Redactions

What did the Nazis know about the Manhattan Project?

by Alex Wellerstein, published September 13th, 2013

The primary motivation of much Manhattan Project secrecy was to keep the Germans from finding out that the United States and United Kingdom were feverishly working on developing nuclear weapons. So it seems a pretty sensible question to ask: Did it work? That is, did the secrecy keep the Germans from knowing about Allied progress on the bomb?

Strangely enough, I wasn’t able to find much of anything published on the question of what knowledge, if any, the Axis powers had about the atomic bomb. The fact that they didn’t develop one themselves is not strong evidence — it just might mean that such knowledge was very limited, or not believed, or not shared correctly. I can’t do the topic the justice it deserves, because I’m not conversant enough with the sources of Axis foreign intelligence, but I can present some thoughts and intriguing little discoveries on here regarding the German program. If anyone has further thoughts, or evidence, I’m all ears.

Farm Hall, the British country estate.

Farm Hall, the British country estate.

Where might we look for such evidence? The major, obvious source are the Farm Hall transcripts. Farm Hall was the British country manor where ten of Germany’s nuclear scientists were kept for six months. Their conversations were bugged. They were, on August 7th, told about the atomic bombing of Hiroshima, and the transcripts were carefully probed at the time, and many times since, for any insight given into what the German nuclear weapons program had been at the time. The transcripts are a notoriously tricky primary source, in part because the original German copies have apparently since been lost (so we only have an English translation), and because there are some indications that the scientists were aware they were being bugged. Separately there is the psychological complexity of the issue, as the scientists were trying to come to terms with themselves, an imagined German public, and an imagined world public regarding their participation (or lack thereof) in making nuclear weapons for Hitler.1

With that said, is there anything in the Farm Hall transcripts that enlightens us one way or the other? The most significant part is that the announcement of Hiroshima, first given orally, “was greeted with incredulity.” See, for example, this sort of exchange:

HEISENBERG: Did they use the word uranium in connection with this atomic bomb?

ALL: No.

HEISENBERG: Then it’s got nothing to do with atoms, but the equivalent of 20,000 tons of high explosive is terrific. […]

GERLACH: Would it be possible that they have got an engine [reactor] running fairly well, that they have had it long enough to separate “93”? [neptunium]

HAHN: I don’t believe it.

HEISENBERG: All I can suggest is that some dilettante in America who knows very little about it has bluffed them in saying: “If you drop this it has the equivalent of 20,000 tons of high explosive” and in reality doesn’t work at all. […]

WEIZSÄCKER: I don’t think it has anything to do with uranium. […]

HAHN: If they really have got it, they have been very clever in keeping it secret.2

All of which has been sometimes taken as pretty strong evidence that these guys didn’t know much about the Allied project. But a closer reading is less clear, because, among other things, not everyone is participating in this discussion. One of the many problems with the German nuclear program was a lack of coordination and a lack of shared knowledge. That Otto Hahn knew nothing of it seems entirely believable, but irrelevant, since he wasn’t really working on the nuclear program in any kind of military capacity. Werner Heisenberg and Carl Friedrich von Weizsäcker worked together so it makes sense that they would be on basically the same page. But what about the others? 

Farm Hall mugshots: Werner Heisenberg, Carl Friederich von Weiszäcker, Otto Hahn, and Kurt Diebner.

Farm Hall mugshots: Werner Heisenberg, Carl Friederich von Weiszäcker, Otto Hahn, and Kurt Diebner.

Walter Gerlach was in a more administrative role, so one might imagine he would know of any foreign intelligence on the subject. He speaks very little in this part of the transcript, only the question about reactors, and he is not one of the outright initial doubters. Asking whether they could have had reactors does not indicate that he was unaware of an Allied bomb project in general, especially given the compartmentalization of the Manhattan Project. He does, much later in the transcript, apparently express private surprise with Heisenberg that “they had known nothing about the preparations that had been made in America,” though. And what of Kurt Diebner? Diebner ran the other major research wing of the German nuclear program, separate from Heisenberg. He says almost nothing in this section of the transcript, only noting that “there is also a photochemical process” for enriching uranium. Again, this tells us nothing about what he knew.3

Probing the transcript further, we find a few other odd exchanges:

HAHN: From the many scientific things which my two American collaborators sent me up to 1940, I could see that the Americans were interested in the business. 

WEIZSÄCKER: In 1940 van der Grinten wrote me, saying he was separating isotopes with General Electric.

HARTECK: Was van der Grinten a good man?

WEIZSÄCKER: He wasn’t really very good but the fact that he was being used showed that they were working on it.4

I read these as Hahn and Weizsäcker trying to recall whether they had any indication of Allied interest. Considering their only memories are from 1940 (before the Manhattan Project really began), they are actually a good indication that they did not have any truly specific intelligence.

Heisenberg three times tells a story about being contacted from someone in the German Foreign Office about uranium questions:

HEISENBERG: About a year ago, I heard from Segner [probably Sethke] 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.”5

Now that is a strange story. I have no idea what this Sethke would have been referring to — some strange rumor. Whether it is just nonsense, or based on some actual intelligence, it’s impossible to know from just this snippet. Later, when Heisenberg tells another version of the story (this time making his answer that it was “absolutely possible”), he specifies it was in July 1944 and that it was “a senior SS official” who had asked him about the bomb.6

More Farm Hall mugshots: Walter Gerlach, Paul Harteck, Max von Laue, Karl Wirtz.

More Farm Hall mugshots: Walter Gerlach, Paul Harteck, Max von Laue, Karl Wirtz.

There is also one small exchange before the German scientists were told about Hiroshima. On August 4th, Heisenberg, Gerlach, and Hahn had this exchange:

GERLACH: The [British] Major [Rittner] asked me what we had known about scientific work in enemy countries, especially on uranium. I said, “Absolutely nothing. All the information we got was absurd.”

HEISENBERG: In that respect one should never mention any names even if one knew of a German who had anything to do with it.

GERLACH: For instance, I never mentioned the name of that man Albers (?). The “Secret Service” people kept asking me: “From whom did you get information?” and I always replied: “There was an official in Speer’s ministry and in the Air Ministry who gave it out officially.” I did not say it was Albers (?) who did it.

HEISENBERG: I had a special man who sent me amazing information from Switzerland. That was some special office. Of course I have burnt all the correspondence and I have forgotten his name.

HAHN: Did you actually get any new information from him?

HEISENBERG: At that time I always knew exactly what was being discussed in the Scherrer Institute regarding uranium. Apparently he was often there when Scherrer lectured and knew what they were talking about. It was nothing very exciting but, for instance, he once reported that the Americans had just built a new heavy water plant and that sort of thing.7

And there it ends. Other than the mention of heavy water, it is too vague to make much sense of. (The Manhattan Project built several heavy water plants are part of what they called the P-9 Project, as part of their “leave no stone unturned” approach. They upgraded an existing ammonia plant at Trail, British Columbia to produce heavy water, and built three supplementary facilities at military sites in West Virginia, Indiana, and Alabama.)

