Posts Tagged ‘1960s’

Meditations

Kilotons per kilogram

Monday, December 23rd, 2013

Nuclear weapons can be made to have pretty much as much of a bang as one wants to make them, but with increased explosive yield comes an increased weapon weight. We always talk vaguely about being able to make H-bombs to arbitrarily high yields, but recently I’ve been mulling over this fact somewhat quantitatively. I gave a talk last month at the History of Science Society Meeting on US interest in 50-100 MT bombs around the time of the Limited Test Ban Treaty, and while working on this paper I got  slightly obsessed with what is known as the yield-to-weight ratio.

Little Boy — a big bang compared to a conventional bomb, but still a very crude nuclear bomb.

Little Boy — a big bang compared to a conventional bomb, but still a very crude nuclear bomb.

What makes nuclear weapons impressive and terrible is that their default yield-to-weight ratio — that is, the amount of bang per mass, usually expressed in terms of kilotons per kilogram (kt/kg) — is much, much higher than conventional explosives. Take TNT for example. A ton of TNT weighs, well, a ton. By definition. So that’s 0.001 kilotons per 1,000 kilograms; or 0.000001 kt/kg. By comparison, even a crude weapon like the Little Boy bomb that was dropped on Hiroshima was about 15 kilotons in a 4,400 kg package: 0.003 kt/kg. That means that the Little Boy bomb had an energy density three orders of magnitude higher than a regular TNT bomb would. Now, TNT isn’t the be-all and end-all of conventional explosives, but no conventional explosive gets that much boom for its buck compared to a nuke.

The Little Boy yield is much lower than the hypothetical energy density of uranium-235. For every kilogram of uranium-235 that completely fissions, it releases about 17 kt/kg. That means that less than a kilogram of uranium-235 fissioned in the Little Boy bomb to release its 15 kilotons of energy. Knowing that there was 64 kg of uranium in the bomb, that means that something like 1.3% of the uranium in the weapon actually underwent fission. So right off the bat, one could intuit that this is something that could probably be improved upon.

Fat Man — a lot better use of fissile material than Little Boy, but no more efficient in terms of yield-to-weight.

Fat Man — a lot better use of fissile material than Little Boy, but no more efficient in terms of yield-to-weight.

The Fat Man bomb had a much better use of fissile material than Little Boy. Its yield wasn’t that much better (around 20 kilotons), but it managed to squeeze that (literally) out of only 6.2 kilograms of plutonium-239. Pu-239 releases around 19 kilotons per kilogram that completely fissions, so that means that around 15% of the Fat Man core (a little under 1 kg of plutonium) underwent fission. But the bomb itself still weighed 4,700 kg, making its yield-to-weight ratio a mere 0.004 kt/kg. Why, despite the improve efficiency and more advanced design of Fat Man, was the yield ratio almost identical to Little Boy? Because in order to get that 1 kg of fissioning, it required a very heavy apparatus. The explosive lenses weighed something like 2,400 kilograms just by themselves. The depleted uranium tamper that held the core together and reflected neutrons added another 120 kilograms.  The aluminum sphere that held the whole apparatus together weighed 520 kilograms. The ballistic case (a necessary thing for any actual weapon!) weighed another 1,400 kg or so. All of these things were necessary to make the bomb either work, or be a droppable bomb.

So it’s unsurprising to learn that improving yield-to-weight ratios was a high order of business in the postwar nuclear program. Thermonuclear fusion ups the ante quite a bit. Lithium-deuteride (LiD), the most common and usable fusion fuel, yields 50 kilotons for every kilogram that undergoes fusion — so fusion is nearly 3 times more energetic per weight than fission. So the more fusion you add to a weapon, the better the yield-to-weight ratio, excepting for the fact that all fusion weapons require a fission primary and usually also have very heavy tampers.

I took all of the reported American nuclear weapon weights and yields from Carey Sublette’s always-useful website, put them into the statistical analysis program R, and created this semi-crazy-looking graph of American yield-to-weight ratios:

Yield-to-weight ratios of US nuclear weapons

The horizontal (x) axis is the yield in kilotons (on a logarithmic scale), the vertical (y) axis is the weight in kilograms (also on a log scale). In choosing which of the weights and yields to use, I’ve always picked the lowest listed weights and the highest listed yields — because I’m interested in the optimal state of the art. The individual scatter points represent models of weapons. The size of each point represents how many of them were produced; the color of them represents when they were first deployed. Those with crosses over them are still in the stockpile. The diagonal lines indicate specific yield-to-weight ratio regions.

A few points of interest here. You can see Little Boy (Mk-1), Fat Man (Mk-3), and the postwar Fat Man improvements (Mk-4 — same weight, bigger yield) at the upper left, between 0.01 kt/kg and 0.001 kt/kg. This is a nice benchmark for fairly inefficient fission weapons. At upper right, you can see the cluster of the first H-bomb designs (TX-16, EC-17, Mk-17, EC-24, Mk-24) — high yield (hence far to the right), but very heavy (hence very high). Again, a good benchmark for first generation high-yield thermonuclear weapons.

What a chart like this lets you do, then, is start to think in a really visual and somewhat quantitative way about the sophistication of late nuclear weapon designs. You can see quite readily, for example, that radical reductions in weight, like the sort required to make small tactical nuclear weapons, generally results in a real decrease in efficiency. Those are the weapons in the lower left corner, pretty much the only weapons in the Little Boy/Fat Man efficiency range (or worse). One can also see that there are a few general trends in design development over time if one looks at how the colors trend.

First there is a movement down and to the right (less weight, more yield — improved fission bombs); there is also a movement sharply up and to the right (high weight, very high yield — thermonuclear weapons) which then moves down and to the left again (high yield, lower weight — improved thermonuclear weapons). There is also the splinter of low-weight, low-yield tactical weapons as well that jots off to the lower left. In the middle-right is what appears to be a sophisticated “sweet spot,” the place where all US weapons currently in the stockpile end up, in the 0.1-3 kt/kg range, especially the 2-3 kt/kg range:

Yield-to-weight ratios -- trends

These are the bombs like the W-76 or the B-61 — bombs with “medium” yield warheads (100s rather than 1,000s of kilotons) in relatively low weight packages (100s rather than 1000s of kilograms). These are the weapons take advantage of the fact that they are expected to be relatively accurate (and thus don’t need to be in the multi-megaton range to have strategic implications), along with what are apparently sophisticated thermonuclear design tricks (like spherical secondaries) to squeeze a lot of energy out of what is a relatively small amount of material. Take the W-76 for example: its manages to get 100 kilotons of yield out of 164 kilograms. If we assume that it is a 50/50 fission to fusion ratio, that means that it manages to fully fission about 5 kilograms of fissionable material, and to fully fuse about 2 kilograms of fusionable material. And it takes just 157 kg of other apparatus (and unfissioned or unfused material) to produce that result — which is just a little more than Shaquille O’Neal weighs.

Such weapons aren’t the most efficient. Weapon designer Theodore Taylor wrote in 1987 that 6 kiloton/kilogram had been pretty much the upper limit of what had even been achieved.1 Only a handful of weapons got close to that. The most efficient weapon in the US stockpile was the Mk-41, a ridiculously high yield weapon (25 megatons) that made up for its weight with a lot of fusion energy.

