Posts Tagged ‘Centrifuges’


More on Centrifuge History

Monday, June 25th, 2012

I wrote about centrifuges a few weeks ago, and have learned some new, interesting things since then. John Krige, a professor at the History, Technology, and Society program at Georgia Tech, has two quite provocative articles  published about interactions between the US and the UK regarding centrifuges in the mid-to-late 1960s. They are worth your attention.

European centrifuges (URENCO)

Krige's first article is "Hybrid knowledge: the transnational co-production of the gas centrifuge for uranium enrichment in the 1960s," just published online (and forthcoming in print, I believe) in the British Journal for the History of Science (BJHS).1 As the title may tip you off, this is an article for a primarily history of science/science studies crowd, and speaks in that idiom. Don't let the jargon scare you off, though: as far as the genre goes, it's readable and the underlying point is an important one. It concerns the interchanges of centrifuge information between the US and the UK in the early 1960s, which were done under the 1955 US/UK Agreement for Co-operation on the Civil Uses of Atomic Energy, and their consequences when the UK, Netherlands, and Germany decided to go into a cooperative, profitable effort to produce a commercial centrifuge enrichment plant in 1967. (What eventually became URENCO, I believe.)

The US thought this was a somewhat dodgy enterprise — they really didn't think centrifuges would be as profitable as gaseous diffusion, their chosen enrichment method, but the UK disagreed — but were happy to support it, so long as the UK didn't give away any "restricted data" that had been produced by the US. And there's the rub: the UK and US had been exchanging information for a long time, and the UK really thought that it had produced a completely indigenous design (taking off from Gernot Zippe's unclassified contributions) without any significant US "data" in it. The US disagreed and threatened to cut off all future US-UK exchanges if the latter didn't let them verify to their satisfaction that there wasn't any US data in the design. The UK, for its part, thought that it had a really superior centrifuge design compared to the US, and were worried that if the US claimed parts of it were "theirs," it would completely muddy up their attempts to get clear of the US monopoly on the enrichment of uranium.

In the end, the US decided the UK design was kosher enough, and all was well with them. But it's a fascinating (and to me, totally unknown) episode in the US-UK "special (nuclear) relationship," one which really highlights some fundamentally interesting aspects of both US and UK atomic policy, and the fundamentally transnational (as Krige puts it) nature of modern centrifuge development (an Austrian working in the USSR develops technology that he then further works on in the US and the UK which is then turned into a company with the UK, Germany, and Netherlands, etc.). It also gets into some good history of science questions about how one identifies the source of any given piece of design or machinery — and how difficult that can be.

US centrifuges (Piketon)

The second paper by John is "The Proliferation Risks of Gas Centrifuge Enrichment at the Dawn of the NPT: Shedding Light on the Negotiating History," just published online (and imminently forthcoming in print) in The Nonproliferation Review.2 This essay was a winner of an annual prize by the journal (one of two) and John gave a presentation on it last Thursday at GWU (which you can watch online — John is the first of the two speakers/winners, after the introduction by Stephen Schwartz).

In this paper, John tackles the question of the apparent ambiguity in the 1968 Nuclear Non-Proliferation Treaty (NPT) about whether centrifuge-style enrichment activities (like that currently pursued by Iran) were considered a protected form of "peaceful use" to be allowed and encouraged. It has been speculated that at the time of the treaty's writing, the risks posed by centrifuge enrichment — which is a lot smaller scale than gaseous diffusion plants, and thus easier to hide or protect — weren't considered by the NPT drafters, and thus represent an unanticipated "loophole" in the treaty terms.

What John has found is that while centrifuges were not discussed in the official record, they were discussed extensively on the backchannel by the US and the UK. In particular, the UK was extremely worried about the proliferation potential for the gas centrifuge. They, after all, were pursuing the technology themselves, and knew it could be a potent game-changer in breaking the gaseous diffusion monopoly. They wondered if it would not be the angle pursued by a future proliferating state, and conveyed as much to the US.