After the scientists had heard the official BBC radio announcement, they all began to believe it was true, and worked out fairly quickly how it probably would have worked (though even there, they were still impressively confused at times) and famously hashed over why they didn’t get one made. No further invocations of foreign information or intelligence were made that I found.8

My overall impression is that for the bulk of the ten scientists, the Allied atomic bomb probably did come as a genuine surprise of immense magnitude. But there are enough hints there to suggest that various bits and pieces were out there amongst their foreign intelligence officials, whether they shared all of that with the scientists or not. And as we’ve see in the Soviet case, just because the spies know something doesn’t mean it percolates back to the scientists working on it — the use of foreign intelligence is not a straightforward operation. And there are several scientists whose reactions were not individually recorded (e.g. Diebner). Of the scientists who talked a lot, they seemed genuinely clueless about what the Americans had done, but not all of them talked.

Are there any other indications? One thing that one finds on the Internet are assertions that the last attempt by the Nazis to deposit saboteurs on American soil, Operation Elster (Magpie), was supposedly aimed at sabotaging the Manhattan Project. Like all such Nazi efforts, the saboteurs in question were rounded up pretty quickly. Were they really targeting the Manhattan Project? I suspect not. The sources that give such information all seem to trace back to a postwar memoir of one of those captured. David Kahn has written that he thinks it is nonsense; I am inclined to agree.9) The idea that a single pair of spies would be sent to gain information on, much less sabotage, the Manhattan Project is too silly to be believed without corroborating evidence.

J. Edgar Hoover, 1941. Source.

J. Edgar Hoover, 1941. Source.

But there is one last interesting source that I stumbled across. In early February 1945, J. Edgar Hoover wrote a memo to Harry Hopkins (one of Roosevelt’s closest aides) explaining that the FBI had information that indicated German interest in atomic matters. Specifically, Hoover wrote:

As you are well aware, the Army for the past two years has been vitally interested in a highly secret project for the development of an atomic explosive. […]

Recently, in connection with the operation of a radio station by a German agent under control of the Federal Bureau of Investigation but which station the Germans believe to be a free station, an inquiry was received from Germany containing the following questions regarding the status of atomic explosive experimentation in the United States:

First, where is the heavy water being produced? In what quantities? What method? Who are users?

Second, in what Laboratories is work being carried on with large quantities of uranium? Did accidents happen there? What does protection against Neutronic Rays consist of in these laboratories? What is the material and the strength of coating?

Third, is anything known concerning the production of bodies or molecules out of metallic uranium rods, tubes, plates? Are these bodies provided with coverings for protection? Of what do these coverings consist?10

Now this looks like a legitimate technical intelligence inquiry. These are very specific questions regarding reactor construction. Not necessarily bomb construction, mind you. But it does look like someone working on reactors passed some questions up the chain of command. (The fact, incidentally, that this came to the FBI from a double-agent is also telling — the German foreign intelligence networks were notoriously compromised, yet another reason they missed so much.)

The questions reveal, though, that whomever asked them did not realize that the Americans had already been building massive, industrial-sized, carbon-moderated (not heavy water!) nuclear reactors in Hanford, Washington. Note the lack of any queries regarding uranium enrichment. Note that the questions are narrowly technical, the kind of questions you would ask if you are trying to build your own reactor, not ferret out a clandestine bomb program.

That the Germans were asking such basic, ignorant questions so late in the game — the Red Army was bearing down on Berlin and their atomic program, like so many other things, was in a tizzy11 — is perhaps the greatest indication that they knew very little about the American Manhattan Project indeed. That they were asking questions at all is not surprising, but the lateness perhaps is. The Soviet physicist Georgii Flerov figured out that the Americans must be working on a nuclear program in 1942, when he noticed that nobody was publishing on the subject — specifically, that nobody was citing his publication on the spontaneous fission of uranium-238. One wonders why the Germans were less observant of this fact, especially given the amount of “brain drain” their own institutes suffered.12 They also appear to have missed or misunderstood all of the various leaks, accidental disclosures, and other signs that drove General Groves and others involved with Manhattan Project security so mad. Many pieces were there for them to put together, but they didn’t solve the puzzle.13

Allied troops disassembling the German experimental research reactor at Haigerloch.

Allied troops disassembling the German experimental research reactor at Haigerloch as part of Alsos.

Lastly, we have the take of Samuel Goudsmit, the head of the Alsos expedition. In an unpublished memorandum written in late 1945, claimed that the Alsos investigation into the German work had shown that “the enemy was equally ignorant of Allied scientific and technical work,” though notes that in 1939, a team of three Germans were sent to the USA to learn about American interest in uranium research. (This was well before there was much American interest in such.) As he was prone to do, Goudsmit generalized greatly from this, assuming that scientific and technical intelligence was too difficult to pick up during that war. The Soviets, as always, proved an important exception to Goudsmit’s generalizations.14 In any case, though, this does indicate that there aren’t probably an exciting espionage gems hiding in the Alsos records.

Wrapping everything up, my basic conclusion is that if German intelligence had an inkling about the American atomic bomb program, they didn’t develop the idea and they didn’t communicate it to several of their top scientists on the program. Heisenberg seems genuinely foolish on the entire subject. Diebner’s lack of participation makes it hard to gauge his knowledge, but it strikes me as strange (though not impossible) that he would know of such things but Heisenberg would be ignorant of them. Entirely separate is the question of who asked the SS to investigate what the Americans were doing with heavy water — but the queries there demonstrate that whomever is asking knows almost nothing about the Allied program, and may in fact be trying to find out how to improve their own reactor work.

A consistent theme in the Farm Hall transcripts and the Alsos investigation is that the Germans seem to have honestly thought that their work on the “uranium problem” was well beyond what anyone else might have been doing, and that the Allies would be desperate to “buy” their reactor research in the postwar. They apparently were not motivated to check to see whether this arrogance was founded, and part of the depression and desperation one sees them going through after Hiroshima and Nagasaki is a remark on their perception of irrelevance. As Otto Hahn chided them right after they learned of Hiroshima: “If the Americans have a uranium bomb then you’re all second raters.”

