Redactions

The Height of the Bomb

by Alex Wellerstein, published August 8th, 2012

The United States justly gets the lion’s share of credit for making and using the atomic bomb. The Manhattan Project was an international effort, we all know, but the U.S. bore the greatest amount of the labor, the cost, and the ultimately responsibility. When people get mad about the bomb, they get mad at the United States. It makes sense.

The importance of the United Kingdom, in some narratives of the bomb, was mostly in pushing the idea, sending a handful of scientists to help, and signing off on the use of the bomb. (Let’s not even get into Canada, who, according to this narrative, just provided some uranium and a lab that wasn’t allowed to communicate with the rest of the Manhattan Project.)

Several members of the British Mission to Los Alamos: William Penney, Otto Frisch, Rudolf Peierls, and John Cockroft. Photo via Los Alamos.

That handful of scientists, though, included some fairly important people. James Tuck did crucial work relating to the development of the explosive lens in the Trinity and Nagasaki bombs. Klaus Fuchs, aside from being the most significant Soviet spy on the project, helped tremendously with the design of the implosion bomb and the neutron initiators. And so on.

William Penney (later Baron Penney), who later ran the British atomic bomb project, did a whole variety of interesting things. He was crucial in developing means of assessing the effects of the bomb, was the only member of the British delegation to witness the bombing of Japan (he was on an observation plane on the Nagasaki mission), and was one of the first Allied scientists who went into Hiroshima and Nagasaki after the war.

One of the other topics he worked on was the question of what height the bombs should be detonated at for maximum effect.

Illustration of one of the effects of a bomb detonated in the air: a reflection of the blast wave off of the ground, which produces a powerful shock wave known as a Mach stem. From Glasstone and Dolan’s The Effects of Nuclear Weapons (1957 edn.).

This was a non-trivial issue: prior to nuclear weapons, it was pretty common for a bomb to detonate just when it actually physically made contact with its target. With atomic bombs, though, that isn’t ideal. Set one off too high, and much of the blast is going off into outer space and not the target. Too low, and a lot of it is going off straight into the ground. There is no truly “right” height, in the sense that any height will produce different effects that may or may not be desirable, but if the goal is the destruction of civilian buildings, then there are heights that work much better for that than others.

All of which Penney wrote up in a charming December 1944 report on “The Height of Burst of the Gadget.”

Click for the PDF.

It’s a chilling — and fascinating — document for a few reasons. One is that it goes against any myth that the height of the bomb was set to minimize fallout exposure. This is discussed in great length by Sean Malloy in a recent article in Diplomatic History, which I will be posting a review of fairly soon.  The entire reasoning for the height of the bomb detonation was about blast and fire effects. Radiation didn’t come into it. Later, when it was questioned as to whether there were fallout issues, the Manhattan Project principals said that they thought the height of the blast would avoid a lot of fallout — which is somewhat true — but this isn’t what caused them to set the height of the blast.

Another interesting bit is that Penney actually wants you to set the bomb off very low — 500 feet or so above the ground — rather than very high. The reason, though, is that Penney is assuming a much smaller bomb than actually was built: his calculation is based on the notion that the bomb will only be about 1 kiloton in yield, whereas previous guesses had been that it would be 10 kilotons or so in yield.

William Penney in the 1950s, looking like a character out of a Le Carré novel

Penney’s document is remarkable in its frankness about the point of the bomb: to destroy civilian houses. He also makes a big distinction between the types of targets available:

There is a significant difference in the blast resisting characteristics of German towns and of Japanese towns. While in Germany a broad distinction may be made between industrial buildings and the remainder, it is true that there is no pronounced contrast in the strength of one building or another, with the exception of the multi-floored reinforced concrete structures which are relatively few in number. In Tokyo or Yokahama, some areas consist entirely of extremely strong steel framed and concrete structures built to resist earthquakes, whereas other much larger areas contain only comparatively flimsy wooden houses with tiled roofs. … Therefore, it may be said that if the gadget is to be used in area attack against a German town, only one height of fusing is required for attack anywhere. Such is not the case for area attack on Tokyo. If the accuracy of delivery can be guaranteed within 500 yards, then the bursting height for attack on wooden houses can be set twice as high as for attack on the business and shopping areas. If this accuracy cannot be guaranteed, then some suitable compromise must be worked out from tactical and statistical arguments.

In other words, all German buildings would be more or less affected in the same way in an atomic bomb blast. Japanese buildings, however, vary between very strong industrial buildings and very flimsy civilian buildings. If the goal is to target civilians, you have much more leeway in the blast height.

Two very interesting things here: One, an atomic attack on Germany is still being explicitly discussed. Two, the “area attack” being discussed is one that contemplates the direct and purposeful targeting of civilians — perhaps even at a detriment to targeting industrial facilities.

Penney then moves on to consider what kind of damage you’re trying to maximize: “complete destruction” versus “severe but not unrepairable damage.” Penney notes that “opinion in England” has gone from favoring “severe” damage to favoring “complete destruction.” Why? Because it turns out that “severe” damage is pretty quick to repair, as the Londoners discovered after the V-1 attacks (“the robot attacks,” as Penney calls them), and because “complete destruction” “implies many casualties, and this in turn has a very serious effect on the efficiency of fire fighting.

Dwell on that for a moment. The more people you kill, the less people who can put out the fires. Lest you think this is perhaps just a moment of remarkable cruelty, Penney actually elaborates on this theme at length later in the report. He makes a distinction here between the “Fire Force” and “fire guards,” which, if I understand it correctly, is the distinction between professional and amateur fire prevention forces:

The explosion of a gadget in either Germany or Japan, causing large amount of [“complete destruction” class] damage will almost certainly result in fires. While the general impression among the Fire Force in England is that the Japanese are likely to prove the most efficient fire guards in the world (because their ordinary lives gives them continual experience), the large number of casualties associated with [this class of] damage may well lead to such confusion in Japan that the critical incubation period of the fires [to become a firestorm] is passed unobserved. Thereafter the fire guards are useless, and only the Fire Force counts. The possibility of eliminating a large fraction of the Fire Force of a Japanese town by getting the fireman into the radioactive contaminated area to fight fires is attractive and realistic. The success of a follow-up attack may be greatly increased in this way. … If a gadget can be followed or accompanied by small [incendiary devices] the probability of a devastating fire, spreading well beyond the limits of the blast damage, will be greatly increased.