The US was itself comparatively unworried. It thought that it (and its European allies) could control the spread of centrifuge technology through classification and export controls, and still were dubious that the centrifuge would play a bit role in world affairs anytime soon. I pushed John on this at the talk (you can hear me asking a rambling question about this at the 1:41:24 mark in the video linked above), and he elaborated in a way that I thought was more compelling: the US was weary about getting the treaty signed (they had finally gotten the Soviets on board, and the NPT treaty process was over a decade old at that point), and were worried that any attempt to modify the treaty at that point would bog it down for years to come. Furthermore, the UK was engaging in said partnership with the Dutch and the West Germans, and the US really wanted to make sure the Germans were still on board with the NPT.

(The West Germans were really not too pleased with the NPT and it was a huge hassle to get them to ratify it; like many nations, they appropriately saw it as an infringement on their national sovereignty and their future security options. Of course today the Germans are big supporters of the NPT — it's interesting how these things switch around, depending on where you are sitting at the time.)

The UK didn't push the matter, because it didn't want to rankle the treaty process, either, and because it too wanted to profit off of the centrifuge. So both the US and UK let the matter slide. (I think John's work highlights something that I've been thinking for a short while now: there's a lot of potential for a "deep" history of the NPT, one that goes beyond the open record.)

Iranian centrifuges (Natanz)

Whether this affects one's interpretations of the NPT today — John thinks that there is basically no real legal argument against Iran being able to develop centrifuges, and certainly no argument that the early NPT drafters had left an unanticipated "loophole" in place that anyone is taking advantage of — seems to me, someone not at all versed in international law, to be unclear. (Do off-the-record conversations between two parties count towards later interpretations of a treaty's intent?) But either way, it's a fascinating story. The apparent US lack of concern about specifically centrifuge proliferation has come back to haunt it, these decades later.

  1. John Krige, "Hybrid knowledge: the transnational co-production of the gas centrifuge for uranium enrichment in the 1960s," BJHS (online May 2012). []
  2. John Krige, "The Proliferation Risks of Gas Centrifuge Enrichment at the Dawn of the NPT: Shedding Light on the Negotiating History," The Nonproliferation Review 19, no. 2 (July 2012), 219-227. []

Elusive Centrifuges

Friday, June 1st, 2012

To round off this week of centrifuges, I thought we might actually look at a few of them. Photographs of real-life enrichment technologies are not too common. You can find quite a number of pictures floating around of Calutron (electromagnetic enrichment) technology from World War II, but that's because the United States decided pretty early on that Calutrons weren't too sensitive. (Rightly or wrongly; just because they are inefficient doesn't mean they don't work. Iraq famously pursued Calutron technology during its pre-1991 nuclear program; the major technical snag seemed to be that somebody bombed the facilities.)

But gaseous diffusion? Laser enrichment? Aerodynamic enrichment? Not so much, beyond photographs of BIG buildings or very schematic conceptual diagrams. With centrifuges, though, there are some images from a variety of time periods and sources. As I mentioned on Monday, you can find some pretty nifty Zippe-type centrifuge photographs in old research reports from the 1950s that the Department of Energy still hosts pretty accessibly. These are kind of amazing, given how they more or less disassemble the devices in what looks like a pretty helpful fashion.

"Scoop assembly for handling gas inside the rotor and parts of rotor." (1959)

"Molecular pump and rotor." (1959)

...and so on with the "powdered magnetic core, completed stator, and driven end of rotor showing steel plate and supporting needle," and "upper magnetic bearing, rotor, and top of scoop assembly," and even a nice little one of the rotors mounted up for stress testing. Interesting that these things are out there — especially when the CIA apparently decided, in 2003, that showing rotors of pre-1991 Iraqi centrifuges was too sensitive to put up on the web (after they had already put them up for awhile).

There are a few photos of URENCO centrifuge plants from Europe, but not as many as you'd think from a venture whose corporate slogan is "enriching the future." I'm partial to this gold-tinted one that's been floating around the web for awhile; it looks like Scrooge McDuck was the contractor (but I'm pretty sure it's just the lighting — other images I've seen show them to be silvery):

It's hard to get a sense of scale from cascade photos like this, though.

