text: Radioactive waste is waste material containing radioactive chemical elements that does not have a practical purpose. It is sometimes the product of a nuclear process, such as nuclear fission. The majority of radioactive waste in mass and volume terms is low level waste which is often items such as used protective clothing which is only slightly contaminated.\n \n \n\n\n\nNORM (naturally occurring radioactive material)\nProcessing of substances containing natural radioactivity, this is often known as NORM. Much of this waste is alpha particles emitting matter from the decay chains of uranium and thorium.\n\n\nCoal contains a small amount of radioactive nuclides, such as uranium and thorium, but it is less than the average concentration of those elements in the Earth's crust. They become more concentrated in the fly ash because they do not burn well [1]. However, the radioactivity of fly ash is still very low. It is about the same as black shale and is less than phosphate rocks, but is more of a concern because a small amount of the fly ash ends up in the atmosphere where it can be inhaled.[2].\n\n\nOil and gas\nResidues from the oil and gas industry often contain radium and its daughters. The sulphate scale from an oil well can be very radium rich, while the water, oil and gas from a well often contains radon. The radon decays to form solid radioisotopes which form coatings on the inside of pipework. In an oil processing plant the area of the plant where propane is processed is often one of the more contaminated areas of the plant as radon has a similar boiling point as propane.[3]\n\nMineral processing\nWastes from mineral processing can contain natural radioactivity.\n\n\nMedical\nRadioactive medical waste tends to contain beta ray and gamma ray emitters. It can be divided into two main classes. In diagnostic nuclear medicine a number of short-lived gamma emitters such as 99mTc are used. Many of these can be disposed of by leaving it to decay for a short time before disposal as normal trash. :\n\n\n\nIndustrial\nIndustrial source waste can contain alpha, beta, neutron or gamma emitters. Gamma emitters are used in radiography while neutron emitting sources are used in a range of applications, such as oil well logging.[4]\n\nNuclear fuel cycle\nAn overview of waste from the nuclear fuel cycle was written by B.V. Babu and S. Karthik, Energy Education Science and Technology, 2005, 14, 93-102.\n\n\nFront end\nWaste from the front end of the nuclear fuel cycle is usually alpha emitting waste from the extraction of uranium. It often contains radium and its decay products.\n\nUranium dioxide (UO2) concentrate from mining is not very radioactive - only a thousand or so times as radioactive as the granite used in buildings. It is refined from yellow cake (U3O8), then converted to uranium hexafluoride gas (UF6). As a gas, it undergoes enrichment to increase the 235U content from 0.7% to about 3.5% (LEU). It is then turned into a hard ceramic oxide (UO2) for assembly as reactor fuel elements.\n\nThe main by-product of enrichment is depleted uranium (DU), principally the 238U isotope, with a 235U content of ~0.3%. It is stored, either as UF6 or as U3O8. Some is used in applications where its extremely high density makes it valuable, such as the keels of yachts, and anti-tank shells. It is also used (with recycled plutonium) for making mixed oxide fuel (MOX) and to dilute highly enriched uranium from weapons stockpiles which is now being redirected to become reactor fuel. This dilution, also called downblending, means that any nation or group that acquired the finished fuel would have to repeat the (very expensive and complex) enrichment process before assembling a weapon.\n\n\nThe back end of the of the nuclear fuel cycle, mostly spent fuel rods, often contains fission products that emit beta and gamma radiation, and may contain actinides that emit alpha particles, such as 234U, 237Np, 238Pu and 241Am, and even sometimes some neutron 