Forbidden spheres

by Alex Wellerstein, published August 29th, 2012

Spheres are special shapes for nuclear weapons designers. Most nuclear weapons have, somewhere in them, that spheres-within-spheres arrangement of the implosion nuclear weapon design. You don’t have to use spheres — cylinders can be made to work, and there are lots of rumblings and rumors about non-spherical implosion designs around these here Internets — but spheres are pretty common.

A photograph of a rather suspicious sphere-within-a-hemisphere, from the inside of Israel’s secret nuclear site, Dimona, taken by Mordechai Vanunu in 1986.

Spheres also happen to be fairly common sights in the non-nuclear weapons design as well. What interests me is what happens when you take a perfectly non-nuclear sphere, like, say, a soccer ball, and move it into a nuclear context. To the trained eye, it takes on a rather interesting new meaning:

Image from the cover of A.Q. Khan on Science and Education.

Presumably Dr. Khan was not using the ball above to express his love of sport, but instead was using it to convey in broad terms what the truncated icosahedron shape has to do with implosion weapons — it is the geometry of the explosive lenses used in the Trinity “gadget” and “Fat Man” bomb designs, similar to the one sketched on the upper-right side of the chalkboard above.

(I will just also note that somebody — presumably not Dr. Khan himself, but who knows — has rendered in chalk a truly excellent reproduction of figure 2.07a from Glasstone and Dolan’s Effects of Nuclear Weapons, 1977 edition.)

All of which is to say that spheres are important from a nuclear point of view, and the context of spheres can change their meaning dramatically. Nothing too surprising or controversial there, I hope.

Such is the background I want you to be thinking of when you read the below line item from the notes of a Technical Board Meeting at Los Alamos, from May 1947.1

8. The Director [Norris Bradbury] asked for an expression of opinion as to what might be the difficulties that would arise if he asked that all possibly revealing shapes in the various Tech offices be removed. For example, spherical ash trays and such things that are not actually bomb parts or models, but cause security people concern because they feel that the presence of such items makes security policing difficult. It was agreed that the Director would bring this up at the next colloquium.

Imagine the scenario: you’re a security officer working at Los Alamos. You know that spheres are weapon parts. You walk into a technical area, and you see spheres all around! Is that an ashtray, or it is a model of a plutonium pit? Anxiety mounts — does the ashtray go into a safe at the end of the day, or does it stay out on the desk? (Has someone been tapping their cigarettes out into the pit model?)

You must admit, there’s a certain familial resemblance.

All of this anxiety can be gone — gone! — by simply banning all non-nuclear spheres! That way you can effectively treat all spheres as sensitive shapes.

What I love about this little policy proposal is that it illuminates something deep about how secrecy works. Once you decide that something is so dangerous that the entire world hinges on keeping it under control, this sense of fear and dread starts to creep outwards. The worry about what must be controlled becomes insatiable — and pretty soon the mundane is included with the existential.

I’ve posted this quote before, from Mordechai Vanunu’s lawyer, but it never gets old. Secrecy is contagious:

If something is secret, and something else touches it, it too becomes secret. Secrecy becomes a disease. Everything around the secret issue becomes secret, so the trial became a secret, so I became a secret.

So, did Los Alamos actually end up adopting the policy of No Spheres in the War Room? It may very well have! Below is an excerpt from Joseph Masco‘s highly-recommended book, The Nuclear Borderlands: The Manhattan Project in Post-Cold War New Mexico:

One weapons scientist explained to me how he breached security at Los Alamos simply by bringing a sack lunch into the plutonium facility. He left his lunch on his office desk and stepped out for a minute. He came back to find a commotion. A security officer informed him that the orange he left on his desk was, in fact, a classified object.

He learned that any spherical object became a nuclear secret once it passes over the line demarcating the secure from the open areas of the laboratory, as it could be taken as a model for the plutonium pit that drives a nuclear weapon.

The weapons scientist was told that in the future he could eat the fruit or store it inside his office safe with the rest of his classified documents, but if he left the orange out on his desk unsupervised it was a security infraction that could be referred to the FBI for investigation.

Truth, rumor, exaggeration? A distinction that’s not mine to know. But it’s still pretty amusing. One wonders how many “inappropriate lunch” cases the FBI has to investigate.

Image source: floating around the Internet.

I’ve asked some contacts I have at Livermore if they had such a policy out there, and they said they hadn’t heard of one. But maybe they’ve just never made the mistake of bringing a sphere to lunch. 

  1. Citation: Los Alamos Technical Board Notes (2 May 1947), copy in Chuck Hansen papers, National Security Archive, George Washington University, Washington, D.C., Box 51, “U.S. Nuclear Testing Program, 1944-1947, 1959.” []

23 Responses to “Forbidden spheres”

  1. Cheryl Rofer says:

    At a lecture by Sam Glasstone in the mid-1960s, he drew some concentric circles on the blackboard and then said, “It used to be classified to draw concentric circles.”

