Paul Ryan, in the debate with Biden:
Letâ€™s look at this from the view of the ayatollahs. What do they see? They see this administration trying to water down sanctions in Congress for over two years. Theyâ€™re moving faster toward a nuclear weapon; theyâ€™re spinning the centrifuges faster.
I suppose we have to give Ryan a pass on this as a metaphor, but taken literally it makes little sense. Ex hypothesi Iran has competent nuclear engineers, otherwise there’s no major risk from its ambitions. For this reason, Gaddafi’s abortive nuclear weapon programme, abandoned in 2003, was taken seriously to be sure but never rose to an existential threat to anybody. So the Iranian engineers are surely running their centrifuges to their design limits.
According to the competent-seeming folks at GlobalSecurity.org:
The primary limitation on rotor wall speed is the strength-to-weight ratio of the rotor material. […] At present, maraging steel is the most popular rotor material for proliferants. With maraging steel, the maximum rotor wall speed is approximately 500 m/s. Fiber-reinforced composite rotors may achieve even higher speeds [advanced design carbon fiber rotors can exceed 600 m/sec]. However, the needed composite technology is not within the grasp of many potential proliferants. Another limitation on rotor speed is the lifetime of the bearings at either end of the rotor.[…]
Speeding up enrichment centrifuges isn’t like overclocking your PC processor – oops, reboot. You risk explosive failure, disruption of your cascade, and leaks of small but nasty quantities of corrosive and radioactive uranium hexafluoride gas:
The casing is needed both to maintain a vacuum and to contain the rapidly spinning components in the event of a failure. If the shrapnel from a single centrifuge failure is not contained, a “domino effect” may result and destroy adjacent centrifuges.
However, it’s a hopeful and pleasing image for the Romney-Ryan campaign. As their advanced mystification-enrichment machine spins faster and faster, it may explode, spreading fragments of radioactive BS all over the GOP ticket.
19 thoughts on “Centrifuge failures”
Interesting choice of quote to examine.
How about examining this one? “When my friend [Paul Ryan] talks about fissile material, they have to take this highly enriched uranium, get it from 20% up. Then they have to be able to have something to put it in. There is no weapon that the Iranians have at this point.”
Seems to me that Mr. Biden proved Mr. Ryan’s point that the current administration isn’t particularly concerned about Iranian enrichment.
He merely proved that unlike Romney/Ryan, the administration is refusing to be panicked by Netanyahu into another preventive war. Remember how well that turned out in Iraq? 20% enriched uranium isn’t a bomb. 95% enriched uranium, which Iran doesn’t have, isn’t a bomb. By report, constructing a simple gun-type bomb isn’t too difficult from that. The Hiroshima bomb was of this type and wasn’t tested, everybody expected it to work. The Trinity test was of the much trickier plutonium implosion design used on Nagasaki.
Still, Biden’s point holds: Iran is years away from actual possession of a deliverable atomic weapon. Obama’s red line is there. I don’t agree with it but there is certainly a case for it. What’s the case for Romney/Ryan’s red line of fuzzily defined “capability”, apart from the fact that their equally reckless pal Bibi wants it?
“â€¦ actual possession of a deliverable atomic weapon. Obamaâ€™s red line is there.”
Citation, please? (This is a fact-based blog, after all).
I fail to see the point of a red-line, the crossing of which results in the very thing one is trying to prevent. “If you cross that line and really have a bomb, we’ll _absolutely_ react to prevent you from getting a bomb, and this time we’ll mean it! Oh, waitâ€¦”
Obama made a clear threat in his UN speech:
“The United States will do what we must to prevent Iran from obtaining a nuclear weapon.”
Thanks for the UN quote, but that’s clearly inconsistent with your statement that “Obama’s red line” is at “actual possession of a deliverable atomic weapon”.
So which is it?
Per Richard Rhodes (The Making of the Atomic Bomb), the gun-design can be used with U235 but not with Pu239. The neutron capture cross-section of Pu239 is too large and a gun design will fizzle rather than explode.
Regardless of the fissile substance, gun designs are extremely inefficient. Implosion designs are much more efficient and useful with both Pu239 and U235. Rhodes implies (but doesn’t flat out state) that the physical properties of Pu239 (it undergoes a number of phase changes under temperature and pressure changes) make it more effective in implosion systems.
In Ryan’s defense (I can’t believe I’m defending that jerk), the step from weapons grade uranium to bomb isn’t very big if Iran is willing to accept an inefficient device. On the other hand, the fact is that most modern weapon designs are based on Pu239 triggers rather than U235. As long as the Iranians aren’t reprocessing Pu from reactor rods, they have a bunch of engineering problems to solve that will require testing of the trigger device. In other words, we will know what they are up to the moment they begin testing.
OTOH, essentially everybody, (With the exception of the North Koreans, natch…) who has tried to detonate a nuclear bomb, has succeeded on the very first try. Or so I’ve heard, anyway. So it can’t really be that hard.
So, it works except when it doesn’t?
With that logic, the fact that Iran hasn’t gotten the bomb yet must mean they don’t really want it. Since it’s not really that hard, you know.
Seems to me that Mr. Biden proved Mr. Ryanâ€™s point that the current administration isnâ€™t particularly concerned about Iranian enrichment.
Henry your comment is like willfully throwing your head against someone’s closed fist. If they weren’t concerned why is the Obama Administration being “credited” and “damned” for launching the first cyberwar attack against another nation?
I think the metaphor is even worse that you describe. I’m not an expert in the field by any means, but as I understand it the point of using a centrifuge is to separate the rare U-235 (bomb making isotope) from the more common U-238 (which won’t work in bombs). Due to the different masses of the two isotopes and the design of the centrifuge the two isotopes travel on different paths in the device and collect in different places. But, I believe, if you were to simply speed up a centrifuge that would tend to cause the two masses to end up on the same path. Basically the 235 would be pushed more against the wall of the container and more of the 238 would go to the collection spot where the 235 is supposed to go. Thus the effect would be to diminish the utility of the centrifuge.
Nah, you got that wrong: The centrifuges barely spin fast enough to make it work as it is; Faster certainly would be better.
Is anyone finding the formatting of this blog is now messed up on their IPhones? It started about two days ago. The width of the blog is now too narrow, about a third of what it used to be, meaning you have to scroll a lot to read each post.
I’ve passed this on to our support technician.
Perhaps he is talking about the ability to run centrifuges allows one to diagnose problems with the current design and improve on them, perhaps they aren’t at 500 m/s yet.
Are you implying that Rep. Ryan might actually be speaking from knowledge? The person he reminded me of was myself at 17: a clever youth able to use his wit to disguise a fundamental ignorance of the world and inability to connect to the concerns of other people. But what is pardonable in an adolescent is inexcusable in a mature candidate for high office.
On your specific issue, I refer you to Brett above, an actual engineer. The Iranians are, by common consent, succeeding in enriching uranium, which Gaddafi never managed to do. They are running, not testing, centrifuges.
One never designs a system then walks away. I also do not accept the appeal to authority, poor form James.
Aluminum tubes redux. GOP wing nut hacks with no science or engineering knowledge, easily cowed and trained to repeat techno sounding bits to servile Faux news blondes, who recycle them tirelessly.
Metamessage: Be afraid, be very afraid. And then vote for us, the tough guys. Sure we’re all chicken hawks, but hey, whatever.
Thanks. Yes, it’s messed up on my iPhone too.
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