Posts Tagged ‘Resources’


Nuclear history bibliography, 2015

Friday, February 5th, 2016

It’s (roughly) that time of the year again: my annual nuclear history bibliography for the previous year. (It’s a little later than usual this time around, but I’ve been busy teaching and writing.) The game is more or less the same as it was for 2014, 2013, and 2012: I’ve tried to compile any and all references to scholarly or at least semi-scholarly articles and books I’ve founded that were published in 2015 that would be relevant and of interest to those people (like myself) who consider themselves interested in “nuclear history,” construed broadly. As before, I’ve avoided listing websites (except the Electronic Briefing Bulletins of the National Security Archive, because they are a really uniquely valuable form of “publication”), have avoided anything that was simply an updated edition of a book published prior to 2015, and have stuck mostly to scholarly articles (with my own publications being an exception, because, well, I made the list).

The hands of the censor: Charles L. Marshall, Director of Classification, declassifying a document as part of the Atomic Energy Commission's 1971-1976 "declassification drive." Source: Nuclear Testing Archive. Click for the uncropped version.

The hands of the censor: Charles L. Marshall, Director of Classification, declassifying a document as part of the Atomic Energy Commission’s 1971-1976 “declassification drive.” Click the image for the full-sized version. Source: Nuclear Testing Archive, Las Vegas, Nevada, document NV0148015.

This list is no doubt missing a lot, but it’s a start. If you think I missed something, or think something ought not be on here, add it as a comment below (comments that are just references will be read but probably not “approved” — consider them just a way to send me a quick message). I have not read the vast majority of the references below (one only has so much time…), and do not vouch for them in any way. In most cases, I’ve just glanced enough to confirm that they seem to have a historical component that relates to nuclear technology.

The list was compiled by (tediously) searching through broad keyword searches in a variety of online databases, along with looking at the titles and abstracts of specific journals that are known to carry a lot of this sort of thing.

In the past, it has usually taken about a week for this list to fully stabilize, as people remind me of all the things I’ve missed. So check back then if you want the most up-to-date version. (I will also update the 2014 bibliography at the same time, with a few extra references I found.) At that point, I will also post the bibtex and RIS version for those who want to import these into a citation manager. Note that some of the processing below is done mechanically (I export from Zotero then use PHP to clean up the links/etc. because it is easier than figuring out how to modify Zotero’s internal style sheets), so there may be a few weird little bugs related to that here and there.

And if you’re bored to death by bibliographies — don’t worry. I’m starting up the regular blog posts again next week.

See the bibliography by clicking here

News and Notes

In Memoriam: Richard G. Hewlett (1923-2015)

Tuesday, September 8th, 2015

Richard Greening Hewlett, the first official historian of the Atomic Energy Commission, has passed away at the age of 92.1

I never knew Hewlett, but nobody can work in this field without acknowledging the huge debt they owe him for his work. Hewlett began working for the Atomic Energy Commission (AEC) in 1957, working to write a volume on the Manhattan Project and establishment of the AEC. In doing so he was also establishing the History Office of the AEC, which was dedicated to cataloguing and preserving these vital records. One of his greatest coups was discovering, entirely by chance, a locked safe in a basement of an AEC building that turned out to contain the Bush-Conant files relating to the creation of the atomic bomb, one of the most important document bases for any history of the Manhattan Project (and one which I have relied upon extensively).

Richard G. Hewlett, posing in 1958 with the Bush-Conant document collection.

Richard G. Hewlett, posing in 1958 with the Bush-Conant document collection.

Hewlett continued at his post through the abolishment of the AEC and the subsequent creations of its successors, the Energy Research and Development Administration and the Department of Energy. He retired in 1980, and went on to co-found History Associates, one of the only private companies dedicated to doing serious historical work.

Hewlett’s volumes on AEC history are extremely useful resources, and I end up citing them often. They can be tricky to work with, though, since Hewlett was not always able to cite his sources very precisely (on account of many of them being classified or kept internally), and the sort of “official historian” he was meant that he rarely strayed too far beyond the most “orthodox” versions of these histories (he was never courting controversy). I have found in many instances that when I look up a document that Hewlett cited, it turns out that he basically just paraphrased what the document said and presented that as what happened — and sometimes that is valid, sometimes that is not. Documents require their own contextualization, their own careful reading, to get the full story, and Hewlett’s approach can feel a little naive in retrospect. It is an old-style of history, official or not.