Gristly thoughts, no? This is also the only area of the report where radioactivity is mentioned: as a way to kill firefighters, so you can encourage a massive conflagration to develop.

Fire damage in Hiroshima shown in red

In reality, a massive firestorm did erupt in Hiroshima and Nagasaki, and was responsible for the majority of the deaths in each. Making the bombs go off at just the right height for maximizing this sort of damage was a high priority — it even required the development of new kinds of bomb fuses just for this purpose.

The bomb that went off above Hiroshima, 67 years ago this week, was set off at 600 meters above the ground. The Nagasaki bomb was detonated at 500 meters. Both of those heights were chosen to maximize damage — especially for the “flimsy” wooden houses of Japanese civilians. 

It’s easy to demonize the people who made these kind of decisions — especially when they describe the pre-irradiation of firefighters as “attractive.” But this is the logic of total war, when you’ve given up on the idea of a morality of war fighting and decide that the ends — and not the means — are all that matter. 

Whether one thinks the bombing of Hiroshima and Nagasaki were justified or not, it must be remembered that along with whatever else they were they were massacres of civilians. It was not an incidental or accidental side-effect: it was what they were planned to be. When the scientists at Los Alamos made plans for how to use the atomic bomb, they optimized them for the burning of civilians. This should not be forgotten or glossed over, even if one thinks it was still the right thing to do.

Meditations

Hiroshima at 67: The Line We Crossed

by Alex Wellerstein, published August 6th, 2012

Today is the 67th anniversary of the bombing of Hiroshima. Sixty-seven isn’t a particularly exciting anniversary, being neither divisible by five or ten, but I get the feeling that it’s been talked about more this year than it was in the last few years. Maybe it’s all of the concderns regarding Iran and the Middle East? Maybe because it’s the first anniversary post-Fukushima? I’m not sure, but something’s in the air.

67 also happens to be the number of Japanese cities we firebombed before dropping two atomic bombs on Hiroshima and Nagasaki.

I wrote up a short, quick essay on the anniversary of Hiroshima for a group that didn’t pick it to be used (which is fine), but I thought I’d share it here.  I’ve added some illustrations, because you can do that with blogs.


THE LINE WE CROSSED

We have been debating the morality, strategy, and history of the bombings of Hiroshima and Nagasaki for sixty-seven years. From their first use, the bombs were the subject of intense adulation and exuberance, as well as deep anxiety and ambivalence. Almost immediately the bomb was viewed as something completely new, and after the Japanese declared their surrender days later, the bomb was given the credit for ending the war.

Paul Tibbets in the Enola Gay

Whether it deserved that credit, or whether the war could have been ended without it, has been the subject of debate for nearly that long. Over the decades various arguments about the reasons for using the bombs, and their possible justifications, have been aired, confronted, revised, and rebutted. But even the arguments in favor of the bombing acknowledge that the United States crossed a line when it used the first nuclear weapons on inhabited cities. (Those who argue against the use of the bomb necessarily invoke such an argument.) The justification for such a “special” weapon — to use the terminology of the day  — was that it was necessary to “shock” the Japanese into rapid submission for a net saving of lives.

But was a line really crossed? The atomic bombs killed tens of thousands of civilians immediately in each city, with more casualties attributed to their lingering effects over time. Looked at in a vacuum, this certainly looks like a particularly egregious moral transgression.

Within the context of the time, however, the atomic bombs were merely a refinement of an existing “art”: the mass firebombing of cities. This “terror bombing,” as it was sometimes called, reached its highest form under the leadership of Curtis LeMay in the Pacific theatre, where B-29s in massive numbers flew repeated, low-altitude nighttime raids against sixty-seven Japanese cities. They dropped explosives, napalm, and thermite onto streets of wooden houses, creating massive, inextinguishable conflagrations that sucked the air out of shelters and burned people alive. The incendiary bombs were specially developed for the destruction of Japanese houses: the small bomblets were designed to break through the ceilings, stop on the first floor, and spray a cone of flaming, jellied gasoline into the interior. The thermite and magnesium were added so that the existing fires would burn too hot to be put out.

Over two long nights in March 1945, over 300 B-29s were sent to burn the megalopolis of Tokyo. Estimates vary as to the exact numbers, but in the neighborhood of 100,000 people were killed, with another million people injured, and another million made homeless. Success was measured in raw percentages of the total area destroyed.

1945: Tokyo at left, Hiroshima at right

In such a context, it is hard to see Hiroshima and Nagasaki as the attacks that crossed the line. The line was already crossed — we were already burning men, women, and children by the thousands. Hiroshima and Nagasaki added the effects of radiation (which were little understood at the time by those who ordered the use of the atomic bombs ), but the firebombings were not without their lingering, scarring effects on the survivors, either.

How did this happen? As was the case with the decision to develop, produce, and use the atomic bomb, it was a process of gradual accumulation. Small decisions seemed to lead to big “inevitable” consequences. Strategic bombing began as an attempt to find clever, scientifically-informed ways to shut down the enemy’s war-making capability, and it ended with a butchery that would have been recognizable to Genghis Khan.

Hiroshima and Nagasaki crossed a line only insomuch as they were more spectacular, ripped straight out of science fiction — the burning of civilians alive with atomic fire rather than gasoline.

