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Monday, May 18, 2009

Reading List: The Silent Man

Berenson, Alex. The Silent Man. New York: G.P. Putnam's Sons, 2009. ISBN 978-0-399-15538-3.
This is a compelling page-turner in which the nightmare scenario of “loose nukes” falling into the hands of jihadi terrorists raises the risk of a nuclear detonation on U.S. soil. Only intrepid CIA agent (and loose cannon—heroes in books like this never seem to be of the tethered cannon variety) John Wells can put the pieces together before disaster strikes and possibly provokes consequences even worse than a nuclear blast.

The author has come up with a very clever scenario to get around many of the obvious objections to most plots of this kind. The characters of the malefactors are believable, and the suspense as the story unfolds is palpable; this is a book I did not want to either put down or have come to an end too quickly. Still, I have some major quibbles with the details, which I'll describe in the spoiler block below (I don't consider anything discussed a major plot spoiler, but better safe than sorry).

Spoiler warning: Plot and/or ending details follow.  
There are number of factual goofs (or invocations of artistic license, if you prefer). The Russian nuclear warheads stolen by the terrorists are said to be from SS-26 Iskander tactical missiles. Yet according to both the Russian military and NATO, this missile uses only conventional warheads. The warheads are said to have been returned for refurbishing due to damage from the missile's corrosive liquid fuel, but the Iskander is, in fact, a solid fuel missile

The premise of constructing an improvised gun assembly nuclear weapon from material from the secondary of a thermonuclear warhead seems highly implausible to me. (They couldn't use the fissile material from the primary because it is plutonium, which would predetonate in a gun design, and they can't fire the implosion mechanism of the primary without the permissive action link code, without which the implosion system will misfire, resulting in no nuclear yield.) Anyway, the terrorists plan to use highly enriched U-235 from the secondary in their gun bomb. The problem is that, unless I'm mistaken or the Russians use a very odd design in their bombs, there is no reason for a fusion secondary to contain anywhere near a critical mass of U-235 or, for that matter, any U-235 at all. In a Teller-Ulam design the only fissile material in the secondary is the uranium or plutonium “spark plug” used to heat the lithium deuteride fuel to a temperature where fusion can begin, but, even if U-235 is used, the quantity is much less than that required for a gun assembly bomb.

Even if the terrorists did manage to obtain sufficient U-235, I'm far from certain the bomb would have worked. They planned to use a gun assembly with a Russian SPG-9 recoilless rifle propelling the projectile into the target. They weld the tube of the bazooka directly to the steel tamper surrounding the target. But that won't work! The SPG-9 projectile is ejected from the tube by a small charge, but its rocket motor, which accelerates it to full velocity, does not ignite until the projectile is about twenty metres from the tube. So the projectile in the bomb would be accelerated only by the initial charge, which wouldn't impart anything like the velocity needed to avoid predetonation. Finally, the terrorists have no initiator: they just hope background radiation will generate a neutron to get things going. But if they aren't lucky, the whole assembly will be blown apart by the explosive charge of the SPG-9 round before nuclear detonation begins.

Now, if you don't know these details, or you're willing to ignore them (as I was), they don't in any way detract from what is a gripping story. There's no question that a small group of terrorists who came into possession of a sufficient quantity of highly enriched uranium could construct a simple gun bomb which would have a high probability of working on the first try. It's just that the scenario in the novel doesn't explain how they obtained a sufficient quantity, nor does it describe a weapon design which is likely to work.

Spoilers end here.  

Posted at 22:35 Permalink