  1. The best copy of the transcripts is Jeremy Bernstein’s heavily annotated version, Hitler’s Uranium Club: The Secret Recordings at Farm Hall, Second Edition (New York: Copernicus Books, 2001). My quotations and citations refer to this specific version. [↩]
  2. Bernstein, 116-117. [↩]
  3. Photochemical processes for enriching uranium were investigated during the Manhattan Project, but not seriously pursued. [↩]
  4. Bernstein, 119. [↩]
  5. Bernstein, 124. [↩]
  6. Bernstein, 139. [↩]
  7. Bernstein, 108. Note that the (?)’s are in the original transcript. [↩]
  8. There is one small bit about talking about thorium with an (Indian) Japanese spy, but it seems unrelated to the bomb question directly, and the spy in question doesn’t seem to have known anything. [↩]
  9. David Kahn writes in Hitler’s Spies: German Military Intelligence in World War II, “[Erich] Gimpel’s [one of the spies] ghostwritten book, Spy for Germany, must be used with the greatest caution, as it differs in a number of critical points from his statement [to the FBI]. The most important are the book’s claims that he was assigned to ferret out atomic secrets, that he succeeded to some extent, and that he radioed a message to Germany. None of these are supported by his statement or by Colepaugh’s [a collaborator] or by postwar interrogations of his spymasters, and the atomic claim is specifically contradicted by a statement of Schellenberg’s [a top Nazi spy].” There just doesn’t seem to be any hard evidence behind the assertion that Elster had something to do with the Manhattan Project. Gimpel’s books provide zero believable details about the matter — he reports that he was just supposed to figure out what was going on (no list of targets, names, theories, etc. [↩]
  10. J. Edgar Hoover to Harry Hopkins (9 February 1945), in Harrison-Bundy Files Relating to the Development of the Atomic Bomb, 1942-1946, microfilm publication M1108 (Washington, D.C.: National Archives and Records Administration, 1980), Folder 62: “Security (Manhattan Project),” Roll 4, Target 8. [↩]
  11. See Samuel Goudsmit, Alsos (Tomash, 1983 [1946]), 183-185. [↩]
  12. At one point in the Farm Hall transcripts, it is noted that “Hahn remarked on the fact that there had been no publication of work on uranium fission in British or American scientific journals since January 1940, but he thought there had been one published in Russia on the spontaneous fission of uranium with deuterons.” So, at least retrospectively, Hahn realizes that there was this silence, with the exception of Flerov (probably the Russian he is thinking about). [↩]
  13. Goudsmit describes a conversation between Paul Rosbaud and Walther Gerlach in February 1945 in which Rosbaud asks Gerlach, “Have you considered that the American, British, or Russian scientists know as much or perhaps more about it than you do?” If this actually occurred, one wonders if Gerlach didn’t follow up on the issue, ergo the spy query. But this is just supposition. On the conversation, see Goudsmit, Alsos, 185. In any case, the whole conversation, if true, is further evidence of Gerlach’s ignorance at that point — he was still under the delusion that the Allies would have something to gain from the German work on heavy water. [↩]
  14. Samuel Goudsmit to C.P. Nichols, “Scientific Intelligence” (26 November 1945), Goudsmit papers. [↩]

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News and Notes

Webcast: “What’s become of our nuclear golden age?”

by Alex Wellerstein, published September 9th, 2013

A 1959 advertisement for Union Carbide in the Saturday Evening Post.

We no longer live in the nuclear age, or, at least, we don’t think we do — so I concluded awhile back. But that won’t stop me from talking about it! This Wednesday, September 11th, 2013, I will be participating in a live webcast at the Chemical Heritage Foundation in Philadelphia:

On Sept. 11, 2013 the Chemical Heritage Foundation will present a live online video discussion, “Power and Promise: What’s become of our nuclear golden age?” Guests Alex Wellerstein and Linda Richards will take stock of our turbulent nuclear past and look at how it has shaped our current attitudes, for better and for worse.

Some say we are on the verge of a bright nuclear future in which nuclear power will play a major role in responding to climate change. Others say that we should expect more Fukushimas. Whichever way our nuclear future goes, there will be energy and environmental tradeoffs. On CHF’s blog you can decide on the tradeoffs you are willing to make. Tweet to vote your choices. Viewers can also tweet questions to the guests before or during the show by using the hashtag #HistChem.

“Power and Promise: What’s Become of Our Nuclear Golden Age?” will air at 6 p.m. EST.  Watch the livecast episode at www.chemheritage.org/live.

Guest Bios:

Alex Wellerstein is an associate historian at the Center for History of Physics at the American Institute of Physics. He holds a Ph.D. in the history of science from Harvard University and his research interests include the history of Cold War technology, including nuclear technology. He blogs at https://blog.nuclearsecrecy.com/.

Linda M. Richards is a former CHF fellow and will be returning in 2014 as a Doan Fellow. She is working on a Ph.D. on nuclear history at Oregon State University. Her dissertation is titled “Rocks and Reactors: The Origins of Radiation Exposure Disparity, 1941-1979.” In 2012 she received a National Science Foundation grant that took her to the International Atomic Energy Agency (IAEA) in Vienna, UN agencies and archives in Geneva, and to North American indigenous uranium mining sites.

About the Show:

#HistChem is a monthly interactive livestreamed show produced by the Chemical Heritage Foundation. It features topically compelling issues that intersect science, history and culture. Hosts are Michal Meyer, editor of Chemical Heritage Magazine, and Bob Kenworthy, a CHF staff member and chemist. The first episode, “How We Learned to Stop Worrying and Love the Zombie Apocalypse,” debuted in August, 2013. Follow the show and related news at chemheritage.org/media

About the Chemical Heritage Foundation:

The Chemical Heritage Foundation is a collections-based nonprofit organization that preserves the history and heritage of chemistry, chemical engineering, and related sciences and technologies. The collections are used to create a body of original scholarship that illuminates chemistry’s role in shaping society. In bridging science with the humanities, arts, and social sciences, CHF is committed to building a vibrant, international community of scholars; creating a rich source of traditional and emerging media; expanding the reach of our museum; and engaging the broader society through inventive public events.

This should be a fun thing, as Linda and I take somewhat different approaches (both interesting) to many nuclear issues, and the CHF team asks great questions. You can Tweet in questions for the show with the right hashtag (#HistChem) and it may somehow magically get to us while we’re talking. And hey, I’ll be wearing a suit!

Update: The video has been posted online, enjoy!

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Redactions

Fears of a German dirty bomb

by Alex Wellerstein, published September 6th, 2013

For good reason, much has been made of the initial fear of a German atomic bomb. But there was another, lesser-known atomic fear as well. If the Germans could make nuclear reactors — which the Americans thought they were probably doing — could they not take the dangerously-radioactive spent-fuel out of them and use them to make dirty bombs? 

Hanford spent fuel rods — the sort of thing that could have been weaponized during World War II as a radiological weapon.

Hanford spent fuel rods — the sort of thing that could have been weaponized during World War II as a radiological weapon.

In the summer of 1942, Arthur Compton, head of the University of Chicago’s Metallurgical Laboratory, wrote a memo to Harvard President and atomic-bomb big-wig James B. Conant expressing the need for “protection against ionizing bombs”:

We have become convinced there is real danger of bombardment by the Germans within the next few months using bombs designed to spread radio-active materials in lethal quantities. … Since protection against the danger from such bombs will be primarily a matter of detection of radiation and instruction with regards to the dangers, it is essential that the matter be brought at once to the attention of the appropriate military officers.1

Compton and his scientists were, at the time, working under the assumption that the Germans were ahead of the Americans, and had already gotten a nuclear reactor running. They estimated that with a 100 kilowatt reactor, 100,000 Curies of radioactivity could be produced daily for bomb usage.

A radiation survey device of the sort produced during World War II by the Victoreen Instrument Company in Cleveland, in collaboration with the University of Chicago scientists.

A radiation survey device of the sort produced during World War II by the Victoreen Instrument Company in Cleveland, in collaboration with the University of Chicago scientists.

