Posts Tagged ‘NUKEMAP’

Visions

The bomb and its makers

Tuesday, July 30th, 2013

In part of the "make this blog actually work again" campaign, I've changed some things on the backend which required me to change the blog url from http://nuclearsecrecy.com/blog/ to http://blog.nuclearsecrecy.com/. Fortunately, even if you don't update your bookmarks, the old links should all still work automatically. It seems to be working a lot better at the moment — in the sense that I can once again edit the blog — so that's something!


In all of the new NUKEMAP fuss, and the fact that my blog kept crashing, I didn't get a chance to mention that I had two multimedia essays up on the website of The Bulletin of the Atomic Scientists. I'm pretty happy with both of these, both visually and in terms of the text.

The first was published a few weeks ago, and was related to my much earlier post relating to the badge photographs at Los Alamos. "The faces that made the Bomb" has so far proved to be the one thing I've done that people end up bringing up in casual conversation without realizing I wrote it. (The scenario is, I meet someone new, I mention I work on the history of nuclear weapons, they ask me if I've seen this thing on the Internet about the badge photographs, I answer that I in fact wrote it, a slight awkwardness follows.)

Charlotte_Serber

Some of the badge photographs are the ones that anyone on here would be familiar with — Oppenheimer, Groves, Fuchs, etc. But I enjoyed picking out a few more obscure characters. One of my favorites of these is Charlotte Serber, wife of the physicist and Oppenheimer student Robert Serber. Here's my micro-essay:

Charlotte Serber was one of the many wives of the scientists who came to Los Alamos during the war. She was also one of the many wives who had their own substantial jobs while at the lab. While her husband, Robert Serber, worked on the design of the first nuclear weapons, Charlotte was the one in charge of running the technical library. While “librarian” might not at first glance seem vital to the war project, consider J. Robert Oppenheimer’s postwar letter to Serber, thanking her that “no single hour of delay has been attributed by any man in the laboratory to a malfunctioning, either in the Library or in the classified files. To this must be added the fact of the surprising success in controlling and accounting for the mass of classified information, where a single serious slip might not only have caused us the profoundest embarrassment but might have jeopardized the successful completion of our job.” Serber fell under unjustified suspicion of being a Communist in the immediate postwar, and, according to her FBI file, her phones were tapped. Who had singled her out as a possible Communist, because of her left-wing parents? Someone she thought of as a close personal friend: J. Robert Oppenheimer.

Charlotte was also the only woman Division Leader at Los Alamos, as the director of the library. She was also the only Division Leader barred from attending the Trinity test — on account of a lack of "facilities" for women there. She considered this a gross injustice.

What I like about Charlotte is not only that she highlights that many of the "Los Alamos wives" actually did work that was crucial to the project (and there were scientists amongst the "wives" as well, such as Elizabeth R. Graves, who I also profiled), and that the work of a librarian can be pretty vital (imagine if they didn't have good organization of their reports, files, and classified information). But I also find Charlotte’s story amazing because of the betrayal: Oppenheimer the friend, Oppenheimer the snitch.

I should note that Oppenheimer's labeling of Charlotte was probably not meant to be malicious — he was going over lists of people who might have Communist backgrounds when talking to the Manhattan Project security officers. He rattled off a number of names, and even said he thought most of them probably weren't themselves Communists. This, of course, meant that they got flagged as possible Communists for the rest of their lives. Oppenheimer's attempt to look loyal to the security system, even his attempts to be benign about it, were terrible failures in the long run, both for him and for his poor friends. Albert Einstein put it well: "The trouble with Oppenheimer is that he loves a woman who doesn't love him—the United States government."