Still, he was essentially carving out the first draft of this historical work, and approaching it seriously, and that required a Herculean effort in its own right, both in terms of collecting the source material and navigating the federal bureaucracy to get these histories published. In a 1997 interview with Public Historian, Hewlett described how Admiral Hyman G. Rickover essentially abused classification restrictions in order to force Hewlett to write a book on the nuclear Navy, with Rickover at the center of it. Hewlett ran into further complications later when he attempted to write about nuclear waste — a topic that does not make the AEC look extremely on top of things.2

I’ve read a number of narratives from public historians working with secret topics. It seems like a tricky prospect. Barton Hacker, who wrote on the history of radiation exposure and protection, told me that his security clearance rarely got him anything that wasn’t basically already knowable from the “outside,” and caused interminable difficulties when he tried to get things published that made anybody currently in office, or any still-existing agency, look anything but perfect. As he put it later, some bureaucrats “objected to what they called ‘editorializing,’ which seems to be the bureaucratic term for drawing conclusions.”3

I have never wanted a security clearance, and would never accept one, for this reason. To learn something interesting but not to be able to tell anyone about it seems like a bad exchange. I want to know things, but I also want to tell things — storytelling is my profession, in a sense. To get a clearance means you are in an entirely different category from the perspective of a classifying agency, and even innocuous information that everybody knows can end up on the cutting-room floor. No thanks.

AEC histories, volumes 1-3

Hewlett’s AEC histories are all scanned and online, posted in various archives by the US federal government, some on the Department of Energy’s History Publications page. Because they are all in the public domain (they are all “work for hire” for the US government, which makes them uncopyrightable), and they are all out of print, I am going to mirror them here:

I find these scanned copies perhaps most useful of all, because they are searchable. The Hewlett volumes can be dull reads in places (he embodies a certain model of official historian that tries to keep up an appearance of “just the facts”), but they make excellent resources to run keyword searches through. It is too bad nobody has really tried to do one of these kinds of volumes for the final chapter of the AEC’s history (1962-1974).4

The source note to The New World has one of my favorite lines about nuclear history and the reason why there are more resources that one might expect:

The records have survived. For this, scholars can thank two much-maligned practices of the bureaucracy: classification and multiple copies. Classified documents endure; they do not disappear from the files as souvenirs. As for copies in sextuplicate, their survival is a matter of simple arithmetic. If the original in one agency is destroyed, the chances are better than even that one of the five carbons will escape the flames in another.5

To this we must add that people like Hewlett took the time to track them down, catalogue them, and get them eventually transferred into repositories (like the National Archives and Records Administration, for all their difficulties). This final action, so crucial for the later historian, does not happen on its own. This may be Hewlett’s greatest legacy in the end. The texts he wrote will inevitably be superseded by later works of history — but those superseding works will be utterly reliant on the preservation work he did, those acts of finding and saving and cataloging of the records. Rest in peace.

  1. I thank Stan Norris for bringing this to my attention. []
  2. Richard G. Hewlett and Jo Anne McCormick Quatannens, “Richard G. Hewlett: Federal Historian,” The Public Historian 19, no. 1 (Winter 1997): 53-83,  esp. 73-77. []
  3. Barton C. Hacker, “Writing the History of a Controversial Program: Radiation Safety, the AEC, and Nuclear Weapons Testing,” The Public Historian 14, no. 1 (Winter 1992): 31-53, on 45. []
  4. My favorite, detail-heavy books that cover the latter period of AEC history well are Brian Balogh’s Chain Reaction: Expert Debate and Public Participation in American Commercial Nuclear Power 1945-1975 (Cambridge University Press, 1991), and J. Samuel Walker’s The Road to Yucca Mountain: The Development of Radioactive Waste Policy in the United States (University of California Press, 2009), though they only cover the power and waste aspects of it (as opposed to, say, the weapons angles). []
  5. Richard Hewlett and Oscar Anderson, A History of the United States Atomic Energy Commission, Volume 1: The New World, 1939-1946 (University Park: Pennsylvania State University Press, 1962), 657. []

Critical mass

Friday, April 10th, 2015

When we talk about how nuclear weapons work, we inevitably mention the “critical mass.” This is the amount of fissile material you need to create a self-sustaining nuclear reaction. But it’s a very tricky concept, one often poorly deployed and explained, and the result, I have found while teaching and while talking to people online, is an almost universal confusion about what it means on a physical level.

