Media Criticism, Political Commentary, War Commentary

There Seems To Be A Step Missing

36 Comments

In all the media discussion over Iran’s incipient nuclear capabilities, two phrases seem to be intermingled. The headline on Fox News uses the word “warhead,” while Jamie Colby is talking to John Bolton, who continues to use the phrase “nuclear weapons.” While Iran having nuclear weapons is obviously nothing to sneeze at (though the White House seems to have a different view), nuclear weapons are not warheads. A warhead is a specific kind of nuclear weapon — one that not only works, but is light enough to be delivered on a missile, and has reentry and guidance systems to deliver it to its target. One does not go from enriching uranium to building warheads in a single step, but I hear no discussion of this. I wish I did.

36 thoughts on “There Seems To Be A Step Missing”

  1. The Iranians don’t need a warhead, though it’s a useful boogieman. All they need is a nuclear weapon small enough to fit into a truck, and a way to smuggle said truck into Tel Aviv undiscovered.

  2. and a way to smuggle said truck into Tel Aviv undiscovered.

    The problem here is what happens when you find a way to smuggle said truck into Tel Aviv in a way that is discoverable and totally interceptable by the Israelis such that they trace it back to you? Then your country gets nuked (perhaps you’d get lucky and it’d only be a demonstration that wouldn’t kill many people) and nobody of any consequence will whine about it. Remember that the number one obstacle to Israelis using nukes is the disapproval of serious powers like the US. Discovering that you attempted to nuke Tel Aviv would both negate the effectiveness of that obstacle and perhaps even get the full approval of the US for the Israeli retaliation.

  3. Karl,
    You make the assumption that the Iranians don’t want to get nuked.
    Its not clear to be that MAD (Mutual Assured Destruction) as a deterrent works with people that think martyrdom is the highest possible calling.

    Paul

  5. It may be a good thing nukes have their emotional impact. It seems to me, if they just wanted to wipe out Israel there are easier ways which I won’t mention.

  6. bbbeard said:

    Happy Now

    No, not at all. An Iranian nuclear power scares the heck out of me.

    I really hope that the Iranian leaders (and others in that region) understand that they really do need Israel in the Middle East to act as a scapegoat for all of their corruption and failings. As long as they can point and say (to their starving masses): “See, the great Satan (Israel and US) are to blame for your predicament. Be angry with them, not us, your benevolent leaders.

  7. If the Iranians are using a U235 bomb as their warhead (seems clear, as there is not a shred of evidence suggesting that they have any significant quantities of plutonium handy, or have any way of making any at this time), testing it seems to me to be beside the point. During the Manhattan project, the US never felt the need to test their U235 bomb (Little Boy) because the design was so simple that there was no real room for failure. It was the plutonium bombs, which used a far more complex implosion mehtod, that were the designs that required testing.

    Keep in mind that plutonium weapons would be necessary to build reliable fusion devices, but if the only thing that the Iranians want is a low-end fission device (the big bang and mushroom cloud being seen as sufficiently terrifying…), U235 will work quite nicely, and the simple ‘gun-type’ design could be implemented without prior testing…

  8. You make the assumption that the Iranians don’t want to get nuked.

    I think it’s safe to assume the Pasdaran junta doesn’t want to be nuked. Men who enjoy political power and privilege rarely wish that for themselves.

  9. For what it’s worth the relevant examples here would seem to be the W33 and W9 warheads, both gun-type HEU artillery shells, weighing 250lbs with a 40 kiloton yield and weighing 850lbs with a 15 kiloton yield, respectively. Given that both of these devices were built in the 1950s it seems likely that the technology to build low-mass gun-type HEU weapons with 15-40 kiloton yield is not significantly difficult, compared to the technology to build compact, light weight 2 stage thermonuclear weapons, for example. In combination with the Shahab-6 missile it seems prudent to say that Iran’s nuclear strike capability is imminent.

    That’s not to downplay the difficulty of building a working warhead, but it does appear that Iran has all the pieces in place already. Also not that Iran could very easily bluff its way into being a nuclear power through a well publicized nuclear test of a device which was not suitable for being a warhead.

    Given the lack of visibility into Iran’s nuclear program we have no way of knowing what their progress is on warhead technology. For all we know they already have the warhead details worked out and will be able to field a functional nuclear warhead on their LRBMs as soon as they can pour Uranium with sufficiently high enrichment levels into molds. The track record in this area would tend to favor the idea that it’s better to assume they have the capability, since the roadblocks to achieving the capability appear to be comparatively insignificant.

