ADVISORY COMMITTEE ON URANIUM Committee established in October 1939 to report to President Franklin Roosevelt on the status of uranium research and make recommendations on the role of the federal government. The committee recognized the explosive potential of nuclear chain reactions and recommended that research funding be increased.
ANTI-BALLISTIC MISSILE SYSTEMS Weapons designed to intercept ballistic missiles, most commonly in midcourse or final reentry phases of their flight. Existing systems are all designed to hit the missile warhead, whether directly or with a spray of pellets, though research continues on possible laser weapons.
ATOMIC BOMB A bomb whose explosive power is generated from the fission of uranium or plutonium.
ATOMIC ENERGY COMMISSION (AEC) Agency established under the Atomic Energy Act of 1946 to regulate and develop the U.S. atomic energy program.
BALLISTIC MISSILE A missile that is propelled upward with a rocket engine in an initial boost phase, after which the engine stops and gravity controls the remaining trajectory as it arcs back to earth.
BIOLOGICAL AND TOXIN WEAPONS CONVENTION (BTWC) Entered into force in March 1975, the BTWC bans the development, production, and stockpiling of any biological agent that has no peaceful use, as well as any weapons or equipment designed to deliver such agents. As of June 2006, 155 of the 171 signatories have ratified the treaty.
CANDU (Canadian deuterium-uranium reactor) A Canadian-designed reactor that uses heavy water as a moderator/coolant and natural uranium for fuel.
CENTRIFUGE A tall, narrow metallic casing with a fast-spinning rotor on the inside. Centrifuges linked together in a cascade are used to enrich uranium. See also GAS CENTRIFUGE ENRICHMENT.
CHAIN REACTION The repetitive process in which neutrons released from an initial fission reaction go on to split other atoms, releasing more neutrons that then trigger more fission reactions and so on. Nuclear weapons have explosive releases of energy because the chain reaction is extremely rapid. Nuclear reactors, on the other hand, control the speed of the chain reaction in order to produce heat (in a power reactor) or large quantities of neutrons (in a research or production reactor).
CHEMICAL WEAPONS CONVENTION (CWC) Bans the development, production, and use of chemical weapons and aims to destroy all chemical weapon stockpiles. The CWC entered into force in April 1997. As of October 2006, there are 180 state parties to the convention.
COMPREHENSIVE TEST-BAN TREATY (CTBT) A treaty banning all nuclear explosions. Opened for signature in September 1996, the treaty will not enter into force until all 44 states listed in Annex 2 of the treaty complete ratification. As of May 2006, 176 states have signed the treaty and 132 have ratified it. However, 10 of the 44 Annex 2 states have not ratified the CTBT, including the United States.
COOPERATIVE THREAT REDUCTION (CTR) A U.S. Department of Defense program started in 1991 to dismantle, secure, or destroy nuclear weapons, their delivery systems, and chemical weapons stockpiles in Russia, Ukraine, Belarus, and Kazakhstan.
CORE The center of a nuclear weapon containing the highly enriched uranium or plutonium. Also, the core can refer to the central area of a nuclear reactor with the fuel elements.
CRITICAL MASS The minimum mass of fissile material needed to sustain a chain reaction. The exact amount varies according to the physical and chemical properties of the material.
CRUISE MISSILE A guided, unmanned device that uses aerodynamic lift to deliver a payload to a target. Cruise missiles are self-propelled and can include some unmanned air vehicles (UAVs).
CUBAN MISSILE CRISIS A confrontation between the United States and the Soviet Union in October 1962. The United States discovered that the Soviets were building nuclear missile installations on Cuba. Tensions eased after thirteen days, when the Soviets agreed to dismantle the installations.
DETERRENCE Nuclear deterrence is the notion that one state must build up a credible and reliable retaliatory nuclear force to deter an enemy state from any preemptive nuclear strike.
ELECTROMAGNETIC SEPARATION A technique to enrich uranium involving the movement of uranium ions through a strong magnetic field. The uranium-238 ions move in a slightly different curve from the uranium-235 ions, thus enabling the two ions to be separated.