One of the ways in which the critical mass is visually explained in Glasstone and Dolan's The Effects of Nuclear Weapons (1977 edn.). Want it on a t-shirt? I've got you covered.

One of the ways in which the critical mass is visually explained in Glasstone and Dolan’s The Effects of Nuclear Weapons (1977 edn.). Want it on a t-shirt? I’ve got you covered.

Where does the term come from? In the Smyth Report released in August 1945, the term “critical size” is used almost universally, while “critical mass” is used exactly once (and parenthetically, at that). A more interesting term, the “critical condition,” is used in a few places. The Los Alamos Primer, from 1943, uses critical “radius,” “volume,” “conditions,” in addition to “mass.” The MAUD Report, from 1941, uses critical “size,” “value,” and “amount” — not mass. The Frisch-Peirels memorandum, from 1940, uses critical “radius,” “size,” and “condition.” Leo Szilard’s pre-fission, 1935 patent on chain reacting systems uses the terms critical “thickness,” and “value,” not mass. This is not to imply that people didn’t use the term “critical mass” at the time — but it was one term among many, not the only term. The earliest context I have found it being used extensively comes from a paper in 1941, where it was being used specifically to talk about whether masses of fissile material could be made to explode on demand and not before.1

Why use “critical mass” instead of other terms? For one thing, talking about the mass can help you get a sense of the size of the problem when fissile material is scarce and hard to produce (producing fissile material consumed 80% of the Manhattan Project’s budget). And it can also help you when talking about safety questions — about avoiding a nuclear reaction until you absolutely want on. So you don’t want to inadvertently create a critical mass. And knowing that the critical mass is so many kilograms of fissile material, as opposed to so many tons, was an early and important step in deciding that an atomic bomb was feasible in the first place.

A 5.3 kg ring of 99.96% pure plutonium-239. Under some conditions, this is enough to produce a significant explosive output. In its current form — unreflected, at normal density, in a ring-shape that prevents any neutrons from finding too many atoms to fission with — it is relatively innocuous.

A 5.3 kg ring of 99.96% pure plutonium. Under some conditions, this is enough to produce a significant explosive output. In its current form — unreflected, at normal density, in a ring-shape that prevents any neutrons from finding too many atoms to fission with — it is relatively innocuous.

What I don’t like about the term, though, is that it can easily lead to confusion. I have seen people assert, for example, that you need a “critical mass” of uranium-235 to start a nuclear reaction. Well, you do — but there is no one critical mass of uranium-235. In other words, used sloppily, people seem to often think that uranium-235 or plutonium have single values for their “critical mass,” and that “a critical mass” of material is what you use to make a bomb. But it’s more complicated than that, and this is where I think focusing on the mass can lead people astray.

Put simply, the amount of fissile material you need to start a nuclear reaction varies by the conditions under which it is being considered. The mass of material matters, but only if you specify the conditions under which it is being kept. Because under different conditions, any given form of fissile material will have different critical masses.

I’ve seen people (mostly online) want to talk about how nuclear weapons work, and they look up what “the” critical mass of uranium-235 is, and they find a number like 50 kg. They then say, OK, you must need 50 kg to start a nuclear reaction. But this is wrong. 50 kg of uranium-235 is the bare sphere critical mass of uranium-235. In other words, if you assembled 50 kg of uranium-235 into a solid sphere, with nothing around it, at normal atmospheric conditions, it will start a self-sustaining chain reaction. It probably would not produce an explosion of great violence — the uranium sphere would probably just blow itself a few feet apart (and irradiate anyone nearby). But once blown apart, the reaction would stop. Not a bomb.

The Godiva Device, a "naked" (get it?) critical assembly used as a pulsed nuclear reactor at Los Alamos. A 54 kg near-bare sphere of 93.7% enriched uranium separated into three pieces. At left, it is separated safely — no reaction. At right, you see what happened when the pieces got close enough to start a critical reaction — not a massive explosion (thank goodness), but enough energy output to damage the machine, and to push those pieces of uranium far enough from each other that they could no longer react.