    Maybe he was referring to something like this.

    • Oh, I’m sure of it. Even today there are very, very specific forms of what can and can’t be drawn by people with clearances. My favorite currently is the “two circles in a rounded square,” which is apparently as daring as someone with a clearance can get when talking to the outside world about thermonuclear weapons:

      One wonders whether drawing anything similar to that but slightly divergent — no matter how innocuous — would get someone in trouble.

  2. Blake says:

    One suspects that modern-day weaponeers may have slightly better than normal cardiovascular health and lower than usual cholesterol.

  3. Mike Lehman says:

    Someone in the Security Dept. has waaay too much time on their hands.

    Is there a Dept. of Common Sense? Because next we’ll be plucking eyes out…

    So let me get this right. Since the Security people aren’t wise enough to distinguish between a secret item and common objects — or even a doodle — the solution is to simply eliminate the confusing simulacra from their sight?

    Somehow, I now understand a little better how another bit of our Constitution gets shredded every time it gets confusingly in the way of new efforts to ensure “national security.”

  4. Nuclear Tan says:

    So I guess all these Slotin accident mockups were verboten back in the day?

    Also from Blake’s photo link here’s a really cool contamination map of Bikini

    A map of Bikini with shot locations

    A nice picture of the Trinity Jumbo device

    • John Coster-Mullen has used the Slotin accident mockups to pretty impressive effect; I’m surprised they’re so cavalier about them. Aside from showing measurable cores (along side things of known size, like Coke bottles), they also show the core carrying case components, which correlate with all of those photos from the Trinity site. (It’s not that I think these are huge security risks — just that I’m surprised their security folks agreed to them being released.)

  5. John Petro says:

    The same nonsensical security reasoning applies to weapons in schools. If it looks like a gun and is shaped like a gun, it must be an actual gun capable of inflicting severe harm, ergo, little Johnny and Judy get expelled for having a toy water pistol or rubber-band gun in their backpack. Sometimes anything in the shape of an “L” merits expulsion or getting sent to the principal and have a notation on one’s records. I imagine that after the tragedy last month in Connecticut some of us who may have found this ridiculous in November have now decided that maybe this theater is worth the potential safety or “feel good” vibe it emits.

  6. Tommi Tuura says:

    For some reason, I can’t help but think about a Donald Duck story “Lost in the Andes!” by Carl Barks…

  7. paul says:

    You guys are just assuming that the rulers and other objects in those pictures are accurate…

    • That they’d have been fudged is an amusing, if improbable, idea! It seems kind of unlikely that they’d cook up miniature rulers, miniature Coke bottles, and — ultimately — a miniature human to model all of this for their own internal record-keeping. There are lots of photos from the same setup and they all are on the same scale. It would make more sense to fudge the objects than the rulers, but that wouldn’t make much sense in context, and the sizes match up to other inferences to core sizes.

  8. […] Schneier dug out this little gem: Forbidden Spheres. A nuclear weapons lab, so the (apparently unconfirmed) story goes, classified all spherical […]

  9. John Coster-Mullen says:

    Don’t worry about the rulers being inaccurate. Los Alamos document LA-555 “Neutron Experiments with Beryllium Spheres” published May 1, 1946 (and still available on the LANL Library website) just three weeks before the Slotin “Criticality Excursion” gives the actual Pu sphere diameter (same as an actual combat core) as 3.62 inches. Oops! They also list the mass and this, given the density of this Pu alloyed with 3% Gallium, makes for about a 3.3 inch diameter if solid. The difference is the diameter of the spherical cavity in the very center of precisely one inch that being the maximum size of the Urchin initiator. For that diameter, you have to plod through other Los Alamos declassified reports to find out it was a “standard 0.8-inch diameter ball-polonium” diameter or you could also just read LA-555 to find out it had a 0.830 inch O.D. Oh my!

    It’s actually all there hiding in plain sight.

  10. Kevin says:

    When I was in the Navy, I always found it interesting that most of the crew didn’t know the exact time/date that we would return to port because there was no “need to know”…Yet all of the wives were waiting on the pier waiting for liberty call.

    I guess it was a security risk for the crew to know when we would return, but not a security risk for the base ombudsman to make sure that the ladies knew exactly when hubby’s ship would be going pierside. Ditto for the ship’s phone numbers.

    The other thing I always thought funny was the list of questions about the ship that I couldn’t answer because they were “classified”…how fast would she go, what type of weapons could she carry, etc. Seems reasonable, until you grab a copy of “Jane’s Fighting Ships” and find all of the answers.

  11. […] so all round objects become classified. (quote is from linked article) This culture of secrecy is especially obvious where nuclear bombs […]