also destroy our economy (including the ability to grow and transport food). This is why Iran's satellite program makes many so nervous. The argument has long been that it would be OK for Iran to have a few nukes, because they would have to be insane to trade one US city for their whole country. The problem with that theory is that with a satellite launch capability, they could effectively wreck the entire US with one bomb, and they wouldn't even have to design a re-entry vehicle for the warhead. We also probably wouldn't know that their launch contained a bomb until it detonated.

It's scenarios like this which cause some people (such as myself) to take a differing view on nuclear bunker-busters to your own. It's often not possible to use conventional munitions to take out a deep underground facility, so a ground-penetrating nuke might be the only way. I realize that many people have different opinions on this, but mine is that absolutely anything is better than a nuclear Iran. I'd sure prefer it to be done conventionally, but if not, a nuclear ground-penetrator might be the only option short of a megaton-range surface detonation, and for a truly deep complex in rock such as granite, a ground-penatrator might indeed be the only option in case of an emergency.

There are practical deterrents to the use of ground-penetrating nuclear devices, the prime physical ones being reliability. I don't know what design concept they are using, but I'd imagine that it would have to be a Uranium explosive-assembly core, rather than a plutonium implosion core. Implosion requires incredible precision, and the G-forces encountered by an earth penetrator could, I'd think, cause the explosive lenses to deform or change alignment slightly. The problem with that is that unlike plutonium, which is somewhat volatile and could disperse and thus be unrecoverable, the core of an undetonated Uranium-based weapon would be far more likely to be recoverable, and that type of core is far easier to build than an implosion device. Thus, if your ground-penetrator fails to detonate, you may well have just handed the target the raw material for an easy to make nuclear weapon. Plutonium, due to having a volatile isotope, must be imploded, but Uranium 235 can be used either by explosive assembly or implosion.

There are already plenty of low-yield tactical nukes in the arsenals of several nations (including the US), the only difference with a ground-penetrator would be the ability to take out a deep bunker with a low-yield below-ground detonation rather than the present option of a high-yield surface detonation (which would have far greater fallout).

There was a big difference in the design philosophy between nukes of the US and USSR. American missile technology was much more precise than the Soviets with the early ICBMs so the US made smaller, cleaner warheads. The Soviets on the other hand designed their nukes for the biggest possible bang. Although Soviet missile accuracy improved in the late 70s and 80s, their warheads were essentially the same- big, honking H-bombs.

Another way of describing it is primarily based upon throw weight. In the dawn of the missile age, The US could make a warhead of equivalent yield much smaller and lighter than the Soviets. Therefor, the Soviets had to build much larger and more powerful missiles to deliver similar yields. They did so, which is why they had such a big early lead in the space-race: they had bigger more powerful rockets due to having to design launchers for heavier warheads.

As Soviet physics advanced, they already had the greater throw weight, so they were able to compensate for their lesser CEP (Circular Error Probability, a way of measuring accuracy) via larger yield.

Another type of nuke was designed in the 70s called a neutron warhead. It was designed not for its explosive potential but the ability to cause a deadly pulse of radiation which would kill all humans (I've always wanted to work that into a conversation somehow.) who aren't in hardened shelters. This is a very "clean" but ghoulish weapon designed in anticipation of a super-power conflict in Europe. [since Europeans were tired of being bombed flat, I suppose being zapped like a frog in a microwave was an easier sell.]

One conundrum that I've never understood: The M-1 tank was designed for the European theater, to fight the Soviets, in an environment that had a high probability of being both chemical and nuclear. Tanks are normally excellent protection against some nuclear effects, and in this case need to be.

So, why on earth did they include depleted uranium in the armor composite?!!?!?!? If you hit DU with a neutron pulse (such as from a neutron or other nuclear weapon anywhere in the area) the resulting fission in the DU would bombard the crew compartment with levels of radiation far in excess of what they would receive even unprotected outside. For this reason I felt is was insane to use DU in the Chobham armor of the M-1, and I've never been able to find a good enough reason for it?

I have to agree with you. The "nuclear bunker-buster" is probably necessary for specific targets.

It is pretty scary to consider since everybody on the planet knows who and what they are being built for.

If you go after a regime like Iran or NK with these weapons, then you had better nail the targets on the first volley. Once it starts, either one will let fly with all they have.

Their countries are toilets. What have they got to lose?

