56 thoughts on “Iranian Nuclear Facility Explosion”

  1. If it had been a tacnuke we would have news of the US going to a heightened readiness state – bombers launching, recalls of military on leave, etc.

      1. This Administration would go before the UN and pledge to work with the Iranians to improve the safety at their nuclear weapon facilities, so such tragedies are prevented.

  4. A corrupt nation with little industrial base, lax quality controls, run by 7th century imams, fiddling with atomic explosives – what could go wrong?

  5. Tactical nuke? I don’t think the Iranians have the technical know-how.
    Fizzled nuke or one HONKING pile of chemical explosives are possibilities. Waiting for the report from the radioisotope detectors.

    1. I don’t think the Iranians have the technical know-how.

      Another country in the region, that isn’t happy with either the Iranian nuclear program, or Obama’s feckless response to it, does.

      1. If your thinking the country I’m thinking, setting off a tactical nuke in a foreign country is a huge political risk should their fingerprints be found. Then again, letting Iran develop their own bomb is a huge military risk.

      1. The idea that “anyone can make an atom bomb” is idiocy promulgated by people who looked at a cartoon of an atomic bomb, and thought “How hard can that be?” They probably never built even a Leggo item in their lives.

        The Manhattan Project, at its peak, employed 125,319 people. Granted they were building two types of bombs, but anyone building a bomb from scratch has to replicate most of their work.

        India’s first try at an atomic bomb was a dud. So, probably, was North Korea’s. So (at least) two nations couldn’t do it right the first time, despite the fact that the technology was almost as much in the public domain as it is today.

        1. It is also harder to build a small tactical nuke than it is to build a Little Boy. Still, with powerful computers freely available, and nuke scientists educated in the West, the hurdles might not be all that high.

        2. MfK,

          You blithely ignored what I said. Up until they made the first bomb it was just theory. But the theory, that a critical mass of certain radioactive metals would release lots of energy in an explosion was correct.

          Enriching that metal to be of the correct isotope is the hard part. That’s what took all those Manhattan project workers. That’s what takes the resources of a country.

          Yes, there is a trick to the design of a bomb that does that efficiently. The two bombs dropped on Japan were not efficient (about 3% efficient I believe.) That’s the kind of bomb anyone can build but it requires a lot of hard to get material. Modern bombs use a lot less material.

          Can anybody make a modern bomb? No. That takes expertise that is not publicly available.

          1. Another issue of course is that the subcritical components are radioactively hot (or they wouldn’t be any good) but still have to be machined while hot.

            But that’s a trivial issue compared to getting enough material in the first place.

            Getting the shotgun design right was not hard. It worked on their first test.

          2. That first test was in Japan if you didn’t catch that. It could not be tested before being deployed, as there was only sufficient U-235 available for one device.

      2. Having said that, I very much doubt that a nuke would have gone off accidentally. It’s hard enough to make it happen on purpose. However, large amounts of explosives have a nasty habit of going off by themselves is commonplace. The Halifax explosion, the Texas City disaster, and the PEPCON disaster come to mind. (I linked to them, but the spam filter rejected them.) A conventional accident is highly likely, while an accidental nuclear explosion is almost impossible. Note that I wrote “almost.” It isn’t absolutely impossible, but it’s just not the first thing I would suspect.

          2. “Which blows itself apart and stops the reaction.” Isn’t that what we’re talking about? Make a radioactive mess, kill people nearby. Would that be a much smaller explosion that the one described here?

          3. Well, I’m going to do something unusual on the internet, and not pose as an expert in such matters. I’ve read Richard Rhodes’ books, but that is about the limit of my training. As best I understand it, I am given to believe that you’ve got to hold the materials together for a (relatively) long time to get a good release of energy. That was (partly) the role of the tamper.

          4. Yes, but not necessarily a bomb. To get kilotons or more of energy release, you have to (a) assemble a critical mass quickly enough so that it doesn’t have time to blow itself apart due to pre-detonation, and simultaneously (b) kick out enough neutrons in a controlled fashion to start the chain reaction at the point where it will have maximum effect. The initiator – which is the piece that has to reliably kick out those neutrons – was one of the two really hard problems in bomb design, and IIRC is still classified today.

            The other hard problem was the implosion system for the plutonium bomb. Plutonium was really prone to predetonation, so the gun system used for the uranium bomb wouldn’t work for the Pu bomb.

          5. Mike, you want both halves of the sphere to basically have Mach numbers as they impact.

            I am sort of curious if you can do it just to ‘join the club’ by impacting rocket sleds. (Where the precision of the timing and exact configuration isn’t quite so crucial.)

          6. Rocket sleds (impacting missiles) would more than do it.

            One of the oddest workable weapons was having the core in a single piece, but in a non-spherical shape that couldn’t reach critical mass, then detonating it by making it rounder (and I assume by having a neutron trigger squished during the shaping). We used that in some of the artillery nukes.

          7. BTW, if we’d use some odd-numbered curium isotopes we could possibly make a nuke with a pit the size of a golf ball, but certainly the size of a baseball. Unfortunately the world production of curium seems to total micrograms instead of kilograms.

