At 11:02 a.m. on August 9, 1945 a plutonium implosion bomb, Fat Man, was dropped on Nagasaki. The yield was 22 kilotons. The damage was less extensive, due partly to the geography of the Nagasaki area and partly to the fact that the bomb was dropped about 2 miles off target. Of the 286,000 people living in Nagasaki at the time of the blast, 74,000 were killed and another 75,000 sustained injuries. See; Fission Bomb, Implosion Weapon, Manhattan Project.
National Missile Defense (NMD)
A ground-based anti-ballistic missile system designed to protect a country against ballistic missile threats. See; Ballistic Missile Defense.
National Technical Means (NTM)
Intelligence gathering systems under national control, such as photo-reconnaissance satellites and ground based radars, used to monitor compliance with agreed arms limitations
A massless subatomic particle with no electric charge that is produced in the beta decay process.
A neutral particle of approximately unit mass, present in all atomic nuclei, except those of ordinary hydrogen. Neutrons are required to initiate the fission process, and large numbers of neutrons are produced by both fission and fusion reactions. See; Nucleus.
The neutron bomb differs from standard nuclear weapons insofar as its primary lethal effects come from the radiation damage caused by the neutrons it emits. It is also known as an enhanced-radiation weapon (ERW). The augmented radiation effects mean that blast and heat effects are reduced so that physical structures, including houses and industrial installations, are less affected. Because neutron radiation effects drop off very rapidly with distance, there is a sharper distinction between areas of high lethality and areas with minimal radiation doses. See; Neutron.
In fission bombs the neutrons are produced in the fission process. They are emitted from the highly excited fission products. The way that neutrons interact with matter is quite different from the way that gamma rays interact. Neutrons have negligible interaction with atomic electrons. Their only direct interaction is with nuclei. Neutron interaction in the human body can produce ionizing radiation and subsequent doses of radiation. See; Ionizing Radiation.
Nevada National Security Site
An area of land established as the Atomic Energy Commission’s on-continent proving ground in 1950. The NNSS is located 65 miles northwest of Las Vegas in Nye County and covers an area of approximately 1,360 square miles.
Nevada Test Site
Former name of the Nevada National Security Site.
Non-nuclear weapon state (NNWS)
Under the nuclear Non-Proliferation Treaty, these are states that had not detonated a nuclear device prior to January 1, 1967, (that is, all states other than the United States, the Soviet Union [now Russia], the United Kingdom, France, and China).
Prevention of the spread of weapons of mass destruction.
Nonproliferation Treaty (NPT)
Signed in 1968, the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) provides that signatory nations without nuclear weapons will not seek to build them and will accept safeguards to prevent diversion of nuclear material and technology from peaceful uses to a weapons program. States possessing nuclear weapons at the signing of the NPT agreed not to help non-nuclear states gain access to nuclear weapons, but to offer them access to peaceful nuclear technology. All states agree to work towards the eventual elimination of nuclear weapons.
North Atlantic Treaty Organization
The North Atlantic Treaty Organization (NATO) was established on April 4, 1949, by representatives from 12 nations (Belgium, Canada, Denmark, France, Iceland, Italy, Luxembourg, the Netherlands, Norway, Portugal, the United Kingdom, and the United States; Greece and Turkey joined in 1952, the Federal Republic of Germany in 1955, and Spain in 1982) who gathered in Washington, D.C., to sign the North Atlantic Treaty, which had as its purpose the deterring of potential Soviet aggression in Europe. The signing of the treaty paved the way for the first peacetime alliance participated in by the United States.
Nuclear energy refers to the energy consumed or produced in modifying the composition of the atomic nucleus. Nuclear energy also powers electricity-generating plants in countries throughout the world. It is seen by many as the source of inexpensive, clean power; but, because of the hazardous radiation emitted in producing that power and the radioactivity of the materials used, others feel that it may not be a viable energy alternative to the use of fossil fuels or solar energy.
Nuclear Freeze Movement
The nuclear freeze movement advocates an agreement between the United States and the USSR to halt (freeze) the production and deployment of nuclear weapons and delivery systems. First formulated in 1980 by Randall Forsberg, director of the Institute for Defense and Disarmament Studies in Brookline, Mass., the freeze proposal attracted growing support in the United States during the next two years, when the administration of President Reagan was increasing military spending and preparing to deploy more nuclear missiles in Europe. A series of antinuclear protests culminated in a vast demonstration by nearly half a million people from the United States and other countries in New York City on June 12, 1982.
Fissionable material used or usable to produce energy in a reactor. It includes both fissile and fertile materials. Commonly used nuclear fuels are natural and low-enriched uranium; high-enriched uranium and plutonium are used in some reactors.