In the early 1980s, the United States' DOE built a prototype centrifuge plant at Piketon, Ohio, but abandoned it by 1985. Much more recently (the 2000s) the private United States Enrichment Corporation took over the site and has been building a demonstration plant on it. What's interesting about these centrifuges is that they are of a different model than the previous ones; the "American centrifuge" is a colossally large design. (The fact that they have to label them as "American" is a nice reflection of the fact mentioned on Monday that the US lost its initiative in developing centrifuges. We don't have the "American" gaseous diffusion method or the "American" electromagnetic method.)

The 1980s Piketon photos are pretty impressive. These are from the DOE Digital Archive:

The last one really gives you the sense of scale with those suckers — they are huge!

The current Piketon plant looks pretty similar. USEC has a few photos on their own website:

I find these less inspiring, photographically, than the ones from the 1980s, but they look like the same centrifuges. The length here — some 12 meters long — is functional, and not just an example of the Supersize-Me American culture.  The "American centrifuge" is much more efficient than the other models currently being used, apparently.

Now, all of the above is sort of interesting, but is just something of a prelude for the next batch of photos. In April 2008, Iranian President Mahmoud Ahmadinejad made an official visit to the Natanz site, one of Iran's controversial centrifuge facilities. Surprisingly, his office took several dozen photos of the visit and posted them on the official Presidential website. These have been a goldmine for wonky types wanting to understand Iran's centrifuge developments, and have, of course, served as the illustrations for half a million articles about Iran and the bomb since then. A few of my favorites:

The last one I like because of a small, easy-to-miss detail: you can see one of the blue IAEA safeguard cameras above Ahmadinejad's head. The blue box is a sealed case inside which the video camera is locked, and the closed-circuit camera feed is beamed back to IAEA headquarters in real-time (so I gather). (A correspondent e-mailed to say that at the plant in question, a pilot plant, the cameras aren't real-time — they just stored the footage for the IAEA to pick up, which is every other week or so. I thought I had heard somewhere that they were real-time, but I can't remember where. They do have real-time monitoring in their plants that can do up to 20% enrichment, though.)

Given how relatively few photos there are of centrifuges floating around, why did Iran post so many on its Presidential website? I think the message is pretty clear, personally: they are trying to demonstrate a lack of anything to hide. If the centrifuge program isn't "secret," then it isn't scary, right?

Of course, the obvious rejoinder to this is that they are of course being selective about what they show. Such is the nature of any kind of publicity like this. You show a little, to show that you aren't secretive, but of course, you do hold things back. Whether that holding back violates the NPT or the Additional Protocol and so forth is a question for another day. But I'm always fascinated by the theatre of "transparency," which has — since the early days of the bomb — been part of maintaining nuclear secrecy. Secrecy has never just been about holding things back: it has always been a game of simultaneously withholding and releasing, of giving a little so you can hold back a lot.

How do we distinguish between genuine transparency and transparency in the name of secrecy? That's the $64,000 question, isn't it? Because when you get it wrong, you get a situation like Iraq: trying to prove a negative (that they didn't have active WMD programs hidden away) turned out to be an impossible job (not because it is inherently impossible, but because of the various political and organizational forces stacked against the attempt). One can distinguish between the two in retrospect — once you've actually dismantled the country and its programs and whatnot — but that's disturbingly too late.


The Centrifuge Conundrum (1964/1968)

Wednesday, May 30th, 2012

On Monday I wrote a bit about the history of the Zippe-type gas centrifuge. What's fascinating about the Zippe centrifuges, for me, is that they were pushed internationally for the purpose of commercialization, and because of their origin outside of the United States (and their post-Atoms for Peace publicity), they were not put under as heavy restrictions as other uranium enrichment technologies — despite the fact that they are really the ideal enrichment method for a potential new proliferator. This created a major problem for the United States. Centrifuge technology was both hard for the US to meaningfully control (since it didn't originate in secret American labs), and US companies were eager to "stay competitive" with Europe in the vast new frontier of enrichment possibilities they opened up (which seemed like big money in the 1960s, when the future of nuclear power was still rosy). For this week's document(s), I want to share two different (short) positions on what we might call the "centrifuge problem" of the 1960s.

