Posts Tagged ‘Soviet Union’


Leo Szilard, war criminal?

Friday, February 14th, 2014

Could Leo Szilard have been tried as a war criminal? Now, before anyone starts to wonder if this is a misleading or inflammatory headline, let me say up front: this was a question that Szilard himself posed in a 1949 story published in the University of Chicago Law Review titled, “My Trial as a War Criminal.” It is a work of fiction, but Szilard was serious about the questions it raised about the morality of the atomic bomb.1

Szilard testifying before Congress in the postwar. From the Emilio Segrè Visual Archives.

Szilard testifying before Congress in the postwar. From the Emilio Segrè Visual Archives.

Leo Szilard is one of the most colorful characters in the story of how the atomic bomb got made. An eccentric Hungarian, one of the “Martians” who emigrated to the United States during World War II, Szilard aspired to always being one step of head of the times. You didn’t have to be much ahead to make a difference, he argued, just a little bit. One example of this he gave in a later interview regards his decision to flee Germany shortly after the Reichstag fire. On the day he left, it was an easy trip on an empty train. The next day, the Germans cracked down on those trying to flee. “This just goes to show that if you want to succeed in this world you don’t have to be much cleverer than other people, you just have to be one day earlier than most people. This is all that it takes.”2 In 1939, Szilard was the one who famously got Albert Einstein to write to President Roosevelt, launching the first US government coordination and funding of fission research. During the Manhattan Project itself, Szilard worked at the University of Chicago, helping to develop the first nuclear reactor (CP-1) with Enrico Fermi. After this, though, his active role in the bomb project declined, because General Groves hated the man and worked to exclude him. He attempted in various ways to influence high-level policy regarding the bomb, but was always shut out.

But after the war, Szilard found his place — as a gadfly. He wasn’t a great bomb developer. He was, however, a great spokesman for the dangers of the atomic bomb. Irrepressible, clever, and impossible-to-look-away-from, Szilard could steal the stage, even if no American could pronounce his name. It is in this context that his article, “My Trial as a War Criminal,” was written. The notes on the University of Chicago Law Review version note that it was written in June 1948, but because of “political tensions” Szilard put it off. With the “relaxation” of tensions, Szilard deemed it possible to publish in the Autumn 1949 issue. One wonders exactly what Szilard had in mind; in any case, given that the US first detected the Soviet atomic bomb in September 1949, and from there launched into the acrimonious debate over the hydrogen bomb, it seems like Szilard’s sense of timing in this instance was either perfect or terrible.

Szilard - My Trial as a War Criminal

My Trial as a War Criminal” starts right after World War III has been fought. The Soviet Union has won, after using a new form of biological warfare against the United States.

I was just about to lock the door of my hotel room and go to bed when there was a knock on the door and there stood a Russian officer and a young Russian civilian. I had expected something of this sort ever since the President signed the terms of unconditional surrender and the Russians landed a token occupation force in New York. The officer handed me something that looked like a warrant and said that I was under arrest as a war criminal on the basis of my activities during the Second World War in connection with the atomic bomb. There was a car waiting outside and they told me that they were going to take me to the Brookhaven National Laboratory on Long Island. Apparently, they were rounding up all the scientists who had ever worked in the field of atomic energy. 

In the story, Szilard was given a choice: he could stand trial for being a war criminal, or he could go to Russia and work with them over there. Szilard opted for the former, claiming he had no capability to learn Russian at that point in his life, and that he had no interest in making himself a servant of Soviet science. He is then interrogated at length about his political views and his work on atomic energy. The Soviets have read his articles in the Bulletin of the Atomic Scientists (“Calling for a Crusade” and “Letter to Stalin“) but think they are naive. Szilard reports no real acrimony, however.

His trial for war crimes begins a month later in Lake Success, New York. He was, “apparently as a special favor,” one of the first to be tried. Two major charges were levied against him. The first was that he had tried to push the United States towards developing nuclear weapons in 1939 (the Einstein-Szilard letter). In the eyes of the prosecutor, this was when World War II was still “an imperialist war, since Germany had not attacked Russia until 1941.” The second charge was that he contributed “to the war crime of dropping an atomic bomb on Hiroshima.”

Szilard has several defensive arguments in his favor. First, he points out that he in fact presented a memorandum to (future) Secretary of State James Byrnes in May 1945 which argued that the atomic bomb should not be first used against Japan cities. This memo had been published in the Bulletin as well in December 1947. Second, he also noted that he circulated a petition in July 1945 that called for not using the bomb as a military weapon before giving the Japanese a chance to surrender first, and that he attempted to put it in front of President Truman himself.

Leo Szilard at the University of Chicago in 1954. Source.

Leo Szilard at the University of Chicago in 1954. Source.

Both of these defenses, however, were easily countered. In the case of the memo to Byrnes, an original copy could not be found, and the Bulletin copy had many deletions for security reasons, any one of which could have contradicted the published material. In the case of the petition to Truman, it was noted that it never made it to Truman, because Szilard submitted it by way of General Groves, who of course squashed it. The Russian prosecutor said that Szilard should have known that the architect of the Manhattan Project would never have transmitted such a thing up the chain of command. So neither were considered adequate at exculpating Szilard.

