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Accident Measure Agreement
Requires cooperation of the United States and the former Soviet Union to reduce the risk that an accidental or unauthorized action might trigger a nuclear disaster. Signed and entered into force on September 30, 1971.

Antarctic Treaty
Signed December 1, 1959, and entered into force June 23, 1961. Membership includes 42 states. The Antarctic Treaty internationalizes and demilitarizes the Antarctic Continent and specifies that Antarctica be used for peaceful purposes only. Any measures of a military nature, including testing of any type of weapons, are prohibited.

Atomic Age

More on the Web
Center for Nonproliferation Studies Glossary of Nonproliferation Terms, Organizations, and Treaties.  
Public Broadcasting System Nuclear Reaction Glossary
Atomic Archive Glossary
U.S. Nuclear Regulatory Commission Glossary of Nuclear Terms

This began on 2 December 1942 with the creation of the first self-sustaining nuclear chain reaction in a lab at the University of Chicago in the United States.

Atomic bomb
A weapon which uses fissionable material such as U235 to provide the explosive power. Bombs of this type were dropped on Hiroshima (6 August) and Nagasaki (9 August) in 1945. May be referred to as an A-bomb on subsequent reference.

Ballistic Missile
A missile that is lifted into space by a booster rocket and then descends toward its target in a free falling ballistic trajectory.

Biological Weapons Convention (BWC)
This convention prohibits developing, producing, and stockpiling bacteriological and toxin weapons. Countries must destroy, or divert to peaceful purposes, (not later than nine months after the entry into force of the convention) all agents, toxins, weapons, equipment, and means of delivery. Signed on April 10, 1972, and entered into force on March 26, 1975. Membership includes 124 states. Treaty is of unlimited duration.

The BRAVO test
On March 1, 1954, a deliverable H-bomb using solid lithium deuteride was tested by the United States on Bikini Atoll in the Marshall Islands. Operation BRAVO had a yield of 14.8 megatons of TNT over double its expected yield. It was the largest American nuclear test. The fallout forced the evacuation of the surrounding islands. To this day, radiation levels on Bikini remain high enough to make the island uninhabitable. This test was a key factor in creating the Atmospheric Test Ban Treaty (1963).

Breeder reactor
A special design of nuclear reactor that generates more usable fuel than it consumes.

Canadian Deuterium - Uranium Reactor (CANDU)
A Canadian designed power reactor that uses natural uranium fuel and heavy water as a moderator and coolant. CANDU reactors are in service in Canada, Argentina and Pakistan. This reactor can be refueled while on-line, an attractive feature, especially for small power grids. Of possible proliferation concern is the operator's ability to produce weapons-grade plutonium by controlling the amount of time the fuel spends in the reactor, and removing this spent-fuel without having to shut down the reactor.

Cartagena Declaration
Created a weapons-of-mass-destruction-free zone. It was signed on December 4, 1991, by the heads of state of Bolivia, Colombia, Ecuador, Peru, and Venezuela. The goal is to prevent the introduction of weapons of mass destruction in Latin America and the Caribbean, and to enhance security and cooperation among the states of the region.

A rotating vessel for uranium enrichment. The heavier U238 isotopes in the UF6 gas tend to concentrate at the walls of the centrifuge as it spins. Scopes are placed inside the centrifuge to selectively separate the U238 and U235 isotopes.

Chemical Weapons Convention
Convention on the prohibition of developing, producing, stockpiling, and using chemical weapons. Each state is required to destroy all chemical weapons and production facilities. The CWC was opened for signature on January 13, 1993. Signatories include 159 states with ratification by 24 states. It enters into force 180 days after the deposit of the 65th instrument of ratification.

Conference on Disarmament
Formed in 1979 the Conference on Disarmament had 40 members. In 1994 37 countries participated. 47 non-member states requested participation and were invited to take part in the CD. Requests for membership have been received from 34 states.

The central portion of a nuclear reactor containing the fuel elements, moderator, neutron poisons, and support structures.