Glenn Seaborg (left) and Robert McNamara (right) flank President Kennedy as he visits the Lawrence Berkeley Laboratory in 1962

The first is a 1964 memo from Robert S. McNamara, then the Secretary of Defense, to Glenn T. Seaborg, then the Chairman of the Atomic Energy Commission. It comes at a time — about six months prior to the first Chinese nuclear test — where the United States started to get really serious about proliferation, or as it was often called then, the "Nth country problem."1

Click image for the PDF

McNamara's memo aimed to confront the problem of centrifuge proliferation head-on. Proliferation was a problem in McNamara's eyes because, "...the acquisition of fissionable material for even one or two weapons by a non-nuclear country could have a destabilizing impact on international relations which would be harmful to US security." (This is, of course, exactly why helping other countries proliferate might seem like a good idea to some countries, as Matthew Kroenig has argued in his fairly recent book, Exporting the Bomb.)

But McNamara knew he couldn't end proliferation through simple technical means: "I recognize that the controls which can be placed on technology can only retard, not prevent, its growth and diffusion. Even so the goal of retardation is a worthwhile one." This is actually a very old argument related to the benefits of secrecy: it doesn't stop diffusion of information, but it does slow it down. And slowing it down can be strategically valuable.

Supporting this "retardation" goal (a somewhat unfortunate choice of words), McNamara wanted to slow down the diffusion of centrifuge information. His methods:

  1. "...dampen the incentive of countries capable of developing their own gas centrifuge technology." That is, guarantee nuclear fuel to countries so they are dependent on the US for enrichment and don't feel they need to develop their own enrichment capabilities. He also thinks that the US should support safeguards on natural uranium — which is interesting since as far as I know, unenriched, natural uranium is not safeguarded today.
  2. "...inhibit assistance to less developed countries." Specifically he means keeping classification and export controls up in the US program, since that will make nuclear newbies have a harder time.
  3. " US gas centrifuge technology at a high level so that the US can stay abreast, or ahead, of developments in other countries." This is a very good task to send to the Chairman of the AEC: full steam ahead with centrifuge development! But keep it secret. McNamara is no doubt aware that half of the problem here is that the US hadn't kept abreast, or ahead, of centrifuge developments in other countries (see my previous post on this).

Lastly, Seaborg had asked McNamara if there were any US security objectives that non-proliferation policy might interfere with. (An interesting question.) McNamara says no — the only issue hinted at is the basing of nuclear weapons in NATO countries ("nuclear sharing"), but McNamara seems pretty confident that he doesn't consider that to be proliferation since it is not a creation of an "independent" nuclear state. (This was a major sticking point for the NPT negotiations in the late 1960s; the USSR was desperately afraid of giving the West German "revanchists" control of nuclear weapons and tried to use the NPT as a way of opposing nuclear sharing policies.)

Now let's go to the other document, an extract from Seaborg's office diary from 1968. Seaborg's office diary entries are generally speaking quite short and not usually very revealing, but this one is interesting. It concerns his day on Monday, November 11, 1968. Here's the first relevant section:2

At 10 a.m. I presided over [Atomic Energy] Commission Meeting 2352 (action summary attached) [not attached]. At the Commission Meeting we discussed the possibility of modifying our policy of secrecy on our gaseous diffusion and gas centrifuge methods for enriching U-235. The Europeans and Japanese are developing these methods and our policy seems to be outmoded if we want to influence them and stay abreast of them. Despite objections from [Commissioner James T.] Ramey, who prefers the status quo, we asked the staff to make a study, with the aim of coming up with various plans to make it possible to cooperate with the Europeans and Japanese in this area.

So this is an interesting counter to the McNamara concern. The Europeans and Japanese were pushing ahead in both centrifuge and diffusion technology, and there was a question as to whether the AEC should loosen their restrictions in order to "influence them and stay abreast of them." At least one AEC Commissioner wanted to take a conservative approach, but Seaborg and the others were interested enough in the possibility to order up a staff study, which was often the first step towards a policy change.

There is one more relevant part of that day's diary entry; that evening, Seaborg went to see the German delegation to a nuclear industry conference. Here's what he wrote:

Dr. Michael Higatsberger (of Austria) told me the AEC briefings at Oak Ridge last Thursday and Friday on our nuclear fuel policy were very successful and may have convinced many Europeans that they shouldn't build an enriching facility soon. Charles Robbins (AIF) told me about industry feeling that AEC suppression of industrial work on gas centrifuge is counter to American method of doing business.