Death by gasoline: Tokyo, March 10, 1945

The lesson is not that nuclear weapons do not demand a “special” consideration — indeed, by the time they were put onto long-range rockets, and had their explosive power increased to levels impossible to replicate with conventional means, they certainly deserved to be considered a new moral problem.

Rather, the lesson is that nations do not arrive at these big decisions from a state of innocence. We gradually acclimate to the moral climate we produce from a multitude of smaller decisions. Hiroshima and Nagasaki were not the product of one fateful moral debate, but the accumulation of a thousand small choices. We should be mindful of this especially in this age of drone assassinations, cyber attacks, and indefinite detentions — we may find ourselves in the middle of a much bigger moral morass than we expected.


This isn’t the world’s most strikingly original take on things, I’d be the first to admit. I recently had the opportunity to read a fairly lousy “defense of the bombing” editorial published by a major American magazine (same old arguments mixed with a sense of superiority abetted by a dearth of information), and the author also made the argument that firebombing was the same as atomic bombing. But what I would add to the above, if I were revising it now, was the fact that just because they’re equivalent doesn’t make either of them moral. Which is to say, I don’t think saying, “we were already burning civilians alive!” actually gets you off the hook — it just points at how depraved the strategy actually was. “But we were already committing war crimes for months!” is not a good defense against being charged as a war criminal.

What’s important for me is to recognize that burning civilians alive in great numbers should be considered a terrible idea if you care about fighting a “just war.”

And no, I don’t buy the, “but their soldiers also did awful things.” So what? That justifies burning their mothers, children, and wives? I don’t think so. It justifies killing the soldiers, sure. But everyone else, too? That’s the road to war crimes.

I’m with Robert McNamara on this one, perhaps surprisingly: I’m not sure that firebombing 67 cities and then dropping two atomic bombs was proportional with our goals in World War II, especially if the main goals — a disarmed and occupied Japan — likely could have been accomplished far earlier, if the original idea of “unconditional surrender” had just been modified to what it ended up being in practice (conditional upon being able to keep the Emperor as the titular head of state).

If it were up to me, we’d mark March 10th — the bombing of Tokyo — as an anniversary of significance as well as August 6 and August 9.

Visions

Enough Fallout for Everyone

by Alex Wellerstein, published August 3rd, 2012

Nuclear fallout is an incredible thing. As if the initial, prompt effects of a nuclear bomb weren’t bad enough — take that and then spread out a plume of radioactive contamination. The Castle BRAVO accident was the event that really brought this to the public forefront. I mean, the initial effects of 15 megaton explosion are pretty stunning in and of themselves:

But the fallout plume extended for hundreds of miles:

Why yes, you can get this on a coffee mug!

Superimposed on an unfamiliar atoll, it’s hard to get a sense of how long that plume is. Put it on the American Northeast, though, and it’s pretty, well, awesome, in the original sense of the word:

Of course, it’s all about which direction the wind blows, in the end.

And remember… that’s just a single bomb!

Of course, if you’re interested in the more diffuse amounts of radioactivity — more than just the stuff that you know is probably bad for you — the fallout maps get even more interesting. Here’s what the BRAVO fallout did over the next month or so after the detonation:

Now, you can’t see the numbers there, but they aren’t high — it’s not the same as being immediately downwind of these things. They’re low numbers… but they’re non-zero. But one of the “special” things about nuclear contaminants is that you can track them for a very long time, and see exactly how one test — or accident — in a remote area is intimately connected to the entire rest of the planet. 

And, in fact, nearly everyone born during the era of atmospheric nuclear testing had some tiny bits of fallout in their bones — you can even use it to determine how old a set of teeth are, to a very high degree of accuracy, by measuring their fallout content. (And before you think atmospheric testing is a matter of ancient history, remember that France and China both tested atmospheric nuclear weapons long after the Limited Test Ban Treaty! The last atmospheric test, by China, was in 1980!)

The same sorts of maps are used to show the dispersion of radioactive byproducts of nuclear reactors when accidents occur. I find these things sort of hypnotizing. Here are four “frames” from a simulation run by Lawrence Livermore National Laboratory on their ARAC computer showing the dispersion of radioactivity after the Chernobyl accident in 1986:

Chernobyl ARAC simulation, day 2

Chernobyl ARAC simulation, day 4

Chernobyl ARAC simulation, day 6

Chernobyl ARAC simulation, day 10

Pretty incredible, no? Now, the odds are that there are lots of other contaminants that, could we track them, would show similar world-wide effects. Nuclear may not be unique in the fact that it has global reach — though the concentrations of radioactivity are far higher than you’d find anywhere else — but it may be unique that you can always measure it. 

Yesterday I saw a new set of plots predicting the dispersion of Caesium-137 after the Fukushima accident from 2011. These are just models, not based on measurements; and all models have their issues, as the modelers at the Centre d’Enseignement et de Recherche en Environnement Atmosphérique (CEREA) who produced these plots acknowledge.

Here is their map for Cs-137 deposition after Fukushima. I’m not sure what the numbers really mean, health-wise, but the long reach of the accident is dramatic:

Map of ground deposition of caesium-137 for the Fukushima-Daichii accident

Map of ground deposition of caesium-137 for the Fukushima-Daichii accident by Victor Winiarek, Marc Bocquet, Yelva Roustan, Camille Birman, and Pierre Tran at CEREA. (Source)

Compare with Chernobyl. (Warning: the scales of these two images are different, so the colors don’t map onto the same values. This is kind of annoying and makes it hard to compare them, though it illustrates well the local effects of Chernobyl as compared to Fukushima.)