ENRICHMENT Refers to uranium enrichment—a process of increasing the concentration of fissionable uranium-235 isotopes in relation to nonfissionable uranium-238.
FAT MAN The implosion-type nuclear weapon with a plutonium core dropped on Nagasaki, Japan, on August 9, 1945. The second nuclear weapon ever used in combat, Fat Man had an explosive yield of about 20 kilotons of TNT.
FISSILE MATERIAL A more restrictive subset of fissionable material, fissile materials include atoms that can be split both by slow neutrons and fast neutrons (thus fissile materials can more easily and consistently sustain a chain reaction). Uranium-235 and plutonium-239 are both fissile materials.
FISSION The splitting of a nucleus by a neutron. The fission of a nucleus releases several neutrons, heat, and radiation.
FISSIONABLE MATERIAL Any material whose atoms can fission. Includes all fissile materials, but also materials that can be split by fast neutrons, such as uranium-238.
FUSION The merging of two lighter nuclei to form a single, heavier nucleus. Fusion of light elements releases an incredible amount of energy.
GAS-CENTRIFUGE PROCESS A method of uranium enrichment in which heavier isotopes are separated from lighter ones through centrifugal force.
GASEOUS DIFFUSION A method of uranium enrichment that separates uranium-235 and uranium-238 by taking advantage of their slight differences in mass and thus their rates of diffusion through a porous barrier.
HAIR-TRIGGER ALERT Alert level at which nuclear weapons can be launched within fifteen minutes.
HEAVY WATER Refers to water molecules that have two heavy hydrogen atoms, known as deuterium (one proton and one neutron), in place of the two hydrogen atoms (just one proton). Heavy water is used in reactors to slow down neutrons without absorbing them, allowing for a controlled, sustained chain reaction.
HEAVY-WATER REACTOR A reactor that uses heavy water to slow down the neutrons and control the chain reaction. Also see CANDU.
HIGHLY ENRICHED URANIUM (HEU) Uranium in which the percentage of uranium-235 nuclei is greater than 20 percent. Weapons-grade uranium is enriched to greater than 90 percent. Natural uranium has only 0.7 percent uranium-235 nuclei. Highly enriched uranium is one of only two materials used for the cores of nuclear weapons, along with plutonium.
HYDROGEN BOMB A nuclear weapon many times more powerful than the atomic bomb and which generates explosive energy from nuclear fusion.
INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA) An institution created by the United Nations to further nuclear safety and security, science and technology, and safeguards and verification.
ISOTOPE ISOTOPES are forms of an element that have the same atomic number (number of protons) but have different numbers of neutrons, giving each isotope a different atomic weight. Radioactive elements can have fissile and nonfissile isotopes.
KILOGRAM (kg) One kilogram is equivalent to 2.2 pounds.
KILOTON (kt) A nuclear explosion of 1 kiloton is equal to an explosion of 1,000 metric tons of TNT.
LASER ENRICHMENT METHOD A method of enriching uranium by which a laser is tuned to ionize uranium-235 atoms (in this case giving them a positive charge) without affecting other atoms. These positively charged atoms are attracted to a negatively charged plate and separated. This process has yet to be applied commercially.
LIGHT WATER NORMAL WATER (two hydrogen atoms and one oxygen atom). See also HEAVY WATER.
LIGHT-WATER REACTOR A reactor that uses normal water to control the reactor temperature and the speed of the chain reaction. Light-water reactors use low enriched uranium as fuel.
LIMITED TEST BAN TREATY (LTBT) Entered into force in October 1963, the LTBT banned any nuclear test explosions in the atmosphere, in outer space, or underwater. The treaty has 108 signatories, 94 of which have ratified it. Only 23 have acceded to the treaty.
LITTLE BOY The gun-type nuclear weapon using highly enriched uranium dropped on Hiroshima, Japan, on August 6, 1945. The first nuclear weapon ever used in combat, Little Boy had an explosive yield of about 13 kilotons of TNT.
