Engines of Our Ingenuity

No. 1043:
A SPONTANEOUS A-BOMB?

by John H. Lienhard

Click here for audio of Episode 1043.

Today, a story about fear. The University of Houston's College of Engineering presents this series about the machines that make our civilization run, and the people whose ingenuity created them.

Since 1986, engineers at Los Alamos have been planning a nuclear waste dump at Yucca Mountain, in Nevada. They hope to cast plutonium in glass blocks and bury it underground.

One expert, Charles Bowman, offered a competing plan. He would use the plutonium in a sub-critical reactor -- one that wouldn't run by itself but would have to be driven by a proton beam. That would degrade the plutonium and generate power on the side.

Then Bowman went a step further. He and a colleague wrote a paper criticizing simple burial. Maybe plutonium could leach out of the glass and cause a nuclear explosion. When colleagues read the paper, they asked him to slow down. The suggestion was, may I say, incendiary; and it was based on a long string of ifs.

Nuclear fission goes on all the time in uranium and plutonium. Fission releases energy and neutrons. The neutrons cause more fission. The process is gentle because only a few neutrons hit anything. Atoms are too far apart. Neutrons are too small.

Imagine two magnetic bullets fired toward each other on parallel paths, a half-inch apart. Bullets move too fast to be drawn into a collision. They'd have to move slowly to collide.

In a nuclear reactor, engineers surround uranium with water. Neutrons enter the water and are slowed down. Those that ricochet back into the core can easily hit uranium atoms. That's when fission takes off.

So, said Bowman, if groundwater reached that nuclear waste, an explosion might occur. Colleagues attacked his fabric of assumptions. You reach a point in Bowman's logic -- one said -- where, to get an explosion, a miracle has to occur. Actually, such reactions do occur in nature. But when they do, they simply boil the groundwater away and turn themselves off. They fizzle out. But public fear doesn't fizzle out -- not by a long shot!

As the fuss went on at Los Alamos, the New York Times got wind of it. The next day a Nevada senator showed up in Congress waving the headline: "Scientists Fear Atomic Explosion of Nuclear Waste."

So Los Alamos commissioned a Red Team to attack Bowman's idea; a Blue Team to defend it; and a White Team to summarize the findings. Bowman's work did not stand up to that scrutiny.

Now Science magazine tells how DOE studies the problem to death. They react to politicians instead of getting the dump built and the material put away. Meanwhile, Apaches in New Mexico are saying, "Put the dump on our reservation. We need the jobs."

We all crave theater, and, ever since the first Frankenstein movie, technology has provided theater. But this is no place for the theater of politics. This real problem needs a real solution.

I'm John Lienhard at the University of Houston, where we're interested in the way inventive minds work.

(Theme music)


Taubes, G., Blowup at Yucca Mountain. Science, Vol. 268, No. 5219, 30 June, 1995, pp. 1836-1839.

Broad, W.J., Deadly Nuclear Waste Piles Up With No Clear Solution at Hand. New York Times, March 14, 1995.


The Engines of Our Ingenuity is Copyright © 1988-1997 by John H. Lienhard.

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