Kenneth Bainbridge

The other one I want to highlight on here is that of Kenneth T. Bainbridge. Bainbridge was Harvard physicist and was in charge of organizing Project Trinity, the first test of the atomic bomb in July 1945. It was a big job — bigger, I think, than most people realize. You don’t just throw an atomic bomb on top of a tower in the desert and set it off. It had a pretty large staff, required a ton of theoretical and practical work, and, in the end, was an experiment that, ideally, destroyed itself in the process. Here was my Bainbridge blurb:

During the Manhattan Project, Harvard physicist Kenneth Bainbridge was in charge of setting up the Trinity test—afterward he became known as the person who famously said: “Now we are all sons of bitches.” Years later he wrote a letter to J. Robert Oppenheimer explaining his choice of words: “I was saying in effect that we had all worked hard to complete a weapon which would shorten the war but posterity would not consider that phase of it and would judge the effort as the creation of an unspeakable weapon by unfeeling people. I was also saying that the weapon was terrible and those who contributed to its development must share in any condemnation of it. Those who object to the language certainly could not have lived at Trinity for any length of time.” Oppenheimer’s reply to Bainbridge’s sentiments was simple: “We do not have to explain them to anyone.

I’ve had that Bainbridge/Oppenheimer exchange in my files for a long time, but never really had a great opportunity to put it into print. To flesh out the context a little more, it came out in the wake of Lansing Lamont’s popular book, Day of Trinity (1965). Bainbridge was one of the sources Lamont had talked to, and he gave him the “sons of bitches” quote. Oppenheimer’s full reply to Bainbridge took some digs at the book:

“When Lamont’s book on Trinity came, I first showed it to Kitty; and a moment later I heard her in the most unseemly laughter. She had found the preposterous piece about the ‘obscure lines from a sonnet of Baudelaire.’ But despite this, and all else that was wrong with it, the book was worth something to me because it recalled your words. I had not remembered them, but I did and do recall them. We do not have to explain them to anyone.”

The “obscure lines” was some kind of code supposedly sent by Oppenheimer to Kitty to say that the test worked. In Bainbridge’s files at the Harvard Archives there is quite a lot of material on the Lamont book from other Manhattan Project participants — most of them found a lot of fault with it on a factual basis, but admired its writing and presentation.

Bainbridge makes for a good segue into my other BAS multimedia essay, “The beginning of the Bomb,” which is about the Trinity test and which came out just before the 68th anniversary, which was two weeks ago. It also was somewhat of a reprise of themes I’d first played with on the blog, namely my post on “Trinity’s Cloud.” I’ve been struck that while Trinity was so extensively documented, the same few pictures of it and its explosion are re-used again and again. Basically, if it isn’t one of the “blobs of fire” pictures, or the Jack Aeby early-stage fireball/cloud photograph (the one used on the cover of The Making of the Atomic Bomb), then it doesn’t seem to exist. Among other things related to Trinity, I got to include two of my favorite alternative Trinity photographs.

Trinity long exposure

The first is this ghostly apparition above. What a strange, occult thing the atomic bomb looks like in this view. While most photographs of the bomb are concerned about capturing it at a precise fraction of a second — a nice precursor to the famous Rapatronic photographs of the 1950s — this one does something quite different, and quite unusual. This is a long exposure photograph of several seconds of the explosion. The caption indicates (assuming I am interpreting it correctly) that it is an exposure of several seconds before the explosion and then two seconds after the beginning of the detonation. Which would explain why there are so many pre-blast details available to see.

The result is what you see here: a phantom whose resemblance to the “classic” Trinity explosion pictures is more evocative than definite. And if you view it at full size, you can just make out features of the desert floor: the cables that held up the tower, for example. (Along with some strange, blobby artifacts associated with dark room work.) I somewhat wish this was the image of “the atomic bomb” that we all had in our minds — dark, ghastly, tremendous. Instead of seeing just a moment after the atomic age began, we instead see in a single image the transition between one age and the next.

Trinity mushroom cloud

Most of the photographs of Trinity are of its first few seconds. But this one is not. It may be the only good photograph I have seen of the late-stage Trinity mushroom cloud. It is striking, is it not? A tall, dark column of smoke, lightly mushroomed at the top, with a larger cloud layer above it. “Ominous” is the word I keep coming back to, especially once you know that the cloud in question was highly radioactive.