The components of the B-61 nuclear weapon — the warhead is the bullet-shape in the mid-left. The B-61 was designed for flexibility, not miniaturization, but it's still impressive that it could get 20X the Hiroshima bomb's output out of that garbage-can sized warhead.

The components of the B-61 nuclear weapon — the warhead is the bullet-shape in the mid-left. The B-61 was designed for flexibility, not miniaturization, but it’s still impressive that it could get 20X the Hiroshima bomb’s output out of that garbage-can sized warhead.

But given that high efficiency is tied to high yields — and relatively high weights — it’s clear that the innovations that allowed for the placing of warheads on MIRVed, submarine-launched platforms are still pretty impressive. The really magical range seems to be for weapons that in the hundred kiloton range (more than 100 kilotons but under a megaton), yet under 1,000 kilograms. Every one of those dates from after 1962, and probably involves the real breakthroughs in warhead design that were first used with the Operation Dominic  test series (1962). This is the kind of strategic miniaturization that makes war planners happy.

What’s the payoff of thinking about these kinds of numbers? One is that it allows you to see where innovations have been made, even if you know nothing about how the weapon works. In other words, yield-to-weight ratios can provide a heuristic for making sense of nuclear design sophistication, comparing developments over time without caring about the guts of the weapon itself. It also allows you to make cross-national comparisons in the same fashion. The French nuclear arsenal apparently developed weapons in that same miniaturized yield-to-weight range of the United States by the 1970s — apparently with some help from the United States — and so we can probably assume that they know whatever the United States figured out about miniaturized H-bomb design in the 1960s.

The Tsar Bomba: a whole lot of boom, but a whole lot of weight. The US thought they could make the same amount of boom for half the weight.

The Tsar Bomba: a whole lot of boom, but a whole lot of weight. The US thought they could make the same amount of boom for half the weight.

Or, to take another tack, and returning to the initial impetus for me looking at this topic, we know that the famous “Tsar Bomba” of the Soviet Union weighed 27,000 kilograms and had a maximum yield of 100 Mt, giving it a yield-to-weight ratio of “only” 3.43 kilotons/kilograms. That’s pretty high, but not for a weapon that used so much fusion energy. It was clear to the Atomic Energy Commission that the Soviets had just scaled up a traditional H-bomb design and had not developed any new tricks. By contrast, the US was confident in 1961 that they could make a 100 Mt weapon that weighed around 13,600 kg (30,000 lb) — an impressive 7.35 kiloton/kilogram ratio, something well above the 6 kt/kg achieved maximum. By 1962, after the Dominic series, they thought they might be able to pull off 50 Mt in only a 4,500 kg (10,000 lb) package — a kind of ridiculous 11 kt/kg ratio. (In this estimate, they noted that the weapon might have an impractically large diameter as a result, perhaps because the secondary was spherical as opposed to cylindrical.) So we can see, without really knowing much about the US had in mind, that it was planning something very, very different from what the Soviets set off.

It’s this black box approach that I find so interesting about these ratios. It’s a crude tool, to be sure, but a tool nonetheless. By looking at the broad trends, we get insights into the specifics, and peel back the veil just a tiny bit.

Notes
  1. Theodore B. Taylor, “Third Generation Nuclear Weapons,” Scientific American 256, No. 4 (April 1987), 30-39, on 34: “The yield-to-weight ratios of pure fission warheads have ranged from a low of about .0005 kiloton per kilogram to a high of about .1 kiloton per kilogram. [...] The overall yield-to-weight ratio of strategic thermonuclear warheads has been as high as about six kilotons per kilogram. Although the maximum theoretical ratios are 17 and 50 kilotons per kilogram respectively for fission and fusion reactions, the maximum yield-to-weight ratio for U.S. weapons has probably come close to the practical limit owing to various unavoidable inefficiencies in nuclear weapon design (primarily arising from the fact that it is impossible to keep the weapon from disintegrating before complete fission or fusion of the nuclear explosive has taken place.” []
Visions

Art, Destruction, Entropy

Friday, December 13th, 2013

Are nuclear explosions art? Anyone who has taken even a glance into modern and contemporary art knows that the official mantra might as well be “anything goes,” but I found myself wondering this while visiting the exhibition “Damage Control: Art and Destruction since 1950” that is currently at the Hirshhorn Museum. The first thing one sees upon entering is a juxtaposition of two very different sorts of “work.” On the right is a fairly long loop of EG&G footage of nuclear test explosions, broadcast in high definition over an entirety of a wall. On the left is a piano that has been destroyed with an axe. This, I thought, is at least a provocative way to start things off.

Edgerton, Germeshausen, and Grier (EG&G) was a contractor for the federal government during the Cold War, responsible for documenting nuclear test explosions. Quite a lot of the famous Cold War nuclear detonation footage was taken by EG&G. They are perhaps most famous for their “Rapatronic” photographs, the ultimate expression of MIT engineer Harold “Doc” Edgerton’s work of slowing down time through photography, but this was only a part of their overall contribution. The film they have at the Hirshhorn is something of an EG&G “greatest hits” reel from the 1950s, and its affect on the others in the audience was palpable. Adults and children alike were drawn to the blasts, displayed one after another without commentary or explanation.1 Their reactions didn’t strike me as one of disgust or horror, but of amazement and awe. Most of the footage was from the Nevada Test Site, so the bombs were generally just blowing up desert scrub, and occasionally houses constructed for effects testing.

The destroyed piano, by contrast, got reactions of shock and disgust. It was the remains of a piece of performance art conducted by Raphael Montañez Ortiz, one of several he’s done, apparently. My wife, a piano player and a nuclear historian, also found it disturbing. “If you know what goes into making a piano…,” she started to say. “But then again, if you know what goes into making a city…,” she caught herself. I overheard other people say similar things.

The difference in reactions isn’t too surprising — it’s a common theme that it is easy to appreciate the destruction of something at a human scale, difficult to appreciate it at the scale of nuclear bomb. A lot of what I’ve spent time doing, with the NUKEMAP and my writing, is to try to understand, and to impart, the scale of a nuclear explosion. A lot of this has involved looking at the attempts of others, as well, from official Cold War visualizations made for secret committees to popular films, as they have tried to communicate this to their target audiences. The hardest thing is that our brains appear only to be wired for empathy at the individual level, and don’t readily apply it to large groups or large areas. The best work in these areas conveys both the broad scope of destruction, but then ties it into the personal. They individualize the experience of mass ruination.

And the EG&G footage isn’t trying to do that. It was data meant for very specific technical purposes. It was developed in order to further the US nuclear program, and defense against Soviet nuclear weapons. Which is why I somewhat question its inclusion, or, at least, its decontextualization. It is art only in the sense that it has aesthetics and it has been put into an art gallery. One can read into it whatever one wants, of course, but it wasn’t created to have deep meaning and depth in that sense. (Whether one cares about authorial intention, of course, is its own can of modern art worms.) Just as a small example of what I mean, Andy Warhol famously made a print of mushroom clouds for his own “disaster” series (a few of which, but not this print, were featured in the exhibit):

"Atomic Bomb," Andy Warhol, 1965.