            If we had some, there might be interesting nuclear rocket applications where a large lander (due to some shielding overhead) could have very high ISP with a non-cryogenic propellant.

          8. Kind of like a King David’s Spaceship but for bombs?

            I think it’d have to be a Uranium bomb for the rocket sleds to work. But then you might as well just suck the air out of a cannon and put the Uranium target at one end and fire the Uranium shell at it.

          10. The initiator – which is the piece that has to reliably kick out those neutrons – was one of the two really hard problems in bomb design

            This is required for a plutonium bomb, but is not required for Uranium. Even though the Dayton Project was part of the Manhattan project I do not believe initiators were used with the bombs dropped on Japan. I could be wrong.

            When the shock wave from the implosion of the plutonium core arrives, it crushes the detonator. Hydrodynamic forces acting on the grooved shell thoroughly and virtually instantly mix the beryllium and polonium, allowing the alpha particles from the polonium to impinge on the beryllium atoms. Reacting to alpha particle bombardment, the beryllium atoms emit neutrons in a rate of about 1 neutron each 5–10 nanoseconds. These neutrons trigger the chain reaction in the compressed supercritical plutonium. Placing the polonium layer between two large masses of beryllium ensured contact of the metals even if the shock wave turbulence performed poorly.

            My emphasis. There are currently no known gun-type weapons still in service. All modern weapons do require an initiator which allows less material to be used. Timing is critical which may account for the duds we see occurring.

          11. Bring enough enriched uranium together, and you get runaway fission.

            True, but there is a little more to it.

            The barrel had an inside diameter of 6.5 inches (16.5 cm). Its length was 70.8 inches (1.8 m), which allowed the bullet to accelerate to its final speed of 984 feet per second (300 m/s) before coming into contact with the target.
            When the bullet is at a distance of 9.8 inches (25 cm), the combination becomes critical. This means that some free neutrons may cause the chain reaction to take place before the material could be fully joined (see nuclear chain reaction).
            Typically the chain reaction takes less than 1 μs (100 shakes), during which time the bullet travels only 0.3 mm. Although the chain reaction is slower when the supercriticality is low, it still happens in a time so short that the bullet hardly moves in that time.
            This could cause a fizzle, a predetonation which would blow the material apart before creating much of an explosion. Thus it is important that the frequency at which free neutrons occur is kept low, compared with the assembly time from this point. This also means that the speed of the projectile must be sufficiently high; its speed can be increased but this requires a longer and heavier barrel.

            Now don’t try this at home if you’re a crazed Iranian.

        2. For a quick start of the chain reaction at the right moment a neutron trigger/initiator is used. An initiator is not strictly necessary for an effective gun design, as long as the design uses “target capture” (in essence, ensuring that the two subcritical masses, once fired together, cannot come apart until they explode). Considering the 70 spontaneous fissions per second, this only causes a delay of a few times 1/70 second, which in this case does not matter. Initiators were only added to Little Boy late in its design.

          So they did use an initiator, but it’s not required.

  6. If so there’ll be an announcement soon we have assets that can detect the gamma radiation from space.

      1. Only if it’s a secret we’d rather not have the WH broadcast. Then, they’ll make sure everyone knows.

  7. There’s a lot that can go energetically wrong in a chemical facility, especially one run under “Insh’Allah” safety and control rules. The bang might not even have come from the extraction side of the plant. If it has, though, we’ll be hearing about it: it’s a sucker bet that the surrounding nations are all breaking out the samplers and spending a lot of time in the meteorological shop, calculating the prevailing winds.

  8. Stuxnet worm grown to Godzilla proportions. Both the BBC and the Times of Israel reports stated that the Parchin plant had been declared off limits to IAEA inspectors by the Iranians. Meanwhile, our leaders continue their tireless search for peace with their endless talks with the Mullahs about limiting their nuke program.

  9. I remember seeing footage of the Pepcon blast taken from three miles away, and that bang, although loud, wasn’t enough to break glass at that distance. Pepcon was the biggest chemical explosion in US history: a rocket fuel (ammonium perchlorate) factory on top of a natural gas line. The Iranian blast was enough to break glass 12 km away, which is about twice as far as the camera was from Pepcon. What happened in Iran was almost certainly a nuclear detonation.

    3. Well, according to Wikipedia, there were broken windows up to 10 miles (~16 km) away from the PEPCON explosions. Further, there were several explosions. The largest was estimated at 1 kiloton TNT equivalent.

      The damage reached a radius of up to 10 miles (16 km), including shattered windows, doors blown off their hinges, cracked windows and injuries from flying glass and debris.

      So this is consistent with the detonation of several hundred tons of conventional explosives or equivalent.

    4. The Texas City explosion was about 2.7 to 3.2 times bigger. It’s doubtful that it was a nuclear detonation – probably a stockpile of explosives and precursors.

  10. My own not-even-back-of-the-envelope calculation points toward either a fizzle nuclear yield or, somehow, tens of tons TNT equivalent chemical explosion, in either case detonated underground. If it were aboveground it would have had to be at least several kT to break glass at 12 km.