One of the things I found while researching the behavior of mushroom clouds for the NUKEMAP3D was that while the mushroom cloud is an ubiquitous symbol of the bomb, it is specifically the early-stage mushroom cloud whose photograph gets shown repeatedly. Almost all nuclear detonation photographs are of the first 30 second or so of the explosion, when the mushroom cloud is still quite small, and usually quite bright and mushroomy. The late-stage cloud — about 4-10 minutes, depending on the yield of the bomb — is a much larger, darker, and unpleasant thing.

Why did we so quickly move from thinking of the atomic bomb as a burst of fire into a cloud of smoke? The obvious answer would be Hiroshima and Nagasaki, where we lacked the instrumentation to see the fireball, and only could see the cloud. But I’m still struck that our visions of these things are still so constrained to a few examples, a few moments in time, out of so many other possibilities, each with their own quite different visual associations.

News and Notes | Visions

The NUKEMAPs are here

Thursday, July 25th, 2013

I’m super excited to announce that last Thursday, at an event hosted by the Center for Nonproliferation Studies at the Monterey Institute for International Study, I officially launched NUKEMAP2 and NUKEMAP3D. I gave a little talk, which I managed to record, but I haven’t had the time (more details below on why!) to get that up on YouTube yet. Soon, though.

A Soviet weapon from the Cuban Missile Crisis, centered on Washington, DC, with fallout and casualties shown.

A Soviet weapon from the Cuban Missile Crisis, centered on Washington, DC, with fallout and casualties shown.

NUKEMAP2 is an upgraded version of the original NUKEMAP, with completely re-written effects simulations codes that allow one a huge amount of flexibility in the nuclear detonation one is trying to model. It also allows fallout mapping and casualty counts, among other things. I wanted to make it so that the NUKEMAP went well beyond any other nuclear mapping tools on the web — I wanted it to be a tool that both the layman and the wonk could use, a tool that rewarded exploration, and a tool that, despite the limitations of a 2D visualization, could work to deeply impress people with the power of a nuclear explosion.

The codes that underly the model are all taken from Cold War effects models. At some point, once it has been better documented than it is now, I’ll probably release the effects library I’ve written under an open license. I don’t think there’s anything quite like it out there at the moment available for the general public. For the curious, there are more details about the models and their sources here.

The mushroom cloud from a 20 kiloton detonation, centered on downtown DC, as viewed from one of my common stomping grounds, the Library of Congress.

The mushroom cloud from a 20 kiloton detonation, centered on downtown DC, as viewed from one of my common stomping grounds, the Library of Congress.

NUKEMAP3D uses Google Earth to allow “3D” renderings of mushroom clouds and the nuclear fireball. Now, for the first time, you can visualize what a mushroom cloud from a given yield might look like on any city in the world, viewed from any vantage-point you can imagine. I feel like it is safe to say that there has never been a nuclear visualization tool of quite this nature before.

I got the idea for NUKEMAP3D while looking into a story for the Atlantic on a rare photo of the Hiroshima mushroom cloud. One of the issues I was asked about was how long after the detonation the photograph was taken — the label on the back of the photograph said 30 minutes, but there was some doubt. In the process of looking into this, I started to dig around the literature on mushroom cloud formation and the height of the Hiroshima cloud at various time intervals. I realized that I had no sense for what “20,000 feet” meant in terms of a cloud, so I used Google Earth to model a simple 20,000 foot column above the modern-day city of Hiroshima.

I was stunned at the size of it, when viewed from that perspective — it was so much larger than it even looked in photographs, because the distance that such photographs were taken from makes it very hard to get a sense of scale. I realized that modeling these clouds in a 3D environment might really do something that a 2D model could not. It seems to switch on the part of the brain that judges sizes and areas in a way that a completely flat, top-down overlay does not. The fact that I was surprised and shocked by this, despite the fact that I look at pictures of mushroom clouds probably every day (hey, it’s my job!), indicated to me that this could be a really potent educational tool.