A result of this was that in the fall of 1942, the first steps were taken to, at a minimum, detect whether the Germans used any kind of radiological attack against the Allies. Survey meters were developed that would trigger alarms if they detected high levels of radioactivity. These were secretly dispersed to Manhattan District offices in Boston, Chicago, New York, San Francisco, and Washington, DC. At each location, a small number of officers were trained in their use. Further instruments were held in reserve in case they needed to be deployed further. If the alarms went off,  or if there were other suspicious signs (like reports of a large-scale blackening of photographic film), scientists at the University of Chicago were kept on the ready to be brought in to assess the situation.2

This was a fairly small program, as far as they go. Those involved were acutely aware that the secrecy of the atomic bomb made it impossible to adequately prepare for this possibility. They were stuck in a bind that was very common during the wartime period. The atomic bomb was, at that time, what I like to call an “absolute secret”: the fact that there was a “secret” at all was itself a secret. They could not draw attention to matters relating to atomic energy without drawing attention to the fact that they were engaged in a secret research program with regards to atomic energy. This is a very peculiar situation, one primarily specific to the war, when the secrecy of the project could not be acknowledged (they could not simply say, “oh, the details are secret,” as they could in the Cold War).

What did they think the Germans would do with such a radiological weapon? They considered four possibilities. First, it could be used as an “area-denial” weapon, by making areas uninhabitable. Second, it could be used to contaminate critical war infrastructure (e.g. airports). Third, it could be used as a “radioactive poison gas” to attack troops. Fourth, it could be used “against large cities, to promote panic, and create casualties among civilian populations.”3 Their assessment of the effects, by 1943, was grim:

Areas so contaminated by radioactive material would be dangerous until decay of the material took place, perhaps for weeks or months. … As a gas warfare instrument the material would be ground into particles of microscopic size to form dust and smoke and distributed by a ground-fired projectile, land vehicles, or aerial bombs.  In this form it would be inhaled by personnel.  The amount necessary to cause death to a person inhaling the material is extremely small.  It has been estimated that one millionth at a gram accumulating in a person’s body would be fatal.  There are no known methods of treatment for such a casualty.4

In the time-honored method of worrying about threats, they also then immediately realized that maybe the United States should be weaponizing fission products: “It is the recommendation of this Subcommittee that if military authorities feel that the United States should be ready to use radioactive weapons in case the enemy started it first, studies on the subject should be started immediately.” Note that this isn’t really a deterrent capability, it is a response capability. Deterrence requires your enemy knowing that you have the capability to respond, and secrecy precluded true deterrence.

1943 - Oppenheimer to Fermi

In this context, there is an interesting letter in the J. Robert Oppenheimer papers at the Library of Congress, where Oppenheimer is writing to Enrico Fermi in May 1943 on “the question of radioactively poisoned foods.” From the context, it is clear that both Edward Teller and Fermi had devoted time to this project. The full document is available here. Two parts stand out. One is that one of the acute problems in looking into the issue was, as Oppenheimer put it, difficult to study the subject “without telling anyone about it.” That is, it would be hard to investigate some of the substances in question “without letting a number of people into of the secret of why we want” the substances. The “absolute secret” bind again.

The other is Oppenheimer’s criteria for the project being worth looking into:

…I think that we should not attempt a plan unless we can poison food sufficient to kill a half a million men, since there is no doubt that the actual number affected will, because of non-uniform distribution, be much smaller than this.5

Frank Oppenheimer later called this a very “bloodthirsty” statement by his brother; the historian Barton Bernstein instead argued that this was just scientists trying to help the war effort.6 Either way, it makes Oppenheimer look like a very cold fish indeed. And not much of a “dove.” Even if one isn’t clear how much of a “non-uniform distribution” he was assuming.

1943 - Oppenheimer to Fermi - quote

The offensive angle was basically dropped — they didn’t think they’d need it, and they were focused intently on making the actual atomic bomb, a much more devastating weapon. But defensive measures did proceed. By late 1943, it was thought that the use of radioactive poisons against the UK by the Germans was of low probability, but an unpleasant possibility.7 To avoid being completely taken by surprise in such an event, General Groves (with the concurrence of General Marshall) had four officers from the European Theater of Operations staff briefed on the subject “under most complete secrecy,” and a Manual on Use of Radioactive Materials in Warfare was drawn up for these four officers. Signals officers were instructed to report any “peculiar or unexplained effects” on photographic films or personnel, and the officers in question were given radiation detection instruments to use in the case of suspected cases.

In March 1944, General Groves had the matter brought to the attention of General Dwight D. Eisenhower, commanding general of the Supreme Headquarters Allied Expeditionary Force, fearing that the Nazis might use such weapons to prevent an Allied invasion of Europe. Eisenhower concluded that since the Combined Chiefs of Staff had not brought up the issue, that they must consider that “the enemy will not implement this project.” To keep secrecy, in order to “to avoid a possible scare,” Eisenhower informed only a handful of people, which he acknowledged was not really enough to counter “enemy action of this nature”: “No US or British Commander participating in OVERLORD [the landing at Normandy] has been briefed.” However, radiation detectors were being kept in the UK for deployment on short notice, and a “cover” letter was sent out with symptoms of radiation poisoning listed as a “mild disease of unknown etiology” that was going around, requesting any medical officers to report further cases.8

Dry-run of using radiation detection equipment during a beach landing, as part of "Operation Peppermint." Source.

Team performing a dry-run of a beach landing with radiation detection equipment, as part of “Operation Peppermint.” Source.

The plan to deploy radiation monitoring during the D-Day invasions was dubbed “Operation Peppermint,” one of the more amusing code-names of the war. Dry runs of the detection apparatus were taken before D-Day, and German bomb craters were surveyed for radioactive residues, but since no evidence of German radiological weapons preparations or use were uncovered, the “Peppermint” preparations were never put into effect. 

We now know that the Germans never got anywhere near this kind of plan. They didn’t even get a reactor running by the end of the war, the necessary prerequisite for this kind of operation. It wasn’t a totally crazy fear, though. There are aspects of radiological warfare which would make it preferable to, say, chemical warfare from the German point of view. Still, there’s an aspect to this of the old saying, “when the only tool you have is a hammer, every problem looks like a nail.” When you’re studying radioactive hazards intently, every threat looks like a radioactive hazard.

The secrecy angle is what intrigues me the most about this story: the secrecy of the bomb made it difficult to enact serious preparation from this related, but separate threat. The secrecy of one fear made addressing another fear difficult, because the relevant information of both fears were too deeply entangled. 