Another interesting paring — an Austrian saying that the US had probably convinced the Europeans not to create in their own collective enrichment facility, and an American nuclear industry representative (the AIF was the Atomic Industrial Forum, a nuclear lobby group) saying that AEC control over centrifuge work is "counter to [the] American method of doing business." (The UK, Netherlands, and Germany did create URENCO in 1971, so not all of them were apparently convinced. URENCO uses gas centrifuges for its enrichment, and is where A.Q. Khan got access to the centrifuge technology that he later took back to Pakistan and exported to quite a few other places.)

What I like about these two documents is they paint a picture of the various political, technical, and economic forces pulling in different directions on the centrifuge problem. Gas centrifuges, like all enrichment technology, have been duel-use since birth, but the fact that they developed outside of US auspices made them especially difficult to control. This difficulty then presented the problem of whether one ought to try and control them, and if so, how. Heavy controls might slow things down, but it also could easily encourage others to press ahead with independent development. Loosening restrictions might increase diffusion, but could also increase dependence on US assistance.

  1. Citation: Robert S. McNamara to Glenn T. Seaborg (23 May 1964), copy in Nuclear Testing Archive, Las Vegas, NV, document NV0903211. []
  2. Glenn T. Seaborg, Office Diary entry (11 November 1968), copy in Nuclear Testing Archive, Las Vegas, NV, document NV0910540. []

Zippe’s Centrifuges

Monday, May 28th, 2012

R. Scott Kemp, a friend of mine at Princeton's Science and Global Security program, has just informed me that the latest issue of Technology and Culture has come out with his new article: "The End of Manhattan: How the Gas Centrifuge Changed the Quest for Nuclear Weapons."1

It's a good read and I highly recommend tracking down a copy if you are interested in nuclear history, but especially if you're interested in the history of proliferation. Scott's article is the best account I've read about how the gas centrifuge went from being a more-or-less abandoned approach to uranium enrichment during World War II to being the proliferation concern of the late-20th and early-21st centuries.

Major components of a Zippe centrifuge, 1959

Gas centrifuges had been one of the many types of enrichment technology pursued during the Manhattan Project. Early on, they were heavily favored over the more technically daunting electromagnetic and the totally-untried gaseous diffusion method. Jesse W. Beams at the University of Virginia was the country's centrifuge expert and he had been looking into using them for isotopic separation as early as 1940. As a result, all of the Manhattan Project centrifuge work was concentrated with him at his laboratory, and in 1941, nearly four times more was allocated to the centrifuge project as was the more speculative gaseous diffusion method.

This is an interesting point to note — we give the Manhattan Project management a lot of credit for trying everything. They spent far more money than a more "optimized" project might have, because they investigated a lot of things that didn't work out. But despite this approach, they still centralized the work being done on any specific method, usually within a single laboratory, often under the direction of a single scientific luminiary. So Ernest Lawrence was the don of the electromagnetic method; Arthur Compton oversaw reactor research; Harold Urey ran diffusion; and so on. Which seems like a great idea on the face of it. But what if the person you chose just didn't take the research in the right directions? What if, within that short timescale, they just didn't hit upon the right answer?

Such was the case with Beams, in Kemp's assessment: Beams just didn't figure out how to get centrifuges to work sufficiently well enough. As a result, the Manhattan Project folks proclaimed centrifuges a dead end and dropped the approach in 1944. After the war, there was little US interest in centrifuges — it didn't seem like they were very workable, certainly not compared to gaseous diffusion. And since gaseous diffusion worked fine for them, they didn't look too far afield. The lesson of the war, as the US saw it, was that centrifuges weren't worth the effort.

Schematic of Zippe's short bowl "ultracentrifuge," 1958

But in Europe and the USSR, though, work on centrifuges continued. Scott's account goes into this in some wonderfully wonky technical detail. The end result is that Gernot Zippe, an Austrian physicist, who in the early 1950s figured out (with others) how to fix the problems that Beams had with his centrifuges. Amazingly, he did this while being a prisoner of war in the Soviet Union.