LOW ENRICHED URANIUM (LEU) Uranium in which the percentage of uranium-235 nuclei is less than 20 percent. Low enriched uranium is usually between 2 and 6 percent and is used as fuel in light-water reactors. Natural uranium has only 0.7 percent uranium-235 nuclei.
MANHATTAN PROJECT Top-secret U.S. project initiated in 1942 to build an atomic bomb. General Leslie Groves directed the project, which had facilities in Chicago, Illinois; Hanford, Washington; Oak Ridge, Tennessee; and Los Alamos, New Mexico. J. Robert Oppenheimer directed research at Los Alamos. The effort concluded with the first ever nuclear device, known as Trinity, which was tested in the New Mexico desert on July 16, 1945.
MEGAWATT (MW) A measure of power equal to 1 million watts. When describing a nuclear power plant: 1 million watts of electricity (MWe); when describing a research or production reactor: 1 million watts of thermal energy (MWt).
METRIC TON One metric ton is equal to 1,000 kilograms—equivalent to 2,200 pounds or 1.1 tons.
MILLING A process in which natural uranium ore is crushed into powder and then leached to concentrate the uranium oxide (U308) to around 80 percent. See also YELLOWCAKE.
MISSILE TECHNOLOGY CONTROL REGIME (MTCR) Established in 1987, the MTCR is a voluntary association of thirty-four countries that seeks to limit, through export controls, the proliferation of missiles, rocket systems, unmanned air vehicles, and related technology.
MULTIPLE INDEPENDENTLY TARGETABLE REENTRY VEHICLE (MIRV) Refers to land- or sea-based ballistic missiles carrying multiple warheads that, upon reentry, can independently maneuver and strike separate targets. For example, the U.S. MX missile carried ten warheads.
NATIONAL INTELLIGENCE ESTIMATE (NIE) An authoritative report, coordinated with all U.S. intelligence agencies, on a specific national security issue, usually forecasting future events and implications.
NEUTRON An uncharged particle found in atomic nuclei. Neutrons have a slightly greater mass than protons do.
NON-PROLIFERATION TREATY (NPT) Entered into force in 1970, the NPT is intended to prevent the proliferation of nuclear weapons and weapons technology, promote peaceful nuclear energy cooperation, and move toward disarmament. As of March 2005, 188 states adhered to the treaty. North Korea withdrew from the treaty in January 2003. India, Pakistan, and Israel are the only countries never to have signed the NPT.
NUCLEAR ENERGY The energy released by nuclear reactions (fission or fusion) or by spontaneous radioactivity.
NUCLEAR FUEL Any material used to generate nuclear energy. Natural uranium and low enriched uranium are the most commonly used fuels. Some reactors use highly enriched uranium or plutonium.
NUCLEAR FUEL CYCLE A series of steps that processes uranium ore into usable nuclear fuel. The back end of the fuel cycle includes the disposition or recycling of spent nuclear material after its use in a reactor.
NUCLEAR FUEL-FABRICATION PLANT A facility where natural or enriched uranium is manufactured into fuel rods that are used in reactors.
NUCLEAR REACTOR A facility where fissionable material is used to generate heat through a controlled chain reaction. The heat is then used to generate electricity, usually by powering a turbine. Reactors produce plutonium as a by-product and thus can be used to as a source for fissile material for nuclear weapons.
NUCLEAR SUPPLIERS GROUP (NSG) Created in 1974 after India’s peaceful nuclear test, the NSG is a group of forty-five nuclear supplier states that aims to control the spread of nuclear and nuclear-related (dual-use items) technology through strong national export control laws.
NUCLEAR WEAPONS Weapons whose explosive energy comes from a nuclear reaction, including both atomic (fission) bombs and hydrogen (fusion) bombs.
PLUTONIUM–239 A fissile isotope of plutonium manufactured in nuclear reactors as uranium-238 is bombarded with neutrons and undergoes radioactive decay. Plutonium-239 is one of only two materials used for the cores of nuclear weapons, along with highly enriched uranium.
POTSDAM CONFERENCE Meeting between U.S., British, and Soviet leaders from July 17 to August 2, 1945, on various subjects including postwar plans for Europe. Also, the leaders of the United States, United Kingdom, and China issued the Potsdam Declaration, calling for the unconditional surrender of Japan.