Szilard is then released on bail. The rest of the story concerns the trials of Secretary of War Stimson, Secretary of State Byrnes, and President Truman. This part revolves around a legal discussion of what it means to be a “war crime.” In the story, the tribunal adopts the definition used at Nuremberg that a war crime was any “violations of the customs of war” and “planning a war in violation of international agreements.” The use of the atomic bombs was necessarily a violation of the customs of war, because it was not customary to drop atomic bombs on other nations during World War II. And the Russian prosecutor was able to gather ample evidence that various US officials had urged war with the Soviet Union under conditions not allowed by the United Nations charter, which only allows war in the face of armed attack. So when Byrnes wrote in a book that the United States should consider “measures of last resort” if the Soviets refuse to leave East Germany, this was taken as evidence of the latter charge. (Refusing the leave occupied territory is not an “armed attack,” and “measures of last resort” can only be understood as implying war.)

Stimson’s section gets the closest to the meat of the question — whether the atomic bombs were justified. Stimson’s defense is the same as his 1947 article from Harper’s — that the bombs were used to hasten the war and to save a net number of lives. The Russians point out, however, that even the US Strategic Bombing Survey concluded that the atomic bombs were not necessary to end the war,3 and that Stimson had access to sufficient intelligence about Japanese communications to know that Japan was on its last legs.

Szilard receives notice — in his bathrobe — that he has won the "Atoms for Peace" award in 1960. Source.

Szilard receives notice that he has won the “Atoms for Peace” award in 1960. At the time, he was in a hospital, being treated (successful) for bladder cancer. Source.

In the end, Szilard notes that practically all of them were expected to be found guilty. But a deus ex machina saves the day — the Soviets’ viral biological agents somehow get out to their own populations, their vaccines fail, and the United States is desperately appealed to for assistance. Under new settlement terms, all war crime prosecutions were ended, and “all of us who had been on trial for our lives were greatly relieved.”

Such ends Szilard’s story. It’s a curious one, and doesn’t go where you might think based on the title alone. Szilard seems to be making a strong point about the way in which war crime tribunals always favor the winners, and that if you apply the Nuremberg standards to the United States’ conduct during World War II and the early postwar, it is clear that no one, even a dissident like Szilard, would be safe. It isn’t a hand-wringing, self-flagellating confession. There is none of the “physicists have known sin” moralizing of J. Robert Oppenheimer. It isn’t even a discussion of what happened regarding the atomic bombing, whether it was justified or not, whether it was terrible or not. It is a gentle story, albeit one that subtly introduces a revisionist argument about the bombings of Hiroshima and Nagasaki, one that continues to be debated to this day.

One can also read the piece as being instead a complaint about the definition of “war crimes” from Nuremberg — are they nothing more than using new weapons and talking about war? The actual Nuremberg principles, also include “wanton destruction of cities, towns, or villages, or devastation not justified by military necessity.” Now whether the atomic bombings fall under that is a tricky question — how does one define “justified by military necessity”? On this sort of unclear requirement, the whole edifice hinges.4

Szilard glasses 1960 LIFE

This whole story came to my attention because Bill Lanouette, author of the Szilard biography Genius in the Shadowse-mailed me after seeing my post on Andrei Sakharov. He noted that according to Rhodes’ Dark Sun, Sakharov was very affected by Szilard’s story. Sakharov showed it to his colleague Victor Adamsky, who reported that:

A number of us discussed it. It was about a war between the USSR and the USA, a very devastating one, which brought victory to the USSR. Szilard and a number of other physicists are put under arrest and then face the court as war criminals for having created weapons of mass destruction. Neither they nor their lawyers could make up a cogent proof of their innocence. We were amazed by this paradox. You can’t get away from the fact that we were developing weapons of mass destruction. We thought it was necessary. Such was our inner conviction. But still the moral aspect of it would not let Andrei Dmitrievich and some of us live in peace.5

What’s interesting to me is that the Soviet weapon designers seem to have read Szilard’s story in a much more moralistic light than I did. For me, Szilard’s story is more about the difficulty of having anything like a consistent stand on what “war crimes” might be — that the actions of the United States could easily be seen from another nation’s perspective as highly damning, even if from a more sympathetic position they might be justifiable. Sakharov and Adamsky apparently understood the story to be about the indefensibility of working on weapons of mass destruction full-stop. It is a curious divergence. Assuming my reading is not naive, I might suggest that the Soviet scientists saw not so much what they wanted to see, but what confirmed their existing, latent fears — something in Szilard’s story resonated with something that they already had inside of them, waiting to be released.

  1. Leo Szilard, “My Trial as a War Criminal,” University of Chicago Law Review 17, no. 1 (Autumn 1949), 79-86. It was later reprinted in Szilard’s book of short stories, The Voice of Dolphins. []
  2. Spencer Weart and Gertrude Weiss Szilard, eds., Leo Szilard: His version of the facts; Selected recollections and correspondence (Cambridge, Mass.: MIT Press, 1978), 14. []
  3. “Based on a detailed investigation of all the facts, and supported by the testimony of the surviving Japanese leaders involved, it is the Survey’s opinion that certainly prior to 31 December 1945, and in all probability prior to 1 November 1945, Japan would have surrendered even if the atomic bombs had not been dropped, even if Russia had not entered the war, and even if no invasion had been planned or contemplated.” []
  4. Szilard’s story also notes that just because these principles were developed after the war ended did not prohibit them from being applied to activities during the war — otherwise all of the Germans would have gotten off the hook. []
  5. Richard Rhodes, Dark sun: The making of the hydrogen bomb (Simon & Schuster, 1995), 582. []

Sakharov’s turning point: The first Soviet H-bomb test

Friday, January 31st, 2014

The Soviets set off their first megaton-range hydrogen bomb in November 1955. It was the culmination of many years of effort, in trying to figure out how to use the power of nuclear fission to release the power of nuclear fusion in ways that could be scaled up arbitrarily.1 The Soviet bomb was designed to be a 3-megaton warhead, but they set it off at half strength to avoid too much difficulty and fallout contamination. Unlike the US, the Soviets tested their version version by dropping it out of a bomber — it was not a big, bulky, prototype like the Ivy Mike device. But it was not an uneventful test. The details are little talked about, but it serves as an impressive parable about what can go wrong when you are dealing with science on a big scale.