  1. Arthur H. Compton to James B. Conant (15 July 1942), Bush-Conant file, Roll 7, Target 10, Folder 75, “Espionage.” [↩]
  2. Manhattan District History, Book 1, Volume 14, Foreign Intelligence Supplement No. 2 (Peppermint), 31 July 1952. [↩]
  3. “Use of Radioactive Material as a Military Weapon” (n.d., c.a. early 1943). [↩]
  4. Ibid. [↩]
  5. J. Robert Oppenheimer to Enrico Fermi (25 May 1943), J. Robert Oppenheimer Papers, Library of Congress. [↩]
  6. Barton J. Bernstein, “Oppenheimer and the Radioactive Poison Plan,” Technology Review, 88 (May-June 1985), 14-17. There is also some follow-up in Barton J. Bernstein, “Four physicists and the bomb: The early years, 1945-1950,” Historical Studies in the Physical and Biological Sciences, 18, No. 2 (1988), pp. 231-263, on 252-253. [↩]
  7. Leslie Groves to George C. Marshall (30 November 1944), Manhattan Engineer District (MED) records, Records of the Army Corps of Engineers, RG 77, National Archives and Records Administration, Box 64, “Security.” [↩]
  8. Dwight D. Eisenhower to George Marshall (11 May 1944), Correspondence (“Top Secret”) of the Manhattan Engineer District, 1942-1946, microfilm publication M1109 (Washington, D.C.: National Archives and Records Administration, 1980), Roll 5, Target 8, Folder 18, “Radiological Defense.” [↩]

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Meditations

Who Made That Firebomb?

by Alex Wellerstein, published August 30th, 2013

My least favorite section in the New York Times Magazine is the insipid “Who Made That?” column. In theory, it’s a great idea for a regular feature. We’re surrounded by gadgets and inventions with rich histories that we never think about. But in practice, the column always dwells on trivial inventions (“Who Made That Loofah Mitt? Sippy Cup? Kickstand?”) and ones with boring stories at that (or, at least, they are stories boringly told). Most of the time, the story is, “some guy thought this was a good idea, then sold it out of his basement for awhile, and then it became successful, and now it is ubiquitous.” Snore.1

An E6R2 "amiable cluster" of M69 firebombs, produced by Standard Oil Co.

An E6R2 “amiable cluster” of M69 firebombs, produced by Standard Oil Development Co.

There are a number of things wrong with this approach. One is that it reinforces a notion of the “lone inventor” that wasn’t even very accurate by the late-19th century. Most American inventions (as measured by patents, for example) are generated in collaborative groups by corporations.2 The idea that invention, even American invention, is a product of quirky kooks is a romantic myth. Another issue is that it generally sees all of these as “solitary” instances of invention — rather than the more common cases of incremental development, cross-pollination, and so on. And yet another issue is that most inventions (again, measured by patents or whatever else you want to use as a proxy) are abject failures. That is, almost no patents end up turning a profit, almost no inventions end up being very successful. The Times column generally makes it sound like all one needs is a good idea, and it’ll take off on its own. But the reality is much more weird and idiosyncratic than that. The columns end up being fluffy and trivial without being interesting, which to me is a cardinal sin. I mean, if you need to do something fluffy and trivial to get by, I understand that. But don’t be boring about it.

The one good thing about “Who Made That?” is that usually it doesn’t focus in on the few “canonical” inventions that everybody likes to talk about. There is some real value in getting away from the standard stories, as usual. We’ve heard so much about the invention of the atomic bomb. But when was the last time you heard about the invention of the firebomb? Obviously this is because one of these is a technological marvel, improbably created in an impressively short amount of time. I’m not knocking the bomb as the more interesting invention case. But the firebombs are impressive in their own way — and in a very deep sense, the story of their invention is the more shocking one, if only for its banality.

The atomic bomb represents, in a sense, a case of a special almost-one-off invention meant to be something novel and terrible. The firebomb, by contrast, is a weapon developed for a doing terrible things as a regular mode of operation. That is, the moral arguments in favor of the atomic bombs are usually structured in the form of “we had to do this twice in order to achieve a greater good.” It’s harder to do that with firebombs because we used them so many times. It’s one thing to say, “ah, once or twice we had to target large numbers of civilians to make a point.” It’s another to make the targeting of civilians your everyday job, when you start measuring success less by knocking out specific military targets and instead by total area destroyed. So who made that firebomb? A now all-too-familiar mixture of American industry, universities, and government. The list of contractors involved in American incendiary weapons during World War II includes Brown University, University of Chicago, Du Pont, Eastman Kodak, Harvard University, Monsanto, Standard Oil Development, and Stanford University, among others, all working under the auspices of Vannevar Bush’s Office of Scientific Research and Development, the Chemical Warfare Service, and other parts of the military.

AN-M69 incendiary bomb

The incendiary raids against Japan dropped numerous types of bombs in different combinations. But the one to focus on, because of its ubiquity and importance in the Pacific theatre, is the AN-M69 Incendiary Bomb. This was a cluster-based napalm weapon created by the Standard Oil Development Company, specifically designed to destroy Japanese civilian houses. The most common cluster assembly (the M19) held 38 individual AN-M69s and would release them 5,000 feet above the target. The wind would catch their parachute streams, moving them apart from one another and orienting them nose-down. (Doing this would also arm the bombs by pulling out their safety plungers.) After impact, the bombs would wait 3 to 5 seconds, seemingly inactive. This is to make sure each one is lying on its side, so that, finally, a stream of burning napalm would be explosively blasted out of the tail: “If unobstructed, the burning fuel charge will travel up to 300 ft horizontally, and when it strikes a surface, the flaming fuel charge smears out producing a mass of flames 6 to 10 ft high.”

Each B-29 could carry 40 clusters in their bomb bays. So that’s 1,520 AN-M69s per plane, and the raids could range from dozens to hundreds of planes. You can do the math, there. Over 40,000 tons of AN-M69s were dropped on Japanese cities during the war. It took about 125 tons per square mile to completely burn out an area of a Japanese city. The AN-M69 had, a once-classified postwar report announced triumphantly, “the highest fire-starting efficiency per cluster, or per ton, or per bomber of any incendiary bomb” developed during the war.3

Clusters of M-69 incendiary bombs rain down over Nagoya, Japan, summer of 1945.

Clusters of M-69 incendiary bombs rain down over Nagoya, Japan, summer of 1945.

The AN-M69 wasn’t the only incendiary bomb. I want to give a quick shout-out also to the E19 Incendiary Bomb, an 11 pound incendiary developed by my alma mater, Harvard University, as a combination of magnesium, oil, thermite, and white phosphorous. It didn’t burn as well as the AN-M69, but had greater penetrating power. But, as the aforementioned report notes, “this factor diminished in importance as the war went on,” presumably because we had stopped trying to directly target troublesome factories and military bases, and had instead moved on to targeting flimsy civilian structures. As a result, “the E19 bomb was never seriously considered for production.” But don’t worry Harvard, you still get some credit in the development of napalm (jellied gasoline) itself, as part of coordinated work with Eastman Kodak and Standard Oil Development. Some 80 million pounds of napalm were produced and used during the war.

Standard Oil Development’s creation of the AN-M69 started in early October 1941 — almost exactly two months before the attack on Pearl Harbor. The initial instigation was to find a way to make incendiary weapons that did not involve large amounts of magnesium, which was in short supply. The work was funded by the Office of Scientific Research and Development. Much of the technical details (horizontal fuse, hexagonal assembly, etc.) are probably mildly interesting to engineers but for the rest of us are probably just of interest in that they are a banal, everyday description of how to develop an efficient weapon for burning lots of things (and people) up.

The "Central German" test structure for the M69 tests. Colorized to highlight fire.

The “Central German” test structure for the M69 tests. Colorized to highlight fire.

The ballistic properties, cluster dispersal patterns, failure rates, and the ability to set various types of target ablaze were, of course, meticulously tested. Reading the developmental history of the firebomb, one finds the names of no individual inventors, only the organizations involved. It is not a history of brilliance or ingenuity, though no doubt there were lots of little brilliant insights along the way. It is, rather, an engineering job. What makes it disturbing is that the engineering is very explicitly directed towards the destruction of civilian life. The main structures they were tested on were mock “German houses” and mock “Japanese houses.” Not factories — houses. 37% of all “German houses” the AN-M69 were tested on were “beyond fire-guard control” within 6 minutes. For the more simple Japanese houses, it was 68%. The results of this testing, the report informs, “were used to make preliminary estimates of the quantities of incendiary bombs required to destroy Japanese cities.”