“Atomic Bomb,” Andy Warhol, 1965.

Now Warhol is a complicated character, but since he was explicitly an artist I think it is always fair game to talk about his possible intentions, the aesthetics of the piece, the deeper meanings, and so on. Warhol’s art has generally been interpreted to be about commercialization and commodification. The mushroom cloud in repetition becomes a statement about our culture and its fascination with mass destruction, perhaps. Coming in the mid-1960s, after the close-call terrors of the early years of the decade, perhaps it was maybe too-little too-late, but still, it has an ominous aesthetic appeal, perhaps now more than then.

Because I don’t think this image was widely circulated at the time, I doubt that Warhol knew that Berlyn Brixner, the Trinity test photographer, had made very similar sorts of images of the world’s first nuclear fireball at “Trinity”:

TR-NN-11, Berlyn Brixner, 1945.

“TR-NN-11,” Berlyn Brixner, 1945.

Brixner appreciated the aesthetics and craft of his work, to be sure. But the above photograph is explicitly a piece of technical data. It is designed to show the Trinity fireball’s evolution over the 15-26 millisecond range. Warhol’s instrument of choice was the silkscreen printer; Brixner’s was the 10,000 fps “Fastax” camera. There’s a superficial similarity in their atomic repetition. You could make a statement by putting them next to each other — as I am doing here! — but properly understood, I think, they are quite different sorts of works.

Don’t get me wrong. Re-appropriating “non-art” into “art” has been a common move over much of the 20th century at the very least. But the problem for me is not that people shouldn’t appreciate the aesthetics of the “non-art.” It’s that focusing on the aesthetics makes it easy to lose sight of the context. (As well as the craft — Brixner’s work was exponentially more difficult to produce than Warhol’s!) The EG&G footage in the exhibit doesn’t explain much of how, or why, it was made. It seems to be asking the viewer to appreciate it solely on its aesthetic grounds. Which I think is the real problem. Many of the tests they show resulted in significant downwind fallout for the populations near the Nevada Test Site. Many of them involved the development of new, ever-more elaborate ways of mass destruction. Many of them were the product of years of top scientific manpower, untold riches, and a deep political context. To appreciate them as simply big, bright booms robs them of something — no matter how aesthetically beautiful those big, bright booms actually are. 

Gustav Metzger's "auto-destructive" art.

Gustav Metzger’s “auto-destructive” art.

What makes it more ironic is that the exhibit actually does give considerable context to some of the works that are explicitly “art.” You have to explain the context of Gustav Metzger’s “auto-destructive” art — it involves him filming himself painting on canvases with a strong acid, so the artwork destroys itself in the process. Without the context there, what is left is just a boring, not-very-comprehensible movie of a man destroying a blank canvas. But anyway.

In terms of the audience at the exhibit, which was fairly well-attended when I was there with my wife, the most interesting part was the handling of children. The Smithsonian museums are of course explicitly places that people take their children while visiting the city, so it’s no surprise that you probably find more of them at the Hirshhorn than you would at MOMA or other similar institutions. But children add a level of anxiety to an exhibit about destruction. They were wowed by the wall-o’-bombs but not, it seemed, by the piano. Parents seemed to let them wander free through most of it, but there were several films where I saw kids get yanked out by their parents once the parents realized the content was going to be disturbing. In one of these films, the “disturbing” content was of a variety that might have been hard for the children to directly understand — the famous film of the Hindenburg going up in flame, for example, where the violence was real but seen from enough of a distance to keep you from seeing actual injuries or bodies. The one I saw the kids getting really removed from (by their parents, not the museum) was footage of the 2011 Vancouver riots. I wasn’t impressed too much with the footage itself (its content was interesting in a voyeuristic way, but there seemed to be nothing special about the filming or editing), but the immediacy of its violence was much more palpable than the violence-at-a-distance that one saw in most of the other such works. It’s cliche to trot out that old quote attributed (probably wrongly) to Stalin that one death is a tragedy, a million is a statistic, but there’s something deeply true to it about how we perceive violence and pain.

Damage Control exhibit site

There are a lot of works in the exhibit. As one would expect, some hew to the theme very closely, some are a bit more tenuous. Overall, though, it was pretty interesting, and if you’re in town, you ought to check it out. The original comment my wife made about pianos and cities stuck with me as I looked at all of the various meditations on “destruction.” In it, I kept coming back to the second law of thermodynamics. On the face of it, it is a very clinical, statistical law: “the entropy of an isolated system never decreases.” It is actually quite profound, something that the 19th-century physicists who developed it knew. Entropy can be broadly understood as “disorder.” The second law of thermodynamics says, in essence, that without additional energy being put into it, everything eventually falls apart. It takes work to keep things “organized,” whether they are apartments, bodies, or cities.2 Ludwig Boltzmann, who helped formulate the law, stated gnomically in 1886 that:

The general struggle for existence of animate beings is not a struggle for raw materials – these, for organisms, are air, water and soil, all abundantly available – nor for energy, which exists in plenty in any body in the form of heat Q, but of a struggle for [negative] entropy, which becomes available through the transition of energy from the hot sun to the cold earth.

In other words, life itself is a struggle against entropy. Our bodies are constantly taking disordered parts of the world (heat energy, for example, and the remains of other living things) and using them to fuel the work of keeping us from falling apart.

But the other way to think about this law is that generally it is easier to take things apart than it is to keep them together. It is easier to convert a piano into a low-energy state (through an axe, or perhaps a fire) than it is to make a piano in the first place. It is easier to destroy a city than it is to make a city. The three-year effort of the half-a-million people on the Manhattan Project was substantial, to be sure, but still only a fraction of the work it took to make the cities of Hiroshima and Nagasaki, and all that they contained, biological and material, in the first place.

Of course, the speed at which entropy increases is often controllable. The universe will eventually wear out — but not for a long time. Human civilization will necessarily go extinct — but it doesn’t have to happen anytime soon. What hits home with the “Damage Control” exhibit is how we as a species have to work so hard to keep everything together, while simultaneously working so hard to find ways to make everything fall apart. And in this, perhaps, it is a success, even if I left with many niggling questions about the presentation of some of the works in particular.

Notes
  1. Various guys in the audience would occasionally try to give explanation to their loved ones, and they were generally incorrect, alas. “That must be at Alamogordo… That’s got to be an H-bomb…” no, no, no. Of course, I was there with my wife, and I was talking up my own little storm (though less loudly than the wrong guys), but at least I know my stuff for the most part… []
  2. The key, confusing part about the second law is the bit about the “isolated system.” It doesn’t say that entropy always increases. It says that in an isolated system — that is, a system with no energy being input into it — entropy always increases. For our planet, the Sun is the source of that input, and you can trace, through a long series of events, its own negative entropy to the Big Bang itself. []
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Nixon and the bomb: “I just want you to think big, Henry!”

