Nuclear security

Nuclear explosions: Preserving images of terrifying, swift power

The force of nuclear weapons has to be seen to be believed. Now, thanks to a project headed by Gregg Spriggs at Lawrence Livermore National Laboratory in California, the public can see the destructive power of atomic blasts as never before.

Starting in 1945 the United States conducted 210 above-ground nuclear tests, all of them documented on film, from as many angles as possible.

That ended in 1963 when, for the good of the planet, the U.S. and the Soviet Union agreed to stop testing in the atmosphere.

Unlike most of us, Spriggs understands the physics that produces these spectacular images – fireballs that can spread two miles across, and reach temperatures of 10 to 15 million degrees kelvin. At the outer edge of the fireball is a shockwave; what the fireball doesn't vaporize, the shockwave crushes.

"When it starts off, it's moving at Mach 100, a hundred times the speed of sound," Spriggs said, showing correspondent David Martin footage of one test's shockwave.

And then there is the mushroom-shaped cloud, which climbs into the sky, spewing radiation. "That's directly tied to the nuclear fallout which is very, very sensitive to the cloud height," he said.