The effects testing, done very carefully by both universities (Harvard again, along with the University of Chicago), corporations (Standard Oil Development, Texas Company), and the military (Ordnance Department) are also pretty grim. These involved mock bedrooms, with beds and boudoirs and even vanity mirrors, to simulate how effect these weapons would be against “Central German structures,” “experimental Japanese rooms,” and other models of homes. Just in case there was any lingering doubt as to what these weapons were meant to accomplish, and to put to rest the lingering misconception that the destruction of civilian life was an inadvertent consequence imprecise weaponry.

Test of an AN-M69 against an "enemy building model" (Japanese style).

Test of an AN-M69 against an “enemy building model” (Japanese style).

Some 4,400 tons of AN-M69s were dropped on Tokyo during two May 1945 bombing raids, destroying 22.1 square miles. The famous March 1945 raid destroyed 12.5 square miles with only 279 B-29 bombers.4 The area of the Hiroshima bombing where domestic houses were severely damaged was only 8.5 square miles, by comparison.

I don’t want to sound naive about these things. Obviously, World War II was a state of “total war” by all sides, and very little was considered off-limits. But I still feel that too many Americans today don’t take into account exactly what was done in the name of total victory — we still view World War II as the “good war” of the “Greatest Generation.” Purposeful mass burning of civilians doesn’t usually come into it. At the end of the day, I don’t think I really believe in “good wars” — there are wars of necessity, and there are wars of “greater good/necessary evil.” I don’t think you get any better than that, unfortunately.

Hypertrophic scars and keloids on a napalm-bombed child. I don't know who this is of — I suspect it is from the Vietnam War. It is from SIPRI's Incidenary Weapons (1975), chapter 3, "Thermal effects of incendiary weapons on the human body," without a source listed. It puts a "human face" on these weapons, though, like no other photograph I've seen.

Hypertrophic scars and keloids on a napalm-bombed child. I don’t know who this is of, or even when it was taken — I suspect it is from the Vietnam War. It is from SIPRI’s Incendiary Weapons (1975), chapter 3, “Thermal effects of incendiary weapons on the human body,” without a source listed. It puts a “human face” on these weapons, though, like no other photograph I’ve seen. There is something about the beauty of the unscarred eye that makes the damage so palpable.

During the war, the inventive forces of the United States went to work to find creative engineering solutions to the problem of burning millions of civilians alive. I really don’t want to use the phrase “banality of evil,” since it has been so over-applied, and I don’t really believe in “evil” as a useful historical concept, but there is certainly a terrible banality at work here when one reads about the work that went into crafting these unassuming little bombs. They are so less flashy, as inventions, than the atomic bomb, of course. But that doesn’t make them any less worth our attention. Arguably, it is their “normal-ness” and their easy assimilation into regular military doctrine that makes them more important for us. The more interesting moral questions don’t involve what one would do in exceptional situations, but one does in the every-day.

  1. For an example of how to do something of this right, take a look at the discussion of the Victorian teapot in Neil MacGregor’s A History of the World in 100 Objects. MacGregor manages to take something supposedly mundane — a simple teapot — and use it as a fascinating window into the history of imperialism and globalization. [↩]
  2. See, e.g., David F. Noble, America by Design: Science, Technology, and the Rise of Corporate Capitalism (1977). [↩]
  3. Almost all of my information here comes from “Fire Warfare: Incendiaries and Flame Throwers,” Summary Technical Report of Division 11, National Defense Research Committee, Volume 3 (Washington, DC, 1946). It was originally classified as “confidential.” There is a scanned copy online, along with many other reports on the subject, at the extremely useful website, Japan Air Raids (japanairraids.org). The images of the bombs and tests come from other reports on that page. [↩]
  4. The May 1945 raids had significant number of other types of incendiary bombs as well, though the AN-M69s were the overwhelming majority. The March 1945 raids were almost exclusively AN-M69s. [↩]

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The Spy, the Human Computer, and the H-bomb

by Alex Wellerstein, published August 23rd, 2013

One of the most enigmatic documents in early Cold War nuclear history is the so-called Fuchs-von Neumann patent. It was Los Alamos secret patent application number S-5292X, “Improvements in method and means for utilizing nuclear energy,” and dates from April 1946. It is mentioned, cryptically, often with heavy redaction, in many official histories of the hydrogen bomb, but also has recently surfaced as an object of historian’s speculation. The most obvious reason for its notoriety comes from its authors, but its importance  goes deeper than that.

The Los Alamos identification badges for Klaus Fuchs and John von Neumann. Courtesy of Los Alamos National Laboratory.

The Los Alamos identification badges for Klaus Fuchs and John von Neumann. Courtesy of Los Alamos National Laboratory.

The co-inventors were Klaus Fuchs and John von Neumann. Fuchs was a brilliant German physicist who was later exposed as the most important of the Soviet spies at Los Alamos. Von Neumann was a brilliant Hungarian mathematician and physicist, a “ringer” they brought in especially to help manage the explosive lens program, and is generally considered one of the smartest people in the 20th century. As one of the major contributors to the invention of modern computing, it was often remarked in his time that he was much smarter than the machines he was developing — he could do crazy-complicated math in his head without breaking a sweat. And he was a vehement anti-Communist at that — a man who spoke openly about the benefits of instigating thermonuclear war with the Soviets. So on the face of it, it’s an improbable match-up — the Soviet spy and the anti-Communist human computer. Of course, viewed in context, it’s not so improbable: they were both talented physicists, both worked at Los Alamos, and nobody at the lab knew Fuchs was a spy.

The patent is interesting to historians because it allegedly plays a key role in answering the (still quite murky) question of whether the Soviets got the H-bomb through espionage or by their own hard work. We know that Fuchs passed it on to the Soviets — the question is, what did it contain, and how did the Soviets use it? The reason it shows up recurrently is because the patent is allegedly one of the first suggestions of the concept of radiation implosion, that is, using the radiation output of a fission bomb as a means of initiating fusion. In 1951, this would become one of the central components of the so-called Teller-Ulam design of the hydrogen bomb, on which all subsequent hydrogen bombs were based.

Record of invention for the Fuchs-von Neumann design, "Improvements in Method and Means for Utilizing Nuclear Energy."

Record of Invention for the Fuchs-von Neumann design, “Improvements in Method and Means for Utilizing Nuclear Energy.” This copy is from the records of the Joint Committee on Atomic Energy in the Washington, DC, National Archives.

The contents of the patent itself is still officially secret in the United States. What is officially declassified  is little more than its title and some relevant dates — not much to go on. All descriptive aspects of it are totally classified. Which, generally speaking, makes it very hard to evaluate the aforementioned question of how useful it would have been to the Soviet Union, since we don’t officially know what is in it.