    1. Hmm… 12 km is a long way. Let’s see, that’s about 7 miles (sorry, I still have to think in miles for surface distances). That’s pretty far.

      I was told that, when they tested the Saturn V engines in Huntsville, it shattered some glass in the city, which is probably about that far away. So, 5 F-1 equivalents?

    2. The Texas City explosion broke windows in Houston, 40 miles away. It was estimated at 2.7-3.2 kt equivalent. I would surmise that the windows that broke were only loosely held in their frame. The same may be true in this case.

  11. It is notable that the site was of interest to IAEA as a place where Iran might be testing chemical implosion triggers for bombs. That means they would have lots of HE around. I looked at the site on Google Earth, and found 8 obvious explosives bunkers, lined up in 2 rows and each in a revetment with a berm. From the Google measurements of the berms, and assuming a standard maximum angle of repose of 60 degrees for dried loose material, I found the greatest height of each of the 8 storage facilities should be 10m, because you don’t pile explosives above the revetment protecting everything else from their potential blast wave.

    The length for each bunker was 20m, and the width 10m. They look like triangular prisms, so I cut the volume of each in half, then assumed 20% of the volume would be assigned to stacking access and ventilation, …and got about 8,000m^3. With explosives of similar density to RDX, I got a mass just under 15,000 tons of explosives maximum for each bunker. With 8 bunkers that is a potential 120,000 tons of HE.

    Even one of them would be spectacular enough to give reported effects. If sabotage by US or Israeli forces took all 8 bunkers at once the damage would be considerable. I await Google Earth’s next set of pics of the area with interest.

        1. Their post offices might be 6 km apart, but from the Google map link Changi is about a half mile from the site and Hamamak starts at about a mile out. That’s more than the usual blast radius of a redneck Thanksgiving turkey frying accident, but the report does seem to dramatically downscale the damage, which may of course be the angle the New York Times is desperately pursuing.

        2. I thought this area of Hamamak was pretty cute. If those are parked cars, either a large fraction of the population decides to go jogging in the little park at the same time or they work in whatever was built under all those trees.

        3. As an aside, a big enough chemical explosion is going to have a lot in common with a similarly sized (in terms of energy released) nuclear explosion, such as thermal effects. What will be different will be the first few seconds which will be very different for a nuclear detonation and the presence of radioactive fallout from a nuclear bomb. But you want to burn trees at 3 km? That’s possible with enough bang.

      2. The entire area is apparently a large complex with multiple sites. Here is the high explosive test chamber that was the subject of IAEA interest a few years back. It’s quite a way northeast of Ed’s spot, and also not that close to the spot pictured on the BBC report.

        See ISIS for background info.

        Recent photos appear to show those buildings with roofs gone, and tarped over.

  12. It’s a largely underground facility, so if they report that it broke glass 12km away is true, it was beyond big. You’d need about 5kt in a surface blast (less for a detonation at altitude, but still in the kiloton range) to break windows at 12km (7.5 miles!). For an underground blast, even a shallow one, you’d need considerably more to create the needed overpressure on the surface.

    So, *IF* the window breakage is accurate, this was huge (and the death toll far higher). It’s possible that this was chemical; that facility is also a rocket testing one. However, it’s IMHO unlikely to create that massive a blast, so… that leaves us with two possibilities; the 12km report was either wrong or an isolated incident due to local acoustic propagation (the facility is in a valley) or, it wasn’t chemical but nuclear. And, if nuclear, I don’t think a mass of enriched Uranium accidentally going critical would do it (they use explosive assembly for a reason). That’d leave two scenarios; a stored nuke had its explosive assembly charges triggered (Perhaps in a fire… unlike the implosion method used with Plutonium and also modern Uranium cores, explosive assembly can be triggered by a fire). Or, IMHO more likely, somebody decided that if Iran wants a nuke so badly, give them one… a ground penetrator.

    Whatever the cause, if the cloud is radioactive, things will be interesting; Teheran is just 20 miles northeast – and the afternoon winds today are from the southeast (I have no idea what they were at the time of detonation).

    My guess; if this was a nuclear attack, Iran may well choose to keep quiet about it; publicly admitting it would force them into a war against someone who has already proven the will and ability to nuke them.

    If this does happen to be something (whether sabotage or otherwise) the Israelis did, all I want to say is “Thank you!”. (and if, highly unlikely though it is, it was Obama, I’ll say the same to him).

    1. I don’t think we should rule out something EID related. Hassan figures he’s got an ingenious new method for cooking a goat for the lab’s big feast to celebrate the end of Ramadan, and kabooooom.

      My question is that since you don’t need kilotons of conventional explosives to trigger a nuclear device, why were they stockpiling so much? Could they have intended it for calibrating seismic equipment so they can get a reliable yield estimate on an underground detonation, or perhaps using it as part of a cover story after a test?

    2. Looks like a road going underground in the middle of the area here . There are a lot of industrial buildings out there.

  13. Curiously, though perhaps not unexpected, this story appears to not have made the mainstream news in the US.

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