Map of ground deposition of caesium-137 for the Chernobyl accident

Map of ground deposition of caesium-137 for the Chernobyl accident, by Victor Winiarek, Marc Bocquet, Yelva Roustan, Camille Birman, and Pierre Tran at CEREA. (Source)

Lastly, they have an amazing animated map showing the plume as it expands across the Pacific. It’s about 5MB in size, and a Flash SWF, so I’m just going to link to it here. But you must check it out — it’s hypnotic, strangely beautiful, and disturbing. Here is a very stop-motion GIF version derived from their map, just to give you an incentive to see the real thing, which is much more impressive:

Fukushima-Daichii activity in the air (caesium-137, ground level) (animated)

There’s plenty of fallout for everyone — well enough to go around. No need to be stingy. And nearly seven decades into the nuclear age, there’s a little bit of fallout in everyone, too.

Update: The CEREA site seems to be struggling a bit. Here’s a locally-hosted version of the full animation. I’ll remove this when CEREA gets up and running again…

Redactions

What Bohr told Beria

by Alex Wellerstein, published August 1st, 2012

In June 1945, Niels Bohr left the United States to return to Copenhagen. He had spent the end of World War II at Los Alamos, mostly as a “father confessor” to the physicists there, but also giving some substantial help on the work of the bomb (he was the one who arbitrated a dispute over which neutron initiator should be used in the implosion bomb).

Rare color photograph of Niels Bohr and his wife Margrethe. Courtesy of the Emilio Segre Visual Archives, from the Dodge Collection.

Ever since he was whisked out of Denmark, Bohr had also been trying to advocate for a postwar international control scheme for nuclear weapons. He tried to convince Winston Churchill, to no effect, and was somewhat successful in convincing Roosevelt on the soundness of such a scheme.

He had a much greater influence on the Los Alamos scientists, like Robert Oppenheimer, and Bohr’s line of thinking can be seen very plainly in the Acheson-Lilienthal Report that Oppenheimer would later contribute to. At the heart of Bohr’s approach was the free exchange of scientific information and scientists — an end of secrecy, he argued, would make it impossible to have a secret nuclear arms race. (This was the same opinion that Vannevar Bush and James Conant had independently come to, as remarked previously on this blog.)

By November 1945, Bohr was feeling quite stressed about how the bomb was being handled. The British Ambassador to the United States, Roger Makins, reported to General Groves on November 7 that:

Bohr is disturbed over the political developments with regard to the atomic bomb. He feels the press treatment of it is creating unnecessary mystification and ill feeling. He cannot understand why so much play is being made over ‘secrets’ which may or may not be shared with the Soviet Union. He considers that there are no essential secrets to the Soviet Government which are not known to them already, and believes that the United States Government’s sole advantage is in production and production experience.

So in a way it is not surprising that the Soviet Union targeted Bohr as a possible intelligence asset. After all, the “let’s get rid of secrecy” argument is not too far from the “let’s share the bomb” argument, which is what had motivated Klaus Fuchs and Ted Hall and numerous others. It is also not surprising, then, that Bohr agreed to meet with a Soviet physicist, Yakov Terletsky, when he desired a conversation about the postwar atomic situation — Bohr was willing to talk to anyone on such a subject.

Lavrenty Beria on the cover of Time magazine, 1953. Creepy looking guy.

But Terletsky was not just a random interested party — he had been sent to Bohr by the NKVD, the organization led by Lavrenty Beria and the predecessor of the KGB. 

This week’s documents pertain to the Soviet side of the Bohr-Terletsky interview. The one that I have scanned comes from the same Russian nuclear history book I discussed last week, though the copy in the book is incomplete. I have managed to scrounge up copies of these documents from various places on the web and in print and have performed a rudimentary translation on them. (As always, I am happy to have my translations corrected. The original Russian is in the footnotes.)

On the left, the letter to Stalin from Beria. On the right, an excerpt from the Bohr-Terletsky interview.

The first document is a letter from Beria to Stalin, reporting on who Niels Bohr is and what they’ve been up to with him. The Wilson Center has this dated in late November 1945, but it may be sometime in early December 1945 as well.

Label: “Special files”, “Top Secret.” No. 1372-B
[Handwritten:] Make known to Merkulov. L. Beria. 8/X11 [8 Dec.].

Comrade STALIN I.V.

The famous physicist, Professor Niels BOHR, who was involved with the work on the atomic bomb, has returned from the USA to Denmark and started to work at the Institute for Theoretical Physics in Copenhagen.

Niels BOHR is known as a progressive-minded scholar and a staunch supporter of the international exchange of scientific achievements. This gave us grounds to send a group of workers to Denmark, under the guise of investigating equipment of Soviet scientific institutions taken away by the Germans,  to establish contact with Niels BOHR to seek information on the problem of the atomic bomb.

The comrades sent: Colonel VASILEVSKY, Candidate of Physical and Mathematical Sciences TERLETSKY, and engineer and translator ARUTYUNOV. Having found appropriate approaches, they have got in touch with BOHR and organized two meetings with him.

The meetings were held on November 14 and 16 under the pretext of TERLETSKY visiting Soviet scientists at the Institute for Theoretical Physics.

Comrade TERLETSKY said to BOHR that while in transit in Copenhagen, he felt it his duty to visit the famous scientist, and that he warmly remembered BOHR’s lectures at Moscow University.

During the interviews, Bohr was asked a series of questions prepared in advance in Moscow by Academician KURCHATOV and other scientists involved in the atomic problem.

Attached are the list of questions, BOHR’s answers, and an evaluation of the responses by Academician KURCHATOV.

L. BERIA
Printed in three copies.
Copy No. 1 – addressee.
No. 2 – Secretary of the NKVD.
No. 3 – Section “C”.
Operator Sudoplatov.
Typist Krylov.

