• Choose a category
• All
• Classic-Fiction

By Root 655 0

So we don’t worry too much about it. But a bang? A nuclear explosion? Impossible. For that you require U-235 over ninety per cent pure, the stuff we dropped on Hiroshima. Now that is nasty stuff. There was a hundred-and-thirty-two pounds of it in that bomb, but it was so crudely designed–it really belonged to the nuclear horse-and-buggy age–that only about twenty-five ounces of it fissioned: but was still enough to wipe out the city. Since then we have progressed–if that’s the word I want. Now the Atomic Energy Commission reckons that a total of five kilograms–eleven pounds–is the so-called “trigger” quantity, enough for the detonation of a nuclear bomb. It’s common knowledge among scientists that the AEC is most conservative in its estimate–it could be done with less.’

Ryder said: ‘No U-238 was stolen. You used the word “understandably”. Couldn’t they have stolen it and converted it into U-235?’

‘No. Natural uranium contains a hundred-and-forty atoms of U-238 to each atom of U-235. The task of leaching out the U-235 from the U-238 is probably the most difficult scientific task that man has ever overcome. We use a process called “gaseous diffusion”–which is prohibitively expensive, enormously complicated and impossible to avoid detection. The going cost for a gaseous diffusion plant, at today’s inflated rates, is in the region of three billion dollars. Even today only a very limited number of men know how the process works–I don’t. All I know is that it involves thousands of incredibly fine membranes, thousands of miles of tubes, pipes and conduits and enough electrical power to run a fair-sized city. Then those plants are so enormous that they couldn’t possibly be built in secret. They cover so many hundreds of acres that you require a car or electric cart to get round one. No private group, however wealthy or criminally-minded, could ever hope to build one.

‘We have three in this country, none located in this State. The British and French have one apiece. The Russians aren’t saying. China is reported to have one in Langchow in Kansu Province.’

‘It can be done by high-speed centrifuges, spinning at such a speed that the marginally heavier U-238 is flung to the outside. But this process would use hundreds of thousands of centrifuges and the cost would be mind-boggling. I don’t know whether it’s ever been done. The South Africans claim to have discovered an entirely new process, but they aren’t saying what and US scientists are sceptical. The Australians say they’ve discovered a method by using laser beams. Again, we don’t know, but if it were possible a small group–and they’d all have to be top-flight nuclear physicists–could make U-235 undetected. But why bother going to such impossible lengths when you can just go to the right place and steal the damned stuff ready-made just as they did here this afternoon?’

Ryder said: ‘How is it all stored?’

‘In ten-litre steel bottles each containing seven kilograms of U-235, in the form of either an oxide or metal, the oxide in the form of a very fine brown powder, the metal in little lumps known as “broken buttons”. The bottles are placed in a cylinder five inches wide that’s braced with welded struts in the centre of a perfectly ordinary fifty-five-gallon steel drum. I needn’t tell you why the bottles are held in suspension in the airspace of the drum–stack them all together in a drum or box and you’d soon reach the critical mass where fissioning starts.’

Jeff said: ‘This time it goes bang?’

‘Not yet. Just a violent irradiation which would have a very nasty effect for miles around, especially on human beings. Drum plus bottle weighs about a hundred pounds, so is easily moveable. Those drums are called “bird-cages”, though Lord knows why: they don’t look like any bird-cage I’ve ever seen.’

Ryder said: ‘How is this transported?’

‘Long distance by plane. Shorter hauls by common carrier.’

‘Common carrier?’

‘Any old truck you can lay your hands on.’ Ferguson sounded bitter.

‘How many of those cages go in the average truck shipment?’

‘That hi-jacked