The Zippe centrifuges weren't anything magical. There was no "secret," per se, and they didn't involved any special materials. They just involved working out a few engineering details that made the devices reliable and stable. The major new features introduced by another Austrian POW, Max Steenbeck, and implemented by Zippe were:

  1. "a 'point' bearing that allowed the centrifuge rotor to spin on the tip of a needle (like a toy top) with almost no friction."
  2. "the application of loose bearings and weak damping, which allowed the centrifuge to adjust itself so that it spun quietly on its center-of-mass axis without vibration instead of trying to force the axis of rotation"
  3. "to drive the rotation using electromagnetic fields, just as the armature of an electric motor drives its internal rotating shaft"

That's it. In engineering terms, these are clever, but hardly revolutionary. These three relatively simply engineering changes "solved essentially all the mechanical problems that had plagued Manhattan Project centrifuges," Scott writes. In fact, he argues:

It wasn't that the centrifuge wasn't possible in the World War II period — it's just that Beams never figured it out. Scott notes:

The flawed centrifuge was made viable by the application of engineering solutions that were mostly invented around the turn of the twentieth century and all of which predated the Manhattan Project—evidence that the latter’s centrifuge program was frustrated not by the limitations of manufacturing or the technology of the day, but rather by a preliminary design that was never developed to its fullest possible extent.

So the gas centrifuge was really completely viable as early as World War II, but the Manhattan Project scientists just couldn't get it to work. I thought that was a pretty bold conclusion, one that goes in the face of the standard "superiority myth" that pervades the Manhattan Project work.

Things get really interesting, though, after Zippe et al. figure out how to make it work. Zippe and his colleagues actually convinced the Soviets to let him out early (and to pay him!) if he helped them commercialize centrifuges in Europe. (I think we can file this under "cool things that can happen once Stalin buys the farm.") Zippe and his colleagues were released from the USSR in 1956, and he went to East Germany. From there, though, he made his way west, and became a centrifuge evangelical — he wanted to commercialize them.

He went around Europe and the United States showing folks how to make efficient gas centrifuges. In 1958 and 1959 he spent time at the University of Virginia (Beams' home turf) showing them how it was done. Amazingly, this work seems to have been unclassified — you can find the progress reports, featuring the diagrams and photographs I've used in his article, on the Department of Energy's Information Bridge.2

In 1960, the US realized that the centrifuge was actually going to be a proliferation issue, and started trying to classify the technology again. The problem was, of course, that all of the key developments were produced by non-Americans not in the United States. So in effect the US was saying that nobody in the United States was going to be allowed to work on this without a security clearance, while scientists in Europe could pursue it with a freer hand.

The result of all of this Atoms-for-Peace (Atoms-for-Cash?) enthusiasm with regards to gas centrifuges is that the technology is pretty well dispersed.  Scott concludes that:

Today, at least twenty countries have built or acquired centrifuge technology, and the history lesson drawn here suggests that it is within the capability of nearly any state to do so.

As Scott (and Alex Glaser and Houston Wood) have argued elsewhere in another great article,3 all of this should put to rest any idea that technical solutions alone can limit future nuclear proliferation — we live in a definitely post-Manhattan Project world, and this stuff just isn't rocket science anymore.

  1. R. Scott Kemp, "The End of Manhattan: How the Gas Centrifuge Changed the Quest for Nuclear Weapons," Technology and Culture 53, no. 2 (June 2012), 272-305. []
  2. The photograph of the centrifuge is from Gernot Zippe, "A Progress Report: The Development of Short Bowl Ultracentrifuges," UVA/ORL-2400-59 (1 July 1959); the diagram is from Gernot Zippe, J.W. Beams, and A.R. Kuhlthau, "The Development of Short Bowl Ultracentrifuges," UVA/ORL-2400-58. Scott's article brought both of these reports to my awareness. []
  3. Houston G. Wood, Alexander Glaser, and R. Scott Kemp, "The gas centrifuge and nuclear weapons proliferation," Physics Today 61, no. 9 (September 2008), 40-45. []