Yakov Terletsky was a physicist from Moscow State University. In Richard Rhodes’ Dark Sun, Terletsky described his meeting with Beria the first time, in 1945, in vivid detail:

He was of average height, aging, with a skull that narrowed slightly toward the top, with severe features and no shadow of warmth or a smile. Beria did not give the impression I had expected from seeing his portraits before, of a young, energetic member of the intelligentsia wearing a pince-nez. Everyone sat down at the big conference table. In the middle of the table was a large white marble ash tray in the shape of a polar bear with little ruby eyes. That was the only object on the long table… it was obvious that no one used it.

Terletsky wasn’t actually the best guy to send — he was a total novice to nuclear physics. His expertise was in statistical physics, and he had less than a week’s understanding of the basics behind nuclear technology. Beria wanted him sent, though, rather than a more experienced physicist. A suspicious master of human intelligence, Beria knew that Bohr would also learn from the exchange — and he didn’t want Bohr to know anything about what the Soviets did or did not know about the bomb. 

Yakov Terletsky

Terletsky asked Bohr 22 questions. I’ve included a few of the most interesting ones here; these come from the Wilson Center’s Cold War International History Project.

1. Question: By what practical method was uranium 235 obtained in large quantities, and which method now is considered to be the most promising (diffusion, magnetic, or some other)?

Answer: The theoretical foundations for obtaining uranium 235 are well known to scientists of all countries; they were developed even before the war and present no secret. The war did not introduce anything basically new into the theory of this problem. Yet, I have to point out that the issue of the uranium reactor and the problem of plutonium resulting from this — are issues which were solved during the war, but these issues are not new in principle either. Their solution was found as the result of practical implementation. The main thing is separation of the uranium 235 isotope from the natural mixture of isotopes. If there is a sufficient amount of uranium 235, realizing an atomic bomb does not present any theoretical difficulty. … The Americans succeeded by realizing in practice installations, basically well-known to physicists, in unimaginably big proportions. I must warn you that while in the USA I did not take part in the engineering development of the problem and that is why I am aware neither of the design features nor the size of these apparatuses, nor even of the measurements of any part of them. I did not take part in the construction of these apparatuses and, moreover, I have never seen a single installation. During my stay in the USA I did not visit a single plant. While I was there I took part in all the theoretical meetings and discussions on this problem which took place. I can assure you that the Americans use both diffusion and mass-spectrographic installations.

Bohr played his cards close to his chest, here. He told Terletsky nothing that is not already in the Smyth Report. He later explained that you could feed the material from one plant to another, which is also in the Smyth Report. (Did Bohr truly never “visit a single plant”? I’m not sure. This oral history suggests that he did briefly visit Oak Ridge in 1944, but it’s the only account of that I’ve seen, and the interviewee may be mistaken about the timing of that. If Bohr did visit Oak Ridge, it would be an interesting thing in the context of this interview.) Bohr’s line was also very conducive to the control issue — the production of fissile material, he’s arguing, is not a matter of secrecy, but of technology. In this and many other exchanges, one gets the impression that Bohr is trying to convince Terletsky — and his handlers, whom Bohr could not be so naive as to not know existed — of the wisdom of international control.

 8. Question: How many neutrons are emitted from every split atom of uranium 235, uranium 238, plutonium 239 and plutonium 240?

Answer: More than 2 neutrons.

9. Question: Can you not provide exact numbers?

Answer: No, I can’t, but it is very important that more than two neutrons are emitted. That is a reliable basis to believe that a chain reaction will most undoubtedly occur. The precise value of these numbers does not matter. It is important that there are more than two.

A direct technical question with an evasive answer. Did Bohr know the precise number of neutrons? Undoubtedly. Would he tell? No. Why not? Because “the precise value” actually does matter for critical mass calculations. His dismissal of the importance of this value constrains his discussion, again, almost to the level of the Smyth Report. (He may have gone a tiny bit beyond, but not in a serious way. The Smyth Report does not say the amount of neutrons released per fission, but it does say that it was known in 1940 that it was between 1 and 3. Obviously it couldn’t have been less than two, though, if the reactor and bomb were going to work. So Bohr has not really said much, here.)

15. Question: Does the pile begin to slow as the result of slag formation in the course of the fission of the light isotope of uranium?

Answer: Pollution of the pile with slag as the result of the fission of a light isotope of uranium does occur. But as far as I know, Americans do not stop the process specially for purification of the pile. Cleansing of the piles takes place at the moment of exchange of the rods for removal of the obtained plutonium.

This is an odd question with a confused answer. It’s a reference to so-called “Xenon-poisoning” in the first industrial-sized nuclear reactors at Hanford. Xenon-135, a fission product, builds up as the reaction commences. However, it is also a neutron absorber, so the reactions tend to slow down as more of the isotope is created. This is the “pollution” Bohr refers to. It was a major issue at Hanford. The way to fix it is to cycle through the fuel loads more often. So Bohr’s answer is not very clear, though he may have just been ignorant on Hanford issues.

Xenon-poisoning was mentioned in the first edition of the Smyth Report, but deleted from subsequent re-printings by General Groves. The discrepancy was noticed by the Soviet translators — yet another case where an attempt at secrecy actually highlighted what was meant to be hidden.

19. Question: Of which substance were atomic bombs made?

Answer: I do not know of which substance the bombs dropped on Japan were made. I think no theorist will answer this question to you. Only the military can give you an answer to this question. Personally I, as a scientist, can say that these bombs were evidently made of plutonium or uranium 235.

I’m pretty sure Bohr is lying here. It seems highly unlikely that he was unaware of the differences between the gun and implosion bombs, or the fact that there were both uranium-235 and plutonium bombs used.

 20. Question: Do you know any methods of protection from atomic bombs? Does a real possibility of defense from atomic bombs exist?

Answer: I am sure that there is no real method of protection from atomic bomb. Tell me, how you can stop the fission process which has already begun in the bomb which has been dropped from a plane? It is possible, of course, to intercept the plane, thus not allowing it to approach its destination — but this is a task of a doubtful character, because planes fly very high for this purpose and besides, with the creation of jet planes, you understand yourself, the combination of these two discoveries makes the task of fighting the atomic bomb insoluble.