Friday, October 25th, 2013

Richard Nixon was a President so utterly fascinating that if he didn’t exist, historians would have had to invent him. He was both clever and odious, politically appealing but personally unpleasant. Flawed enough that he managed to pointlessly lose the Presidency because of his insecurities, his desire for even more of a landslide than he already had. Anti-semitic, homophobic, racist — but also canny, both with regards to foreign policy and American domestic politics. And what a gift for historians of the future, that he compulsively recorded himself saying awful things? It’s almost too much to be believed, the truth being much more stranger than any fictionalized President could be.

Nixon portrait cropped

We don’t talk much about Nixon and the bomb, which is perhaps a little odd. The Nixon years were those of détente, which has something to do with it, and there were no “close calls” or fiery public rhetoric about the bomb. Nixon only rarely shows up personally in my work; he didn’t appear to get involved with nuclear matters to the degree that Kennedy or Eisenhower did, for example, much less those like Reagan or Truman.

But this is an oversight. Nixon and the bomb is an immensely interesting subject, as I recently learned. Last week I was at a nuclear history/policy conference hosted by Francis Gavin, among a few others, that was itself immensely interesting and fruitful. Before going, I thought I should get around to reading Gavin’s latest book, Nuclear Statecraft: History and Strategy in America’s Atomic Age, since he had bothered to invite me and all.1

Gavin - Nuclear Statecraft - cover

It’s incredibly interesting as a book of history written with a mind towards those who care about policy. Each chapter tackles a major issue in nuclear history and gives a unique perspective or new findings on it. For example, the Kennedy and Johnston administrations get lots of credit for adopting a “flexible response” approach to nuclear targeting, but Gavin reports that while they gave speeches on this, in practice their war plans were little more flexible than Eisenhower’s, because privately they judged flexibility to be difficult and dangerous. That was new to me, and a nice point about the difference between public statements and official policy, and the trickiness of divining information about secret programs from the party line.

The chapter that really wowed me was on Nixon. Again, I hadn’t given Nixon and the bomb all that much thought. But Gavin points out that it deserves much more attention, because while on paper Nixon looked like an exemplary arms controller, but in private, he is revealed as a total maniac something much more complicated.

For his arms control cred, just consider that Nixon was the one who signed the SALT treaty, the ABM treaty, and the Biological Weapons Convention. He was also President when the Nuclear Non-Proliferation Treaty was ratified, and when the SALT II talks began. Kind of a non-trivial list of treaties and agreements — an impressive record for any US President. But as Gavin puts it:

The documents, however, reveal that Kissinger and, especially, Nixon had a different notion of how nuclear weapons affected international relations. … Theirs was a realist view—they believed that world politics was driven, as it had been for centuries, by geopolitical competition between great powers. The “nuclear revolution” had not changed this core feature of the international system. In relations with the Soviets, the message to their opponents was clear: “Look, we’ll divide up the world, but by God you’re going to respect our side or we won’t respect your side.”2

As evidence of this, Gavin has lots of excerpts from conversations between Nixon and Kissinger about nukes and treaties. They are universally disdainful of arms control. While Nixon was beginning the bomb the hell out of Cambodia (one of his least popular policies), he remarked to Kissinger: “Looking back over the past year we have been praised for all the wrong things: Okinawa, SALT, germs, Nixon Doctrine. Now [we are] finally doing the right thing.” Which tells you a lot about Nixon’s worldview: what mattered to him, in the end, was winning in Vietnam. Full stop. Everything else was just a distraction.

Nixon contemplative

As for arms control, Nixon told Kissinger that “I don’t give a damn about SALT; I just couldn’t care less about it.” On the kinds of technical matters that concerned security wonks, like the number of radars or missile interceptors, Nixon privately explained that “I don’t think it makes a hell of a lot of difference,” and that he thought the arms controllers were real chumps about this kind of thing. He opposed an anti-ballistic missile site in the nation’s capital because:

I don’t want Washington. I don’t like the feel of Washington. I don’t like that goddamn command airplane or any of this. I don’t believe in all that crap. I think the idea of building a new system around Washington is stupid.

Which you have to admit is sort of a novel argument against anti-ballistic missiles, right? Because you don’t actually like the nation’s capital that you’re President of. He dismissed the Biological Weapons Convention as “the silly biological warfare thing, which doesn’t mean anything,” as opposed to what he considered the really important stuff — again, the war in Vietnam.3

For Dick and Henry, treaties were just pieces of paper that would probably be violated the moment they proved less than useful for a state. Realpolitik, plain and simple. But they were not just flying by the seat of their pants. Their approach to international politics was, Gavin argues, coherent. It just didn’t give a lot of credence to the idea that nuclear weapons had any special importance with regards to international order, since they really didn’t think that they were going to get into a genuine shooting war with the USSR anytime soon. Worse, they thought that arms control successes could lead towards the Soviets attempting to take concessions elsewhere — that if they were “good” in one arena they could then get away with being “bad” in another.

Dick and Henry

But my favorite quotes are from Nixon about Vietnam. During a spring offensive by the North Vietnamese in 1972, Nixon told Kissinger:

We’re going to do it. I’m going to destroy the goddamn country, believe me, I mean destroy it if necessary. And let me say, even the nuclear weapons if necessary. It isn’t necessary. But, you know, what I mean is, what shows you the extent to which I’m willing to go. By a nuclear weapon, I mean that we will bomb the living bejeezus out of North Vietnam and then if anybody interferes we will threaten the nuclear weapons.

A week later, he continued to a somewhat horrified Kissinger:

Nixon: I’d rather use the nuclear bomb. Have you got that ready?
Kissinger: That, I think, would just be too much.
Nixon: A nuclear bomb, does that bother you?… I just want you to think big, Henry, for Christ’s sake! The only place where you and I disagree is with regard to the bombing. You’re so goddamned concerned about civilians, and I don’t give a damn. I don’t care.
Kissinger: I’m concerned about the civilians because I don’t want the world to be mobilized against you as a butcher.4

Yeesh. Which just goes to show, that Nixon’s realpolitik approach to nuclear weapons does seem to be slightly unhinged at times — that nukes were not necessarily off the table when he thought about the things he really cared about, at least when he was trying to get a rise out of Kissinger.

As for the NPT, Nixon opposed it during his election campaign, both because he felt treaties were by themselves unenforcible and because he thought there might be some American allies who could use their own nukes. (As a possible example of the kind of difficulty the NPT created, consider that Nixon was the one who helped formulate the pact with Golda Meir that involved Israel never admitting it possessed nuclear weapons so as to maintain good relations with the USA. The NPT put limitations on the US with regards to its Middle Eastern ally, which is not something Nixon would have been happy about.)

Nixon madman

Lastly, there is the “madman” approach that Nixon and Kissinger cooked up — that Kissinger should convince the Soviets that Nixon was unhinged enough to start nuking if things went too sour in Vietnam or elsewhere. This is perhaps Nixon’s most significant engagement with the nuclear question, and it was all psychological, all ploy. And, as Gavin points out, of questionable effectiveness.

Gavin doesn’t defend Nixon’s position on nukes and treaties; he just points out that Nixon actually had a position, and that it was actually deeply at odds with his (mostly positive) public record. The reason Nixon felt free to sign so many agreements is in part because he didn’t take them very seriously. How’s that for an ironic twist? If you don’t think arms control treaties actually matter, then what’s the harm in signing a few more of them?