Critical Mass
The minimum mass of a fissionable material that will just maintain a fission chain reaction under precisely specified conditions, such as the nature of the material and its purity, the nature and thickness of the tamper (or neutron reflector), the density, and the physical shape. For an explosion to occur, the system must be supercritical (i.e., the mass of the material must exceed the critical mass under the existing conditions).

Critical organ
That part of the body that is most susceptible to radiation damage under the specific conditions under consideration.

Pertaining to a critical mass (the least amount) of fissionable material that can achieve self-sustaining nuclear chain reactions.

A unit of radioactivity equal to that emitted by 1 gram of pure radium.

Depleted Uranium
Uranium having less than the natural 0.7% U-235. As a by-product of enrichment in the fuel cycle it generally has 0.25-0.30% U-235, the rest being U-238. Can be blended with highly-enriched uranium (eg from weapons) to make reactor fuel.

1. As isotope of hydrogen with one proton and one neutron in the nucleus, making this isotope about twice as heavy as normal hydrogen which does not have a neutron. In normal water a deuterium atom occurs in 1 in 6,500 hydrogen atoms.
2.An isotope of hydrogen used in the fusion reaction of a nuclear weapon.

A sudden, rapid rise in the power level of a reactor caused by supercriticality.

The process whereby the nucleus of a particular heavy element splits into (generally) two nuclei of lighter elements, with the release of substantial amounts of energy.

1. Nuclear fusion is a process during which light atoms fuse to form heavier ones. During the fusion of elements with low atomic numbers substantial amounts of energy are released.
2. The merging of different elements into a union.

Geneva Protocol
Prohibits the use in war of asphyxiating, poisonous, or other gases, and bans bacteriological methods of warfare. Signed June 17, 1925. Membership includes 141 states. Most of the parties in joining the Geneva Protocol made reservations to the effect that they would abide by the terms of the Protocol as long as other states did not resort to the use of CW.

Ground Zero
The point on the surface of land vertically below or above the center of a burst of a nuclear weapon; frequently abbreviated to GZ .

Gun-Type Weapon
A device in which two or more pieces of fissionable material, each less than a critical mass, are brought together very rapidly so as to form a supercritical mass which can explode as the result of a rapidly expanding fission chain reaction.

The length of time for a radioactive substance to lose half of its radioactivity from decay. At the end of one half-life, only 50% of the original radionuclide remains.

Heavy water
Water containing an elevated concentration of molecules with deuterium ("heavy hydrogen") atoms.

The first use in warfare of a nuclear weapon occurred on August 6, 1945, at 8:16:02 a.m. over Hiroshima, Japan. In an instant 80,000 to 140,000 people were killed and 100,000 more were seriously injured. Hiroshima ceased to exist as a functioning city. The bomb exploded almost directly over the center of the city. Two square miles of the city were completely leveled by the bomb.

Implosion Weapon
A device in which a quantity of fissionable material has its volume suddenly decreased by compression so it becomes supercritical and an explosion can take place.

India-Pakistan Agreement on Chemical Weapons
Signed in 1992, it provides for "the complete prohibition of chemical weapons" and commits both governments to become regional signatories of the Chemical Weapons Convention. However, it does not commit India or Pakistan to ratify the CWC.

International Atomic Energy Agency (IAEA)
Established in 1957 in Vienna, Austria. The United Nations recognizes the IAEA as the agency responsible for international activities concerned with the peaceful uses of atomic energy. Membership is 122 states.

The approximate amount of energy that would be released by the explosion of 1,000 tons of TNT.

Lop Nor
The People's Republic of China tests its nuclear weapons at Lop Nor. The first Chinese-made atom bomb (a fission device) was tested there on Oct. 16, 1964; the first guided missile on Oct. 27, 1966; and the first thermonuclear (fusion) device on Dec. 28, 1966.

Low-level waste
Waste materials containing very low levels of radioactivity, requiring essentially no shielding or heat removal.

(mg-dth) n. One million deaths. Used as a unit in reference to nuclear warfare.

Nuclear Energy
Heat energy produced by the process of nuclear fission within a nuclear reactor. The coolant that removes heat from the reactor core is normally used to boil water. The resultant steam drives turbines that rotate electrical generators.

