During World War II, the United States launched the Manhattan project, which produced the first atomic bombs. With technological advancements based on this fundamental research, in December 1942 the first nuclear reactor was tested in an abandoned handball court at the University of Chicago. This test proved the viability of large scale nuclear power reactors for utility scale use.
Throughout the 1960s and early 1970s there was a lot of contention over the safety of nuclear power plants for commercial use.
Nuclear reactor accidents
Three Mile Island: In 1979, at Three Mile Island in Pennsylvania, an enclosed reactor failed when internal temperatures exceeded 2,750 degrees Celsius. This could have resulted in a terrible explosion, but did not. The containment building, which was built specifically for such mishaps, prevented any immediate deaths, and contained the radiation leakage to minimal proportions. However, studies indicated that the cancer rate increased slightly among the nearby population and public fear was stoked.
Chernobyl: In 1986, in Chernobyl, Russia, a nuclear reactor with substandard engineering and a poorly designed containment structure melted down and released radioactivity. The accident exposed thousands of people to high levels of radiation, particularly during the cleanup. A 300-square-mile area around the site was evacuated, and there were 31 immediate deaths, with 500 more people hospitalized for various reasons. It is estimated that between 6,000 and 24,000 people died from cancer since the accident.
Fundamentals of Nuclear Power
There are two distinct types of nuclear energy: fusion and fission. When atomic nuclei undergo either fusion or fission, it is the binding energies that provide the usable power output. In fusion, atoms are combined, or fused. In fission, atoms are dissociated.
All matter is made up of very dense particles called electrons, protons, and neutrons. The subatomic particles move incredibly fast and electrons are in motion most of the time around the nucleus, which is made up of the protons and neutrons.
The number of protons and neutrons defines the properties of the element, and is called the nucleus. Protons have a positive charge, neutrons have no charge, and electrons have negative charge. In most atoms, the number of protons, neutrons, and electrons are equal, and the net charge is zero because the positive charges balance out the negative charges.
The number of protons determines the atomic number of the atom, and this gives the element its fundamental identity. The simplest element is hydrogen, with one proton in the nucleus. Helium has two protons and lithium has three.
Nuclear binding energy is the force that holds protons and neutrons together.
Isotopes: Elements can have different versions characterized by slight changes in the composition of the nucleus; the different versions are called isotopes. Isotopes occur when the number of protons does not match the number of neutrons. All elements have at least two isotopes, and some have dozens.
Uranium is the element used in nuclear reactors, and all known isotopes are unstable. Uranium exists as either U-234 or U-235 (with atomic weights of 234 and 235, respectively). However, the most common form of uranium is U-238.
Ions: If an atom has more or fewer electrons than protons, it is called an ion, and there is a net electrical charge. When there are more electrons than protons, the net charge is negative; more protons than electrons results in a positive net charge.
Nuclear Power: Fission
At the core of a nuclear reactor are U-235 atoms, and these are bombarded by high speed neutrons. When an atom of U-235 is struck by a neutron, the atom instantly splits into two separate nuclei, each lighter than the original. Neutrons are emitted, along with gamma rays, which are extremely energetic photons that can penetrate most substances without hindrance, and heat energy is produced.
When one of the emitted neutrons from the original nuclear reaction strikes another uranium atom, the new uranium nucleus splits, thereby releasing even more energy, and creating new atoms as a byproduct. A chain reaction occurs when enough neutrons are being emitted by the fission.