But in the last couple of years, things have changed on this latter point. The patent application is still classified in the United States.1 But the contents of the patent appear to have been declassified, and published, in Russia. I’ve talked a bit in the past about how the Russians have declassified a bunch of information about the American bomb project that they got from espionage, despite the fact that this information is still probably classified in the United States. It would be really, really wonderful to know the back-story on why they do this, and whether there is any discussion with American classification authorities before the Russians start releasing information about old American bomb designs. The book series in question is Atomni’ Proekt SSSR (USSR Atomic Project: Documents and Materials), which is cheerfully described on the inside as “intended for everybody interest in the history of the Soviet Atomic Project.” Indeed!

In this case, the late Herb York told me that the late German Goncharov, one of the editors of the Atomni’ Proekt SSSR series, approached him and told him somewhat informally that he thought this information should be declassified. York told me that he couldn’t really officially respond to Goncharov about this, but he showed it to some people in Livermore, but they weren’t very interested. Anyway, whatever the case, Goncharov apparently got the whole thing published in 2009 in volume 3, book 1 of the series.

Fuchs-von Neumann H-bomb design

The above image, supposedly the Fuchs-von Neumann concept, had appeared in a few other sources prior to that, but not with explanatory text. The only person who has published a serious analysis of it is the physicist and historian Jeremy Bernstein, who wrote about it in Physics in Perspective in 2010.2 At the time, Bernstein only had access to the diagram and its above legend, which was first seen in print in Gregg Herken’s Brotherhood of the Bomb. Bernstein’s caption of the above device (which he credits Carey Sublette for deciphering) is as follows:

The design for thermonuclear ignition that Klaus Fuchs turned over to his Soviet control in March 1948. The detonator (box) on the left represents a gun-type fission bomb consisting of a projectile and target of highly enriched uranium (71 kg of 70% pure U235), which when joined form a supercritical mass and produce an explosive chain reaction. The projectile is carried forward by its momentum, striking the beryllium-oxide (BeO) capsule on the right, which contains a liquid 50:50 D–T mixture, compressing it by a factor of about 3, as represented by the outer circle. The radiation produced in the fission bomb heats up the BeO capsule, producing completely ionized BeO gas, which exerts pressure on the completely ionized D–T gas, compressing the capsule further to an overall factor of about 10, as represented by the inner circle.

The interpretation is pretty good, considering the lack of additional source material! But the Russians have since released the entire document — including its original description of how it is meant to work, in the original English. Here is an excerpt:

The detonator is а fission bomb of the gun type. The active material is 71 kg of 40% pure U233 [sic].3 The plug (48.64 kg) sits in the projectile, which is shot bу the gun into the target, the remaining 22-24 kg sits in the target. The tamper is ВеО. The fission gadget has аn efficiency of 5% (calculated). The tamper, which is transparent for the radiation from the fission bomb, is surrounded bу an opaque shell which retains the radiation in the tamper and also shields the booster and main charge against radiation.  […]

The primer contains 346 gm of liquid D-Т in 50:50 mixture, situated in the tamper. It is first compressed bу the projectile to 3-fold density. This precompression may not bе necessary. As the tamper and primer аге heated bу the radiation, the primer is further compressed, possibly to 10-fold density. (Radiation transport equalises the temperature in primer and tamper, and gives therefore rise to а pressure differential.) The compression opens the “gap” for the ignition of the primer. The primer is likely to have а very high efficiency (~80 %) of energy release.

The booster beyond the radiation shield contains D with about 4% Т. It is ignited bу the neutrons from the primer. Beyond the booster is the main charge of pure D, а cylinder of about 30 сm radius to contain the neutrons and arbitrary length.

So what’s happening here is that the big piece of uranium is being shot against another piece. In the process, it rams into a bunch of fusion fuel (the 50:50 deuterium-tritium mixture), and just mechanically compresses it by a factor of 3. Just brute force. Then the fission bomb starts to detonate, using its radiation to ionize and heat the beryllium-oxide tamper. This causes it to ionize and blow off, compressing that 50:50 DT mixture, and starting a fusion reaction (they hope). This produces a huge number of neutrons, which then go and hit some more fusionable fuel (a DT mixture with only 4% tritium). The neutrons from this then go on to continue and ignite a final reservoir of pure deuterium “of arbitrary length.”

The report then estimates that with 1 cubic meter of deuterium, it would have a blast range of 5 miles, a flash burn range of 10 miles, and prompt gamma radiation for 2 miles. It’s not clear what values they mean exactly for those ranges (is blast 1 psi, 5 psi, 10 psi, 20 psi?), but playing with the NUKEMAP makes me think they are talking about something in the megaton range. For 10 tons of deuterium, it says: “Blast ~ 100 square miles, Flash burn to horizon оr 10,000 square miles if detonated high up. Radioactive poison, produced bу absorption of neutrons in suitable materials, could bе lethal over 100,000 square miles.” Which is something in the many tens of megatons.

So was this radiation implosion? Well, kind of. The design uses the radiation energy to blow up the tamper, basically, compressing some fusion fuel. That’s part of how the Teller-Ulam design would later work. But the entire thing is done in the context of the non-workable Classical Super — the idea that you can start a fusion reaction at one length of a column of fusionable material and it will propagate down the rest of it. Radiation implosion, here, is really just trying to get a better initial “spark” of energy to start the Classical Super reaction. This is very different from Teller-Ulam, where the complete implosion of the secondary is a key and fundamental aspect. All of which is to say, while this is a kind of radiation implosion (mixed in with a lot of other complicated things), it’s pretty far from what is required to make a working hydrogen bomb, because the Classical Super idea just doesn’t work. The fusion reaction of the sort proposed just can’t sustain itself. Even Fuchs and von Neumann appear to have only perceived the importance of their invention as reducing the amount of tritium needed versus other Classical Super designs.4

The "Classical Super" design from 1946. A gun-type design is surrounded by a beryllium oxide tamper. There is a tubealloy (depleted uranium) shield to keep radiation off of the fusion fuel. The idea is to ignite a fusion reaction in a D+T mixture, which then ignites fusion reactions in a pure D mixture of arbitrary length.

The unworkable “Classical Super” design from 1946. A gun-type design is surrounded by a beryllium oxide tamper. There is a tubealloy (depleted uranium) shield to keep radiation off of the fusion fuel. The idea is to ignite a fusion reaction in a D+T mixture, which then ignites fusion reactions in a pure D mixture of arbitrary length. The Fuchs-von Neumann device is, in effect, just an attempt make the initial ignition easier, and does not question the (faulty) underlying assumption about propagation of the fusion reaction.5

So what did the Soviets do with this information? Other documents in the series give some indication of that, and I’ve included the full set here (warning: large PDF, 13.5 MB), although it is completely in Russian.