Nuclear Fuel Cycle
The sequence of operations for nuclear power generation, consisting of fuel manufacture, its irradiation in a nuclear reactor, handling, and storing the spent fuel elements following discharge from the reactor. In the "once-through" cycle, the spent fuel is sent to a long-term repository; alternatively, in a "closed" cycle, spent fuel is reprocessed to separate plutonium, which is "recycled" with uranium in the form of "mixed oxide" fuel
Nuclear Power Plant
An electrical generating facility using a nuclear reactor as its heat source to provide steam to a turbine generator.
The spread of nuclear weapons-related components or technology to countries that are not currently nuclear capable.
Particulate and electromagnetic radiation emitted from atomic nuclei in various nuclear processes. The important nuclear radiations, from the weapons standpoint, are alpha and beta particles, gamma rays, and neutrons. All nuclear radiations are ionizing radiations, but the reverse is not true; X rays, for example, are included among ionizing radiations, but they are not nuclear radiations since they do not originate from atomic nuclei.
A device in which nuclear fission may be sustained and controlled in a self-supporting nuclear reaction. The varieties are many, but all incorporate certain features, including fissionable material or fuel, a moderating material (unless the reactor is operated on fast neutrons), a reflector to conserve escaping neutrons, provisions of removal of heat, measuring and controlling instruments, and protective devices. The reactor is the heart of a nuclear power plant. See; Light-Water Reactor, Pressurized-Water Reactor, Reactor.
Nuclear Regulatory Commission (NRC)
The Nuclear Regulatory Commission (NRC) is an independent U.S. government agency. The NRC came into existence in 1975 under the provisions of the 1974 Energy Reorganization Act. The major concern of the NRC is the use of nuclear energy to generate electric power. It licenses the construction and operation of nuclear reactors and other nuclear facilities as well as the possession, use, processing, transport, handling, and disposal of nuclear materials. (The U.S. Department of Energy has authority over U.S. nuclear weapons plants).
Nuclear waste refers to the entire array of radioactive materials created by all aspects of nuclear technology. The most widely known wastes are those produced by the civilian nuclear industry and the nuclear weapons program. Other sources of nuclear waste include radioactive materials produced for medical, research, and industrial applications, and the contaminated sections of dismantled nuclear facilities.
Nuclear Weapon (or Bomb)
A general name given to any weapon in which the explosion results from the energy released by reactions involving atomic nuclei, either fission, fusion or both. Thus, the A- (or atomic) bomb and the H- (or hydrogen) bomb are both nuclear weapons. See; Fission, Fusion, Thermonuclear.
Nuclear-Weapon-Free Zone (NWFZ)
A geographical area in which nuclear weapons are not allowed to be built, possessed, transferred, deployed, or tested.
Nuclear weapon states
The five states that detonated a nuclear device prior to January 1, 1967 (China, France, the Soviet Union, the United Kingdom, and the United States.
Nuclear Weapon-cable States
Those states not party to the Nuclear Nonproliferation Treaty but which have the ability to build nuclear weapons (India, Israel, and Pakistan).
Nuclear Weapon Incident
An unexpected event involving a nuclear weapon, facility, or component resulting in any of the following, but not constituting a nuclear weapon(s) accident: a) an increase in the possibility of explosion or radioactive contamination; b) errors committed in the assembly, testing, loading, or transportation of equipment, and/or the malfunctioning of equipment and material, which could lead to an unintentional operation of all or part of the weapon arming and/or firing sequence, or which could lead to a substantial change in yield, or increased dud probability; and c) any act of God, unfavorable environment, or condition resulting in damage to a weapon, facility, or component.
A potential consequence of nuclear war, where smoke from burning cities would cause a severe worldwide drop in temperatures, lasting for weeks or months with large scale ecological impacts.
Any particle that comprises the nucleus, e.g., the neutron or proton. See; Nucleus.
The small, central, positively charged region of an atom which carries essentially all the mass. Except for the nucleus of ordinary hydrogen, all atomic nuclei contain both protons and neutrons. The nuclei of isotopes of a given element contain the same number of protons, but differ in the number of neutrons. Thus, they have the same atomic number, and so are the same element, but they have different mass number (and masses). The nuclear properties (e.g. radioactivity, fission, neutron capture, etc.) of a given element are determined by both the number of neutrons and the number of protons. See; Electron, Neutron, Proton.
Oralloy, Oak Ridge Alloy
A highly enriched uranium metal, typically 93.5% U235, oralloy is used in U.S. nuclear weapons. (See also tuballoy.)
Outer Space Treaty
Prohibits the placement of WMD in orbit around the earth, on the moon or any other celestial body, or otherwise in outer space. The treaty also stipulates that the exploration and use of outer space be carried out for the benefit and in the interest of all countries, and that the moon and other celestial bodies are to be used exclusively for peaceful purposes.
The transient pressure, usually expressed in pound per square inch, exceeding the ambient pressure, manifested in the shock wave from an explosion. The peak overpressure is the maximum value of the overpressure at a given location and is generally experienced at the instant the shock wave reaches that location. See; Shock Wave.