  10. While Iran having nuclear weapons is obviously nothing to sneeze at (though the White House seems to have a different view), nuclear weapons are not warheads. A warhead is a specific kind of nuclear weapon — one that not only works, but is light enough to be delivered on a missile, and has reentry and guidance systems to deliver it to its target.

    The Iranians have been working on long range missiles for years. To do that, they’ve had to work on guidance systems and reentry vehicles, otherwise there wouldn’t be much point in having the missile. They seem to be having some success in this area. The next step is to develop a nuclear device that can fit inside their RV design and make it work. As Scott pointed out, an enriched U-235 bomb is relatively simple.

  11. Also note that it’s possible to create a nuclear weapon even with 20% enriched Uranium, it just takes a lot more material and is very wasteful. At this point we should really have already switched the topic of discussion to about when, not whether, Iran will have its first nuclear weapons test.

  12. Paul,
    I’m with Titus here. Many members of the Iranian theocracy may preach the glories of martyrdom, but it seems to be in a very much “you go first” sort of way. It’s one thing to try and bilk others into dying for their country, but there sure seems to be a lack of volunteers from those in power…I wonder why that might be.

    ~Jon

  13. Larry,

    Guidance systems really aren’t all that big an issue. Certainly the existing inertial systems that the Iranians use on the current range of tactical ballistic missiles (perhaps supplemented by a rigged-up GPS system, or several other exotic options) will provide more than sufficient use for a battlefield or theatre-level weapon. Remember, we aren’t talking about taking out hardened silos here…most of the (early) uses for these weapons would be population centers or large military concentrations, neither of which is particularly demanding in terms of accuracy when using nukes.

    Now, if the Iranians want to move to a full-spectrum capability (counterforce, etc.), that will require a more capable guidance package, but that clearly can wait…

  14. There is no link to a specific story in the OP but the Fox story I heard quoted the IAEA verbatim as follows:

    “Evidence collected by IAEA officials raises concerns about the possible existence in Iran of past or current undisclosed activities relate to the development of a nuclear payload for a missile.” The “nuclear payload for a missile” statement is the IAEA’s words.

    And the IAEA chief, Yukiya Amano, made essentially the same claim in a statement.
    missile.

  16. and a way to smuggle said truck into Tel Aviv undiscovered.

    It is probably easier to fill a truck with chemical fertilizer and explode it. Remember the Oklahoma city bombing, or the 1993 WTC bombing. You can detect poorly shielded nuclear materials with a Geiger counter.

    North Korea’s “fizzle” was supposedly for a plutonium implosion type bomb which is a more complex device than the one Iran is most likely to produce.
    Never heard of North Korea having gas centrifuges of the type required to make HEU. They supposedly separate plutonium from burned up reactor fuel. Pakistan and Iran have gas centrifuges. Supposedly Khan stole the design while he was working at Urenco. There have been allegations for a long time that Pakistan/Iran/North Korea have a shared ballistic missile development program. If they do have connections at this level it is not unreasonable to consider they may share nuclear weapons research as well.

  18. Making a practical warhead for missile delivery involves either a very large booster (space vehicle sized) or hydrogen fusion enhanced fission (aka, the h-bomb). Both are significant development efforts which are remotely monitored. As for “let’s just put it in a truck”, there’s practical limits for WMDs detonated at ground level. If your national goal is to take out a building and scare the locals, a McVeigh style improvised weapon is a lot cheaper, quicker to develop, and its development is a lot harder to remote monitor. A non-enhanced fission bomb in a truck would not do much more damage.. at most a handful of buildings instead of just the one.. and the cleanup would be cheap, just hose down the dust and sweep it up.

  19. Well, Little Boy had like 12-15 kt yield while the Oklahoma City bombing had much smaller yield like 0.002 kt (source Wikipedia). There is little comparison between both explosions in terms of magnitude (or propaganda value) of the blast. However it is much more expensive and harder to dissimulate a nuclear weapon than a chemical fertilizer bomb. There are less sources for the material, which makes it more impractical to use for terrorist acts.
    The delivery system is a really hard problem to solve. Even if you have a proper ballistic missile, with appropriate payload (which is doubtful for the case of Iran) you need to develop reasonably accurate guidance. You also need to work on reentry shapes and other technology which is not clearly in possession by Iran. Israel has several missile defense systems (Arrow, Patriot). So you will want decoys and evasive maneuvering. You probably need to miniaturize the payload or otherwise require a huge missile to launch it (like the Soviet Union did with R-7). IIRC the gun type bombs are also harder to miniaturize than implosion devices.