We need to consider the establishment of international control over all countries as the only means of defense against the atomic bomb. All mankind must understand that with the discovery of atomic energy the fates of all nations have become very closely intertwined. Only international cooperation, the exchange of scientific discoveries, and the internationalization of scientific achievements, can lead to the elimination of wars, which means the elimination of the very necessity to use the atomic bomb. This is the only correct method of defense.

I have to point out that all scientists without exception, who worked on the atomic problem, including the Americans and the English, are indignant at the fact that great discoveries become the property of a group of politicians. All scientists believe that this greatest discovery must become the property of all nations and serve for the unprecedented progress of humankind. You obviously know that as a sign of protest the famous OPPENHEIMER retired and stopped his work on this problem. And PAULI in a conversation with journalists demonstratively declared that he is a nuclear physicist, but he does not have and does not want to have anything to do with the atomic bomb. …

We have to keep in mind that atomic energy, having been discovered, cannot remain the property of one nation, because any country which does not possess this secret can very quickly independently discover it. And what is next? Either reason will win, or a devastating war, resembling the end of mankind.

Ah, Bohr really got going here — Terletsky got him on a topic where he could pontificate very freely (notice the length at which he speaks here, compared to the technical questions).

21. Question: Is the report which has appeared about the development of a super-bomb justified?

Answer: I believe that the destructive power of the already invented bomb is already great enough to wipe whole nations from the face of the earth. But I would welcome the discovery of a super-bomb, because then mankind would probably sooner understand the need to cooperate. In fact, I believe that there is insufficient basis for these reports. What does it mean, a super-bomb? This is either a bomb of a bigger weight then the one that has already been invented, or a bomb which is made of some new substance. Well, the first is possible, but unreasonable, because, I repeat, the destructive power of the bomb is already very great, and the second — I believe — is unreal.

This is an odd question to ask, with an even odder answer. That the idea of a “superbomb” (сверхбомбы, here) was out and about by this point is something I’ve remarked on previously. They’re basically asking Bohr what he knows about the idea of a hydrogen bomb, something that was explored during the Manhattan Project. In any case, Bohr’s answer is very misleading — whether because he was being deliberately misleading or because he was just uninformed, I don’t know. But his dismissal of the idea that you could optimize bomb design for a larger explosion, or that you could use other materials for nuclear explosions, is completely incorrect.

22. Question: Is the phenomenon of overcompression of the compound under the influence of the explosion used in the course of the bomb explosion?

Answer: There is no need for this. The point is that during the explosion uranium particles move at a speed equal to the speed of the neutrons’ movement. If this were not so the bomb would have given a clap and disintegrated as the body broke apart. Now precisely due to this equal speed the fissile process of the uranium continues even after the explosion.

This last question is a puzzler. It’s unclear exactly what was asked here (something is lost in multiple translations), but it sounds a lot like they are asking about whether compressing fissile material is necessary. Bohr doesn’t really answer it — he basically says that the bomb explodes a bit after it runs its reaction (which is true, but not super relevant, I don’t think), when he knows, from being at Los Alamos, that compression is used during the implosion of the bomb. But again, it’s hard to make sense of either the question or the response.

Kurchatov in the 1950s. Photo credit: Ioffe Physical Technical Institute, courtesy AIP Emilio Segre Visual Archives.

Lastly, we turn towards an evaluation of Bohr’s responses by Igor Kurchatov, a.k.a. “The Beard,” the head scientist on the Soviet bomb program. This is dated “December 1945,” which is why I am suspicious about the November dating of the Beria document above (since this was attached to it).

EVALUATION
Answers given by Professor Niels BOHR
on questions relating to the atomic problem

Niels Bohr was given two sets of questions:

1. Concerning the main directions of work.

2. Containing specific physical data and constants.

BOHR gave some answers to the first group of questions. BOHR gave a definitive answer to the question on the U.S. methods used for producing uranium-235, which has quite satisfied Professor [Isaak] KIKOIN, Corresponding Member of Academy of Sciences, who asked this question.

Niels BOHR made a crucial point about the effectiveness of uranium in the atomic bomb. This comment should be subjected to theoretical analysis, which should be entrusted to professors LANDAU, MIGDAL and POMERANCHUK.

Academic KURCHATOV
December 1945.

Kurchatov’s analysis is interesting. Bohr’s “definitive” answer on uranium-235 production is only significant if you distrust the Smyth Report. (And it makes sense that the Soviets would distrust it.) It is really unclear to me what the “effectiveness” comment is referring to — my assumption is that it refers to question 22, which is hard to parse in any event.

What’s most interesting to me about Kurchatov’s analysis is how positive it is, when Kurchatov surely must have known that Bohr wasn’t telling them much — either because he didn’t know it, or because he didn’t want to tell them.

And yet, he’s still writing up the operation as a big success. My guess is that he’s trying to make Beria happy about everyone who participated — Bohr, Terletsky, and so on. Bohr didn’t give them much information, but it wasn’t really Terletsky’s fault.

Bohr and Ivan Pavlov, the famous Russian physiologist, probably in the 1920s or 1930s. One wonders what they would have discussed. Courtesy of the Emilio Segre Visual Archives.

But let’s flip this around: What did Bohr learn from Terletsky? If Bohr took seriously that Terletsky was representative of the interest of Soviet physicists in the bomb, he probably would have assumed that they didn’t know much. The questions Terletsky asked do not reveal very much knowledge on the subject matter, and certainly don’t reveal insight from intelligence sources (number 22 might hint at it, but that’s it, and even then, it’s not very clear).

