Oct. 18, 2006 —While North Korea was testing a nuclear bomb, France was verifying its nuclear arms, too — with a battalion of soundless, black, cabinet-sized calculators buried beneath a meadow.
The world's established nuclear powers have for the past decade foregone real test blasts for the onscreen kind, harnessing the world's most powerful computers to simulate as best as possible what happens when a nuclear bomb explodes.
So why should any nation test-blast weapons anymore if supersimulators can do the job? Because, nuclear experts say, it has turned out to be tougher than most people thought to mimic the "real thing."
Scientists working in a secretive compound at Bruyeres-le-Chatel, south of Paris, are still several years away from being able to replicate nuclear fusion, or trying out a new bomb design without detonating it. Their American counterparts are only slightly closer, despite billions of dollars spent on supercalculators and superlasers.
"We're not really there yet," said Don Johnston, spokesman for supercomputing programs at Lawrence Livermore National Laboratory, a U.S. government nuclear research facility in California. "The more you find out, the more you realize you don't know."
North Korea's test deep inside a mountain last week sent shivers across the globe, revived fears of a nuclear apocalypse and talk of test bans, and drew new attention to these simulation efforts.
In the most basic nuclear weapon, like that dropped on Hiroshima, two loads of highly enriched uranium are slammed together to create a critical mass, a fission chain reaction, and a blast.
Most modern weapons are implosion devices, in which conventional explosives surround a radioactive core and rapidly compress it into a supercritical state.