Andrei Sakharov, from nuclear weapons designer to aged dissident.

Andrei Sakharov, from young nuclear weapons designer to aged dissident. Source.

Andrei Sakharov has a stunning chapter on it in his memoirs. It makes for an impressive story in its own right, but Sakharov also identifies the experience as a transformative one in his own thinking about the responsibility of the scientist, as he made his way from nuclear weapons designer to political dissident.2

Sakaharov starts out by talking about going to Kazakhstan to see the test. He had by this time been assigned two armed KGB officers, known euphemistically as “secretaries,” whose jobs were to act as bodyguards and “to prevent undesirable contacts.” Sakharov claims not to be have been too bothered by them. They lived next door.

The test of the device, code-named RDS-37, was to be the 24th Soviet nuclear test, and was the largest ever tested at the Semipalatinsk test site. This created several logistical difficulties. In order to avoid local nuclear fallout, it was going to be an airburst. The size of the bomb, however, brought up the possibility that it might accidentally blow the bomber that delivered it out of the sky. To avoid this, the bomber was painted white (to reflect the thermal radiation), and a big parachute was applied to the bomb so that the bomber could get away fast enough. Sakharov was satisfied enough with the math on this that he asked if he could ride along on the bomber, but the request was denied.

Sakharov’s account lingers on the incongruity between testing nuclear weapons in beautiful, wild places. Siberia was “a new and spellbinding experience for me, a majestic, amazingly beautiful sight.” He continued: “The dark, turbulent waters of the Irtysh, dotted with a thousand whirlpools, bore the milky-blue ice floes northward, twisting them around and crashing them together. I could have watched for hours on end until my eyes ached and my head spun. Nature was displaying its might: compared to it, all man’s handiwork seems paltry imitation.

The RDS-37 test device. Source.

The RDS-37 test device. Source.

A test trial-run on November 18th went smoothly, but the first test attempt, on November 20th, did not. As David Holloway recounts in Stalin and the Bomb, that same Siberian wintery majesty that dazzled Sakharov made for difficult testing conditions.3 The fully-loaded Tu-16 bomber had to abort when the test site was unexpectedly covered by clouds, making them unable to see the target aiming point and rendering the optical diagnostic systems inoperable. The plane was ordered to land, only now it had a fully-armed experiment H-bomb on board. There was concern that if it crashed, it could result in a nuclear yield… destroying the airfield and a nearby town. The airfield had meanwhile iced over. Igor Kurchatov, the lead Soviet nuclear weapons scientist, drove out to the airfield himself personally to see the airfield. Sakharov assured him that even if it crashed, the odds of a nuclear yield were low. An army unit at the airfield quickly worked to clear the runway, and so Kurchatov ordered the plane to land. It did so successfully. Kurchatov met the crew on the field, no doubt relieved. Sakharov recalls him saying, “One more test like [this one] and I’m retiring.” As for Sakharov, he called it “a very long day.”

Two days later, they gave it another go. This time the weather cooperated, as much as Siberian weather cooperates. The only strange thing was a temperature inversion, which is to say, at higher altitudes it was warmer than at lower altitudes, the opposite of the usual. The meteorologists gave the go-ahead for the testing.

Sakharov stayed at a laboratory building on the outskirts of a small town near the test site. An hour before the test, Sakharov saw the bomber rising above the town. It was “dazzling white,” and “with its sweptback wings and slender fuselage extending far forward, it looked like a sinister predator poised to strike.” He recalled that “for many peoples, the color white symbolizes death.” An hour later, a loud-speaker began the countdown.

The white bomber. Source.

The white bomber. Source.

Sakharov described the test in vivid detail:

This time, having studied the Americans’ Black Book4, I did not put on dark goggles: if you remove them after the explosion, your eyes take time to adjust to the glare; if you keep them on, you can’t see much through the dark lenses. Instead, I stood with my back to ground zero and turned around quickly when the building and horizon were illuminated by the flash. I saw a blinding, yellow-white sphere swiftly expand, turn orange in a fraction of a second, then turn bright red and touch the horizon, flattening out at its base. Soon everything was obscured by rising dust which formed an enormous, swirling grey-blue cloud, its surface streaked with fiery crimson flashes. Between the cloud and the swirling durst grew a mushroom stem, even thicker than the one that had formed during the first [1953] thermonuclear test. Shock waves crisscrossed the sky, emitting sporadic milky-white cones and adding to the mushroom image. I felt heat like that from an open furnace on my face — and this was in freezing weather, tens of miles from ground zero. The whole magical spectacle unfolded in complete silence. Several minutes passed, and then all of the sudden the shock wave was coming at us, approaching swiftly, flattening the feather-grass.

