Enough Fallout for Everyone

Posted August 3rd, 2012 by Alex Wellerstein

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

But the fallout plume extended for hundreds of miles:

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

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

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

And remember… that’s just a single bomb!

Of course, if you’re interested in the more diffuse amounts of radioactivity — more than just the stuff that you know is probably bad for you — the fallout maps get even more interesting. Here’s what the BRAVO fallout did over the next month or so after the detonation:1

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

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

The same sorts of maps are used to show the dispersion of radioactive byproducts of nuclear reactors when accidents occur. I find these things sort of hypnotizing. Here are four “frames” from a simulation run by Lawrence Livermore National Laboratory on their ARAC computer showing the dispersion of radioactivity after the Chernobyl accident in 1986:2

Chernobyl ARAC simulation, day 2

Chernobyl ARAC simulation, day 4

Chernobyl ARAC simulation, day 6

Chernobyl ARAC simulation, day 10

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

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

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

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

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

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

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

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

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

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

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

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

  1. Image from “Nature of Radioactive Fall-Out and Its Effects on Man, Part 1,” Hearings of the Joint Committee on Atomic Energy, Special Joint Subcommittee on Radiation (May 27-29 and June 3, 1957), on 169. []
  2. These images are courtesy of the DOE Digital Archive. []

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11 Responses to “Enough Fallout for Everyone”

  1. Paul Guinnessy says:

    There’s a talk at Goddard today on this very issue regarding aerosols.

  2. Blake says:

    For a discussion on health effects of the Japan meltdowns, I recommend the paper by Hoeve and Jacobson “Worldwide health effects of the Fukushima Daiichi nuclear accident”. Long story short, the fallout levels outside of Japan are trivial and projected cancer deaths throughout all of North America are conservatively estimated at between 0-10 using the linear no threshold model. As many people have died of cancer in the US alone in the time it took me to write this. The paper’s Diablo Canyon meltdown simulations, I have to admit though, were pretty unsettling.

    • I think those models reflect that; outside of Japan the numbers drop off very quickly. Of course, that’s not a whole lot of relief for the Japanese, but it certainly helps that (unlike Chernobyl) all of that stuff just blew over a very large area of water, which is a much better place for it to disperse than, say, Eastern Europe.

      I hope the post didn’t come off as alarmist — I try to be realistic about these things.

  3. Mike Lehman says:

    Superimposing the CASTLE BRAVO plume on a map of the East Coast graphically illustrated the impracticality of war in the age of thermonuclear weapons. The Air Force got what it wanted, then began to realize that they really didn’t want or need it a few years later. Why? In part, it was fallout. I am still surprised the map was declassified as early as it was, but the Lucky Dragon and hundreds of native islanders made it impossible to keep this event quiet. And that is important.

    In 1954, fallout was:
    1. Officially, nothing more than a “nuisance.”*
    2. A highly classified source of intelligence.

    * A 1950 atomic weapon effects card issued to military personnel described fallout as a “nuisance.”

    CASTLE BRAVO was as much a compromise of an intelligence method as it was an environmental disaster. And anything that could spread 7,000 square miles of lethal to near-lethal fallout is way more than a “nuisance.” It’s a little hard to get your mind around how secret most information was about fallout was then. There was still very little actual data available on it even as people began clamoring for fallout shelters in the late 50s as the realization of what it took to defeat it sank in.

    The dispersion maps are deceiving though, as they only show one side of fallout’s life cycle, its dispersion. True enough, that’s what you’re worried about if you see a mushroom cloud upwind from your location. It’s what happens next to fallout (or radiation escaping from Fukushima) that such maps fail to show — the re-concentration of the various isotopic constituents of fallout by a variety of biological and environmental means.

    Think about it for a moment. Dispersion is good, right? If it continued to infinity, even better, especially assuming that graphical representation meant this stuff was really being diluted and spread evenly throughout the environment…

    But it’s not.

    Plutonium is pretty nasty stuff. Inhale a tiny chunk and you may have sealed your fate. The models do a good job of roughly mapping the dispersion side of things, but they really don’t account for that tiny bit of Pu, which is concentrated and will stay concentrated at that point enough to do potentially lethal damage to your body. This was referred to as the “hot-point problem” and is a relatively unexplored issue that is one of the unfinished bits of science that might tell us more about the threats posed by radiation.