  20. You can detect poorly shielded nuclear materials with a Geiger counter.
    .
    Standard Shipping Container
    Gross Weight: 30,480kgs (67,200 lbs)
    Tare Weight: 4000 kgs (8,800 lbs)
    Dimensions: 12.2m x 2.4m x 2.6m (40’x8’x8.5’)
    .
    Warhead: 114 kgs (250 lbs) Give it 500 kgs (1100 lbs) to be generous.
    .
    30480 – 4000 – 500 = 25980 kgs of shielding.
    .
    Lead: 11.3 g/cm^3
    Volume of shielding = 25980 * 1000/11.3 = 2,300,000 cm^3
    .
    Assume one can wedge the widget into a cubic meter.
    .
    Surface Area: 6 x 100 x 100 = 60,000 cm^2
    -> 38 cm of lead shielding.
    .
    This isn’t dealing with a fanatic working on the cheap, this is a nation state. They can afford a whole lot of lead.

  22. I think even 5KT (That’s 5000 tons of TNT) in down town Tel aviv would be an issue.

    Its pretty clear that Inida has Nuke missile technology, and probably Pakistan as well. How hard would it be for Pakistans tech to leak to the Iranians?

    Pakistan seems to have done it with centrifuges and not reactors , so its likely their weapons are all U235.

  23. Folks, I keep on flashing back to the casualties the Iranians took in the Iran/Iraq War, and their human wave tactics… and thinking that the rulers n Iran might just not care about Iranian civilian casualties.

  24. and a way to smuggle said truck into Tel Aviv undiscovered.

    The problem here is what happens when you find a way to smuggle said truck into Tel Aviv in a way that is discoverable and totally interceptable by the Israelis such that they trace it back to you? Then your country gets nuked (perhaps you’d get lucky and it’d only be a demonstration that wouldn’t kill many people) and nobody of any consequence will whine about it. Remember that the number one obstacle to Israelis using nukes is the disapproval of serious powers like the US. Discovering that you attempted to nuke Tel Aviv would both negate the effectiveness of that obstacle and perhaps even get the full approval of the US for the Israeli retaliation.

    Ten minutes after the discovery of the truck, Al Jazeera carries an interview with an Iranian mullah who tells 1.2 billion Mohammedans, “It’s a hoax! The dirty Joooooos are trying to set up the false pretext for an attack to wipe out Islam! We told you they can’t be trusted! Fatwa! Kill the Jooooos! All of them! Now!”

    Meanwhile, the United Nations takes swift, decisive action to appoint a study committee to determine whether a sternly worded diplomatic communiqué is warranted … and to whom it should be delivered.

  25. Mike, maybe Israel will blink, but my bet is that the logic of MAD takes over. If an enemy does something that extreme, you have to use nuclear weapons or your MAD policy has no teeth.

  26. The Iranians are claiming 20% enrichment and the article Paul provided says little boy (who was actually a girl?) used 80% U235. The article says the big secret is how easy it is to make a gun type U235 bomb. My question is if a bomb of that type could be made out of the 20% U235 the Iranians are talking about; I understand only a few percent or less of the U235 in little boy actually fissioned.

    Once they have 20% U236 and depleted uranium they could then produce Pu239 presumably at a very high enrichment level. Could that then be used in a bomb (would it be harder or easier.)

    It seems that shortly cities in the world are going to experience mushroom clouds. What then?

  28. I mistyped U236 above. Apparently 20% can produce a bomb but requires a larger critical mass. No more air traffic, eh?

  29. A nuclear weapon launched against the United States needn’t have a reentry vehicle, or be particularly accurate, to do a huge amount of damage. A large enough weapon (megaton range) set off at ~200 miles altitude somewhere above the middle of the country would wreak havoc through electromagnetic pulse. A megaton range weapon is not as “simple” to build as a Little Boy bomb, which I submit is also not as simple as the Wikipedia article makes it look…

  30. The only hard part seems to be separating the isotopes. Bring together a critical mass and you’ve got a bomb.

  32. There’s the little matter of the trigger, a neutron source whose design and performance are not available to the public. Megaton range weapons require fusion boost, whose design is also not publicly known.

  33. There’s the little matter of the trigger

    The problem seems to be once a critical mass is brought together things happen fast. If you don’t bring it together fast enough it blows itself apart before enough material contributes to the explosion which may have been what happened with the North Korean test. The whole problem would then seem to be a matter of velocity and timing. Other factors contribute but are of lesser importance.

    It makes me wonder if a subcritical mass could be triggered with an anode gun? Instead of a round or cylindrical mass you use a thick plate or several stacked and bombard the whole surface at the same time.

  34. Or perhaps a critical mass could be kept from exploding by saturating it with a cathode and turning the cathode off would be the trigger?

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