I just went back and added an edit note (in italics, near the middle of the post) to correct an enormous series of blunders in my original post (I said Deuterium in a lot of places where I meant Tritium). I should know better than to trust my memory even on simple things. I wish that I was older so that I could blame it on a senior moment! :wacko:

I have to agree with you. The "nuclear bunker-buster" is probably necessary for specific targets.

 

It is pretty scary to consider since everybody on the planet knows who and what they are being built for.

 

If you go after a regime like Iran or NK with these weapons, then you had better nail the targets on the first volley. Once it starts, either one will let fly with all they have.

 

Their countries are toilets. What have they got to lose?

Very scary indeed, for a lot of reasons.

I totally agree that if you go after them, and they already have the operational weapons, you had better be positive that you will get them all (which is likely impossible to do with any degree of certainty). Otherwise, they will likely be used in one way or another.

The problem as I see it is that once they have them, it's very likely impossible to know where all of them are with any certainty. With a nuclear program like Iran's, you only need to take out segments of it to delay or halt the acquisition of nuclear weapons. But once they have them, your options are far fewer and vastly more difficult.

It's the "what have they got to lose" part that scares the utter heck out of me. Both Iran and North Korea have massive internal problems. We also IMHO can't think of them from the standpoint of countries with national self-interest, but rather as ruling cliques with primarily much narrower interests. In the case of Iran, this entire nuclear crisis is IMHO driven by their internal political dynamic: they need it to shore up internal support. The Mullah's hold on power was shaky, and slipping before the crisis. I personally feel that this is a dynamic that the Administration is ignoring, as are the European powers trying to strike a deal with Iran. They seem to be utterly ignoring the objective reality of the situation, and are making their offers and policy stances based on what Iran claims it wants. In doing so, they ignore the underlying internal issues that cause Iran to need to keep forging ahead.

This may sound like a crackpot theory, but I think I can prove it. The leaders of Iran may be many things, but they are not morons. If the conventional diplomatic view was correct and they were not primarily motivated by internal issues, it would not be in their best interest to keep stirring the pot by making provocative announcements. Yet, they do so. They do so very consistently. In fact, whenever serious doubt is voiced in the international media regarding whether Iran's program is really aimed at acquiring nuclear weapons, Iran itself usually acts quickly to dispel any doubt. Why? The only answer that fits is that they are playing to an internal audience.

And that is where I see the "what have they got to lose" problem rear it's very ugly head. If one looks at things from the Mullah's (the Guardian Council, in this case) point of view, they see a very different solution set. For their internal problems, both a nuclear program, AND/OR a US attack to destroy it, play right into their hands by shoring up internal support, regardless of whether the US is successful or not. They really do have nothing to lose, as they are only interested in protecting their regime and their own power. They don't care if Iran loses a few cities. This makes them dangerous beyond measure, and the old cold-war concept of MAD (nuclear deterrence) is rather unlikely to work once they gain nuclear weapons. This is without even factoring in the element of religious fanaticism that the Guardian Council and their ilk have.

In my view (and just my opinion, and I may well be wrong) the biggest problem here is that the negotiators are playing by the wrong set of rules, and thus are guaranteed to get nowhere. The only "coin" that could have any meaning in this situation is to make offers that would have the effect of shoring up the Mullah's internal position (not a good play from several points of view, but it is one option in lieu of an attack)..

I hope like heck that I'm wrong, but I see only one real (but small) chance of avoiding the need for a US attack to take out Iran's nuclear program, and that is to exploit fully it's internal dissent and try for a revolution. Given the ongoing crisis and it's effect on Iran's internal politics (resistance to and demonstrations against the regime have diminished), I don't see much hope of this. All I see are choices falling between bad and worse.

As for a US strike, even that is a very dicey proposition from a military point of view. Even if one assumes that the Iranians do not yet have nuclear weapons (probably a safe assumption for another year or so), We need good Intel to hit the vital targets. The main targets would be the centrifugal enrichment arrays, which should be fairly easy to find as they need enormous amounts of electricity (and hence massive power lines) They would be huge facilities, and are most likely deeply underground. Its other, smaller facilities that will be much harder to both find and hit. We would also need to hit Iran's nuclear reactors, and I believe that one of them is scheduled to go on line this year. Once it's running, destroying it will release a huge amount of radiation. Another problem is that if you don't get most of their sites, you merely delay the program.

To get most of it, you need excellent intel, and if Iraq proved anything, it's that we certainly don't have good intel capabilities for this sort of thing. Ugh, what a mess.