Small earth-penetrating nuclear warhead would have lethal side-effects
Low-yield earth-penetrating nuclear weapons, intended to threaten deep bunkers without killing the surrounding population, would release dangerous fallout, according to an analysis by the Federation of American Scientists.
Some nuclear weapons developers have advocated developing and testing new small nuclear weapons as a way to destroy deeply buried bunkers containing enemy leaders or biological weapons. Delivered by a bomb or missile that would strike the ground a high speed and penetrate deeply before exploding, the weapon is intended to destroy the bunker but leave nearby civilians unharmed because the earth over the explosion would contain it.
But the study, performed by Princeton University physicist Robert Nelson, finds this to be technologically impossible. "No earth-burrowing missile can penetrate deep enough into the earth to contain an explosion with a nuclear yield even as small as 1% of the Hiroshima weapon. The explosion simply blows out a massive crater of radioactive dirt, which rains down on the local region with especially intense and deadly fallout," according to the study.
A 1-kiloton explosion, less than one tenth that of the Hiroshima bomb, would need to be under 450 feet of earth to be fully contained. But the U.S. B61-11 deep-penetrating bomb only penetrates about 20 feet. A tactical missile might possibly penetrate to 100 feet, although it would be difficult for a nuclear warhead to function after such an impact.
If an underground explosion is not contained, it becomes very "dirty", in that the earth above it is made radioactive and thrown over a large area. Thus, use of even a small earth-penetrating warhead in a populated area would cause significant civilian casualties, according to the study.
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Scientists who built the first atomic bomb founded the Federation of American Scientists in 1945. More than half of the current American Nobel Laureates today serve on the FAS Board of Sponsors. FAS conducts research, analysis, and advocacy on public policy issues created by advances in science and technology (see www.fas.org).