POWER REACTOR A nuclear reactor built to produce electricity. Other reactors are used for research purposes or for producing plutonium.
PROTON A positively charged particle found in atomic nuclei. Protons have slightly less mass than neutrons do.
RADIOACTIVITY The spontaneous emission of energy from an unstable atomic nucleus.
REPROCESSING The process through which the uranium and plutonium in spent reactor fuel are chemically separated from unwanted by-products.
RESEARCH REACTOR A nuclear reactor designed to provide neutrons for experiments and material testing. Research reactors can also be used for the production of medical isotopes.
STRATEGIC In the context of this book, strategic refers to deployed, long-range nuclear capable missiles and aircraft that act as nuclear deterrence against one’s enemy.
STRATEGIC ARMS LIMITATION TREATY I AND II (SALT) SALT I (1972) was an agreement between the United States and the Soviet Union to freeze the number of strategic ballistic missiles at the 1972 levels. SALT II (1979) placed ceilings on strategic nuclear delivery vehicles and on MIRVed ballistic missiles (see also MULTIPLE INDEPENDENTLY TARGETABLE REENTRY VEHICLE).
STRATEGIC OFFENSIVE REDUCTIONS TREATY (SORT) A 2002 agreement, also known as the Moscow Treaty, between the United States and Russia in which each country pledged that by 2012 the aggregate number of their nuclear warheads will be between 1700 and 2200.
TACTICAL In the context of this book, tactical refers to shorter-range (nonstrategic) nuclear-capable missiles and aircraft.
THERMONUCLEAR BOMB See hydrogen bomb.
TRITIUM A hydrogen isotope with one proton and two neutrons. Tritium can be used in fission weapons to produce extra neutrons that add to the chain reaction. In this way, either less fissile material is required or the yield of the weapon is boosted as much as five times.
UNITED NATIONS MONITORING, VERIFICATION, AND INSPECTION COMMISSION (UNMOVIC) Created in 1999 by the UN Security Council, UNMOVIC was charged with verifying Iraq’s obligation to give up all chemical, biological, and nuclear programs as well as missiles with ranges greater than 150 kilometers.
UNITED NATIONS RESOLUTION 1540 An April 2004 resolution adopted by the UN Security Council that requires states to create and enforce strong export controls, to criminalize proliferation of weapons of mass destruction (WMD), and to secure any WMD-related materials in their territories.
URANIUM A naturally occurring radioactive element. There are two common natural isotopes: uranium-235 (0.7 percent of natural uranium) and uranium-238 (99.3 percent of natural uranium).
URANIUM–235 The only fissionable isotope found in nature. Uranium-235 only makes up 0.7 percent of natural uranium. Light-water reactors use uranium that has about 3 percent uranium-235. Weapons-grade highly enriched uranium usually has 90 percent or more.
URANIUM–238 A fertile isotope, meaning that it does not easily fission, but can be converted into fissile material through neutron absorption. Nearly all (99.3 percent) of natural uranium is composed of this isotope.
URANIUM HEXAFLUORIDE (UF6) Highly toxic gas that is the intermediate stage between yellowcake and enriched uranium. UF6 is the feedstock for all uranium enrichment processes.
URANIUM OXIDE (U3O8) The most common oxide found in natural uranium ore. Uranium oxide is extracted from the crushed ore. Yellowcake is about 80 percent uranium oxide. See also yellowcake.
WEAPONS-GRADE Fissile material ideal for nuclear weapons. This includes uranium enriched to at least 90 percent uranium-235 and plutonium that is approximately 93 percent plutonium-239.
YELLOWCAKE A powdery concentrate of about 80 percent uranium oxide (U3O8) that is produced when uranium ore is crushed and leached. Yellowcake is converted to uranium hexafluoride gas (UF6) in the process of creating enriched uranium.
YIELD The energy released in a nuclear explosion, expressed in equivalent metric tons of TNT. For example, a nuclear yield of 13 kilotons is equivalent to 13,000 tons of TNT.