In a sense, Beria’s decision to send Terletsky was spot-on. Bohr wasn’t going to tell the Soviets anything that wasn’t already publicly known. Beria couldn’t have known that from the beginning, but sending someone like Terletsky would have been a good way to find out for sure — if Bohr had been indiscreet or seemed like a source to be “cultivated,” more contact could have followed later. Bohr’s refusal to give precise numbers on the neutron emissions was his most direct case of clearly not cooperating. They likely would have been a clear signal that Bohr either didn’t know technical details, or that he wasn’t interested in divulging them.

Had Beria sent someone deeper into the atomic problem (like Khariton or Zel’dovitch) the line of questioning likely would have shown Bohr that they knew much more than they were supposed to. Would someone who really knew about the bomb project be able to ask those simple questions with such a straight face?

What’s wonderful about reading this in retrospect is that we know that both Bohr and the Soviets knew more than they let on. This “interview” (or “interrogation”) is a tremendous dance of shadows — two people trying to get information without giving too much away. And like many such exchanges, neither side likely learned very much.


Amusing Soviet fact of the day: During World War II the Red Army’s in-house counter-espionage unit — which served mostly to root out perceived enemies of the people within the Army itself — was called SMERSH (СМЕРШ), an acronym of the phrase “Death to Spies!” Stalin coined this exceptionally silly name himself.

Visions

Rare Photos of the Soviet Bomb Project

by Alex Wellerstein, published July 27th, 2012

I was recently perusing some Russian-language books on the Soviet atomic bomb project at the Library of Congress, and I stumbled across one that was really pretty amazing. The book itself is a catalog of a big exhibit on the Soviet bomb project (“Atomic project USSR: The 60th Anniversary of the Russian nuclear shield” which was held in Moscow in the fall of 2009. Much of the text is a rote repetition of what has been known for years — with some historical weirdness, like repeat using of “we” to mean the USSR, which is not the most encouraging thing for Russians to do — but the images are fantastic, and many of them are quite new.

Calling this “new” is a bit of a stretch, since the book was published three years ago. But it’s new to me, and if it’s new to me, it’s probably new to you! It’s definitely newer than most of the Soviet nuclear program photos that are out there, most of which showed up in the early 1990s when the Russian archives (temporarily) became easier to use.

Before I start, I would like to just point out how crazy it is that this book is so well-produced. It’s on glossy paper. The design is well done. The pictures are in color! None of this would be remarkable if the book was from the United States or a country in Western Europe, but most Russian-language books that I’ve seen in this country look like they were mimeographed on recycled newsprint by old Marxists. Somebody spent a comparative fortune on getting this book published. It’s a slick book; I wish there were an easy place to buy it online.

The whole thing kicks off with this amazing photograph of Vladimir Putin and a number of Russian Orthodox big-wigs at Sarov, the city that was once known as Arzamas-16, the Soviet equivalent of Los Alamos. Apparently the Soviet bomb scientists liked to call the place “Los Arzamas.” Sarov has been the site of a big Russian Orthodox monastery for centuries.

There are some great, rare photographs of key Soviet weapons scientists in the book. From left to right here, we have young, beardless Igor Kurchatov; Kurchatov after he grew his famous beard; a dashing portrait of Georgii Flerov, and finally, Yuli Khariton. Kurchatov agreed not to shave his beard until the enemy was defeated, during World War II, but being “the Beard” somewhat became him so I don’t think he ever shaved it off. He looks like such a goofy kid on the photograph to the left, which I think was taken when he was in his early twenties. The beard photo is from the early 1940s.

Flerov is the guy who really got the Soviet project off the ground initially. His story is pretty fascinating. In 1942, he had hoped to get the Stalin Prize for his work on the spontaneous fission of U-238, which would have kept him from the murderous Eastern Front of World War II, but was rejected because his paper wasn’t cited by anyone, and thus was judged as unimportant. Flerov did a literature search and realized that nobody was publishing on fission anymore — and indeed, all of those who had been publishing on it had dropped off the map completely. He immediately started writing letters — including to Stalin himself — pointing out that this could only indicate that the United States was working on an atomic bomb. Anyway, this is the most dashing photograph I’ve seen of him. It dates from 1940.

Khariton was the head Soviet theorist — something of an equivalent to their Oppenheimer. The photo dates from the 1940s. Khariton, oddly enough, has some links to Freud’s inner circle. I don’t find that changes my understanding of the bomb much, but it’s still unexpected. (Hat-tip to Michael Dennis for forwarding that to me.)

Perspective view of a mine at Taboshar, Tajikistan, from 1944. Taboshar was one of the few early sources of Soviet uranium, known since the 1920s and mined extensively for uranium since 1945. The acquisition of raw uranium was the key setter of the timetable of the Soviet bomb program. They had very few known sources of the ore at the end of World War II, and the United States and the United Kingdom had worked behind the scenes to attempt secure a monopoly on all other known world supplies. General Groves thought their access to uranium was so bad that it would take the Soviets 20 years to get a bomb — but it turned out that uranium is more plentiful than he realized, and concentrations that wouldn’t be economic to mine for the United States turned out to be just fine for Soviet slave labor.

Here we have two diagrams of the Nagasaki atomic bomb (Fat Man) based on information passed on to the Soviets from Klaus Fuchs and other spies. These aren’t particularly sensitive today, but would have been Top Secret–Restricted Data when they were acquired. On the right is the basic dimensions of the body of the bomb, and on the left is a more detailed arrangement showing the electrical systems inside the bomb. As anyone reading this blog no doubt knows, the Soviet Union had a number of spies in high places in both the US and UK sides of the Manhattan Project, which they dubbed “ENORMOZ” in their code language.

What I like about these drawings, aside from their novelty, is that the labels are first in English, and then translated into Russian again — betraying their obvious roots in espionage.