Notes
  1. Francis Gavin, Nuclear Statecraft: History and Strategy in America’s Atomic Age (Cornell University Press, 2012). []
  2. Gavin, 108. []
  3. Gavin, 109-110. []
  4. Gavin, 116, with some of the rest of the quote filled out from elsewhere. []
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Heisenberg’s Dresden story: A wartime atomic mystery

Friday, October 11th, 2013

One of the weirdest stories I’ve come across regarding the Nazis and the atomic bomb is the one that the German physicist Werner Heisenberg told at Farm Hall about being asked about an apparent rumor that the United States was planning to use an atomic bomb against Dresden.

The Farm Hall transcripts reports him telling it several times during his internment, and it changed slightly each time he told it. Here’s the first version:

About a year ago, I heard from Segner from the Foreign Office that the Americans had threatened to drop a uranium bomb on Dresden if we didn’t surrender soon. At the time I was asked whether I thought it possible, and, with complete conviction, I replied: “No.

In a later version, he says he replied that it was possible — perhaps a face-saving maneuver, since by the second time Heisenberg tells the story, he has now started to believe that the reports of the atomic attack against Hiroshima were accurate.

My initial inclination is to think of this as strange idle chatter amongst a group of interned German scientists. A little bit of rumor-swapping, bragging about being in-the-know and being someone worth consulting. But I don’t think Heisenberg just made it up. That’s not really his style, I don’t think, and he repeated it several times over the course of their six month stay at Farm Hall.

Physikalische Blaetter, August 1944

Recently, while looking into some other wartime leaks, I came across an interesting follow-up on this story. The leak in question is a weird one and worth sharing. In August 1944, a German science magazine, the Physikalische Blätter (Physical Newspaper/Gazette/Pages), ran a short, anonymous piece titled “Another Utopia“:1

Transocean Service transmits a report cabled to “Stockholm’s Tidnigen” from London: “In the United States scientific research for a new bomb is underway. The material is uranium, and if the forces bound in this element could be liberated, explosive forces of so far unimagined power could be created. A 5-kilogram bomb could made a hole one kilometer deep and with a radius of 40 kilometers. In a circle of 150 kilometers all buildings were be smashed.”2

That’s a pretty weird thing to just appear in a German magazine, no? To save you the effort: their math on the energy release is way off by any measure — the damage radius described is well over 100 megatons, which is around what you’d get if you combined 5 kg of uranium with 5 kg of anti-matter (a pure E=mc2 conversion), much less if it fissioned with perfect efficiency (which would “only” release 85 kilotons).3 Either they’ve carried a few decimal points incorrectly or they’re just really confused. I suspect the latter.

Was this a “legitimate” leak? That is, did it derive from disclosure of confidential information? It’s hard to tell. The fact that it pinpoints the United States as making an atomic bomb out of uranium seems accurate, but everything else seems to be sketchy and confused. It’s true that the plutonium bomb used only around 6 kg of material… but that almost seems like a coincidence given the rest of what they’re talking about here. I’m inclined to file this under “fantastic atomic energy rumors” which were common even before the discovery of fission.

Werner Heisenberg, later in life

Werner Heisenberg, later in life

Anyway. The interesting bit comes 20 years later, in 1964. Physikalische Blätter was (and is) still around, and they ran a story on their wartime leak story. Much of it is repetitive fluff, a by-the-book (for 1964) accounting of Allied and German nuclear research. But along with this, they did attempt to track down the origin of the leak — with no success. But they did decide, thoughtfully, to try and assess the impact of the leak by surveying a few of the Farm Hall physicists to see whether they were aware of the “Another Utopia” story.

Otto Hahn wrote back that he “knew nothing” of the article at the time, and added that while they knew that there were people abroad probably working on the subject of atomic bombs, and that the stopping of all publications about the subject probably indicated the work was secret, that nonetheless they didn’t suspect that the United States would actually be able to produce such weapons in time for use in the war. He then suggested that the Physikalische Blätter should get in touch with Heisenberg, since he was more plugged into such matters than Hahn.4

And they did get in touch with Heisenberg, whose first response was that he hadn’t seen the article, was surprised to hear about it, suspected it was based on “vague rumors,” but said he would love if they sent him a copy so he could evaluate it further.5 They did this, of course, and his second response was the more interesting one. He said that rumors of this sort occurred repeatedly because of articles related to atomic energy that had already been published, and he did not let such rumors occupy him much during the war. But then Heisenberg wrote (my awkward translation — original German is in the footnotes):

Perhaps I should mention here an exception. In the summer of 1944 (probably early July), an aide of Göring’s came to me with a message from a German representative in Lisbon that there was a pronounced American threat against the German government, that an atomic bomb would be dropped on Dresden in the next six weeks if the government did not immediately sue for peace. The exact conditions of where the message came from were not communicated to me. I was asked by Göring’s adjutant if I thought it was possible that the Americans had already created an atomic bomb. I was understandably made very uncomfortable by this question, because of the large responsibility connected to my answer. I said that I thought it was extremely unlikely, but not impossible, for the Americans to have such a weapon at this time, and I tried to explain that the production of the weapon would in any case require an enormous industrial effort, and that I could not imagine that the Americans had already done it.6

And so the Dresden atomic bomb rumor raises its head again, no less confounding than before! But here we have a little more information on the source: it is supposedly from an agent in Lisbon, Portugal. Which is interesting.

General Groves not amused

General Groves is not amused by spies or leaks

Because as Stan Norris communicated to me when I wrote about German espionage efforts, there was a Nazi double-agent in Lisbon who was assigned to learning about the Manhattan Project. Stan has since sent me a “note to file” that General Groves had written about a meeting he had with the Military Policy Committee on June 21, 1944, where he describes this incident and his response to it. In his notes, Groves wrote the following:

This refers to the German agents who came to this country through Portugal, and the messages that were sent back to Germany in their behalf. These people were picked up as soon as they got into the United States and the messages were framed by me. There was considerable argument by my creeps as to these messages. I overruled them and did not deny that certain work was being done. It was pinpointed at certain universities and certain people, none of whom had anything to do with the project. The amount of the work was minimized, and an attempt to convince the Germans that it was an academic effort and that nothing would come of it. The creeps wanted to say that nothing was being done and that checks at various places had indicated that all potential personnel was being used on other work — I think radar.7

Ah, so now this gets really interesting, right? Because this coincides very well with the timing of Heisenberg’s supposed query — apparently originating in Nazi agents in Portugal — regarding whether Dresden would be atomic bombed! (And no, I don’t know why he calls whomever he is talking to “creeps.”)

Obviously I don’t have the whole story here, but the geographical and chronological proximity is a rather impressive overlap, is it not? Could something have gone wrong, or gotten scrambled, in Groves’ attempt to manipulate one of the few German atomic espionage attempts? I.e., Groves had wanted to suggest that the American program was small and unimportant; somebody instead reported back that it was massive and almost ready to go. It seems not impossible, though this is admittedly scant evidence. Either way, it’s clear that Groves would have been mighty mad to find out this question was being asked of Heisenberg.