That same 20 kiloton cloud, as viewed from airplane height.

That same 20 kiloton cloud, as viewed from airplane height.

I’m also especially proud of the animated mode, which, if I’m allowed to say, was a huge pain in the neck to program. Even getting a somewhat “realistic”-looking cloud model was a nontrivial thing in Google Earth, because its modeling capabilities are somewhat limited, and because it isn’t really designed to let you manipulate models in a detailed way. It lets you scale model sizes along the three axes, it allows you to rotate them, and it allows you to change their position in 3D space. So I had to come up with ways of manipulating these models in realtime so that they would approximate a semi-realistic view of a nuclear explosion, given these limitations.

It’s obviously not quite as impressive as an actual nuclear explosion (but what is?), and my inability to use light as a real property (as you could in a “real” 3D modeling program) diminishes things a bit (that is, I can’t make it blinding, and I can’t make it cast shadows), but as a first go-around I think it is still a pretty good Google Earth hack. And presumably Google Earth, or similar tools, will only get better and more powerful in the future.

Screen captures of the animation for a 20 kt detonation over DC. These screenshots were taken in 10 second intervals, but are accelerated 100X here. The full animation takes about five minutes to run, which is roughly how the cloud would grow in real life.

Screen captures of the animation for a 20 kt detonation over DC. These screenshots were taken in 10 second intervals, but are accelerated 100X here. The full animation takes about five minutes to run, which is roughly how the cloud would grow in real life.

If you’ve been following my Twitter feed, you also probably have picked up that this has been a little bit of a saga. I tried to launch it on last Thursday night, but the population database wasn’t really working very well. The reason is that it is very, very large — underneath it is a population density map of the entire planet, in a 1km by 1km grid, and that means it is about 75 million records (thank goodness for the oceans!). Optimizing the queries helped a bit, and splitting the database up helped a bit. I then moved the whole database to another server altogether, just to make sure it wasn’t dragging down the rest of the server. But on Monday,just when the stories about NUKEMAP started to go up, my hosting company decided it was too much traffic and that I had, despite “unlimited bandwidth” promises, violated the Terms of Service by having a popular website (at that point it was doing nothing but serving up vanilla HTML, Javascript, and CSS files, so it wasn’t really a processing or database problem). Sigh. So I frantically worked to move everything to a different server, learned a lot about systems administration in the process, and then had the domain name issue a redirect from the old hosting company. And all of that ended up taking a few days to finalize (the domain name bit was frustratingly slow, due to settings chosen by the old hosting company).

But anyway. All’s well that ends well, right? Despite the technical problems, since moving the site to the new server, there have been over 1.2 million new “detonations” with the new NUKEMAPs, which is pretty high for one week of sporadic operation! 62% of them are with NUKEMAP3D, which is higher than I’d expected, given the computer requirements required to run the Google Earth plugin. The new server works well most of the time, so that’s a good thing, though there are probably some tweaks that still need to be done for it to happily run the blog and the NUKEMAPs. There is, though I don’t want to make it too intrusive or seem too irritating, a link now on the NUKEMAP for anyone who wanted to chip in to the server fund. Completely optional, and not expected, but if you did want to chip in, I can promise you a very friendly thank-you note at the very least.

Now that this is up and “done” for now, I’m hoping to get back to a regular blogging schedule. Until then, try out the new NUKEMAPs!

News and Notes

Presenting NUKEMAP2 and NUKEMAP3D

Monday, July 22nd, 2013

A longer post is coming later today, but in the meantime, I just wanted to make sure anyone on here knows that NUKEMAP2 and NUKEMAP3D are now online:

  • NUKEMAP2: sequel to the original NUKEMAP, with newly-derived effects equations and lots of brand-new options, including crater size, radioactive fallout plumes (with adjustable wind speeds and fission fractions!), and casualty counts! 
  • NUKEMAP3D: the next dimension of nuclear effects mapping, with 3D modeling and real-time animations of custom-built mushroom clouds and nuclear fireballs.