The Godiva Device, a “naked” (get it?) critical assembly used as a pulsed nuclear reactor at Los Alamos. A 54 kg near-bare sphere of 93.7% enriched uranium separated into three pieces. At left, it is separated safely — no reaction. At right, you see what happened when the pieces got close enough to start a critical reaction — not a massive explosion (thank goodness), but enough energy output to damage the machine, and to push those pieces of uranium far enough from each other that they could no longer react. The workers were fortunately a safe distance away.

So does that mean that 50 kg of uranium-235 is a important number in and of itself? Only if you are assembling solid spheres of uranium-235.

Is 50 kg the amount you need for a bomb? No. You can get away with much smaller numbers if you change the conditions. So if you put a heavy, neutron-reflecting tamper around the uranium, you can get away with around 10 to 15 kg of uranium-235 for a bomb — a factor of 3-5X less mass than you thought you needed. If your uranium-235 is dissolved in water, it takes very low masses to start a self-sustaining reaction — a dangerous condition if you didn’t mean to start one! And it may be possible, under very carefully-developed conditions, to make a bomb with even smaller masses. (The bare-sphere critical mass of plutonium is around 10 kg, but apparently one can get a pretty good bang out of 3-4 kg of it, if not less, if you know what you are doing.)2

Conversely, does this mean that you can’t possibly have 50 kg of uranium (or more) in one place without it detonating? No. If your uranium is fashioned not into a solid sphere, but a cylinder, or is a hollow sphere, or has neutron-absorbing elements (i.e. boron) embedded in it, then you can (if you know what you are doing) exceed that 50 kg number without it reacting. And, of course, there are also impurities — the amount of uranium-238 in your uranium-235 will increase the size of any critical mass calculation.

In other words, under different conditions, the mass of fissile material that will react varies, and varies dramatically. These different conditions include different geometries, densities, temperatures, chemical compositions/phases, and questions about whether it is embedded into other types of materials, whether there are neutron-moderating substances (i.e. water) present, enrichment levels, and so on. It’s not a fixed number, unless you also fix all of your assumptions about the conditions under which it is taken place.

Re-creation of Slotin's fatal experiment with the third core. (Source: Los Alamos)

Re-creation of Louis Slotin’s fatal experiment with the third plutonium core. The problem wasn’t the mass of the core, it was that Slotin inadvertently changed the state of the system (by accidentally letting the reflector drop onto it completely when his screwdriver slipped), which took a safe, non-critical assemble of plutonium and moved it into a briefly-critical state. This produced no explosion, but enough radiation to be fatal to Slotin and damaging to others in the room.

The classic example of this, of course, is the implosion bomb design. The bare sphere critical mass of plutonium-239 is 10 kg. The Nagasaki bomb contained 6.2 kg of plutonium as its fuel. At normal, room-temperature densities, a solid sphere of 6.2 kg of plutonium is not critical. Increase its density by 2.5X through the careful application of high explosives, however, and suddenly that is at least one critical mass of plutonium. Even this is something of an oversimplification, because it’s not just the density that matters: the allotropic (chemical) phase of plutonium, for example, affects its critical mass conditions (and plutonium is notorious for having an unusual number of these phases), and the Nagasaki bomb also included many other useful features meant to help the reaction along like a neutron initiator (which gave it a little shot of about 100 neutrons to start things off), and a heavy, natural-uranium tamper.

What I dislike about the term “critical mass,” as well, is that it can serve to obscure the physical process that defines “criticality.” It can make it seem like reactivity is a function of the mass alone, which is wrong. Worse, it can keep people from realizing why the mass matters in the way it does (among other things). And this can lead to confusion on questions like, “how much explosive power does a critical mass release?” The answer is… it has nothing to do with the critical mass per se. That is a question of bomb efficiency, which can seem like a secondary, separate question. But both the question of criticality and efficiency are really one and the same phenomena — if you understand the underlying physical process on an intuitive level.

Criticality, the “critical condition,” is defined as the point at which a chain reacting system becomes self-sustaining. So we can imagine a whole sea of uranium-235 atoms. Neutrons enter the system (either from a neutron source, spontaneous fissioning, or the outside world). If they are absorbed by a uranium-235 nucleus, they have a chance of making it undergo fission. That fission reaction will produce a random number (2.5 on average) of secondary neutrons. To be critical, enough of these neutrons will then have to go on to find other uranium nuclei to keep the overall level of neutrons (the “neutron economy”) constant. If that total number of neutrons is very low, then this isn’t very interesting — one neutron being replenished repeatedly isn’t going to do anything interesting. If we’ve already got a lot of neutrons in there, this will generate a lot of energy, which is essentially how a nuclear reactor works once it is up and running.