But, here’s the twist. Arguably the exaggerated outcome would have been (and in fact was!) as good an outcome as Groves’ intended minimization, if not a better one! Heisenberg looked at the six-weeks-to-an-atomic-Dresden claim and said, no way — that doesn’t make any sense. He came away from the whole thing convinced it was just ridiculous wartime nonsense. If the report he had gotten was, “do you believe that the only people working on nuclear fission are a bunch of no-names, instead of Bethe and Fermi and Oppenheimer and Wheeler and all of those other physics luminaries we know the Americans have?,” might that not have raised his suspicions even more?

Of course, that doesn’t explain where Dresden, specifically, would have come into the picture. So there’s still something missing here. And it should be noted that Lisbon was a notorious hub of espionage activity for both sides during the war — so it isn’t necessarily the same guy. So some sobriety intrudes.

Dresden after the firebombing, 1945

Dresden after the firebombing, 1945

Lastly, is it possible the Dresden threat could have been real? The Physikalische Blätter story got picked up by the Washington Post, and they got in touch with Richard G. Hewlett, the Atomic Energy Commission’s official historian. He thought Heisenberg’s story was pretty nuts: “I can’t possibly believe there was an actual threat from the U.S. Government.”8 This was, obviously, because the US was still a year away from an atomic bomb at the time, and the idea of it being some kind of legitimate, diplomatic threat seems pretty out of character. Though do remember that Roosevelt asked Groves about using the bomb against Germany in December 1944 — so maybe, somewhere, this kind of idea was kicking around inside the heads of some people who knew about the Manhattan Project work but didn’t know how close it was to completion — maybe even someone who was working some kind of diplomatic/espionage backchannel. I don’t know.

As it was, Dresden was of course catastrophically attacked. Over the course of three days in February 1945, some 1,250 Allied heavy bombers pounded the city with incendiaries and high explosives, killing well over 20,000 people and burning the heart out of a city that until that point had been spared the horrors of area bombing. Could Dresden have been kept “pristine” on the theory that it might have been a good atomic bombing target, in the same way that Hiroshima, Nagasaki, Kokura, and Niigata had been? The Physikalische Blätter speculated that maybe this was the case, though there is no evidence that supports this conclusion.9 I doubt it, personally — the selection of Dresden as a target has its own trajectory that seems independent of any possible atomic narrative, and the idea that it would have been selected as a possible atomic bomb target as early as the summer of 1944 seems rather far-fetched. It should be noted, as well, that the narrative about the atomic bomb in mid-1960s Germany was very much tinged by the Cold War context; it was a common thread of discussion in both the West and the East that the United States would be willing to throw Germany under the bus if it came to a real confrontation with the Soviets.

Still, it’s an interesting constellation of stories: the leak, Heisenberg’s query, and Groves’ attempt at misinformation. If Groves’ misinformation attempt was really did result in the query to Heisenberg, what tremendous irony would abound. Ironic that Groves’ attempt to minimize the effort would result in a exaggerated interpretation; irony that the exaggerated interpretation would lead to total dismissal by the expert.

Notes
  1. Noch eine Utopie,” Physikalische Blätter 1, No. 8 (1944), 118. I was surprised to find all of PB online and without a paywall. This particular article is appended to a longer report on “Science and War.” []
  2. “Transozean-Innendienst verbreitet eine Nachricht, die sich “Stockholms Tidningen” aus London melden läßt: “In den Vereinigten Staaten werden wissenschaftliche Versuche mit einer neuen Bombe ausgeführt. Als Material dient Uran, und wenn die gebundenen Kräfte in diesem Element frei würden, dann könnten Sprengwirkungen· von bisher nicht geahnter Kraft erzeugt werden. Eine 5-kg-Bombe könnte dann ein Loch von 1 km Tiefe und 40 km Radius hervorbringen. In einem Umkreis von 150 km würden alle festen Gebäude in Trümmer gehen.” []
  3. The rule of thumb is that the completely fissioning of a kilogram of fissile material produces about 17 kilotons of yield. []
  4. “Ich wußte gar nichts von dem Inhalt des Artikels im Augustheft 1944 der Physikalischen Blätter, und so möchte ich daraus schließen, daß er mir auch damals nicht bekannt war. Wir alle waren natürlich während des Krieges der Meinung, daß man im Ausland, vor allem in Amerika, wohl an einer Herstellung von Atombomben arbeiten wird, denn es wurden ja auch in Deutschland Vorversuche darüber gemacht mit dem Versuch der Aufstellung eines Atomreaktors. Und da nach Kriegsanfang alle Publikationen aus dem Gebiete aufhörten, schlossen wir natürlich, daß im Ausland geheime Arbeiten gemacht würden. Andererseits glaubte keiner von uns, daß während der Kriegszeit eine Atombombe fertiggestellt werden könnte. Ich erinnere mich an das Erstaunen, das wir alle hatten, als wir von der Bombe im August 1945 in englischer Gefangenschaft erfuhren. Da Prof. Heisenberg der Vorsitzende des sogen. Uran-Vereins war, also die Arbeiten zur Herstellung eines Kernreaktors geleitet hat, ist wohl Herr Heisenberg die beste Quelle, zu erfahren, ob jemand von uns die Mitteilung in den Phys. Blättern kennt.” Otto Hahn, quoted in E. Brüche, “Was wußte man 1943/44 in Deutschland von der Atombombe?Physikalische Blätter 20, No. 5 (1964), 220-225, on 222. []
  5. “Sie schreiben davon, daß in den Phys. Blättern bereits 1944 eine Notiz über die amerikanischen Versuche mit Atombomben erschienen sei. Dies ist mir völlig neu, aber zugleich interessant und unbegreiflich; denn die ersten amerikanischen Atombombenversuche haben ja bekanntlich im Frühjahr 1945 stattgefunden. Es kann sich also eigentlich nur um ziemlich vage Vermutungen gehandelt haben. Ich wäre Ihnen sehr dankbar, wenn Sie mir eine Kopie jenes Artikels in den Phys. Blättern zukommen lassen könnten; dann kann ich besser beurteilen, ob ich diesen Artikel jemals gesehen habe und wie ich darauf reagiert habe.” Werner Heisenberg, quoted in E. Brüche, “Was wußte man 1943/44 in Deutschland von der Atombombe?” Physikalische Blätter 20, No. 5 (1964), 220-225, on 222. []
  6. “An die von Ihnen erwähnte Notiz in den Phys. Blättern aus dem Jahr 1944 konnte ich mich nicht mehr erinnern, aber Gerüchte dieser Art sind – schon aufgrund des Flüggeschen Artikels in den “Naturwissenschaften” – immer wieder aufgetreten und haben mich daher nicht allzu sehr beschäftigt. Vielleicht sollte ich hier eine Ausnahme erwähnen. Im Sommer 1944 (wahrscheinlich Anfang Juli) kam einmal der Adjutant von Göring zu mir mit der Mitteilung, es sei über die deutsche Vertretung in Lissabon eine amerikanische Drohung gegen die deutsche Regierung ausgesprochen worden, es werde innerhalb der nächsten sechs Wochen eine Atombombe über Dresden abgeworfen werden, wenn die Regierung nicht in irgendeiner Art um Frieden bäte. über den genauen Inhalt der Bedingungen wurde mir nichts mitgeteilt. Ich wurde von dem Adjutanten Görings gefragt, ob ich es für möglich hielte, daß die Amerikaner bereits über eine Atombombe verfügten. Mir war diese Frage begreiflicherweise sehr unangenehm, weil mit der Antwort auf jeden Fall eine große Verantwortung verbunden war. Ich habe dann gesagt, daß ich es zwar für außerordentlich unwahrscheinlich, aber nicht für völlig unmöglich hielte, daß die Amerikaner zu diesem Zeitpunkt über eine solche Waffe verfügten, und habe versucht zu erklären, daß die Herstellung der Waffe auf jeden Fall einen enormen industriellen Aufwand erfordern müßte, von dem ich mir nicht denken könnte, daß die Amerikaner ihn schon geleistet hätten.” Ibid. An article on uranium fission by Siegfried Flügge appeared in Die Naturwissenschaften in June 1939; Heisenberg cites this as the reason for all of the speculation. Flügge himself was asked about the “Another Utopia” article as well and he responded with a diatribe about how nobody credits him for anything. []
  7. Leslie Groves, Notes on the Military Policy Committee of June 21, 1944 (undated, but prior to 1964), Leslie R. Groves Papers, National Archives and Records Administration, RG 200, Entry 7530M, Box 4, “Working Papers.” Courtesy of Robert S. Norris. []
  8. Howard Simons, “Were We Vulnerable: Swedish Report in World War II Tipped U.S. A-Bomb Hand,” Washington Post (27 December 1964), E3. Simons’ story butchers many of the facts, including getting the nationality of Physikalische Blätter wrong (which PB took issue with in its reprinting of it), and even misspells Hewlett’s name. []
  9. “Dresden – Schicksal und Warnung,” Physikalische Blätter 21, no. 4 (1965), 196. []
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The final switch: Goldsboro, 1961