“Jump!” I shouted as I leaped from the platform. Everyone followed my example except for my bodyguard (the younger one was on duty that day); he evidently felt he would be abandoning his post if he jumped. The shock wave blasted our ears and battered our bodies, but all of us remained on our feet except for the bodyguard on the platform, who fell and suffered minor bruises. The wave continued on its way, and we heard the crash of broken glass. Zeldovich raced over to me, shouting: “It worked! It worked! Everything worked!” Then he threw his arms around me. [...]

The test crowned years of effort. It opened the way for a whole range of devices with remarkable capabilities, although we still sometimes encountered unexpected difficulties in producing them.

But they soon learned that a bruised bodyguard was the least of the injuries sustained in the test. Scientists and soldiers had been stationed far closer to the blast than Sakharov was. The scientists were fine — they were lying flat on the ground and the blast wave caused them no injury. One of them lost his cool and ran away from the blast, but he was only knocked down by it. But a nearby trench held a platoon of soldiers, and the trench collapsed. One young soldier, in his first year of service, was killed.

RDS-37 detonation

RDS-37, detonating. This is considerably sped up; it shows about 50 seconds of footage compressed into only a few seconds. Video source here.

There was also a nearby settlement of civilians affected by the blast wave. In theory it was at a distance remote enough to avoid anything serious; this had been calculated. But the aforementioned inversion layer reflected the shock wave back down to Earth with unusual vehemence — underscoring how even a little misunderstanding of the physics can translate into real problems when you are talking about millions of tons of TNT (something learned by the US a year earlier, at the Castle Bravo test). The inhabitants of the town were in a primitive bomb shelter. After the flash, they exited to see the cloud. Inside the shelter, however, was left a two-year-old girl, playing with blocks. The shock wave, arriving well after the flash, collapsed the shelter, killing the child. 

The ceiling of a woman’s ward of a hospital in another nearby village collapsed, seriously injuring many people. Glass windows broke at a meat-packing plant a hundred miles from the test site, sprinkling ground beef with splinters. Windows broke throughout the town where Sakharov was stationed.

RDS-37, seen from a local town. Also sped up. Same source as the previous.

The consequences of an explosion are hard to predict,” Sakharov concluded.

Had we been more experienced, the temperature inversion would have caused us to delay the test. The velocity of the shock wave increases as the temperature does: if the air temperature rises with altitude, the shock wave bends back towards the ground and does not dissipate as fast under normal conditions. This was the reason the shock wave’s force exceeded our predictions. Casualties might have been avoided if the test had been conducted as scheduled on November 20, when there was no temperature inversion.

As with Castle Bravo, there was a grim, almost literary connection between technical success and human disaster. They had shown the way forward for deployable, multi-megaton hydrogen bombs, but with a real cost — and that cost only an insignificant hint of what would happen if the weapons were used in war. Sakharov concluded:

We were stirred up, but not just with the exhilaration that comes with a job well done. For my part, I experienced a range of contradictory sentiments, perhaps chief among them a fear that this newly released force could slip out of control and lead to unimaginable disasters. The accident reports, and especially the deaths of the little girl and the soldier, heightened my sense of foreboding. I did not hold myself personally responsible for their deaths, but I could not escape a feeling of complicity.

That night, the scientists, the politicians, and the military men dined well. Brandy was poured. Sakharov was asked to give the first toast. “May all of our devices explode as successfully as today’s, but always over test sites and never over cities.”

Sculpture of Andrei Sakharov by Peter Shapiro, outside the Russia House Club & Restaurant on Connecticut Ave in Washington, DC. Image source.

Sculpture of Andrei Sakharov by Peter Shapiro, outside the Russia House Club & Restaurant on Connecticut Ave in Washington, DC. Image source.

The immediate response was silence. Such things were not to be said. One of the military higher-ups flashed a crooked grin, and stood to give his own toast. “Let me tell a parable. An old man wearing only a shirt was praying before an icon. ‘Guide me, harden me. Guide me, harden me.’ His wife, who was lying on the stove, said: ‘Just pray to be hard, old man, I can guide it myself.’ Let’s drink to getting hard.

Sakharov blanched at the crudity (“half lewd, half blasphemous”), and its serious implications. “The point of his story,” he later wrote, “was clear enough. We, the inventors, scientists, engineers, and craftsmen, had created a terrible weapon, the most terrible weapon in human history; but its use would lie entirely outside our control. The people at the top of the Party and military hierarchy would make the decisions. Of course, I knew this already — I wasn’t that naive. But understanding something in an abstract way is different from feeling it with your whole being, like the reality of life and death. The ideas and emotions kindled at that moment have not diminished to this day, and they completely altered my thinking.

  1. The Soviets tested their first thermonuclear bomb in 1953, the RDS-6s, which used fusion reactions. But it was not a true, multi-megaton capable hydrogen bomb. The 1953 device was “just” a very, very big boosted bomb, where 40 kilotons of fissioning produced 80 kilotons of fusioning which in turn produced another 280 kilotons of fissioning, for 400 kilotons total. The design could not be scaled up arbitrarily, though, and it did not use radiation implosion (like the Teller-Ulam design, known in the USSR as the “Third Idea.” It was a big bomb, but the 1955 test was the design that became the basis for their future nuclear warheads. []
  2. Andrei Sakharov, Memoirs, trans. Richard Lourie (New York: Knopf, 1990), 188-196. []
  3. David Holloway, Stalin and the bomb: The Soviet Union and atomic energy, 1939- 1956 (New Haven: Yale University Press, 1994), 314-316. []
  4. From elsewhere in the Memoirs, it seems that Sakharov may be referring here to the 1950 edition of Samuel Glasstone’s The Effects of Atomic Weapons. There was a hardcover edition that apparently had a black cover. Sakharov notes that the nick-name only “partly” came from the cover; he implies that the contents are “black” as well. However there is nothing about goggles or glare in the version of the text I have, so maybe it is something different. []