Supercriticality, which is what is more important for bomb design (and the initial stages of running a reactor) is when your system produces more than one extra neutron in each generation of fissioning. So if our uranium atom splits, produces 2 neutrons, and each of those go on to split more atoms, we’re talking about getting two neutrons for every one we put into the system. This is an exponentially-growing number of neutrons. Since neutrons move very quickly, and each reaction takes place very quickly (on the order of a nanosecond), this becomes a very large number of neutrons very quickly. Such is a bomb: an exponential chain reaction that goes through enough reactions very quickly to release a lot of energy.

The Trinity Gadget - Sectional View

A sectional view of a rendering of the Trinity “Gadget” I made. The 6.2 kg sphere of plutonium (the second-to-last sphere in the center, which encloses the small neutron initiator) is a safe-to-handle quantity by itself, and only has the possibility of becoming super-critical when the high explosives compress it to over twice its original density. Sizes are to scale.

So what are the conditions that produce these results? Well, it’s true that if you pure enough fissile material in one place, in the right shape, under the right conditions, it’ll become critical. Which is to say, each neutron that goes into the material will get replaced by at least another neutron. It will be a self-sustaining reaction, which is all that “criticality” means. Each fission reaction produces on average 2.5 more neutrons, but depending on the setup of the system, most or all of those may not find another fissile nuclei to interact with. If, however, the system is set up in a way that means that the replacement rate is more than one neutron — if every neutron that enters or is created ends up creating in turn at least two neutrons — then you have a supercritical system, with an exponentially-increasing number of neutrons. This is what can lead to explosions, as opposed to just generating heat.

In a bomb, you need more than just a critical reaction. You need it to be supercritical, and to stay supercritical long-enough that a lot of energy is released. This is where the concept of efficiency comes into play. In theory, the Fat Man’s 6.2 kg of plutonium could have released over 100 kilotons worth of energy. In practice, only about a kilogram of it reacted before the explosive power of the reaction separated the plutonium by enough that no more reactions could take place, and “only” released 20 kilotons worth of energy. So it was about 18% efficient. The relative crudity of the Little Boy bomb meant that only about 1% of its fissile material reacted — it was many times less efficient, even though it had roughly 10X more fissile material in it than the Fat Man bomb. The concept of the critical mass, here, really doesn’t illuminate these differences, but an understanding of how the critical reactions work, and how the overall system is set up, does.

This understanding of criticality is more nuanced than a mere mass or radius or volume. So I prefer the alternative phrasing that was also used by weapons designers: “critical assembly” or “critical system.” Because that emphasizes that it’s more than one simple physical property — it’s about how a lot of physical properties, in combination with engineering artifice, come together to produce a specific outcome.

I’ve been playing around with the scripting language Processing.js recently, in my endless quest to make sure my web and visualization skills are up-to-date. Processing.js is a language that makes physics visualizations (among other things) pretty easy. It is basically similar to Javascript, but takes care of the “back end” of graphics to a degree that you can just say, “create an object called an atom at points x and y; render it as a red circle; when it comes into contact with another object called a neutron, make it split and release more neutrons,” and so on. Obviously it is a little more arcane than just that, but if you have experience programming, that is more or less how it works. Anyway, I had the idea earlier this week that it would be pretty easy to make a simple critical assembly “toy” simulation using Processing, and this is what I produced:

Critical Assembly Simulator

The gist of this application is that the red atoms are uranium-235 (or plutonium), and the blue atoms are uranium-238 (or some other neutron-absorbing substance). Clicking on an atom will cause it to fission, and clicking on the “fire neutron initiator” button will inject a number of neutrons into the center of the arrangement. If a neutron hits a red atom, it has a chance to cause it to fission (and a chance to just bounce off), which releases more atoms (and also pushes nearby atoms away). If it hits a blue atom, it has a chance to be absorbed (turning it purple).

