The Chemistry of Nuclear Weapons Nuclear weapons are weapons capable of mass destruction. They are powered by two reactions, fission and fusion. These weapons produce massive explosions and hazardous radioactive products. Some miniaturized tactical weapons have the force of a kiloton of TNT. While other strategic weapons create thousands of kilotons of force.

However, only two nuclear bombs have been used in actual warfare. The Atomic Bomb and the Hydrogen Bomb. Nuclear fission is the splitting of an atom into two or more parts. When such an occurrence takes place, a very large amount of energy is released.

This can occur very quickly as in an atomic bomb, or in a more controlled manner allowing the energy to be captured for useful purposes. Only a few naturally occurring substances are easily fissionable. These include uranium-235 and plutonium-239, two isotopes of uranium and plutonium. Isotopes are forms of the same chemical element that have the same number of protons in their nuclei, but a different number of neutrons. Starting a fission reaction is accomplished by bombarding fissionable nuclei with neutrons. This causes the nuclei to fly apart, splitting into two fission products and emitting two or three neutrons of their own.

These neutrons may break apart other nearby fissionable nuclei, starting a chain reaction, and resulting in the release of a great deal of energy in the form of radiation and heat. The major fragments of the split atoms are now different chemical elements, all highly radioactive. These fission products include such isotopes as iodine-131, cesium-137 and strontium 90. Another form of nuclear energy is called fusion. Fusion means joining smaller nuclei to make a larger nucleus. The sun uses nuclear fusion of hydrogen atoms into helium atoms.

This gives off heat and light and other radiation. Two types of hydrogen atoms, deuterium and tritium, combine to make a helium atom and an extra particle called a neutron. Also given off in this fusion reaction is energy. Scientists have been working on controlling nuclear fusion for a long time, trying to make a fusion reactor to produce electricity.

But they have been having trouble learning how to control the reaction in a contained space. Temperatures greater than 1,000,000 degree Celsius are required to create a fusion. In Hydrogen Bombs fission is used to get temperatures that high and initiate fusion. Sustained, controlled fusion reactions, however, require the maintaining of the nuclear fuel at extremely high temperatures long enough to allow the reactions to take place. At these temperatures the fuel is plasma, and magnetic fields have been used in attempts to contain this plasma. To produce fusion energy, scientists have also used high-powered laser beams pointed at tiny pellets of fission fuel.

Fusion is mostly used in Hydrogen Bombs. The Atomic Bomb gets its explosive force from a sudden release of nuclear energy from fission. The Atom Bomb is probably the most famous nuclear weapon. It was tested successfully in very secretive Manhattan Project (The Century). An Atomic Bomb is detonated by bringing together very rapidly two sub critical masses of fissionable material. The explosion caused by this generates massive amounts of heat, a shockwave, and intense nuclear radiation.

The fallout of the bomb makes everything radiantly contaminated. The Atomic Bomb is surrounded by a layer of lithium deuteride and an outside layer that is made of fissionable material which causes a bigger reaction and explosion. The Atom Bomb was the first atomic bomb ever dropped. After the invasion of Poland by Nazi Germany Albert Einstein and Leo Szilard warned the U.S. government of the danger threatening the world if the Nazis should be the first to make a nuclear bomb (The Century). Oppenheimer then began to seek a process for the separation of uranium-235 from natural uranium and to determine the critical mass of uranium required to make such a bomb. The U.S. Army was given the responsibility of organizing the efforts of British and U.S. physicists to seek a way to harness nuclear energy for military purposes, an effort that became known as the Manhattan Project.

Oppenheimer was instructed to establish and administer a laboratory to carry out this assignment. In 1943 he chose the plateau of Los Alamos, near Santa Fe, New Mexico (The Century). The Hydrogen Bomb weapon deriving a large portion of its energy from the nuclear fusion of hydrogen isotopes. In fusion lighter elements are joined together to form heavier elements, and the end product weighs less than the components forming it. The difference in mass is converted into energy. Because extremely high temperatures are required to initiate fusion reactions, a hydrogen bomb is also known as a thermonuclear bomb.

The presumable structure of a hydrogen bomb is as follows: an Atomic Bomb is surrounded by a layer of lithium deuteride (a compound of lithium and deuterium) and then by a tamper, or thick outer layer, frequently of fissionable material, that holds the contents together in order to obtain a larger explosion. The atomic explosion produces neutrons that fission the lithium into helium, tritium, and energy, and creates the extremely high temperature needed for the subsequent fusion of deuterium with tritium, and of tritium with tritium. Explosion of the neutron bomb, which has a minimal atomic trigger and a non fissionable tamper, produces blast effects and a hail of lethal neutrons but almost no radioactive fallout. The first thermonuclear bomb was exploded in 1952 at Enewetak by the U.S., the second in 1953 by the USSR. The Hydrogen Bomb gets most of its energy from the fusion of Hydrogen isotopes.

Since extremely high temperatures are needed to make the fusion reaction, it is also known as the thermonuclear bomb (Parshall). It causes a showering of lethal neutrons, but no radioactive fallout derives from it. The formula for the hydrogen bomb is. In simpler terms it is LiH surrounded by an Atom Bomb which is surrounded by TNT. Many scientists are responsible for the studying and creating the nuclear bombs.

One was Otto Hahn, a German chemist and physicist. Noted for important work on radioactivity, he received the 1944 Nobel Prize in chemistry for splitting the uranium atom and discovering the possibility of chain reactions. The development of the atomic bomb was based on this work. Another famous person was Lise Meitner an Austrian-Swedish physicist and mathematician. (Bergerund). She discovered the Protactinium-231 isotope and investigated the disintegration products of radium, thorium, and actinium and the behavior of beta rays radioactivity.

Her conclusion, from experimental research in bombarding the uranium nucleus with slow-speed neutrons, that fission of the nucleus had occurred, contributed to the development of the Atom Bomb. The last is J. Robert Oppenheimer, an American physicist. He taught at the Univ. of California and the California Institute of Technology and was from 1947 director of the Institute for Advanced Study at Princeton. Director (1942-45) of the laboratory at Los Alamos, N. Mex., that designed and built the first Atom Bomb (Parshall). Oppenheimer later became a main proponent of the civilian and international control of atomic energy. He was chairman (1946-52) of the general advisory committee of the U.S. Atomic Energy Commission, but in 1953 the AEC suspended him as an alleged security risk (Bergerund).

Oppenheimer strongly opposed (1949), on both technical and moral grounds, the development of the Hydrogen Bomb. The Manhattan project was the begging of the finishing of the bomb. It was a wartime effort to design and build the first nuclear weapons. A $2-billion effort, centered at Oak Ridge, Tenn., and Hanford, Wash., was required to obtain sufficient amounts of the two necessary isotopes, uranium-235 and plutonium-239. (Bergerund). The design and building of the bombs took place at Los Alamos, N. Mex., where J. Robert Oppenheimer directed a large group of American and European-refugee scientists.

Following the test explosion of a plutonium device on July 16, 1945, near Alamogordo, N. Mex., a uranium bomb and a plutonium bomb were dropped on, respectively, Hiroshima (Aug. 6) and Nagasaki (Aug. 9). Bergerund, Eric M. Dropping the Bomb. New York: Newsday, 1995. Parshall, Gerald. Shock wave. U.S. A: U.S. News and World, 1995. The Century.

Narr. Peter Jennings. ABC Special Report, 1999. Nuclear Fusion Basics.

January 2000.326.