The mushroom cloud from a 20 kiloton explosion, centered on downtown San Francisco, as viewed from my old house in the Berkeley Hills. Estimated fatalities: 75,200.

The mushroom cloud from a 20 kiloton explosion, centered on downtown San Francisco, as viewed from my old house in the Berkeley Hills. Estimated fatalities: 75,200.

Technically the sites went live last Thursday, July 18, but there were some technical issues that took until the weekend to finalize (if they are, indeed, finalized) due to the heavy database usage of the new features (e.g. the casualty database). But I've moved things around a bit, optimized some sloppy queries, and now things seem to be doing pretty good despite being under a very heavy user load. More information soon!

News and Notes | Visions

The new NUKEMAP is coming

Friday, July 12th, 2013

I'm excited to announce, that after a long development period, that the new NUKEMAP is going to debut on Thursday, July 18th, 2013. There will be an event to launch it, hosted by the James Martin Center for Nonproliferation Studies of the Monterey Institute of International Studies in downtown Washington, DC, from 10-11:30 am, where I will talk about what it can do, why I've done it, and give a demonstration of how it works. Shortly after that, the whole thing will go live for the entire world.

Nukemap preview - fallout

Radioactive fallout dose contours from a 2.3 megaton surface burst centered on Washington, DC, assuming a 15 mph wind and 50% yield from fission. Colors correspond to 1, 10, 100, and 1,000 rads-per-hour at 1 hour. This detonation is modeled after the Soviet weapons in play during the Cuban Missile Crisis.

I don't want to spill all of the beans early, but here's a teaser. There is not just one new NUKEMAP. There are two new NUKEMAPs. One of them is a massive overhaul of the back-end of the old NUKEMAP, with much more flexible effects calculations and the ability to chart all sorts of other new phenomena — like radioactive fallout (finally!), casualty estimates, and the ability to specify airbursts versus ground bursts. All of these calculations are based on models developed by people working for the US government during the Cold War for use in government effects planning. So you will have a lot of data at your instant disposal, should you want it, but all within the smooth, easy-t0-use NUKEMAP interface you know and love.

This has been a long time in development, and has involved me chasing down ancient government reports, learning how to interpret their equations, and converting them to Javascript and the Google Maps API. So you can imagine how "fun" (read: not fun) that was, and how Beautiful Mind my office and home got in the process. And as you've no doubt noticed in the last few weeks, doing obsessive, detailed, mathematical technical work in secret all week did not give me a lot of inspiration for historical blog posts! So I'll be glad to move on from this, and to get it out in the light of day. (Because unlike the actual government planners, my work isn't classified.)

Above is an image from the report which I used to develop the fallout model. Getting a readable copy of this involved digging up an original copy at the National Library of Medicine, because the versions available in government digital databases were too messed up to reliably read the equations. Some fun: none of this was set up for easy translation into a computer, because nobody had computers in the 1960s. So it was designed to help you draw these by hand, which  made translating them into Javascript all the more enjoyable. More fun: many of these old reports had at least one typo hidden in their equations that I had to ferret out. Well, perhaps that was for the best — I feel I truly grok what these equations are doing at this point and have a lot more confidence in them than the old NUKEMAP scaling models (which, by the way, are actually not that different in their radii than the new equations, for all of their simplifications).

But the other NUKEMAP is something entirely new. Entirely different. Something, arguably, without as much historical precedent — because people today have more calculation and visualization power at their fingertips than ever before. It's one thing for people to have the tools to map the bomb in two dimensions. There were, of course, even websites before the NUKEMAP that allowed you to do that to one degree or another. But I've found that, even as much as something like the NUKEMAP allows you to visualize the effects of the bomb on places you know, there was something still missing. People, myself included, were still having trouble wrapping their heads around what it would really look like for something like this to happen. And while thinking about ways to address this, I stumbled across a new approach. I'll go into it more next week, but here's a tiny teaser screenshot to give you a bit of an indication of what I'm getting about.