The goal, if one can put it that way, is to cause a chain reaction that will fission all of the atoms. As you will see from clicking on it, in its initial condition it is hard to do that. But you can manipulate a whole host of variables using the menu at the right, including adding a neutron reflector, changing the number of atoms and their initial packing density, the maximum number of neutrons released by the fission reaction, and even, if you care to, changing things like the lifetimes of the neutrons, the likelihood of the neutrons just scattering off of atoms, and whether the atoms will spontaneously fission or not. If you have a reflector added, you can also click the “Implode” button to make it compress the atoms into a higher density.3

The progress of a successful reaction using an imploded reflector. The little yellow parts are a "splitting atom" animation which is disabled by default (because it decreases performance).

The progress of a successful reaction using an imploded reflector. The little yellow parts are a “splitting atom” animation which is disabled by default (because it decreases performance).

This is not a real physical simulation of a bomb, obviously. None of the numbers used have any physically-realistic quality to them, and real atomic bombs rely on the fissioning of trillions of atoms in a 3D space (whereas if you try to increase the number of atoms visible to 1,000, much less 10,000, your browser will probably slow to a crawl, and this is just in 2D space!).4 And this simulator does not take into account the effects of fission products, among other things. But I like that it emphasizes that it’s not just the number of atoms that determines whether the system is critical — it’s not just the mass. It’s all of the other things in the system as well. Some of them are physical constants, things pertaining to the nature of the atoms themselves. (Many of these were constants not fully known or understood until well after 1939, which is why many scientists were skeptical that nuclear weapons were possible to build, even in theory.) Some of them are engineering tricks, like the reflector and implosion.

My hope is that this kind of visualization will help my students (and others) think through the actual reaction itself a bit more, to help build an intuitive understanding of what is going on, as a remedy to the aspects of a prior language that was created by scientists, diffused publicly, and then got somewhat confused. “Critical mass” isn’t a terrible term. It has its applications. But when it can lead to easy misunderstandings, the language we choose to use matters.

  1. E.g. “Can system be controlled safely by dividing mass into two parts? Yes. We believe that it is possible with suitable technical supervision to assemble masses which will be known fractions of the critical mass and which will not explode during the assembly.” The authorship of the report is apparently several members of the Uranium Committee, but their specific names are unlisted. “Fast neutron chain reactions — Summary of discussion on recommendations of the Sub-section on theoretical aspects on October 24, 1941,” (24 October 1941), copy in Bush-Conant File Relating the Development of the Atomic Bomb, 1940-1945, Records of the Office of Scientific Research and Development, RG 227, microfilm publication M1392, National Archives and Records Administration, Washington, D.C., n.d. (ca. 1990), Reel 10, Target 21, Folder 162A, “Reports — Chain Reactions [1941].” []
  2. On the “how low can you go” question, I have found table A.1 in this report useful:International Panel on Fissile Material, “Global Fissile Material Report 2013: Increasing Transparency of Nuclear Warhead and Fissile Material Stocks as a Step toward Disarmament,” Seventh annual report of the International Panel on Fissile Material (October 2013). There is documentary evidence suggesting the Soviets managed to weapons with cores as little as 0.8 kg of plutonium, and got significant (e.g. >1 kiloton) yields from them. []
  3. For those who want it, the source code is here. It is sparsely commented. It is written, again, in Processing.js. []
  4. Just to put this into perspective, 1 kg of plutonium-239 is ~2.5 x 1024 atoms. []

Nuclear history bibliography, 2014

Friday, January 2nd, 2015

It’s time for the third-annual Nuclear History Bibliography wrap-up, that special feature of this blog where I spend a few hours searching academic databases for interesting keywords and then give you the results, with the aim of giving a rough guide to the state of the field as it is represented in print. The rules are the same as last time and the time before: the boundary of what is being defined as “nuclear history” is a vague one (the connection to nuclear technology has to be somewhat explicit, and it has to be a mostly historical work, talking about what happened and less about what is happening or should happen), it has to have a 2014 publication date on it (even if it actually was first visible before or after the year), and it has to be primarily something that was “published” (I have not tried to include all websites, but I have added a few “electronic publications” where they seemed too interesting to omit, at the end).