Friday, September 27th, 2013

The threat of nuclear weapons accidents isn’t a new one. Even in 1945, Los Alamos physicists sweated when contemplating all that could possibly go wrong with their bombs, if they went off at the wrong place or the wrong time. Or didn’t go off at all. That’s the bind, really: a nuclear state wants a weapon that always goes off exactly when you tell it to, and never goes off any other time. That’s a hard thing to guarantee, especially when the stakes are so high in both directions, and especially since these two requirements can be directly in tension.

Schlosser - Command and Control book

I recently heard Eric Schlosser give that elegant formulation at a talk he gave last week in support of the release of his new book, Command and Control: Nuclear Weapons, the Damascus Accident, and the Illusion of Safety. I haven’t had a chance to read the book, yet (it’s currently en route), but I’m looking forward to it. I read Schlosser’s Fast Food Nation a decade (!) ago and found it completely eye-opening. But I went to his talk last week not sure what to expect. From McDonald’s to nuclear weapons accidents? Stranger things have happened, but I worried that maybe he would take the “easy” route with regards to the accidents, not bothering to learn to nitty-gritty technical details that let one talk about such things sensibly, or, at the very least, sensationalize the findings. So I was pretty pleased to find that neither seemed to be the case. Schlosser has seriously done his homework, spending 6 years digging through records, FOIAing documents, and interviewing weapons designers. His discussion of the risks seemed right on the mark so far as I could tell — they don’t need to be exaggerated one bit to be perfectly horrifying. He answered questions expertly, even a tough, devil’s-advocate one from Hugh Gusterson. So I’ve been looking forward to reading the full book.

Last week, the Guardian released a new document, obtained by Schlosser through a FOIA request, regarding one particular accident, the 1961 crash of a B-52 near Goldsboro, North Carolina, which resulted in the jettisoning of two Mark-39 hydrogen bombs. The document in question is a government nuclear expert’s evaluation of a popular account of the Goldsboro accident, in which he finds some major errors (like overstating the yield of the bomb), but ultimately concludes that at least one of the bombs was, in fact, pretty damned close to accidental detonation: “one simple, dynamo-technology, low voltage switch stood between the United States and a major catastrophe … It would have been bad news – in spades.

The bomb in question, stuck in the mud.

The bomb in question, stuck in the mud.

I’ve been watching how the above document has been discussed by people on the web. The most interesting response has been people saying, “I thought that bomb lacked a nuclear core?” You know that there have been too many nuclear weapons accidents when people start getting them confused with one another. The missing-bomb-that-maybe-lacked-a-core is the 1958 Tybee bomb, where a Mark-15 hydrogen bomb was lost near Savannah, Georgia. Different bomb, different day.

The other response I commonly saw was one that assumed that any such fears of a bomb going off accidentally were exaggerated. Now this is kind of an interesting response. For the one thing, they’re discounting a contemporary, internal, once-classified evaluation made by a relevant expert. In exchange, they’re parroting either general skepticism at the idea that a nuclear weapon could technically be unsafe, or they are parroting a standard line about how hard it is to set off an implosion bomb accidentally, because all of the lenses need to detonate at exactly the same time. Which is sometimes the right approach (though not all American bomb designs were “one-point safe” — that is, there were designs that ran a real risk of producing a nuclear yield even if just one of the explosive lenses accidentally fired), but in this case, it’s entirely irrelevant, for reasons I’ll explain below.

I’ve been in touch with Schlosser since the talk, and he shared with me a video he had (somehow) gotten his hands on produced by Sandia National Laboratory (the weapons lab that specializes in making bombs go off at just the right moment) about the Goldsboro accident. He’s put it up on YouTube for me to share with you. It is only a few minutes long and worth the watch.

I love the CGI — “all the sudden, now that weapon system is free.” The bomb looks so… liberated. And the part at the end, where they talk about how they had plenty of opportunities for future data, because there were so many accidents, is wonderfully understated. But the stuff that really hits you in your gut is the description of exactly what happened:

“All of the sudden now that weapon system [the Mk-39] is free. As the weapon dropped, power was now coming on, and the arming rods were pulled, the baroswitches began to operate.1 The next thing on the timing sequence was for the parachute to deploy. When it hit the ground, it tried to fire.” “There was still one safety device that had not operated. And that one safety device was the pre-arming switch which is operated by a 28 volt signal.” “Some people could say, hey, the bomb worked exactly like designed. Others can say, all but one switch operated, and that one switch prevented the nuclear detonation.” “Unfortunately there had been some 30-some incidents where the ready-safe switch was operated inadvertently. We’re fortunate that the weapons involved at Goldsboro were not suffering from that same malady.”

What’s amazing about the above, in part, is that everything in quotation marks is coming from Sandia nuclear weapons safety engineers, not anti-nuclear activists on the Internet. This isn’t a movie made for public consumption (and I’ve been assured that it is not classified, in case you were wondering). It’s a film for internal consumption by a nuclear weapons laboratory. So it’s hard to not take this as authoritative, along with the other aforementioned document. Anyone who brushes aside such concerns as “hysterical” is going to have to contend with the fact that this is what the nuclear weapons designers tell themselves about this accident. Which is pretty disconcerting.

