Peaceful Atomic Blasting

Everyone who has seen an atomic explosion must have wondered how its enormous force could be put to peaceful use. Chemical explosives, comparatively puny, have shaped the modern world, dug its canals and tunnels, won its coal and ore, but until recently, atomic explosives were too secret and too radioactive to be considered seriously. Now it appears that within a few years they may become man's most powerful tool for fitting the earth to his use.

Last week the Senate's Subcommittee on Disarmament released a discussion by Atomic Energy Commissioner Willard F. Libby of Test Rainier, the world's first tentative trial of peaceful atomic blasting. The bomb used, said Dr. Libby, was "a little fellow" with the power of only 1,700 tons of TNT, and it exploded at the end of a 1,900 ft. tunnel cut into the soft volcanic rock of a flat-topped Nevada mesa. The end of the tunnel turned back on itself to make the fireball build its own prison. When the bomb exploded, the shock wave made a short run through the rock and plugged the tunnel tight before the dangerous gases could race around the bends. The whole mountain jumped about six inches, but no radioactivity escaped into the open.

Rock Bubble. A few days after the explosion, Libby told the Senators, a crew began drilling down into the rock. The drillers did not know what to expect, and they took no chances, but everything was normal for several hundred feet: no heat, no radioactivity. Then suddenly the drill dropped into an empty cavity 50 ft. high. It was floored with broken rock, slightly radioactive and averaging about 40DEG hotter than the rock around it. Below the place where the bomb itself had been was a thin zone of dark, intensely radioactive rock.

Apparently the fireball blew an enormous bubble, 110 ft. in diameter, in the heart of the mountain. Its skin was made of melted and vaporized rock that trapped nearly all of the radioactivity. Around it was a zone of rock shattered by the shock wave into an estimated 400,000 tons of rubble. When the gases cooled a few seconds later, some of the rubble fell down, filling the bubble and leaving the cavity that the drillers found.

Dr. Libby is delighted with the performance of the little fellow that shattered 400,000 tons of rock without increasing Nevada's surface radioactivity. Now the AEC's Project Plowshare (atomic blasting) can be speeded up. Some of the possibilities:

Harbors. Bomb tests in the Pacific have already blasted craters big enough for harbors. They created a lot of radioactivity, but more advanced bombs can be safer. Even the cleanest bomb will release neutrons that can make certain substances radioactive, but Libby says that in many cases this will be nothing to worry about. Four elements that form most of the earth's crust (aluminum, magnesium, silicon and oxygen) are not activated by neutrons. Sodium, found in rocks and in sea water, is strongly activated, but its activity disappears in a few days. An atom-blasted harbor, say on the almost harborless coast of Peru, should be safe after a short time.

Power. The heat of feeble Test Rainier was dissipated through 400,000 tons of rock, but Dr. Libby thinks that a bomb exploded under a different kind of mountain might create a mass of very hot rock. Water forced into it would turn to steam that might be used in turbines to produce cheap power.

Oil. One of the most prominent uses of atomic blasting has been hungrily discussed for years in the petroleum industry. Oilfields commonly play out when a good part of their oil is still in the ground. An atom bomb exploded in the oil-bearing formation might have several good effects. It would create new channels for the oil to flow through. Its heat would make the oil more liquid and ready to flow. Some of the oil might be turned into high-pressure gas that would drive other oil to the surface.

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