Natural uranium (NU) refers to refined uranium with the same isotopic ratios as found in nature. It contains 0.7 percent uranium-235, 99.3 percent uranium-238, and a trace of uranium-234 by weight. In terms of the amount of radioactivity, it contains approximately 2.2 percent uranium-235, 48.6 percent uranium-238, and 49.2 percent uranium-234. General Name, Symbol, Number uranium, U, 92 Chemical series actinides Group, Period, Block ?, 7, f Appearance silvery gray metallic Atomic mass 238. ... Uranium-235 is an isotope of uranium that differs from the elements other common isotope, uranium-238, by its ability to cause a rapidly expanding fission chain reaction. ... There are two objects with this name: Unterseeboot 238 Uranium-238, the most common isotope of uranium This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ... U-234 is an isotope of uranium. ... Radioactivity may mean: Look up radioactivity in Wiktionary, the free dictionary. ...

Natural uranium can be used to fuel both low- and high-power reactors. Historically, graphite moderated reactors and heavy water moderated reactors have been fueled with natural uranium in the pure metal (U) or uranium dioxide (UO₂) ceramic forms, however experimental fuelings with uranium trioxide (UO₃) and triuranium octaoxide, (U₃O₈) have shown promise. Graphite (named by Abraham Gottlob Werner in 1789, from the Greek γραφειν: to draw/write, for its use in pencils) is one of the allotropes of carbon. ... Heavy water is dideuterium oxide, or D2O or 2H2O. It is chemically the same as normal water, H2O, but the hydrogen atoms are of the heavy isotope deuterium, in which the nucleus contains a neutron in addition to the proton found in the nucleus of any hydrogen atom. ... The word ceramic is derived from the Greek word Κεραμεικος (the name of a suburb of Athens), and in its strictest sense refers to clay in all its forms. ...

The 0.72% U-235 is not sufficient to produce a self-sustaining critical chain reaction in light water reactors or nuclear weapons; these applications must use enriched uranium. Several things have been named Chain Reaction, after the chain reaction process best known in connection with nuclear fission: Chain Reaction, a film Chain Reaction, a 1990s record label Chain Reaction, a 1980s game show Chain Reaction, a 1970s band A Square Dance Call on the A1 List A Series... In speaking of nuclear reactors, light water is ordinary water. ... The mushroom cloud of the atomic bombing of Nagasaki, Japan, 1945, rose some 18 km (11 mi) above the hypocenter. ... Enriched uranium is uranium whose uranium-235 content has been increased through the process of isotope separation. ...

During the Manhattan Project, the name tuballoy was used to refer to natural uranium in the refined condition; this term is still in occational use at present. Control panels and operators for calutrons at the Y-12 Plant in Oak Ridge, Tennessee. ...

See also

• Depleted uranium
• Enriched uranium
• Nuclear engineering
• Nuclear fuel cycle
• Nuclear physics
• Nuclear reactor
• Nuclear weapon
• Oklo reactor

// Depleted uranium (DU) is uranium which contains a reduced proportion of the fissile isotope U-235 and (usually) the highly radioactive but rare isotope U-234, compared to natural uranium. ... Enriched uranium is uranium whose uranium-235 content has been increased through the process of isotope separation. ... Nuclear engineering is the practical application of the principles of nuclear physics and the interaction between radiation and matter. ... The nuclear fuel cycle consists of front end steps that lead to the preparation of uranium for use as fuel for reactor operation and back end steps that are necessary to safely manage, prepare, and dispose of the highly radioactive spent nuclear fuel. ... Nuclear physics is the branch of physics concerned with the nucleus of the atom. ... A nuclear reactor is a device in which nuclear chain reactions are initiated, controlled, and sustained at a steady rate (as opposed to a nuclear explosion, where the chain reaction occurs in a split second). ... The mushroom cloud of the atomic bombing of Nagasaki, Japan, 1945, rose some 18 km (11 mi) above the hypocenter. ... Oklo is a place in the West African state of Gabon. ...

Link

THE EVOLUTION OF CANDU FUEL CYCLES

Reference

• Design Parameters for a Natural Uranium Fueled Nuclear Reactor, C. M. Hopper et al, ORNL/TM-2002/240, November 2002.