(The transcript is here)
In the last post, I reviewed Biden’s comments about the Benghazi debacle; now I’d like to discuss his thoughts about Iranian nuclear weapons.
VICE PRESIDENT BIDEN: When my friend talks about fissile material, they have to take this highly enriched uranium, get it from 20 percent 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. Both the Israelis and we know we’ll know if they start the process of building a weapon. So all this bluster I keep hearing, all this loose talk — what are they talking about?…We will not allow the Iranians to get a nuclear weapon. What Bibi held up there was when they get to the point where they can enrich uranium enough to put into a weapon, they don’t have a weapon to put it into…Facts matter. All this loose talk about them — all they have to do is get to — enrich uranium in a certain amount and they have a weapon — not true.
It is extremely important to understand that, while one might think going from 20% uranium enrichment to the 90% that is required for a nuclear weapon, means that one is only 20/90 of the way there, this is not correct. The first steps in enrichment require more effort–more centrifuges, more energy–than the later steps, because the amounts of mass that must be dealt with are much greater. The nuclear industry actually has a metric, “separative work units,” to measure this. Enriching uranium from a standing start to 5.6kg of highly enriched uranium requires about 1270 SWU, whereas if you start with a feedstock that is already 20% enriched, you only need less than 200 SWU. Even if you begin with material enriched only to the level needed for a power reactor, only about 400 SWU are needed: a savings of 3:1 compared with starting from scratch. (Here’s another analysis with slightly different numbers but making the same point…4% enrichment is much more than 4/90 of the way there, and 20/90 is far more than 20/90 of the way there.)
Regarding the question of how long it would take to actually turn the fissionable material into a nuclear weapon, Bibi Netanyahu’s visual aid clearly transmitted the message that the enrichment is the more difficult part of bomb-creation. How difficult the actual fabrication of the weapon would be depends on what kind of weapon is being built and how much information is available to the builders. A gun-type weapon, in which two subcritical fissionable masses are slammed together in a barrel, is the type the U.S. used on Hiroshima. These types are large and heavy, but they are also relatively simple. Indeed, the United States did not even test its gun-type design before dropping the Hiroshima bomb, because the confidence level that it would work was very high. The implosion-type weapons, as tested at Alamogordo and dropped on Nagasaki, are more difficult to design and fabricate but can be made smaller and lighter. It seems very likely that by now, more than 60 years after the opening of the atomic age…and with nuclear weapons in the hands of states like North Korea and Pakistan…significant design information is in the hands of the Iranian scientists.
There is no reason to believe that most of the design of a bomb, and much of the fabrication, could not be conducted in parallel with the uranium enrichment, rather than waiting for that activity to be completed. Nor do I see anything that would keep the bomb making from being conducted without knowledge by Western nations–it does not require multiple high-energy-consuming sites as does the enrichment, and it seems the only way it could be detected with any degree of certainty is via human intelligence–ie, trustworthy spies in the right place.
These are extremely serious matters, and are not something that the Vice President of the United States should be grinning about.