Nukemap preview

That's the cloud from a 10 kiloton blast — the same yield as the North Korean's 2013 test, and the model the US government uses for a terrorist nuclear weapon — on mid-town Manhattan, as viewed from New York harbor. Gives you a healthy respect for even a "small" nuclear weapon. And this is only part of what's coming.

Much more next week. July 18th, 2013 — two days after the 68th-anniversary of the Trinity test — the new NUKEMAPs are coming. Tell your friends, and stay tuned.

Redactions | Visions

Castle Bravo revisited

Friday, June 21st, 2013

No single nuclear weapons test did more to establish the grim realities of the thermonuclear age than Castle BRAVO. On March 1, 1954, it was the highest yield test in the United States' highest-yield nuclear test series, exploding with a force of 15 million tons of TNT. It was also the greatest single radiological disaster in American history. 

Castle BRAVO, 3.5 seconds after detonation, photo taken from a distance of 75 nautical miles from ground zero, from an altitude of 12,500 feet. From DTRIAC SR-12-001.

Castle BRAVO, 3.5 seconds after detonation, photo taken from a distance of 75 nautical miles from ground zero, from an altitude of 12,500 feet. From DTRIAC SR-12-001.

Among BRAVO's salient points:

  • It was the first "dry fuel" hydrogen bomb test by the United States, validating that lithium-deuteride would work fine as a fusion fuel and making thermonuclear weapons relatively easy to deploy.
  • It had a maximum predicted yield of only 6 megatons — so it was 250% as explosive than was expected.
  • And, of course, it became famous for raining nuclear fallout down on inhabited islands over a hundred miles downwind, and exposing a crew of Japanese fishermen to fatal levels of radiation.

It was this latter event that made BRAVO famous — so famous that the United States had to admit publicly it had a hydrogen bomb. And accidentally exposing the Japanese fishing supply to radiation, less than a decade after Hiroshima and Nagasaki, has a way of making the Japanese people understandably upset. So the shot led to some almost frank discussion about what fallout meant — that being out of the direct line of fire wasn't actually good enough.

Animation showing the progression of BRAVO's fallout exposure, at 1, 3, 6, 12, and 18 hours. Original source.

Animation showing the progression of BRAVO's fallout exposure, at 1, 3, 6, 12, and 18 hours. Original source.

I say "almost frank" because there was some distinct lack of frankness about it. Lewis Strauss, the secrecy-prone AEC Chairman at the time and an all-around awful guy, gave some rather misleading statements about the reasons for the accident and its probable effects on the exposed native populations. His goal was reassurance, not truth. But, as with so many things in the nuclear age, the narrative got out of his control pretty quickly, and the fear of fallout was intensified whether he wanted it to be or not.

We now know that the Marshallese suffered quite a lot of long-term harm from the exposures, and that the contaminated areas were contaminated for a lot longer than the AEC guessed they would be. Some of this discrepancy comes from honest ignorance — the AEC didn't know what they didn't know about fallout. But a lot of it also came from a willingness to appear on top of the situation, when the AEC was anything but.

"Jabwe, the Rongelap health practitioner, assists Nurse Lt. M. Smith and Dr. Lt. J. S. Thompson, during a medical examination on Kwajalein, 11 March 1954." From DTRIAC SR-12-001.

"Jabwe, the Rongelap health practitioner, assists Nurse Lt. M. Smith and Dr. Lt. J. S. Thompson, during a medical examination on Kwajalein, 11 March 1954." From DTRIAC SR-12-001.