Met Lab - secrecy stamp (photograph by Alex Wellerstein)

If I’ve missed something (extremely likely, especially in the non-English literature), please feel free to let me know in the comment section. I don’t claim to have read even a fraction of these — this citations are just provided so that people (including myself!) can see what they’ve missed in the last year, and maybe follow-up on it later. All I’ve done here is spend several hours searching through various databases (and looking at a few journals that are rather standard for this kind of thing) and filtered out (usually by glancing at the articles themselves) anything that I felt met the above criteria. So it’s not going to be perfect. This year I’ve decided to be civilized about my citation-mongering and have gathered everything together into files for importing into Zotero, EndNote, whatever, here: books: RISBIB; articles: RIS, BIB. In places where I’ve been able to, I’ve linked to the Amazon page of the book, or to the DOI link of the articles.

View the list by clicking here.


General Groves’ secret history

Friday, September 5th, 2014

The first history of the Manhattan Project that was ever published was the famous Smyth Report, which was made public just three days after the bombing of Nagasaki. But the heavily-redacted Smyth Report understandably left a lot out, even if it did give a good general overview of the work that had been done to make the bomb. Deep within the secret files of the Manhattan Project, though, was another, classified history of the atomic bomb. This was General Leslie Groves’ Manhattan District History. This wasn’t a history that Groves ever intended to publish — it was an internal record-keeping system for someone who knew that over the course of his life, he (and others) would need to be able to occasionally look up information about the decisions made during the making of the atomic bomb, and that wading through the thousands of miscellaneous papers associated with the project wouldn’t cut it.

Manhattan District History - Book 2 - Vol 5 - cover

Groves’ concern with documentation warms this historian’s heart, but it’s worth noting that he wasn’t making this for posterity. Groves repeatedly emphasized both during the project and afterwards that he was afraid of being challenged after the fact. With the great secrecy of the Manhattan Project, and its “black” budget, high priority rating, and its lack of tolerance for any external interference, came a great responsibility. Groves knew that he had made enemies and was doing controversial things. There was a chance, even if everything worked correctly (and help him if it didn’t!), that all of his actions would land him in front of Congress, repeatedly testifying about whether he made bad decisions, abused public trust, and wasted money. And if he was asked, years later, about the work of one part of the project, how would he know how to answer? Better to have a record of decisions put into one place, should he need to look it up later, and before all of the scientists scattered to the wind in the postwar. He might also have been thinking about the memoir he would someday write: his 1962 book, Now it Can Be Told, clearly leans heavily on his secret history in some places.

Groves didn’t write the thing himself, of course. Despite his reputation for micromanagement, he had his limits. Instead, the overall project was managed by an editor, Gavin Hadden, a civil employee for the Army Corps of Engineers. Individual chapters and sections were written by people who had worked in the various divisions in question. Unlike the Smyth Report, the history chapters were not necessarily written near-contemporaneously with the work — most of the work appears to have been started after the war ended, some parts appear to have not been finished until 1948 or so.

General Groves not amused

In early August 1945 — before the bombs had been dropped — a guide outlining the precise goals and form of the history was finalized. It explained that:

Tho purpose of the history is to serve as a source of historical information for War Department officials and other authorized individuals. Accordingly, the viewpoint of the writer should be that of General Groves and the reader should be considered as a layman without any specialized knowledge of the subject who may be critical of the Department or the project.

Which is remarkably blunt: write as if Groves himself was saying these things (because someday he might!), and write as if the reader is someone looking for something to criticize. Later the guide gives some specific examples on how to spin problematic things, like the chafing effect of secrecy:

For example, the rigid security restrictions of the project in many cases necessitated the adoption of unusual measures in the attainment of a local objective but the maintenance of security has been recognized throughout as an absolute necessity. Consequently, instead of a statement such as, “This work was impeded by the rigid security regulations of the District,” a statement such as, “The necessity of guarding the security of the project required that operations be carried on in — etc.” would be more accurate.1

This was the history that Groves grabbed whenever he did get hauled in front of Congress in the postwar (which happened less than he had feared, but it still happened). This was the history that the Atomic Energy Commission relied upon whenever it needed to find out what its predecessor agencies had done. It was a useful document to have around, because it contains all manner of statistics, technical details, legal details, and references to other documents in the archive.

"Dante's Inferno: A Pocket Mural" by Louis C. Anderson, a rather wonderful and odd drawing of the Calutron process. From Manhattan District History, Book 5, "Electromagnetic Project," Volume 6.

“Dante’s Inferno: A Pocket Mural” by Louis C. Anderson, a rather wonderful and odd drawing of the Calutron process. From Manhattan District History, Book 5, “Electromagnetic Project,” Volume 6.

