Nuclear technology

Nuclear technology involves using the energy from nuclear reactions in atomic nuclei. While most natural phenomena on Earth rely on gravity or electromagnetism, nuclear reactions involve the tiny centers of atoms. Most nuclei stay apart because they have positive electrical charges that repel one another. However, some nuclei are unstable and undergo decay. This means they release matter or energy to reach a more stable state.

This released energy is known as radiation. Today, nuclear technology is used in many ways, including nuclear medicine, reactors, and even household smoke detectors.

Radioactivity was first discovered in 1896 by Henri Becquerel. He was studying uranium salts when he noticed a new phenomenon. Later, Pierre Curie and Marie Curie investigated this further. They isolated the highly radioactive element radium. They identified three distinct types of radiation: alpha, beta, and gamma. Alpha decay occurs when a nucleus releases an alpha particle, which is two protons and two neutrons. Beta decay is the release of a high-energy electron. Gamma decay is different because it is electromagnetic radiation, not matter. Gamma rays are very high frequency and are the most difficult to block. Early researchers did not realize these rays were ionizing radiation. Many scientists suffered radiation burns or died of cancer due to exposure.

One major way to release nuclear energy is through nuclear fission. This is the process of splitting a nucleus into roughly equal parts. When a nucleus splits, it releases energy and neutrons. If these neutrons are captured by other unstable nuclei, they can cause more fission. This creates a self-sustaining chain reaction. Scientists use a value called "k" to describe this process. If k is larger than 1, the reaction releases more neutrons than it absorbs. A mass of material large enough to sustain this reaction is called a critical mass. If the reaction happens too quickly, it is called prompt critical, which can lead to an explosion.

Nuclear fission is used today to generate electricity in power plants. To make this process safe, scientists must control the reaction. Fast neutrons are hard to capture, so they must be slowed down. This is done using a neutron moderator, which is a material that slows neutrons through collisions. By adding or removing neutron absorbers, engineers can control the rate of fission. The first nuclear fission power plant to produce electricity was the Experimental Breeder Reactor No. 1. It was located in Arco, Idaho, and began operating in 1951. This event helped start the "Atomic Age" of human energy use.

Another process is nuclear fusion, which occurs when nuclei are forced to collide. This process is much more energetic than fission per unit of mass. In stars, fusion provides energy by combining hydrogen and helium. This process, called stellar nucleosynthesis, creates light elements like lithium and calcium. Heavier elements are created through supernova nucleosynthesis. While fusion is powerful, it is very difficult to achieve in a controlled way on Earth. Hydrogen bombs, or thermonuclear weapons, use fusion to create enormous destruction. Scientists are still researching how to achieve controlled, viable fusion power for civilian use.

Nuclear weapons use either fission, fusion, or both to create massive explosions. These weapons are considered weapons of mass destruction because they cause blast, fire, and radiation. Creating these weapons is difficult because of the fuel required. For example, uranium-235 is needed, but it is usually mixed with the more stable uranium-238. Scientists must use isotope separation to enrich the uranium. Alternatively, they can manufacture plutonium in a nuclear reactor. The Manhattan Project developed these technologies during World War II. They conducted the first test, named "Trinity," in New Mexico on July 16, 1945.

History shows the devastating impact of these weapons. In 1945, uranium bombs were used on Hiroshima and Nagasaki in Japan. These events led to the end of World War II. Since then, many countries have developed nuclear programs. The Soviet Union tested its first fission weapon in 1949. The United Kingdom, France, and China also conducted tests later. Many nations signed the Limited Test Ban Treaty in 1963 to stop testing in the atmosphere or underwater. Since 1996, many states have pledged to stop all nuclear testing. Even so, the control and existence of nuclear weapons remain central to international policy.