Liminal 1946: A Year in Flux

Friday, November 8th, 2013

There are lots of important and exciting years that people like to talk about when it comes to the history of nuclear weapons. 1945 obviously gets pride of place, being the year of the first nuclear explosion ever (Trinity), the first  and only uses of the weapons in war (Hiroshima and Nagasaki), and the end of World War II (and thus the beginning of the postwar world). 1962 gets brought up because of the Cuban Missile Crisis. 1983 has been making a resurgence in our nuclear consciousness, thanks to lots of renewed interest in the Able-Archer war scare. All of these dates are, of course, super important.

Washington Post - January 1, 1946

But one of my favorite historical years is 1946. It’s easy to overlook — while there are some important individual events that happen, none of them are as cataclysmic as some of the events of the aforementioned years, or even some of the other important big years. But, as I was reminded last week while going through some of the papers of David Lilienthal and Bernard Baruch that were in the Princeton University archives, 1946 was something special in and of itself. It is not the big events that define 1946, but the fact that it was a liminal year, a transition period between two orders. For policymakers in the United States, 1946 was when the question of “what will the country’s attitude towards the bomb be?” was still completely up for grabs, but over the course of the year, things became more set in stone.

1946 was a brief period when anything seemed possible. When nothing had yet calcified. The postwar situation was still fluid, and the American approach towards the bomb still unclear.

Part of the reason for this is because things went a little off the rails in 1945. The bombs were dropped, the war had ended, people were pretty happy about all of that. General Groves et al. assumed that Congress would basically take their recommendations for how the bomb should be regarded in the postwar (by passing the May-Johnson Bill, which military lawyers, with help from Vannevar Bush and James Conant, drafted in the final weeks of World War II). At first, it looked like this was going to happen — after all, didn’t Groves “succeed” during the war? But in the waning months of 1945, this consensus rapidly deteriorated. The atomic scientists on the Manhattan Project who had been dissatisfied with the Army turned out to make a formidable lobby, and they found allies amongst a number of Senators. Most important of these was first-term Senator Brien McMahon, who quickly saw an opportunity to jump into the limelight by making atomic energy his issue. By the end of the year, not only did Congressional support fall flat for the Army’s Bill, but even Truman had withdrawn support for it. In its place, McMahon suggested a bill that looked like something the scientists would have written — a much freer, less secret, civilian-run plan for atomic energy.

So what happened in 1946? Let’s just jot off a few of the big things I have in mind.

January: The United Nations meets for the first time. Kind of a big deal. The UN Atomic Energy Commission is created to sort out questions about the future of nuclear technology on a global scale. Hearings on the McMahon Bill continue in Congress through February.

Igor Gouzenko (masked) promoting a novel in 1954. The mask was to help him maintain his anonymity, but you have to admit it adds a wonderfully surreal and theatrical aspect to the whole thing.

Igor Gouzenko (masked) promoting a novel in 1954. The mask was to help him maintain his anonymity, but you have to admit it adds a wonderfully surreal and theatrical aspect to the whole thing.

February: The first Soviet atomic spy ring is made public when General Groves leaks information about Igor Gouzenko to the press. Groves wasn’t himself too concerned about it — it was only a Canadian spy ring, and Groves had compartmentalized the Canadians out of anything he considered really important — but it served the nice purpose of dashing the anti-secrecy lobby onto the rocks.

Also in February, George F. Kennan sends his famous “Long Telegram” from Moscow, arguing that the Soviet Union sees itself in essential, permanent conflict with the West and is not likely to liberalize anytime soon. Kennan argues that containment of the USSR through “strong resistance” is the only viable course for the United States.

March: The Manhattan Engineer District’s Declassification Organization starts full operation. Groves had asked the top Manhattan Project scientists to come up with the first declassification rules in November 1945, when he realized that Congress wasn’t going to be passing legislation as soon as he expected. They came up with the first declassification procedures and the first declassification guides, inaugurating the first systematic approach to deciding what was secret and what was not.

Lilienthal's own copy of the mass-market edition of the Acheson-Lilienthal Report, from the Princeton University Archives.

Lilienthal’s own copy of the mass-market edition of the Acheson-Lilienthal Report, from the Princeton University Archives.

March: The Acheson-Lilienthal Report is completed and submitted, in secret, to the State Department. It is quickly leaked and then was followed up by a legitimate publication by the State Department. Created by a sub-committee of advisors, headed by TVA Chairman David Lilienthal and with technical advice provided by J. Robert Oppenheimer, the Acheson-Lilienthal Report argued that the only way to a safe world was through “international control” of atomic energy. The scheme they propose is that the United Nations create an organization (the Atomic Development Authority) that would be granted full control over world uranium stocks and would have the ability to inspect all facilities that used uranium in significant quantities. Peaceful applications of atomic energy would be permitted, but making nuclear weapons would not be. If one thought of it as the Nuclear Non-Proliferation Treaty, except without any authorized possession of nuclear weapons, one would not be too far off the mark. Of note is that it is an approach to controlling the bomb that is explicitly not about secrecy, but about physical control of materials. It is not loved by Truman and his more hawkish advisors (e.g. Secretary of State Byrnes), but because of its leak and subsequent publication under State Department header, it is understood to be “the” position of the United States government on the issue.

