In , German physicists Otto Hahn and Fritz Strassmann showed that uranium could be split into parts to yield energy. Uranium is the principal fuel for nuclear reactors and the main raw material for nuclear weapons. Natural uranium consists of three isotopes: uranium, uranium, and uranium Uranium isotopes are radioactive.
The nuclei of radioactive elements are unstable, meaning they are transformed into other elements, typically by emitting particles and sometimes by absorbing particles. This process, known as radioactive decay, generally results in the emission of alpha or beta particles from the nucleus. It is often also accompanied by emission of gamma radiation, which is electromagnetic radiation, like X-rays. These three kinds of radiation have very different properties in some respects but are all ionizing radiation—each is energetic enough to break chemical bonds, thereby possessing the ability to damage or destroy living cells.
Uranium, the most prevalent isotope in uranium ore, has a half-life of about 4. Uranium decays by alpha emission into thorium, which itself decays by beta emission to protactinium, which decays by beta emission to uranium, and so on.
After several more alpha and beta decays, the series ends with the stable isotope lead Uranium emits alpha particles which are less penetrating than other forms of radiation, and weak gamma rays As long as it remains outside the body, uranium poses little health hazard mainly from the gamma-rays. If inhaled or ingested, however, its radioactivity poses increased risks of lung cancer and bone cancer.
Uranium is also chemically toxic at high concentrations and can cause damage to internal organs, notably the kidneys. Animal studies suggest that uranium may affect reproduction, the developing fetus, [1] and increase the risk of leukemia and soft tissue cancers. The property of uranium important for nuclear weapons and nuclear power is its ability to fission, or split into two lighter fragments when bombarded with neutrons releasing energy in the process.
Of the naturally-occuring uranium isotopes, only uranium can sustain a chain reaction— a reaction in which each fission produces enough neutrons to trigger another, so that the fission process is maintained without any external source of neutrons. Traditionally, uranium has been extracted from open-pits and underground mines. In the past decade, alternative techniques such in-situ leach mining, in which solutions are injected into underground deposits to dissolve uranium, have become more widely used.
Most mines in the U. The milling refining process extracts uranium oxide U 3 O 8 from ore to form yellowcake, a yellow or brown powder that contains about 90 percent uranium oxide. In-situ leach mining leaves the unusable portion in the ground, it does not generate this form of waste.
The total volume of mill tailings generated in the U. This is known as secondary ionization. However, ionization does not have to completely eject an electron off the atom. It can raise the energy of the electron instead, raising the electron energy to a higher energy state. When the electron reverts to its normal energy level, it emits energy in the form of radiation, usually in the forms of ultraviolet rays or radio waves.
Radiation can be both natural and synthetic. Artificially induced radioactivity utilizes primary and secondary ionizations in order to emit X-rays. Most X-ray emission is due to the bombardment of electrons on a metal target. If the electrons have sufficient energy, the inner shell electrons of the atom fall out, and higher-leveled electrons fill in the hole left by the previous electrons. By doing so, packets of energy are released in the forms of X-ray photons. Other forms of ionizing radiation can produce UV and gamma rays in a similar manner.
Radio waves, microwaves, and neutron radiation an important application in fission and fusion all fall under non-ionizing radiation, as their respective energies are too low to ionize atoms. Courtesy of iforms. Prolonged exposure to radiation often has detrimental effects on living matter.
Radiation either ionizes or excites atoms or molecules in living cells, leading to the dissociation of molecules within an organism. The most destructive effect radiation has on living matter is ionizing radiation on DNA. Damage to DNA can cause cellular death, mutagenesis the process by which genetic information is modified by radiation or chemicals , and genetic transformation. Effects from exposure to radiation include leukemia, birth defects, and many forms of cancer.
Most external radiation is absorbed by the environment; for example, most ultraviolet radiation is absorbed by the ozone layer, preventing deadly levels of ultraviolet radiation to come in contact with the surface of the earth. Sunburn is an effect of UV radiation damaging skin cells, and prolonged exposure to UV radiation can cause genetic information in skin cells to mutate, leading to skin cancer.
Alpha, beta, and gamma rays also cause damage to living matter, in varying degrees. Alpha particles have a very small absorption range, and thus are usually not harmful to life, unless ingested, due to its high ionizing power.
Beta particles are also damaging to DNA, and therefore are often used in radiation therapy to mutate and kill cancer cells.
Gamma rays are often considered the most dangerous type of radiation to living matter. Unlike alpha and beta particles, which are charged particles, gamma rays are instead forms of energy. They have large penetrating range and can diffuse through many cells before dissipating, causing widespread damage such as radiation sickness. Because gamma rays have such high penetrating power and can damage living cells to a great extent, they are often used in irradiation, a process used to kill living organisms.
There are several methods to measure radiation; hence, there are several radiation units based on different radiation factors. Radiation units can measure radioactive decay, absorbed dosage, and human absorbed doses. Bq and Ci measure radioactive decay, while Gy and Rad measures absorbed doses.
Sv and Rem measure absorbed doses in Gy and Rad equivalents. The resulting positively charged atom is called an ion , which explains why high energy radiation is called ionizing radiation. The release of the electron produces 33 electron volts eV of energy, which heats the surrounding tissues and disrupts certain chemical bonds. Extremely high-energy radiation can even destroy the nuclei of atoms, releasing even more energy and causing more damage.
Radiation sickness is the cumulative effect of all this damage on a human body that's been bombarded with radiation. Ionizing radiation comes in three flavors: alpha particles, beta particles and gamma rays.
Alpha particles are the least dangerous in terms of external exposure. Each particle contains a pair of neutrons and a pair of protons. They don't penetrate very deeply into the skin, if at all -- in fact, clothing can stop alpha particles.
Unfortunately, alpha particles can be inhaled or ingested, usually in the form of radon gas. Once ingested, alpha particles can be very dangerous. However, even then they don't typically cause radiation sickness -- instead, they lead to lung cancer [source: EPA ].
Beta particles are electrons that move very quickly -- that is, with a lot of energy. Beta particles travel several feet when emitted from a radioactive source, but they're blocked by most solid objects.
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