June 18, 2013

Trying to build a bomb that won't blow up

By Greg Jaffe / The Washington Post

(Continued from page 1)

Iraqi fighters, with help from Iran, built high-tech devices that could pierce the American armor. The Afghan insurgents turned to fertilizer bombs, which are cheap, easy to make and devilishly hard to detect. A typical bomb kills with razor-sharp shrapnel. A fertilizer bomb contains no metal. It kills with an intense wave of intense energy that passes through the thickest armor.

"The ears are the most sensitive," Best said, describing in more detail the damage the bombs could do, as two of his scientists mixed the ammonium nitrate and aluminum powder.

"It isn't the noise that blows the eardrum, but the overpressure from the bomb," he said. The lungs are typically the next to fail, followed by the brain and then the heart.

After about 10 minutes of work and a couple of additional steps, the bombs were done and ready to blow. Taliban insurgents usually make 40-pound fertilizer bombs in yellow, plastic cooking oil containers. Best's bombs were only 10 pounds.

"If we build them any bigger, we are more than likely to crack a window in someone's house," said the physicist on Best's team. "The rich people out here have houses on the river with lots of windows."

The test range consists of a muddy field, two big dirt berms and two rusty shipping containers that serve as an office. Silver sensors shaped like microphones measure the pressure from the blast wave. High-speed cameras record the action at a rate of about 10,000 frames per second, fast enough on this day to track the movement of individual rain drops falling through the sky.

First up on the test range was the plastic bucket of untreated ammonium nitrate fertilizer, which one of Best's scientists set on a smooth steel plate. The plate — or, rather, any dent in it — would offer up a crude measure of the blast's power, even if the more sophisticated technology on the range failed.

Best and his scientists took shelter in one of the cramped shipping containers. Inside, plywood desks were crammed with knives, screwdrivers, hammers and a bag of stale Krispy Kreme donuts. Computers captured readings from the sensors.

"Ready," said the firing officer. "On the count of 3,2,1. Fire."

The blast rippled through the air, strong enough that Best and his team could feel it vibrate in their sternums. "Imagine if you had just stepped on that," Best said. "We are 150 feet away and protected by two berms."

Data from the blast were recorded. Debris from the range was cleared. Now it was time to test the Sandia fertilizer mix. One of Best's scientists set the plastic bucket on the range and retreated to the shipping container. If the Sandia mix worked as promised, it would be a huge breakthrough. Ammonium nitrate fertilizer has been used in bombs in dozens of countries in the past few years. In April, a Texas plant that was manufacturing the fertilizer exploded, killing 15 and wounding 200.

"Ready," said the firing officer. "On the count of 3,2,1. Fire."

Another sternum-shaking boom.

Best and his team walked up a small hill to the range and examined the steel plate on which the bomb had been placed. No dent. Instead, there was a softball-sized hole.

"Not good," Best said.

He and his team returned to the shipping container to check the sensor's readings, which would tell them whether the Sandia mix had done any good at all.

With the wars drawing to a close and American combat casualties falling, the Defense Department is weighing whether to dismantle the division of the Pentagon where Best works and send its people back to the military services. The division, known as the Joint Improvised Explosive Device Defeat Organization, was established in 2006 when dozens of troops were being killed by insurgent bombs every month. Even if it remains open, Best said that his job will likely be eliminated in January.

"I want to stay," he said. "But I can't figure out how to stay."

One of Best's scientists checked the readings on the computer. "It looked like it suppressed the overpressure from the blast by about 5 percent," he said.

Best shook his head. He would need to call Sandia.

"You are still dead," he said. "This was not a success. We still have a guy in a body bag."

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