The 1948 intelligence data is identified as “Material No. 713.” It includes a brief, near verbatim summary (Document No. 32) by the physicist Yakov Terletsky (the same one who interviewed Bohr at Beria’s request), as well as a brief report by Terletsky explaining what this material gave them compared to previous information about the American H-bomb work (Document No. 33). The latter is interesting; they seem most interested in the new theoretical information about the conditions required for deuterium fusion than they are about the specifics of the designs given. The strongest phrase is one where Terletsky says that the intelligence information will help them get beyond general, theoretical calculations and move towards the actual design or construction of a ‘deuterium superbomb, and thus reduce the time required for the practical implementation of the superbomb idea.”6

Document No. 34 includes an order by Beria that Kurchatov and Vannikov be required to write analyses of the intelligence information, and that Khariton be consulted on the information. This was made just a few days after Terletsky’s report. Vannikov and Kurchatov’s analysis is included as Document 35. They seemed quite encouraged and interested in the intelligence, and claim it will help them a lot. Of note is that they in particular mention that, among the useful things in the document, they thought that “the ideas about the role of particles and photons in the transmission of the explosion to the deuterium are new.”7 So they do seem to have picked up on that, though it is again mixed into a lot of other details. They then used this material to propose that the USSR start a full-fledged Super program, along the lines of the unanswered questions (and even some of the answered ones) reflected in the intelligence information.

The end of Beria's April 1948 memo written as a result of the Fuchs intelligence, instructing that Khariton's opinion should be sought, especially with respects to the future work of the KB-11 (Arzamas-16) laboratory.

The end of Beria’s April 1948 memo written as a result of the Fuchs intelligence, instructing that Khariton’s opinion should be sought, especially with respects to the future work of the KB-11 (Arzamas-16) laboratory.

One thing that comes out in this as well is that the Soviet scientists at this point only had one other significant intelligence source related to the Super work, from late 1946 (Material No. 462, which I’ve uploaded here.) This appears to be a summary of the Super lectures that Enrico Fermi gave at Los Alamos, and is focused entirely on the Classical Super approach to the bomb, with many uncertainties. If these two caches were the only significant espionage they had on the American Super program before starting their own Super program, that’s pretty interesting in and of itself, and helps put some pretty strict limitations on what they would have gotten out of the data.

Looking at all this, even with the knowledge that there is probably a lot more to the story, I come away with the following conclusions. First, Bernstein is probably right when he says that the Fuchs-von Neumann approach wouldn’t have helped the Soviets very much in terms of arriving at the Teller-Ulam design. As he puts it:

Part of the irony of this story is that the unlikely collaborators, John von Neumann and Klaus Fuchs, produced a brilliant invention in 1946 that could have changed the whole course of the development of the hydrogen bomb, but was not fully understood until after the bomb had been successfully made.

I think perhaps this might go a little too far in praising radiation implosion — it is brilliant of a sort, but it is only one piece in the overall puzzle. The bigger issue on the road to the Teller-Ulam design was not so much the idea that the radiation could be used to transmit the energy, or even to implode the secondary, but getting away from the Classical Super notion of starting a small reaction that would then propagate onward. Indeed, the real breakthrough in the end appears to have been getting out of that mindset altogether. Ulam’s big idea was of total compression of the secondary by putting the whole thing in a “box,” which Teller then realized could be done more efficiently with radiation implosion. Radiation implosion is just a part of the overall mechanism, one which Ulam later insisted was actually not even required.

But my second, perhaps deeper conclusion is that this intelligence appears to have been much more important than has been previously thought. It didn’t give the Soviets the right idea of how to make an H-bomb. But it did seem to convince them that the Americans were taking this work very seriously, and making serious progress, and that they should set up their own dedicated H-bomb program as soon as possible. That’s a big deal, from an organizational standpoint, arguably a much bigger deal than the idea that it gave them some hint at the final design.

The Soviets were talking about a serious H-bomb program in 1948, before they had a fission bomb, and before USA was really committing itself to making a hydrogen bomb. In this sense, while it isn’t clear that this intelligence saved them any real time on the bomb, it did convince them it was worth spending time on. In the end, that was what produced their successful hydrogen bomb models, in the end. Not the intelligence itself, but the program spurred on by the intelligence. And so in that sense, Fuchs does have a very real role in the Soviet hydrogen bomb program, even if his specific ideas were not realized to be relevant until after the fact. Our focus on the importance of individual design secrets can lead us to underestimate the importance of programmatic and organizational decisions in weapons development.8 We tend to focus on the question of, “did this fact get transmitted, and was it appreciated?” But facts, by themselves, do not build bombs. What they can do, though, is inspire scientists to think that the bombs can and should be made, so that they start the laborious process of actually making them. If the Fuchs intelligence did have this result, then it was very important indeed.

  1. Note that it is, and probably will always be, an application. Secret patent applications cannot be granted until they are non-secret. And even then, the Atomic Energy Act of 1946 explicitly bans the patenting of atomic bombs. For the long, thrilling history of secret atomic patents, check out my page on them and my various articles on the history of the policy. [↩]
  2. Jeremy Bernstein, “John von Neumann and Klaus Fuchs: an Unlikely Collaboration,” Physics in Perspective 12 (2010), 36-50. [↩]
  3. The “detonator” description is very strange. For one thing, using only 40% enriched uranium (I am sure that the U-233 is a typo, because it is not in the Russian version, but the 40% is repeated in both) seems strange for 1946, and there is a marked difference between the specificity of one part of the gun-type design (48.64 kg) and the other (22-24 kg). This may be some kind of strange transcription error; the original drawing that the above diagram is based on says 22.36 kg. 5% efficiency is ridiculously high for such a description, too — “Little Boy” had about a 1% efficiency with 80% enriched uranium. If 5% of the U-235 in the “detonator” underwent fission, it would be around 24 kilotons in yield — somethings quite achievable by less speculative means. [↩]
  4. The 1946 Record of Invention describes the object of the device as follows: “To provide an improved method and means for initiating a self-sustaining thermo-nuclear reaction which minimizes the amounts of materials employed.” (My emphasis.) When you compare this design with other Classical Super designs, it is clear, I think, that they are really trying to keep the amount of tritium down to a minimum, by starting the fusion with the heavy compression of a very small tritium-rich zone. Given that in 1946, the supply of tritium was minuscule, this would be a pretty appealing aspect of such a design. [↩]
  5. The “Classical Super” description comes from notes on Fermi’s Super lectures that were obtained — probably through Fuchs — by Soviet intelligence in 1946. See here: “Из информационного материала № 462 [Re: Information material No. 462],” (28 January 1946), Document #11 in L.D. Ryabev, ed., Атомный проект СССР: Документы и материалы [Atomic Project of the Soviet Union: Documents and Materials], Volume III, Водородная бомба [Hydrogen bomb] (1945-1956), Book 1 (Sarov: RFNC-VNIIEF, 2008), 24-39, diagram on 37. [↩]
  6. “Материал #713а, в целом, позволяет перейти от общих теоретических расчетов к конструированию дейтериевой сверхбомбы и т[аким] о[бразом] сократить время, необходимое для практического осуществления идеи сверхбомбы.” [↩]
  7. “Приведенные в материале #713а принципиальные соображения о роли трития в процессе передачи взрыва от запала из урана-235 к дейтерию, соображения о необходимости тщательного подбора мощности уранового запала и соображения о роли частиц и квантов при передаче взрыва дейтерию являются новыми.” [↩]
  8. Michael Gordin makes this point excellently in his excellent Red Cloud at Dawn when discussing why the Smyth Report is actually a pretty important document for the Soviets: it didn’t give them any details about how to build a bomb, but it did tell them how to start a bomb-building research program. [↩]

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