Science: How Fatal Is the Fail-Out?

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Talk and worry over the H-bomb's radioactive "fall-out" is spreading.

A hot issue in New Zealand's current election campaign is the rumor (since denied) that the U.S. is planning to use Antarctica, 1,800 miles south of New Zealand, as an H-bomb testing ground. New Zealanders feel that 1,800 miles is not enough to shield them from the radioactive aftermath of hydrogen explosions.

In Parliament last week, Sir Winston Churchill said it was his understanding that an "undue number" of bomb tests might afflict the earth's atmosphere for 5,000 years. The Japanese, who get radioactivity from both U.S. and Soviet tests, keep watching their rain apprehensively. Last week they reported a radioactive shower which indicated that the Russians have exploded still another "device" somewhere in darkest Siberia.

The Fear. The reality of the radiation danger is hard to estimate. The truth is that no one knows the entire truth—not even the atomic experts.

The early-type fission bombs killed mostly by blast and heat, which people who had just experienced World War II knew about. Radioactivity, however, was new, and therefore doubly feared. Undetected by any of man's senses, it killed mysteriously. The few Japanese in Hiroshima and Nagasaki who died of radiation sickness received more horrified sympathy than the many who were burned to death or blown to smoking shreds.

Soothing statements during that period of atomic innocence were reasonably accurate. Careful study showed that except in special cases (e.g., an A-bomb exploding in a harbor and drenching a city with "hot" spray) there was little to fear from radioactivity. The bomb's initial burst of gamma rays affected few people. If the bomb exploded high in the air (the approved position), its radioactive fission products were carried aloft and dissipated in the upper atmosphere. When they sifted down thousands of miles away, they could be detected by sensitive instruments, but their activity was far too weak to damage human wellbeing.

This happy situation has changed radically with the growing quantity of fission bombs and the recent development of the hydrogen (fusion) bomb. Not much has been explained about the radioactivity left in the air by the hydrogen bomb. There is a good chance that each old-style fission bomb, or perhaps a fraction of each, can be upgraded to an H-bomb, 1,000 times as powerful. The fission bomb will act as a detonator, starting the explosion of "fusion" ingredients such as heavy hydrogen and lithium. The end product of the fusion reaction is likely to be rich in free neutrons, which can enter almost any material, make it radioactive and create vast amounts of radioactivity.

The Fog. In the new Bulletin of the Atomic Scientists, Physicist Ralph E. Lapp describes the radioactive aftereffects of the U.S. H-bomb tests in the Pacific. Dr. Lapp figures that a is-megaton H-bomb exploded near the ground will make an area of 4,000 square miles, mostly downwind, so radioactive that all people in it will get a "serious to lethal dose" in the first day alone. If they cannot evacuate, they will get more. Dr. Lapp believes that the explosion of 50 superbombs could blanket the entire northeastern U.S. "in a serious to lethal radioactive fog."