    Moving on to my main point here, we need more maps and graphics that illustrate the various ways in which fallout and other radiation are re-concentrated once dispersed. Japan was very lucky that most of the plume from Fukushima headed out to sea, with much of it falling over the ocean where the currents further dispersed it. But eventually even the ocean begins to re-concentrate radiation, as the various and sundry food chains inevitably do.

    On land, the most telling example is that of I-131. With a short half-life, it was considered relatively inconsequential in the scope of fallout risks, until the 1957 Windscale reactor accident demonstrated the ways in which it was quickly re-concentrated. I-131 is deposited on grass at the last stage of its dispersion. Cows eat grass, concentrate I-131 in their milk. Babies drink milk, where I-131 is concentrated in their thyroid at clearly dangerous levels.

    Guess what? Until this process was understood, measuring I-131 in the environment showed it was usually present at levels that were considered far too low to be of concern. But this was obviously misleading, as we now know. So are dispersion maps in the absence of their connection to the environmental processes that inevitably reverse the process of dispersion.

    • Good comments as usual, Mike. I appreciate them.

      Side-note: It’s pretty clear that the BRAVO map was declassified almost exclusively because of the Lucky Dragon incident. (I wonder if it would have been if it had just been Marshallese who were exposed.) However, it’s a very generalized map — and it’s not even clear that it’s strictly accurate.

      Here are three different maps of the BRAVO fallout produced by different sources: AFSWP, NRDL, and RAND. They’re each pretty different — the AFSWP one looks the most like the declassified map (though it is more specific). The NRDL one shows a much “fatter” distribution. The RAND one shows a significant “hot spot” of radioactivity further out from the blast, which significantly complicates any assumptions about the fallout being linearly distributed over distance.

      Which of these is correct? I don’t really know — but it’s interesting to me that there were so many, and how different they were from the “official” one that was declassified.

      • Mike Lehman says:

        Thanks for the other maps. Not knowing the exact provenance of each. I’ll hazard a guess based on my general readings of such testing documents.

        AFSWP (Armed Forces Special Weapons Project — became DASA, IIRC) and AFOAT-1 often worked together, with AFSWP being credited for AFOAT-1′s work as a means to provide cover to it.

        NRDL (Navy Radiation Defense Laboratory) did a lot of work on fallout shelters, but also other defensive measures against radiation like measuring instruments, etc. The founder of the Program in Arms Control, Disarmament and International Security here at the University of Illinois Urbana-Champaign, Arthur Chilton, served at NRDL while in the Navy. Since it’s one of my few published works so far, here’s a link to the ACDIS history:

        RAND did lots of work for the Air Force, including modeling of fallout dispersal.

        My take is that the different plume maps were produced from data generated by different sampling and monitoring methods. AFSWP’s map may be from Air Weather Service sampling aircraft operating in support of and/or training under the direction of AFOAT-1. NRDL’s data may have come from surface vessels and — possibly — from drones not involved in direct sampling support of the test task force, which was usually done by the Air Force. The RAND map may be from a model and based on the other data collected. Pretty much just speculation on my part in the absence of more context.

        One thing’s for sure despite the variance. It was bad day for fallout.

  4. kenneth wolf says:

    I was on the USS CURTISS AV-4 during the bravo test. this video brought back memories long forgotten. Is there any record of the amount of radiation on the CURTISS before march 21,1954?

  5. [...] There are also still many nice mugs: Los Alamos security badge photographs American nuclear targets in the USSR, 1945 The fallout plume from the Castle Bravo hydrogen bomb test, 1954 [...]

  6. […] model, though, made me realize how little I really understood about nuclear fallout. I mean, my general understanding was still right, but I had a few subtle-but-important revelations that changed the way I thought about nuclear […]

  7. jack says:

    was looking for an answer to this – did i miss it?

    how does Fukushima contamination compare with Castle Bravo and more to the point, overall contamination from all test shots executed in the Pacific Proving Ground (over 100)?

    Arnie Gunderson on a radio talk show this morning answered that Fukushima contamination is far worse – wasn’t time to pressure on the air for proof, but it’s hard to believe

    any insight?

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