I've been interested in BRAVO lately because I've been interested in fallout. It's no secret that I've been working on a big new NUKEMAP update (I expect it to go live in a month or so) and that fallout is but one of the new amazing features that I'm adding. It's been a long-time coming, since I had originally wanted to add a fallout model a year ago, but it turned out to be a non-trivial thing to implement. It's not hard to throw up a few scaled curves, but coming up with a model that satisfies the aesthetic needs of the general NUKEMAP user base (that is, the people who want it to look impressive but aren't interested in the details) and also has enough technical chops so that the informed don't just immediately dismiss it (because I care about you, too!) involved digging up some rather ancient fallout models from the Cold War (even going out to the National Library of Medicine to get one rare one in its original paper format) and converting them all to Javascript so they can run in modern web browsers. But I'm happy to say that as of yesterday, I've finally come up with something that I'm pleased with, and so I can now clean up my Beautiful Mind-style filing system from my office and living room.

Why yes, you can

The most famous version of BRAVO's total-dose exposure contours, from Glasstone and Dolan. It looks great on a mug, by the way.

Recently I was sent a PDF of a recent report (January 2013) by the Defense Threat Reduction Information Analysis Center (DTRIAC) that looked back on the history of BRAVO. It doesn't seem to be easily available online (though it is unclassified), so I've posted it here: "Castle Bravo: Fifty Years of Legend and Lore (DTRIAC SR-12-001)." I haven't had time to read the whole thing, but skipping around has been rewarding — it takes a close look at the questions of fallout prediction, contamination, and several "myths" that have circulated since 1954. It notes that the above fallout contour plot, for example, was originally created by the USAF Air Research and Development Command (ARDC), and that "it is unfortunate that this illustration has been so widely distributed, since it is incorrect." The plume, they explain, actually under-represents the extent of the fallout — the worst of the fallout went further and wider than in the above diagram.

You can get a sense of the variation by looking at some of the other plots created of the BRAVO plume:

BRAVO fallout contours produced by the AFSWP, NRDL, and RAND Corp. Source.

BRAVO fallout contours produced by the Armed Forces Special Weapons Project, Naval Radiological Defense Laboratory, and the RAND Corporation. Source. Click image to enlarge.

The AFSWP diagram on the left is relatively long and narrow; the NRDL one in the middle is fat and horrible. The RAND one at the right is something of a compromise. All three, though, show the fallout going further than the ADRC model — some 50-100 miles further. On the open ocean that doesn't matter so much, but apply that to a densely populated part of the world and that's pretty significant!

DTRIAC SR-12-001 is also kind of amazing in that it has a lot of photographs of BRAVO and the Castle series that I'd never seen before, some of which you'll see around this post. One of my favorites is this one, of Don Ehlher (from Los Alamos) and Herbert York (from Livermore) in General Clarkson's briefing room on March 17, 1954, with little mockups of the devices that were tested in Operation Castle:

Ehler and York - Operation Castle devices

There's nothing classified there — the shapes of the various devices have long been declassified — but it's still kind of amazing to see of their bombs on the table, as it were. They look like thermoses full of coffee. (The thing at far left might be a cup of coffee, for all that I can tell —  unfortunately the image quality is not great.)

It also has quite a lot of discussion of several persistent issues regarding the exposure of the Japanese crew and the Marshallese natives. I didn't see anything especially new here, other than the suggestion that the fatality from the Fortunate Dragon fishing boat might have been at least partially because of the very aggressive-but-ineffective treatment regime prescribed by the Japanese physicians, which apparently included the very dubious procedure of repeatedly drawing his blood and then re-injecting it into muscle tissue. I don't know enough of the details to know what to think of that, but at least they do a fairly good job of debunking the notion that BRAVO's contamination of the Marshallese was deliberate. I've seen that floating around, even in some fairly serious forums and publications, and it's just not supported by real evidence.

Castle BRAVO, 62 seconds after detonation. "This image was take at a distance of 50 [nautical miles] north GZ from an altitude of 10,000 feet. The lines running upward to the left of the stem and below the fireball are smoke trails from small rockets. At this time the cloud stem was about 4 mi in diameter." From DTRIAC SR-12-001.