There are also some cool documents reproduced in here. This one is from a report written for Lavrenty Beria, dated February 28, 1945, on the “Progress of the atomic bomb abroad.” It says that it is expected that the United States will produce a bomb by July of that year, and then explains in very basic terms how it works. I also love the punctuation of the technical terms with handwritten English (“High explosive,” “Composition C,” “commercial radium tube.”) Even without much Russian beyond transliteration, you can recognize a bunch of what’s being discussed: the fact that only about 5 kg of plutonium was used in the implosion bomb (actual value was close to 6kg, but who’s counting), the discussion of the different explosives involve in implosion, and, amusingly, the term “tube alloy” as a codename for uranium.

The last line, underlined, says “The explosion is expected approximately July 10.” As Solzhenitsyn wrote in The Gulag Archipelago, “the Organs always earned their pay.”

A nice spread labeled as “the territory of Laboratory No. 2, 1943.” Pretty desolate. Laboratory No. 2 is located just outside of Moscow and was run by Kurchatov, and was the site of the first Soviet nuclear reactor and now the Kurchatov Institute.

This is an outside view of a tent at Laboratory No. 2, also from 1943. Apparently “experiments with uranium” were performed.

And here is an interior view of the same tent. The stack at the right looks like graphite blocks, which the first Soviet reactor was made out of. (As was the first American reactor, of course.)

Here are three views of the assembly of F-1, the first Soviet reactor. On the left, they are laying the graphite blocks; in the middle, you can see it more completely assembled; on the far right, the diagram of the design. One can easily compare these with the first American reactor design, Chicago Pile-1.

The F-1 reactor in 2009. Fun fact of the day: Reactor F-1 is still a functional, operating nuclear reactor. It achieved criticality on December 25, 1946, and is still using its original fuel load. (It is very low power, so that’s not quite as impressive as it sounds.) It’s the oldest functioning nuclear reactor in the world.

This is listed a the central hall of Reactor “A” after it received an upgrade, from the late 1950s. Reactor A was a military production reactor in Chelyabinsk, running on natural uranium fuel, with graphite as the moderator. It was up and running by June 1948, and provided plutonium for the first Soviet atomic bomb.

In other words, this is something like the Soviet equivalent of the B-Reactor at Hanford, though after the aforementioned upgrade, Reactor A was able to run at 500 MW, about twice what B-Reactor could do.

And lastly… the bomb itself. Well, a model of it, anyway. The caption says this is model of the first Soviet bomb at “the Polygon,” which was the code name for the Semipalatinsk test site. Somehow it manages to look very futuristic (the big circles, the large poles) and yet quite rustic (the trees, the way in which everything looks like it has been fashioned by hand by some ancient Kazakh craftsman).

(If anyone has any insight into what function the poles and  the big circle have, I’d love to know.)

This is one of the more intimate photographs of the Soviet bomb I’ve ever seen. Photographs of the Trinity gadget in arrangements like this have been common for a few decades, now, but Soviet equivalents are quite rare.

This may be my favorite photo of the whole set: the most profoundly indicative of the Soviet situation and the most graphically arresting. A bedraggled Russian worker, straight out of Gogol, posing next to a riveted, crude, and terrible atomic bomb. It’s a dystopic juxtaposition: the desperate old paired with the horrible new.

The “bomb” appears to be an early bomb casing model used for aerodynamic testing. I suspect they used these proto-casing the same way the US did: dropping them endlessly from planes, to make sure they wouldn’t spin or pinwheel in unpleasant ways that would rattle the sensitive internal components.

This is from a report on the first atomic bomb test co-written by Beria and Kurchatov for the pleasure of Comrade Stalin. It shows what happened to a Lavochkin La-9 which was 500 meters from the test blast. It’s dramatic, all right.

Igor Kurchatov, father of the Soviet bomb, and Sergei Korolev, father of the Soviet ICBM, hanging out in the 1950s. I can’t quite tell what Korolev has in his hands — it sort of looks like a giant (Lysenko-enhanced) cabbage, but it also looks somewhat reflective, which most cabbages aren’t. Hard to tell, but Kurchatov and Korolev seem rather amused by it. [My father suggests it looks an awful lot like Jiffy-Pop, no doubt acquired through special intelligence sources. Hey, who knows?]

And with a job well done came… an appreciative letter to Stalin. In the Soviet Union, Stalin doesn’t thank you when you accomplish something difficult… you thank Stalin! OK, in truth, it was them thanking Stalin for giving them awards (and not, you know, executing them) after the successful test. But it’s still amusing.

It reads something like this (pardon my likely spotty translation):

Comrade Stalin
Dear Josef Vissarionovich!

We heartily thank you for the high appreciation of our work, which the Party, government and you personally awarded us.

Only the daily attention, care and support that you gave us for those four-plus years of hard work have enabled use to successfully solve the task of organizing the production of nuclear energy and the creation of atomic weapons.

We promise you, dear Comrade Stalin, that we will be working with even more energy and dedication on the further development of the business entrusted to us, and we shall give all our strength and knowledge to justify your confidence in us.

It’s signed by Beria, Kurchatov, Khariton, and a boat load of other Soviet scientists. Was Stalin pleased? Well, no. The note at the upper left is in Stalin’s handwriting, and it says, “Why not Riehl (the German)?” As in, where is Nikolaus Riehl’s signature? Riehl was one of the German scientists who had gone to work on the Soviet bomb after World War II. Ah, that Stalin… never could just take a compliment!

(Riehl’s story is an interesting one — he was half guest, half captive. He got many nice things for his work, but was also in a legally ambiguous status. He was not present at the first Soviet test; he learned of it later from listening to British radio. Riehl’s lack of signature on the letter probably had less to do with trying to offend Stalin — he wasn’t suicidal — but because he had been compartmentalized out of that part of the project.)

Finally, it ends with a picture of “veterans of the first Soviet atomic bomb test,” gathered in 1999. I’ve seen a number of photos of folks with the Soviet bomb, but this one really brought out the fact that it’s actually a very large bomb indeed.