April: The McMahon Act gets substantial modifications while in committee, including the creation of a Military Liaison Committee (giving the military an official position in the running of the Atomic Energy Commission) and the introduction of a draconian secrecy provision (the “restricted data” concept that this blog takes its name from).

June: The Senate passes the McMahon Act. The House starts to debate it. Several changes are made to the House version of the bill — notably all employees with access to “restricted data” must now be investigated by the FBI and the penalty for misuse or espionage of “restricted data” is increased to death or life imprisonment. Both of these features were kept in the final version submitted to the President for signature in July.

June: Bernard Baruch, Truman’s appointee to head the US delegation of the UN Atomic Energy Commission, presents a modified form of the Acheson-Lilienthal Report to the UNAEC, dubbed the Baruch Plan. Some of the modifications are substantial, and are deeply resented by people like Oppenheimer who see them as torpedoing the plan. The Baruch Plan, for example, considered the question of what to do about violations of the agreement something that needed to be hashed out explicitly and well in advance. It also argued that the United States would not destroy its (still tiny) nuclear stockpile until the Soviet Union had proven it was not trying to build a bomb of their own. It was explicit about the need for full inspections of the USSR — a difficulty in an explicitly closed society — and stripped the UN Security Council of veto power when it came to enforcing violations of the treaty. The Soviets were, perhaps unsurprisingly, resistant to all of these measures. Andrei Gromyko proposes a counter-plan which, like the Baruch Plan, prohibits the manufacture and use of atomic weaponry. However, it requires full and immediate disarmament by the United States before anything else would go into effect, and excludes any international role in inspection or enforcement: states would self-regulate on this front.

Shot "Baker" of Operation Crossroads — one of the more famous mushroom clouds of all time. Note that the mushroom cloud itself is not the wide cloud you see there (which is a brief condensation cloud caused by it being an underwater detonation), but is the more bulbous cloud you see peaking out of the top of that cloud. You can see the battleships used for target practice near base of the cloud. The dark mark on the right side of the stem may be an upturned USS Arkansas.

Shot “Baker” of Operation Crossroads — one of the more famous mushroom clouds of all time. Note that the mushroom cloud itself is not the wide cloud you see there (which is a brief condensation cloud caused by it being an underwater detonation), but is the more bulbous cloud you see peaking out of the top of that cloud. You can see the battleships used for target practice near base of the cloud. The dark mark on the right side of the stem may be an upturned USS Arkansas.

July: The first postwar nuclear test series, Operation Crossroads, begins in the Bikini Atoll, Marshall Islands. Now this is a curious event. Ostensibly the United States was in favor of getting rid of nuclear weapons, and in fact had not yet finalized its domestic legislation about the bomb. But at the same time, it planned to set off three of them, to see their effect on naval vessels. (They decided to only set off two, in the end.) The bombs were themselves still secret, of course, but it was decided that this event should be open to the world and its press. Even the Soviets were invited! As one contemporary report summed up:

The unique nature of the operation was inherent not only in its huge size — the huge numbers of participating personnel, and the huge amounts of test equipment and number of instruments involved — it was inherent also in the tremendous glare of publicity to which the tests were exposed, and above all the the extraordinary fact that the weapons whose performance was exposed to this publicity were still classified, secret, weapons, which had never even been seen except by a few men in the inner circles of the Manhattan District and by those who had assisted in the three previous atomic bomb detonations. It has been truly said that the operation was “the most observed, most photographed, most talked-of scientific test ever conducted.” Paradoxically, it may also be said that it was the most publicly advertised secret test ever conducted.1

August: Truman signs the McMahon Act into law, and it becomes the Atomic Energy Act of 1946. It stipulates that a five-person Atomic Energy Commission will run all of the nation’s domestic atomic energy affairs, and while half of the law retains the “free and open” approach of the early McMahon Act, the other half has a very conservative and restrictive flavor to it, promising death and imprisonment to anyone who betrays atomic secrets. The paradox is explicit, McMahon explained at the time, because finding a way to implement policy between those two extremes would produce rational discussion. Right. Did I mention he was a first-term Senator? The Atomic Energy Commission would take over from the Manhattan Engineer District starting in 1947.

A meeting of the UN Atomic Energy Commission in October 1946. Bernard Baruch is the white-haired man sitting at the table at right behind the “U.S.A” plaque. At far top-right of the photo is Robert Oppenheimer. Two people above Baruch, in the very back, is General Groves. Directly below Groves is Manhattan Project scientist Richard Tolman. British physicist James Chadwick sits directly behind the U.K. representative at the table.

A meeting of the UN Atomic Energy Commission in October 1946. At front left, speaking, is Andrei Gromyko. Bernard Baruch is the white-haired man sitting at the table at right behind the “U.S.A” plaque. At far top-right of the photo is a pensive J. Robert Oppenheimer. Two people above Baruch, in the very back, is a bored-looking General Groves. Directly below Groves is Manhattan Project scientist Richard Tolman. British physicist James Chadwick sits directly behind the U.K. representative at the table.

September: Baruch tells Truman that international control of atomic energy seems nowhere in sight. The Soviet situation has soured dramatically over the course of the year. The Soviets’  international control plan, the Gromyko Plan, requires full faith in Stalin’s willingness to self-regulate. Stalin, for his part, is not willing to sign a pledge of disarmament and inspection while the United States is continuing to build nuclear weapons. It is clear to Baruch, and even to more liberal-minded observers like Oppenheimer, that the Soviets are probably not going to play ball on any of this, because it would not only require them to forswear a potentially important weapon, but because any true plan would require them to become a much more open society.

