Vortex

Working fast now, almost in rhythm with the sound of the firing behind him, he molded the C4 onto one of the steel supports steadying the power pylon and stuck a line of detonator cord into it. Satisfied, he crawled away, unreeling detcord as he went.

A shallow drainage ditch running beside the road offered the only piece of real cover for more than a hundred meters. Miller calculated distances and angles and swore viciously. He was well inside the minimum safe distance for setting off the C4, but he didn’t have time to crawl farther. He glanced over the edge of the drainage ditch. Flashes showed where Hernandez and his men were still firing toward the South African bunker.

“First Squad! Break it off and reform here!”

Working quickly and carefully in the darkness, Miller attached a blasting cap, fuze, and fuze igniter to the end of the cord. As he worked, he tried to forget that det cord was itself an explosive. If he rushed the job, it would go off in his face.

Wire and electrical detonators were out of the question for this job.

There was too big a chance of their picking up stray voltage from the transmission tower.

One by one, the Rangers stopped firing and raced over to the drainage ditch. One screamed suddenly and flopped forward, clutching at a leg that had been shot out from under him. Two others hauled him upright and half-pulled, half carried him to the ditch.

Miller took one last look around. None of his men were still out in the open. He took a deep breath and pulled the pin out of the fuze igniter.

Throwing it back toward the tower, he yelled, “Fire in the hole!”

The Rangers went prone, facedown in the dirt. Nobody fucked around when explosives were about to go off. Miller buried his face in the ditch.

Whummmp. Whummmp. Whummmp. Three separate blasts sliced through the supports holding up the transmission tower. Tom pieces of metal whirled away overhead.

Slowly at first and then faster, the tower leaned drunkenly far over to one side. Bolts and struts popped and then snapped off under immense and increasing weights and pressures. Abruptly, everything gave way at once.

With a grating screech of tortured, twisting steel, the tower crashed to the ground. Downed power lines danced and sparked like ghostly flickering blue snakes.

Pelindaba’s backup power source had been knocked out of commission.

PELINDABA CENTRIFUGE URANIUM-ENRICHMENT

PLANT

Indifferent to the outside world, the South African technicians monitoring twenty thousand rapidly spinning centrifuges inside the enrichment plant’s central cascade hall moved through their own universe of high-pitched, howling noise. None of them could hear the alert sirens and nobody in the garrison had yet taken the time to warn them of the attack. Then the lights went out.

Disaster struck instantly.

The scientists and engineers who’d designed the enrichment plant had taken precautions against an accidental loss of one or the other of

Pelindaba’s two independent electric power sources. An automatic transfer system stood ready to shunt electricity from either the coal-fired steam plant or the thirteen-kv transmission line connected to the Pretoria grid. Unfortunately, the South African design team had never imagined the deliberate and simultaneous destruction of both. Esher Levi had found

Pelindaba’s Achilles’ heel.

Like any highly sophisticated and fragile machine, a uranium-enrichment centrifuge carries the seeds of its own destruction inside itself. To successfully and efficiently separate fissionable U-235 from non fissionable U-238, each centrifuge’s carbon-fiber rotor must spin at nearly thirty-five thou sand rpm-producing peripheral velocities of up to five hundred meters per second.

Reaching that kind of rotation isn’t easy. An enrichment centrifuge must be carefully balanced and precisely controlled as it spins faster and faster.

Several critical speeds-speeds where the rotor will begin to vibrate dangerously-must be negotiated before it can reach its operating rpm. End dampers can help reduce these vibrations, but they become uncontrollable if the machine contains a significant amount of uranium hexafluoride gas as it cycles through any of these critical speeds.

All of Pelindaba’s spinning centrifuges were full of uranium hexafluoride gas when the plant lost power.

In fractions of a second inertia and drag were at work. Rotors spun slower and slower. And as the machines decelerated, their carbon-fiber walls began to flex, wobbling about like wet noodles-distorted by the gas trapped inside.

Most of the twenty thousand uranium-enrichment centrifuges shattered simultaneously-hurling carbon fiber fragments spinning at more than a thousand miles an hour into the protective casings surrounding each machine. Each crashing centrifuge sounded exactly like a large-bore shotgun being fired just a few feet away.