There are further details in another document sent to me by Schlosser, a previously-classified review of nuclear weapons accidents from 1987 that clarifies that one of the reasons the Goldsboro bomb in particular almost detonated was because of the way it was tossed from the aircraft, which removed a horizontally-positioned arming pin. That is, an arming pin was supposed to be in a position that it couldn’t be removed accidentally, but the particulars of how violently the aircraft broke up as it crashed were what armed the bomb in question. The other bomb, the one whose parachute didn’t fire, just had its HE detonate while it was in the mud. From the 1987 review:

Before the accident, the manual arming pin in each of the bombs was in place. Although the pins required horizontal movement for extraction, they were both on a lanyard to allow the crew to pull them from the cockpit. During the breakup, the aircraft experienced structural distortion and torsion in the weapons bay sufficient to pull the pin from one of the bombs, thus arming the Bisch generator.2 The Bisch generator then provided internal power to the bomb when the pullout cable was extracted by the bomb falling from the weapons bay. The operation of the baroswitch arming system,3 parachute deployment, timer operation,4 low and high voltage thermal batteries activation, and delivery of the fire signal at the impact by the crush switch all followed as a natural consequence of the bombing falling free with an armed Bisch generator. The nonoperation of the cockpit-controlled ready-safe switch prevented nuclear detonation of the bomb. The other bomb, which free-fell, experienced HE detonation upon impact. One of the secondary subassemblies was not recovered.5

The secondary subassembly is the fusion component of the hydrogen bomb. Normally I would not be too concerned with a lost secondary in and of itself, because bad folks can’t do a whole lot with them, except that in this particular bomb, the secondary contained a significant amount of high-enriched uranium, and lost HEU is never a good thing. The government’s approach to this loss was to get an easement on the land in question that would stop anyone from digging there. Great…

Mk-39 ready-safe switch

From the video, I was also struck by the picture of the ready-safe switch then employed. I’d never seen one of these before. Presumably “S” means “safe” and “A” means “armed.” It looks ridiculously crude by modern standards, one little twirl away from being armed. This little electronic gizmo was all that stood between us and a four megaton detonation? That’s a wonderful thing to contemplate first thing in the morning. Even the later switches which they show look more crude than I’d prefer — but then again, probably all 1950s and 1960s technology is going to look crude to a modern denizen. And again, just to reiterate, we’re not talking about “merely” accidentally igniting the explosives on the primary bomb — we’re talking about the bomb actually sending a little electrical charge through the firing circuit saying “Fire!” and starting the regular, full-yield firing sequence, stopped only by this little gizmo. A little gizmo prone to accidentally firing, in some of the bombs.

Lest you think that perhaps Sandia overstates it (which seems rather unlikely), take also the testimony of Secretary of Defense Robert McNamara into account. In January of 1963, McNamara explained at a meeting between the Defense and State Departments that he was opposed to Presidential pre-delegation of nuclear weapons in part because of the danger of accidental detonation — either ours or the Soviets’. In the meeting notes, posted some time back by the National Security Archive and forwarded to me by Schlosser, McNamara’s participation is listed as follows:

Mr. McNamara went on to describe the possibilities which existed for an accidental launch of a missile against the USSR. He pointed out that we were spending millions of dollars to reduce this problem to a minimum, but that we could not assure ourselves completely against such a contingency. Moreover he suggested that it was unlikely that the Soviets were spending as much as we were in attempting to narrow the limits of possible accidental launch. He went on to describe crashes of US aircraft[,] one in North Carolina and one in Texas, where, by the slightest margin of chance, literally the failure of two wires to cross, a nuclear explosion was averted.

This one’s interesting because it embeds these accidents in a context as well — the possibility of either us, or the Soviets, accidentally launching a nuke and wondering if a full-scale nuclear exchange has to follow. It’s not quite Strangelovian, since that would require a rogue commander, but it is very Fail-Safe.

As to what the Goldsboro blast would look like, the only time we tested this warhead at full yield was the shot “Cherokee” at Operation Redwing, in 1958. It was a pretty big boom, far more impressive than some of the Hiroshima shots that have been posted along with the Goldsboro story:

Redwing_Cherokee_005

And, of course, you can use the NUKEMAP to chart the damage. I’ve added the W-39 warhead to the list of presets in NUKEMAP2, using 4 megatons as the yield (the tested yield was 3.8 megatons, though the W-39 is often stated as an even 4. I rounded up, just because quibbling over 200 kilotons seemed pointless), and a fission fraction of 55%.6 It’s a pretty big explosion, with a fallout plume capable of covering tens of thousands of square miles with hazardous levels of contamination (and nearly a thousand square miles with fatal levels). Note that the Cherokee test was a true airburst (the fireball didn’t touch the ground), and so didn’t generate any significant fallout. The Goldsboro bomb, however, was meant to operate on impact, as a surface burst, and would have created significant fallout.

Again, one doesn’t have to exaggerate the risks to find it unsettling. The bomb didn’t go off, that final switch thankfully did work as intended. But that’s cold comfort, the more you learn about the accident. Our current nuclear weapons are much safer than the Mk-39 was, back in 1961, though Schlosser thinks (following the testimony of experts) there are still some unsettling aspects about several of our weapons systems. If we are going to have nukes, he reasons, we should be willing to spend whatever it costs to make sure that they’ll be safe. That seems to me like an argument guaranteed to appeal to nobody in today’s current political climate, with the left-sorts wanting no nukes and no modernization, and the right-sorts not really wanting to talk about safety issues. But I’ll get to that more another day, once I’ve read the book.

If that bomb had gone off, we’d speak of “Goldsboro” as a grim mnemonic, in the same way that we do “Chernobyl” today. One wonders how that would have changed our approach to nuclear weapons, had the final switch not held strong.

Notes
  1. The “arming rods” were pull-out switches that would activate when the weapon left the bomb bay. The baro(meter) switches were pressure sensitive switches that would make sure the bomb was nearing the appropriate height before starting the next sequence of arming. In the World War II bombs, the next stage in the sequence would be to consult radar altimeters to check the precise distance from the ground. The Goldsboro bombs were set to go off on ground impact. []
  2. A Bisch generator, as the context implies, is an electrical pulse generator. []
  3. Again, a pressure-sensitive switch that tried to guarantee that the bomb was roughly where it was supposed to be. []
  4. Timer switches were often used to make sure that the bomb cleared the aircraft before seriously starting to arm. []
  5. R.N. Brodie, “A Review of the US Nuclear Weapon Safety Program – 1945 to 1986,” SAND86-2955 [Extract] (February 1987). []
  6. Chuck Hansen, in his Swords of Armageddon, estimates that shots Cherokee and Apache of Operation Redwing had an average fission fraction of 55%, but isn’t able to get it any more precise than that. Given what I’ve read about the bomb — that it used an HEU secondary, for example — I would expect it to be at least 55%, if not more. It seems like a pretty “dirty” weapon, emphasizing a big yield in a relatively small package over any other features. See Chuck Hansen, Swords of Armageddon, V-224 (footnote 325). []