Castle BRAVO, 62 seconds after detonation. "This image was take at a distance of 50 [nautical miles] north GZ from an altitude of 10,000 feet. The lines running upward to the left of the stem and below the fireball are smoke trails from small rockets. At this time the cloud stem was about 4 mi in diameter." From DTRIAC SR-12-001.

One thing that I hadn't appreciated as well before is that BRAVO is pretty much a worst-case scenario from a radiological point of view. It was a very high-yield weapon that was very "dirty" right out of the box: 10 of its 15 megatons (67%) were from fission.1

It was detonated as a surface burst, which automatically means quite a significant fallout problem. Nuclear weapons that detonate so that their fireball does not come into contact with the ground release "militarily insignificant" amounts of fallout, even if their yields are very high. (They are not necessarily "humanly insignificant" amounts, but they are far, far, far less than surface bursts — it is not a subtle difference.2 )

But even worse, it was a surface burst in a coral reef, which is just a really, really bad idea. Detonating nuclear weapons on a desert floor, like in Nevada, still presents significant fallout issues. But a coral reef is really an awful place to set them off, and not just because coral reefs are awesome and shouldn't be blown up. They are an ideal medium for creating and spreading contamination: they break apart with no resistance, but do so in big enough chunks that they rapidly fall back to Earth. Particle size is a big deal when it comes to fallout; small particles go up with the fireball and stay aloft long enough to lose most of their radioactive energy and diffuse into the atmosphere, while heavy particles fall right back down again pretty quickly, en masse. So blowing up and irradiating something like coral is just the worst possible thing.3

Castle BRAVO, 16 minutes after detonation, seen from a distance of 50 nautical miles, at an altitude of 10,000 feet. From DTRIAC SR-12-001.

Castle BRAVO, 16 minutes after detonation, seen from a distance of 50 nautical miles, at an altitude of 10,000 feet. From DTRIAC SR-12-001.

Note that the famous 50 Mt "Tsar Bomba" lacked a final fission stage and so only 3% of its total yield — 1.5 Mt — was from fission. So despite the fact that the Tsar Bomba was 3.3 times as explosive than Castle Bravo, it had almost 7 times fewer fission products. And its fireball never touched the ground (in fact, it was reflected upwards by its own shock wave, which is kind of amazing to watch), so it was a very "clean" shot radiologically. The "full-sized," 100 Mt Tsar Bomba would have been 52% fission — a very dirty bomb indeed.

In the end, what I've come to take away from BRAVO is that it actually was a mistake even more colossal than one might have originally thought. It was a tremendously bad idea from a human health standpoint, and turned into a public relations disaster that the Atomic Energy Commission never really could kick. 

In retrospect the entire "event" seems to have been utterly avoidable as a radiological disaster, even with all of the uncertainties about yield and weather. It's cliché to talk about nuclear weapons in terms of playing with "forces of nature beyond our comprehension," but I've come to feel that BRAVO is a cautionary tale about hubris and incompetence in the nuclear age — scientists setting off a weapon whose size they did not know, whose effects they did not correctly forecast, whose legacy will not soon be outlived.

Notes
  1. Chuck Hansen, Swords of Armageddon, IV-299. []
  2. The count difference is about three orders of magnitude or so less, judging by shots like Redwing CHEROKEE. That's still a few rads, but the difference between 1,000 and 1 rad/hr is pretty significant. []
  3. Couldn't they have foreseen this? In theory, yes — they had already blown up a high-yield, "dirty" fission hydrogen bomb on a coral reef in 1952, the MIKE test. But somewhere a number of AEC planners seem to have gotten their wires crossed, because a lot of them thought that MIKE had very little fallout, when in fact it also produced a lot of very similar contamination. Unlike BRAVO, however, MIKE's fallout blew out over open sea. The only radiation monitoring seems to have been done on the islands, and so they don't seem to have ever drawn up one of those cigar-shaped plumes for it. See e.g. the discussion here on page 51. []