The fission part of a fusion bomb. The 'match' which ignites the fusion reaction.

1.To increase or spread at a rapid rate: fears that nuclear weapons might proliferate.
2.To grow or multiply by rapidly producing new tissue, parts, cells, or offspring.

REM (Roentgen Equivalent Man)
A standard unit that measures the effects of ionizing radiation on humans.

Reprocessing (aka recycling )
The mechanical and chemical process of separating out usable products (like uranium and plutonium) from spent nuclear fuel. Ideally, these fissile products can be used again in a reactor.

Spent Fuel
Nuclear fuel elements that are discharged from a nuclear reactor after they have been used to produce power.

The condition for increasing the level of operation of a reactor. The rate of fission neutron production exceeds all neutron losses, and the overall neutron population increases.

Theater Missile Defenses
An aspect of Ballistic Missile Defense that utilizes defensive systems on ships, land, and air for regional protection against ballistic missile attack. (Also referred to as TMD)

An adjective referring to the process in which very high temperatures are used to bring about the fusion of light nuclei (hydrogen), with the accompanying liberation of energy. A thermonuclear bomb is a weapon in which part of the explosion energy results from thermonuclear fusion reactions. The high temperatures required are obtained by means of a fission explosion.

The traditional nomenclature for the three components of U.S. and Soviet strategic nuclear forces-land-based intercontinental ballistic missiles; submarines-launched ballistic missiles; and strategic bombers.

Unclassified Controlled Nuclear Information
Information that is not classified but is judged to be sensitive with respect to DOE defense programs. Its dissemination is therefore controlled and limited. UCNI is a response to a requirement of the Atomic Energy Act.

Viability assessment
A Department of Energy decision making process to judge the prospects for geologic disposal of high-level radioactive wastes .

Warsaw Pact
On May 14, 1955 the Treaty of Friendship Cooperation and Mutual Aid (The Warsaw Pact) was signed by Albania, Bulgaria, Czechoslovakia, Poland, Romania, and the USSR . It was extended to East Germany in 1956. The Pact provided members with mutual assistance in the event of an attack as well as military and political consultation. The Pact ended in 1991.

The product of the uranium extraction process Early production methods resulted in a bright yellow compound, hence the name. It is a mixture of uranium oxides that vary in proportion and in color from yellow to orange to dark green depending on the temperature the material was dried. It is commonly referred to as U3O8. This fine powder is packaged in drums and sent to a conversion plant that produces uranium hexafluoride (UF6) as the next step in the manufacture of nuclear fuel.


ABM: Anti-Ballistic Missile Treaty

ACM: Advanced Cruise Missile

BMD: Ballistic Missile Defence

CANDU: Canadian deuterium uranium reactor

CD: Conference on Disarmament

CTBT: Comprehensive Test Ban Treaty

CTBTO: Comprehensive Test Ban treaty Organisation

DDA: United Nations Department of Disarmament Affairs

DOE: United States Department of Energy

EEZ: Exclusive Economic Zone

ICBM: Inter-Continental Ballistic Missile

ICC: International Criminal Court

ICJ: International Court of Justice

INF: Intermediate Nuclear Forces Treaty

IPU: Inter-Parliamentary Union

IPA: Inter-Parliamentary Assembly of the Commonwealth of Independent States.

MOX: A fuel composed of a mixture of plutonium dioxide and uranium dioxide.

NATO: North Atlantic Treaty Organisation

NPT: The nuclear Non-Proliferation Treaty.

NWC: Nuclear Weapons Convention

NWFZ: Nuclear Weapon Free Zone

NWS: Nuclear Weapon States

OSCE: Organisation for Security and Cooperation in Europe

PACE: Parliamentary Assembly of the Council of Europe

PNND: Parliamentary Network for Nuclear Disarmament

PTBT: Partial Test Ban Treaty

SLBM: Submarine Launched Ballistic Missile

START: Strategic Arms Reduction Treaty

UNDC: United Nations Disarmament Commission

UNGA: United Nations General Assembly

UNIDIR: United Nations Institute for Disarmament Research