**3. Resources of NORM and TE-NORM**

Earlier, we saw that many natural materials contain radioactivity. Some of these materials are used in manufacturing: clays and various minerals. In other cases, radioactive elements are used in manufacturing – not because of the radioactivity, but because of other chemical or physical properties. For example, thorium is radioactive, and it has a high melting temperature; for this reason, thorium is used in the manufacture of some welding electrodes, gas lantern mantles, and jet turbine blades. These products and the wastes from their manufacture will contain low levels of radioactivity. Many fossil fuels are associated with radioactivity; the geochemistry of uranium is such that it is often found in petroleum, natural gas, and coal deposits. The equipment used to extract and process these materials is often contaminated with NORM materials, especially with radium, which can be present in the scales and sludges from processing these materials. Although refined petroleum and natural gas products do not contain large levels of these nuclides, coal can; so, fly ash often contains elevated levels of radioactivity as well. In fact, when 90% or more of the coal is burned, all of the radioactivity is left in the remaining 10% that is ash. Thus, fly ash is considerably more radioactive than is the original coal. Uranium and thorium are fairly common in nature, and many minerals contain elevated levels of these radioactive elements and their decay series nuclides. In particular, minerals containing rare earth elements (such as monazite), titanium minerals, niobium ores, and some precious metal ores can be associated with elevated levels of radio‐ activity. When the minerals are processed, the metal is removed from the ore, and the radio‐ activity concentration in the remaining waste is even higher than in the original ore. In addition to all of these, anything that contains potassium will be somewhat radioactive because 1/100% of potassium is naturally radioactive. Potassium is found in many minerals, some forms of clay, and in many products – consumer and industrial both – so sometimes these items will also give high levels of radiation. Loads of bananas, kitty litter, and salt substitute all contain enough radioactive potassium to set off radiation alarms.
