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ART HOBSON: The bomb and how it works

Variations yield massive damage in different ways by Art Hobson | September 3, 2019 at 1:00 a.m.

The consequences of nuclear weapons are horrendous, but the science is fascinating. To prevent the horror, citizens must learn some of the related science.

Our familiar world is made of atoms. There are only 118 chemically different types of atoms or "elements." Atoms are made of a tiny central nucleus containing two kinds of particles, namely protons and neutrons, and of smaller lighter electrons moving roughly in circles around the nucleus.

Each atom's "chemistry" (the atoms with which it will combine) is determined by its number of electrons, which is equal to its number of protons. This keeps each atom "electrically neutral" because electrons and protons are "oppositely electrified," electrons negative and protons positive. The elements are numbered according to their number of protons (or electrons). For example, number 1 is hydrogen, with one proton in the nucleus. Elements number 92 and 94, uranium and plutonium, are central to nuclear power and nuclear weapons.

Nuclear weapons and nuclear reactors for peaceful energy are highly significant nuclear technologies. One significant link between them is that both can be fueled by uranium, plutonium or hydrogen. The energy they produce comes from either "fissioning" (splitting) uranium or plutonium nuclei, or "fusing" (joining together) hydrogen nuclei.

The world's first nuclear reactor was based on uranium fission. It turned on in 1942 as part of the secret Manhattan Project to build a nuclear bomb during World War II, a project driven by fear of a German nuclear bomb. Indeed, Germany was working in that direction, but their research never achieved a working reactor, much less a bomb.

Fission reactors and bombs are based on a "chain reaction." If a sufficient amount (called a "critical mass") of uranium is assembled, and if the assembly is then showered with neutrons, the neutrons will enter a small fraction of the uranium nuclei, causing those nuclei to fission into roughly two parts plus two or three extra neutrons. These neutrons are key to the chain reaction: They go on to enter other nuclei, which then fission, emitting more neutrons, and so forth. This chain of reactions will fission (split) a significant fraction of the trillion trillions of assembled uranium nuclei, each fission releasing a relatively large (on the atomic scale) amount of energy. The huge energy release can produce electric power in reactors or explosions in bombs.

During 1944 and 1945, at a laboratory in Los Alamos, N.M., an international team of scientists constructed the world's first nuclear weapons: one uranium bomb and two plutonium bombs. The uranium bomb was dropped on Hiroshima, Japan on Aug. 6, 1945. One plutonium bomb was tested in New Mexico in July 1945 and the other fell on Nagasaki, Japan on Aug. 9, 1945. The Hiroshima blast had a "yield" (a truly ironic term) equivalent to 12,000 tons of TNT. Afterward, 140,000 lay dead. By 1950, the death toll had reached 200,000--50 percent of the city's population. The Nagasaki bomb had a yield of 22,000 tons of TNT. It killed 70,000 outright and 140,000 total by 1950.

I wept while writing that paragraph. Why must humans do this to each other? Today, such devices, having yields similar to the Hiroshima bomb, are called "tactical nuclear weapons" and come in the form of land mines, air-dropped bombs, and rocket-launched missiles for battlefield use. As I discussed three weeks ago, the U.S. has hinted at using nuclear weapons against Iran. They would probably be of the "tactical" variety.

Regarding fusion: Fusion reactors are at least 50 years in the future, but hydrogen fusion bombs have unfortunately been around since they were first tested by the United States in 1952. H-bomb fuel is a special naturally occurring form of hydrogen containing one proton and one or two neutrons in the nucleus. Their yield typically runs up to one million tons of TNT, hundreds of times larger than fission bombs. The U.S., Russia, China, France, U.K. and probably North Korea have these monsters, as "deterrence" to prevent other nations from using their H-bombs.

One such bomb can destroy, for example, Detroit or San Francisco. They work by first detonating a fission bomb and then, within the same bomb casing, employing the powerful x-rays emitted from the fission reaction to quickly heat hydrogen to millions of degrees, high enough to "fuse" hydrogen nuclei together to form helium (whose nucleus comprises two protons and two neutrons).

Note the paradox of deterrence: All nations could prevent other nations from using nukes by banning nukes, yet nine nations have nukes.

Commentary on 09/03/2019

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