October: Truman appoints David Lilienthal as the Chairman of the Atomic Energy Commission. Lilienthal is enthusiastic about the job — a New Deal technocrat, he thinks that he can use his position to set up a fairly liberal approach to nuclear technology in the United States. He is quickly confronted by the fact that the atomic empire established by the Manhattan Engineer District has decayed appreciably in year after the end of the war, and that he has powerful enemies in Congress and in the military. His confirmation hearings start in early 1947, and are exceptionally acrimonious. I love Lilienthal as an historical figure, because he is an idealist who really wants to accomplish good things, but ends up doing almost the opposite of what he set out to do. To me this says a lot about the human condition.

November: The US Atomic Energy Commission meets for the first time in Oak Ridge, Tennessee. They adopt the declassification system of the Manhattan District, among other administrative matters.

December: Meredith Gardner, a cryptanalyst for the US Army Signal Intelligence Service, achieves a major breakthrough in decrypting wartime Soviet cables. A cable from 1944 contains a list of scientists working at Los Alamos — indications of a serious breach in wartime atomic security, potentially much worse than the Canadian spy ring. This information is kept extremely secret, however, as this work becomes a major component in the VENONA project, which (years later) leads to the discovery of Klaus Fuchs, Julius Rosenberg, and many other Soviet spies.

On Christmas Day, 1946, the Soviet Union’s first experimental reactor, F-1, goes critical for the first time.

The Soviet F-1 reactor, in 2009. It remains operational today — the longest-lived nuclear reactor by far.

The Soviet F-1 reactor, in 2009. It remains operational today — the longest-lived nuclear reactor by far.

No single event on that list stands out as on par with Hiroshima, the Cuban Missile Crisis, or even the Berlin Crisis. But taken together, I think, the list makes a strong argument for the importance of 1946. When one reads the documents from this period, one gets this sense of a world in flux. On the one hand, you have people who are hoping that the re-ordering of the world after World War II will present an enormous opportunity for creating a more peaceful existence. The ideas of world government, of the banning of nuclear weapons, of openness and prosperity, seem seriously on the table. And not just by members of the liberal elite, mind you: even US Army Generals were supporting these kinds of positions! And yet, as the year wore on, the hopes began to fade. Harsher analysis began to prevail. Even the most optimistic observers started to see that the problems of the old order weren’t going away anytime soon, that no amount of good faith was going to get Stalin to play ball. Which is, I should say, not to put all of the onus on the Soviets, as intractable as they were, and as awful as Stalin was. One can imagine a Cold War that was less tense, less explicitly antagonistic, less dangerous, even with limitations that the existence of a ruler like Stalin imposed. But some of the more hopeful things seem, with reflection, like pure fantasy. This is Stalin we’re talking about, after all. Roosevelt might have been able to sweet talk him for awhile, but even that had its limits.

We now know, of course, that the Soviet Union was furiously trying to build its own atomic arsenal in secret during this entire period. We also know that the US military was explicitly expecting to rely on atomic weapons in any future conflict, in order to offset the massive Soviet conventional advantage that existed at the time. We know that there was extensive Soviet espionage in the US government and its atomic program, although not as extensive as fantasists like McCarthy thought. We also know, through hard experience, that questions of treaty violations and inspections didn’t go away over time — if anything, I think, the experience of the Nuclear Non-Proliferation Treaty has shown that many of Baruch’s controversial changes to the Acheson-Lilienthal Report were pretty astute, and quickly got to the center of the political difficulties that all arms control efforts present.

As an historian, I love periods of flux and of change. (As an individual, I know that living in “interesting times” can be pretty stressful!) I love looking at where old orders break down, and new orders emerge. The immediate postwar is one such period — where ideas were earnestly discussed that seemed utterly impossible only a few years later. Such periods provide little windows into “what might have been,” alternative futures and possibilities that never happened, while also reminding us of the forces that bent things to the path they eventually went on.

  1. Manhattan District History, Book VIII, Los Alamos Project (Y) – Volume 3, Auxiliary Activities, Chapter 8, Operation Crossroads (n.d., ca. 1946). []

How many people worked on the Manhattan Project?

Friday, November 1st, 2013

Everyone knows the Manhattan Project was big. But how big was it? There are lots of ways to try and convey the bigness. The size of the buildings and sites, for example. Or the cost — $2 billion 1945 USD, which doesn’t sound that big, even when converted to modern numbers (e.g. around $30 billion 2012 USD, depending on the inflator you use), since we’re used to billions being tossed around like they are nothing these days. But consider that the USA spent about $300 billion on World War II as a whole — so that means that the atomic bombs made up for a little under 1% of the cost of the entire war. Kind of impressive, but even then, it’s hard to wrap one’s head around something like “the cost of World War II.”

General Groves speaks to a group of Oak Ridge service personnel in August 1945. From the DOE. There are lots of great Oak Ridge photos from the 1940s in this Flickr set.

General Groves speaks to a group of Oak Ridge service personnel in August 1945. From the DOE. There are lots of great Oak Ridge photos from the 1940s in this Flickr set.

