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Nuclear Safeguards Education Portal

Nuclear and Non-Nuclear Material: Basic Terms

In order to produce nuclear weapons or other nuclear explosive devices, both nuclear and non-nuclear material is necessary. Under CSA, the IAEA is responsible for safeguarding all nuclear material. Certain agreements also require safeguards measures on some non-nuclear material.

Americium: A radioactive transuranic chemical element with symbol Am and atomic number 95. Isotopes of americium, which are formed by neutron capture or by the decay of 241Pu, are fissionable and may have the potential to be used in a nuclear explosive device. More.
Depleted uranium: Uranium containing a lesser mass percentage of uranium-235 than in natural uranium. More.
Deuterium and heavy water : A form of water that contains a larger than normal amount of the hydrogen isotope deuterium hydrogen-2, rather than the common hydrogen-1 isotope. Deuterium oxide (2 parts hydrogen-2 to one part oxygen, 2H2O or D20). More.
Direct use material: Nuclear material that can be used for the manufacture of nuclear explosive devices without transmutation or further enrichment. More.
Enriched uranium: Uranium containing a greater mass percentage of uranium-235 than 0.72%. More.
Enrichment: An isotope separation process by which the abundance of a specified isotope in an element is increased, such as the production of enriched uranium or heavy water, or of plutonium with an increase in the fissile isotope. More.
Feed material : Nuclear material that is introduced at the start of a process, such as conversion, enrichment or fabrication, which is then converted into the final product at each step. More.
Fertile material: A material, which is not itself fissile (fissionable by thermal neutrons), that can be converted into a fissile material by irradiation in a reactor. There are two basic fertile materials: uranium-238 and thorium-232. When these fertile materials capture neutrons, they are converted into fissile plutonium-239 and uranium-233, respectively. More.
Fissionable material: A nuclide that is capable of undergoing fission after capturing either high-energy (fast) neutrons or low-energy thermal (slow) neutrons. Although formerly used as a synonym for fissile material, fissionable materials also include those (such as uranium-238) that can be fissioned only with high-energy neutrons. As a result, fissile materials (such as uranium-235) are a subset of fissionable materials. More.
High enriched uranium (HEU): Highly enriched uranium (HEU) has a 20% or higher concentration of 235U. More.
Hold-up: Nuclear material that remain in a plant after shutdown in parts such as process equipment or piping. More.
Indirect use material: All nuclear materials that aren’t included in direct use materials. Materials that require processing to or can’t create a nuclear explosive device. More.
Intermediate product: A nuclear material that is in a processing stage in-between the initial and final product. More.
Isotope: Variants of a particular chemical element which differ in neutron number, although all isotopes of a given element have the same number of protons in each atom. More.
Low enriched uranium (LEU) : Low-enriched uranium (LEU) has a lower than 20% concentration of 235U. More.
Material category: Categorization of nuclear material according to its irradiation status and suitability for conversion into components of nuclear explosive devices. Irradiated direct use, un-irradiated direct use, indirect use material are the three categories. More.
Material form : Classification of nuclear material according to its physical form; material can be either in item form or in bulk form. More.
Mixed oxide (MOX) : Nuclear fuel that contains more than one oxide of fissile material, usually consisting of plutonium blended with natural uranium, reprocessed uranium, or depleted uranium. MOX fuel is an alternative to the low-enriched uranium (LEU) fuel used in the light water reactors that predominate nuclear power generation. More.
Natural uranium: Uranium with the same isotopic ratio as found in nature. It contains 0.7% uranium-235, 99.3% uranium-238, and a trace of uranium-234 by weight (0.0055%). In terms of the amount of radioactivity, approximately 2.2% comes from uranium-235, 48.6% uranium-238, and 49.2% uranium-234. More.
Neptunium : A chemical element with symbol Np and atomic number 93. It is radioactive, pyrophoric, and can accumulate in bones, which makes the handling of neptunium dangerous. The vast majority is generated as a by-product in conventional nuclear power reactors. While neptunium itself has no commercial uses at present, it is widely used as a precursor for the formation of plutonium-238, used in radioisotope thermal generators. Neptunium has also been used in detectors of high-energy neutrons. More.
