Nuclear Materials

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Regulated Materials

  • Special Nuclear Material consists of plutonium, uranium-233  or uranium with U233 or U235 content greater than that found in nature (i.e., >0.71% U235)

  • Source Material is thorium or  uranium with a U235 content equal to or less than that found in nature (i.e., ≤ 0.71% U235)

  • Byproduct Material, in general, is radioactive material other than source or special nuclear material.  Specifically, by-product material is (a) isotopes produced or created in a nuclear reactor; (b) the tailings and waste produced by extracting or concentrating uranium or thorium from an ore processed primarily for its source material content; (c) discrete sources of radium-226 and (d) discrete sources of naturally occurring or accelerator-produced isotopes that pose a threat equal to or greater than a discrete source of radium-226.

  • Radium is a radioactive substance found in nature. Radium is produced by the radioactive decay of uranium. The intensity of radiation from radioactive materials decreases over time. The time required for the intensity to decrease by one-half is referred to as the half-life. The half-life of radium is approximately 1,600 years.

For details regarding the types of materials regulated by the U.S. Nuclear Regulatory Commission (NRC), see Regulation of Radioactive Materials.

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Regulated Activities

For general information, see How We Regulate. For details, see the following related pages:

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In the United States, there are more than 20,000 source, byproduct, and special nuclear materials licenses. Approximately, a quarter of these licenses are administered by the NRC, while the rest are issued by the 37 Agreement States. The NRC administers all licenses for special nuclear material when the quantity of the licensed material is enough that a critical mass could form.

The NRC's Office of Nuclear Material Safety and Safeguards (NMSS) (a) regulates activities that provide for the safe and secure production of nuclear fuel used in commercial nuclear reactors; the safe storage, transportation, and disposal of high-level radioactive waste and spent nuclear fuel; and the transportation of radioactive materials regulated under the Atomic Energy Act of 1954; and (b) develops and oversees the regulatory framework for the safe and secure use of nuclear materials; medical, industrial, and academic applications; uranium recovery activities, low-level radioactive waste sites; and the decommissioning of previously operating nuclear facilities and power plants. The agency's four regional offices (Region I – Northeast, Region II – Southeast, Region III – Midwest, and Region IV – West/Southwest) implement the NRC's materials program in the States for which they are responsible. Materials regulation is also supported by independent advice from the Advisory Committee on the Medical Uses of Isotopes.

The NRC ensures that its materials program complies with the National Environmental Policy Act (NEPA) by conducting NEPA reviews for all major actions within the program. See Materials Environmental Reviews for detailed information on active reviews.

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Page Last Reviewed/Updated Tuesday, August 09, 2022