You have no doubt seen the Times of London story, in which Catherine Philp claims to have obtained a 2007 “technical document” from from Iran that “describes the use of a neutron source, uranium deuteride, which independent experts confirm has no possible civilian or military use other than in a nuclear weapon.” (The Times published a more detailed discussion of UD3 in a separate article).
I have no idea whether the document is authentic, but I do want to confirm that Pakistan appears to have used uranium deuteride (UD3) as a neutron initiator.
The Times story doesn’t adequately convey that this is a relatively novel source of neutrons for a bomb design. Technically inclined readers may recall that earlier accusations against Iran focused on more traditional route of polonium-beryllium (Po-Be). Several colleagues have emailed me, expressing surprise that Pakistan is alleged to have used UD3 instead of the Po-Be.
But yes, it appears that both China and Pakistan explored the use of UD3 as a neutron source. There are two data points of which I am aware.
The first, and most colorful, is a well-known picture (above) of AQ Khan from the cover of his book, modestly titled Dr. A. Q. Khan on Science and Education.
AQ Khan graces the cover, holding a soccer ball (which is basically the size and configuration of the shell of high explosives in a nuclear weapon), standing in front of a blackboard showing a nuclear weapon diagram. The most shocking detail is the notation “Uran Deuteride Initiator.”
(A funny side note, the book Deception (2007) by Adrian Levy and Cathy Scott-Clark reproduces the image, with a portion of the blackboard redacted. Unfortunately, they redacted the wrong portion!)
Now, you may be thinking “How does that work?”
Four scientists from the Southwest Institute of Fluid Mechanics in Sichuan (which is the part of China’s nuclear weapons complex responsible for hydrodynamic research) published a detailed explanation in a 1989 paper entitled “Fusion Produced by Implosion of Spherical Explosive.” The paper is included in the proceedings of an American Physical Society meeting published as Shock Compression of Condensed Matter, (S. C. Schmidt, James N. Johnson, Lee W. Davison, editors, North-Holland, 1990.)
I had previously sort of steered clear of mentioning this on the blog, but between AQ Khan’s entrepreneurial activities and the Times of London, there’s not much point in denying it.
I won’t put the paper on line, but you can readily purchase your own copy.
Late Update | 6:12 pm Danny Stillman and Tom Reed mentioned the picture and the Dong et al paper in Nuclear Express on pp 250-251:
In 1997, a publishing house in Lahore, Pakistan, relaesed a collection of mid-1980s to mid-1990s lectures by A. Q. Khan entitled Dr. A.Q. Khan on Science and Eduction. This book discloses some of Dr. Khan’s early knowledge about nuclear weapons, including a sophisticated neutron initiation scheme. Initiators are the devices needed to assure an adequate supply of neutrons to the weapon core at the moment of maximum supercriticality. During World War II, the United States achieved this result by mixing beryllium and polonium at the center of an implosion. In later years the United States and most other nuclear weapons states turned to pulsed neutron tubes, essentially mini-accelerators, to produce a surge of neutrons when needed. But in 1989, at an American Physical Society conference in Albuquerque, the Chinese explained their very different approach to neutron generators. That Chinese initiation scheme appears with Dr. Khan’s book, and thus the origins of Pakistan’s A-bomb are unambiguously confirmed.
I should say that the first place I heard about all this was a talk we organized at Harvard for Danny. I didn’t link it to Danny since the talk was under the Chatham House-rule, but since he was able to put it in a book …