Nuclear material: Material listed in the IAEA table on the categorization of nuclear material, including: plutonium except that with isotopic concentration exceeding 80% in plutonium-238; uranium- 233; uranium enriched in the isotope 235 or 233; uranium containing the mixture of isotopes as occurring in nature other than in the form of ore or ore-residue; any material containing one or more of the foregoing. More.
Nuclear-grade graphite: Graphite having a purity level better than 5 parts per million boron equivalent and with a density greater than 1.5 g/cm3 for use in a nuclear reactor in quantities exceeding 3 × 104 kg (30 metric tons) for any one recipient country in any period of 12 months. More.
Nuclide: A species of atom characterized by the number of protons (atomic number) and the number of protons and neutrons together (mass number). More.
Plutonium: A transuranic radioactive chemical element with symbol Pu and atomic number 94. It is radioactive and can accumulate in bones, which makes the handling of plutonium dangerous. Plutonium is the heaviest primordial element by virtue of its most stable isotope, plutonium-244, whose half-life of about 80 million years is just long enough for the element to be found in trace quantities in nature. Plutonium is mostly a byproduct of nuclear reactions, where some of the neutrons released by the fission process convert uranium-238 nuclei into plutonium. More.
Product: Nuclear material that has been processed and is ready to leave the facility to its next destination. More.
Scrap: Nuclear material that has been rejected and removed from processing. More.
Source material: The term "source material," means uranium containing the mixture of isotopes occurring in nature; uranium depleted in the isotope 235; thorium; any of the foregoing in the form of metal, alloy, chemical compound, or concentrate; any other material containing one or more of the foregoing in such concentration as the Board of Governors shall from time to time determine; and such other material as the Board of Governors shall from time to time determine. More.
Special fissionable material: The term "special fissionable material," means plutonium-239; uranium- 233; uranium enriched in the isotopes 235 or 233; any material containing one or more of the foregoing; and such other fissionable material as the Board of Governors shall from time to time determine; but the term "special fissionable material," does not include source material. More.
Specified non-nuclear material : Non-nuclear material that can be used to produce other fissionable materials. More.
Thorium: A chemical element with symbol Th and atomic number 90. A radioactive actinide metal, thorium is one of only three radioactive elements that still occur in quantity in nature as a primordial element. Thorium is weakly radioactive: all its known isotopes are unstable, with the six naturally occurring ones (thorium-227, 228, 230, 231, 232, and 234) having half-lives between 25.52 hours and 14.05 billion years. More.
Uranium: A naturally occurring radioactive element with atomic number 92 and symbol U. Natural uranium contains isotopes 234, 235 and 238; uranium isotopes 232, 233 and 236 are produced by transmutation. More.
Uranium-233: A fissile isotope of uranium that is bred from the neutron irradiation of thorium-232. It has been used successfully in experimental nuclear reactors and has been proposed for much wider use as a nuclear fuel. It has a half-life of 159,200 years. More.
Waste: Material, whatever its physical form, remaining from practices or interventions and for which no further use is foreseen (i) that contains or is contaminated with radioactive substances and has an activity or activity concentration higher than the level for clearance from regulatory requirements, and (ii) exposure to which is not excluded from the [Basic Safety] Standards. More.
Zircaloy: Solid solutions of zirconium or other metals. Has very low absorption cross-section of thermal neutrons, high hardness, and ductility and corrosion resistance. One of the main uses of zirconium alloys is in nuclear technology, as cladding of fuel rods in nuclear reactors, especially water reactors. A typical composition of nuclear-grade zirconium alloys is more than 95 weight percent zirconium and less than 2% of tin, niobium, iron, chromium, nickel and other metals, which are added to improve mechanical properties and corrosion resistance. More.