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.