Another approach is to talk about how many people were involved. There are a number of various estimates floating around. Instead of focusing on those, I want to jump directly to the source: a once-secret postwar report on Manhattan Project personnel practices that includes some raw numbers on hiring.1

This report has two very interesting graphs in it. The first is this one, showing total employment by month, broken into the various important Manhattan Project categories:

Manhattan Project contractor employment by month

Let’s just take a moment to marvel at this. They went from pretty much just talking about a bomb, in theory, on paper, in late 1942, and had a project with 125,310 active employees at its peak, 22 months later. That’s a huge ramp-up.

I like this graph because it helps you see, very plainly, the progress of the project. You can see that Oak Ridge (CEW) and Hanford (HEW) construction both got rolling pretty quickly but took about a year to hit their maximums, and that all construction peaked in early 1944. At which point, operations became the main issue — running the plants. It’s interesting to compare how many more people were required for Oak Ridge operations than Hanford operations, and that the “Santa Fe Operations” — Los Alamos, et al. — barely registers on the graph. A couple thousand people at most.

You can also see how rapidly that curve starts to drop off in September 1945 — over 10,000 people left at the end of the war, a significant chunk of them being Oak Ridge operations personnel. There is then a long slumping decline until late 1946, when you start to get an up-tick. This maps on pretty well with what we know about the history of the Manhattan Project in the period before the Atomic Energy Commission took over: Groves’ hard-built empire decayed under the uncertainty of the postwar and the dithering of Congress.

This is where we get the number one usually sees cited for the Manhattan Project: 125,000 or so employees at its peak. Which is impressive… but also kind of misleading. Why? Because peak employment is not cumulative employment. That is, the number of people who work at any given company today are not the number of people who have worked there over the course of its lifetime. Obvious enough, but if one is wondering how many people did it take to make the atomic bomb, one wants to know the cumulative employment, not the number on hand at any one time, right?

Digging around a bit more in the aforementioned personnel statistics of the Manhattan Project (a thrilling read, I assure you), I found this rather amazing graph of the total number of hires and terminations by the project:

Manhattan District Contractors Hires and Terminations through 31 December 1946

Now that number on the left, the total hires, is a pretty big one — over 600,000 total. Unlike the other graph, I don’t have the exact figure for this, but it looks to be around 610,000. That’s a huge number. Why would the numbers be at such odds? Because at the big sites — Oak Ridge and Hanford — there was a pretty high rate of turnover, as the “terminations” bar indicates: over 560,000 people left their jobs on the Manhattan Project by December 1946.

Some of this, of course, is because the job was done and they went home — once the construction was done, you didn’t need as many people working on construction anymore. But it’s also because even during the war, there was a considerable amount of people either quitting or getting fired. People left their jobs all the time, at all times during the war. As the report indicates, the reasons and rates varied by site. For construction at Hanford, they had an average monthly turnover rate of 20%, with a ratio of resignations to discharges set at 3 to 1. Of those who resigned, 26% did so because of illness, 19% were to move to another location (which could be a lot of things), 13% cited poor working conditions, 13% said there was an illness in the family, 14% had got another job somewhere else, 7% cited the poor living conditions, 6% got drafted or otherwise joined the military, and 2% complained about wages. Of those who were discharged, about a quarter of the time it was because they were an “unsatisfactory worker,” and the rest of the time it was because of chronic absenteeism. For construction at Oak Ridge, the average turnover rate was 17%, with mostly the same reasons given, though the resignations to discharge ratio was 2 to 1. (More people, by percentage, complained about the living conditions at Oak Ridge than at Hanford.) For the operations at Oak Ridge, the turnover rate was 6.6%, with a resignations to discharge ration of 1.3 to 1 — of those who left, a little over 40% did so because they were fired.

A 1944 "Stay on the job" rally at J.A. Jones Construction Co. in Oak Ridge. The workers seem a little unimpressed. Source.

A 1944 “Stay on the job” rally at J.A. Jones Construction Co. in Oak Ridge. The workers seem a little unimpressed. Source.

Of course, these numbers run through the entire tenure of the Manhattan Engineer District. When most people want to know how many people it took to make the bomb, they want to know up until August 1945 or so. I don’t have exact numbers on this. However, if we take the data from the report and the graphs, and assume an average monthly turnover rate of about 17% for the entire project, we end up with about the right number total.2 Subtracting all of the people added after August 1945, we get around 485,000 total people required to make the bombs during World War II. Given how much of that employment was front-loaded (again, with a peak in June 1944), I don’t think it’s too far off to assume that probably half a million people were employed to make the bomb. Which, to put that in perspective, means that during World War II, approximately 0.4% of all Americans worked on the bomb project — about one out of every 250 people in the country at the time.

Which is pretty impressive. By contrast, I’ve seen estimates that said that the Soviets used about 600,000 people total to make their atomic bomb. Which is not too different a number, actually — a bit less impressive than one might think if one is only comparing it to the peak of the Manhattan Project. The Soviets had around 170 million people at the time, so it works out to be a pretty similar percentage of the total population as the American project. Of course, one suspects that fewer of the Soviet workers were able to quit because they didn’t like the wage and working conditions. Though I’m sure they had their own form of grim “turnover.”

  1. Manhattan District History, Book I – General, Volume 8 – Personnel (dated 19 February 1946 but with numbers that suggest later additions were made. []
  2. If you want to play with the data yourself, I’ve uploaded it here as a CSV file. Some of it is extrapolated from the top graph. []

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

Friday, 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.

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.”5

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.”6 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.7 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. “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.” []
  6. “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.” []
  7. 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. []