Tuesday, April 12, 2016

There Has Just Got To Be A Better Way

Anyone who has the lightest familiarity with nuclear power knows that it is impossible to steal fuel from an operating reactor. Even assuming a terrorist knew how to shut it down, there is still the problem of very high level radiation within the reactor core that would be fatal in a matter of minutes for anyone who attempted to break in. (Our brave terrorist - pardon the oxymoron - would find this a very unpleasant way to enter paradise.)

The same goes for hijacking the spent-fuel truck or train on the way to the reprocessing plant. After storage for at least five years at the power plant site, the "spent" fuel is still highly radioactive and thermally quite hot. Hijacking 44,000-pound fuel containers - designed to smash into a concrete wall at 60 mph or fall onto a spike from thirty feet without rupturing - is a bit difficult to do surreptitiously.

This leaves us with raiding the reprocessing plant (bad idea) or stealing the fuel from shipments to the power plant (best bet). Assuming that the militants can make off with a huge truck, monitored as all valuable shipments are with global positioning electronics and probably guarded, and that no one notices this cargo with the huge radioactive symbols all over it, the hijackers must plan ahead to make sure their plutonium reclamation plant is near by. Typically the price tag on such a facility is in the hundreds of millions, or billions of dollars - and, of course, they've got to hide this construction from the prying eyes of swarms of government inspectors looking for something to inspect... or, even more difficult to avoid, the office-supply salesmen in the four surrounding counties.

Assuming the truck is hijacked and taken to the secret $100 million facility, the problems are just starting for our ill-intentioned thieves. Now they must cut up the fuel assemblies and dissolve them in nitric acid. After that, the chemical processes to separate the plutonium from the uranium are devilishly tricky - in part because an almost-certainly fatal criticality accident can occur quite easily when the plutonium is in a liquid form. But let's assume that our "clever" terrorists are successful in refining out the plutonium and have shaped it for a bomb. Two big problems:

The first is obtaining the explosive charges necessary to "implode" a sphere of plutonium in on itself - essentially taking a hollow globe and compressing it down to a golf or tennis-ball-sized solid... well, almost solid. Regular explosive won't work, as the charge must have different characteristics as it "burns" to maintain the shape of the shock wave that is doing the compressing. Then there is the matter of the initiator, or trigger - the device that produces a stream of neutrons to start the reaction inside a one-tenth microsecond envelope when they are needed. This was considered by the Manhattan Project team (approximately 130,000 personnel, including arguably the best physicists and engineers in the world) as one of the most difficult items to design. Polonium 210 and beryllium must be mixed thoroughly - but this must occur within the aforementioned 0.0000001-second time frame. But let's suppose they are able to do all this. Sorry, still no cigar.

For you see, problem two, the plutonium they liberated from the Imperialist Yankee Running Dogs is not suitable for making a decent bomb. Since BWR and PWR reactors "burn" fuel slowly, Pu239 is created not only from the U238, but also from the Pu240 isotope. While not a fissionable isotope (which wouldn't make much difference in small concentrations), it is a spontaneous neutron emitter, which bodes ill for aspiring bomb makers. Even a very small amount of Pu240 is sufficient to throw off the timing of the necessary bomb reaction by starting it before the implosion is complete - causing the bomb to fizzle. Oh, you'll get an explosion of sorts - perhaps sufficient to flatten a city block or two - but not as awful as what you could do with ammonium nitrate and a little fuel oil, a la Oklahoma City. (The 1947 Texas City blast - where 512 were killed - was also a fertilizer explosion, which didn't require any plutonium at all.)

Terrorists are, in my mind, among the most despicable of humankind. But this isn't to say they are stupid. If they want to kill people and spread fear, there are a lot of easier ways to do this, and they know it. Poisoning the water supply, blasting a hole in a dam, setting oil storage facilities afire when the wind is blowing toward a heavily populated area - the list goes on and on. But building a dud bomb from hijacked plutonium isn't one of them.