The Manhattan District History became partially available to the general public in 1977, when a partial version of it was made available on microfilm through the National Archives and University Publications of America as Manhattan Project: Official History and Documents. The Center for Research Libraries has a digital version that you can download if you are part of a university that is affiliated with them (though its quality is sometimes unreadable), and I’ve had a digital copy for a long time now as a result.2 The 1977 microfilm version was missing several important volumes, however, including the entire book on the gaseous diffusion project, a volume on the acquisition of uranium ore, and many technical volumes and chapters about the work done at Los Alamos. All of this was listed as “Restricted” in the guide that accompanied the 1977 version.3

I was talking with Bill Burr of the National Security Archive sometime in early 2013 and it occurred to me that it might be possible to file a Freedom of Information Act request for the rest of these volumes, and that this might be something that his archive would want to do. I helped him put together a request for the missing volumes, which he filed. The Department of Energy got back pretty promptly, telling Bill that they were already beginning to declassify these chapters and would eventually put them online.

Manhattan Project uranium production flow diagram, from book 7, "Feed materials."

Manhattan Project uranium production flow diagram, from Manhattan District History, Book 7, “Feed materials.”

The DOE started to release them in chunks in the summer of 2013, and got the last files up this most recent summer. You can download each of the chapters individually on their website, but their file names are such that they won’t automatically sort in a sensible way in your file system, and they are not full-text searchable. The newly-released files have their issues — a healthy dose of redaction (and one wonders how valuable that still is, all these years — and proliferations — later), and some of the images have been run through a processor that has made them extremely muddy to the point of illegibility (lots of JPEG artifacts). But don’t get me started on that. (The number of corrupted PDFs on the NNSA’s FOIA website is pretty ridiculous for an agency that manages nuclear weapons.) Still, it’s much better than the microfilm, if only because it is rapidly accessible.

But you don’t need to do that. I’ve downloaded them all, run them through a OCR program so they are searchable, and gave them sortable filenames. Why? Because I want people — you — to be able to use these (and I do not trust the government to keep this kind of thing online). They’ve still got loads of deletions, especially in the Los Alamos and diffusion sections, and the pro-Groves bent to things is so heavy-handed it’s hilarious at times. And they are not all necessarily accurate, of course. I have found versions of chapters that were heavily marked up by someone who was close to the matter, who thought there were lots of errors. In the volumes I’ve gone the closest over in my own research (e.g. the “Patents” volume), I definitely found some places that I thought they got it a little wrong. But all of this aside, they are incredibly valuable, important volumes nonetheless, and I keep finding all sorts of unexpected gems in them.

You can download all of the 79 PDF files in one big ZIP archive on WARNING: the ZIP file is 760MB or so. You can also download the individual files below, if you don’t want them all at once.

Statistics on the ages of Los Alamos employees, from Ted Hall (19) to Niels Bohr (59). From Manhattan District History, Book 8.

Statistics on the ages of Los Alamos employees, May 1945, from the young spy, Ted Hall (19), to the old master, Niels Bohr (59). From Manhattan District History, Book 8.

What kinds of gems are hidden in these files? Among other things:

And a lot more. As you can see, I’ve drawn on this history before for blog and Twitter posts — I look through it all the time, because it offers such an interesting view into the Manhattan Project, and one that cuts through a lot of our standard narratives about how it worked. There are books and books worth of fodder in here, spread among some tens of thousands of pages. Who knows what might be hidden in there? Let’s shake things up a bit, and find something strange.

Below is the full file listing, with links to my OCR’d copies, hosted on Again, you can download all of them in one big ZIP file by clicking here, (760 MB) or pick them individually from below. Items marked with an asterisk are, as far as know, wholly new — the others have been available on microfilm in one form or another since 1977. Read the full post »

  1. E.H. Marsden, “Manhattan District History Preparation Guide,” (1 August 1945), copy in the Nuclear Testing Archive, Las Vegas, Nevada, accession number NV0727839. []
  2. In fact, I used portions of it — gasp! — on actual microfilm very early on my grad school career, when you still had to do that sort of thing. The volume on the patenting program was extremely useful when I wrote on Manhattan Project patent policies. []
  3. Some of the Los Alamos chapters were later published in redacted form as Project Y: The Los Alamos Story, in 1983. []