Nuclear explosive device

Nuclear explosive device Assembly of nuclear and other materials and fuses that could be used in a test but generally cannot be delivered reliably as part of a weapon. 

II. On August 6, 1945, an atomic bomb (nicknamed as Little Boy ) was dropped by an American B-29 bomber (Enola Gay) over Hiroshima, Japan instantly killing more than 70000 people. On August 9, 1945, the USA dropped a second atomic bomb (nicknamed Fat Man ) killing some 40000 people in Nagasaki, Japan. Because of this large-scale devastation, such nuclear explosive devices have never again been used in a war. 

For instance, in the case of nuclear weapons, the significant quantity , defined as the approximate quantity of nuclear material in respect of which the possibility of manufacturing a nuclear explosive device cannot be excluded, has been set at 8 kg for plutonium and 25 kg for high enriched uranium. 

It has been estimated that the time needed for a country with the appropriate industrial infrastructure and pre-assembly activities to convert a significant quantity of fissionable material into a nuclear explosive device is ... 

The Treaty on the Non-Proliferation of Nuclear Weapons (NPT) is the single most important component of the non-proliferation regime. Under it, the 182 non-nuclear-weapon State Parties have committed themselves not to manufacture or otherwise acquire any nuclear explosive device and to accept IAEA safeguards on all source or special fissionable material to verify that commitment. Under it also the five nuclear weapon State Parties have committed themselves to embark on effective measures relating to nuclear disarmament. 

The proliferation of nuclear weapons would seriously increase the danger of nuclear war. Every effort should be made to implement the Treaty in all its aspects to prevent the proliferation of nuclear weapons and other nuclear explosive devices, without hampering the peaceful uses of nuclear energy by States parties to the Treaty. 

New supply arrangements for the transfer of source or special fissible material or equipment or material especially designed or prepared for the processing, use or production of special fissionable material to non-nuclear weapon States should require, as a necessary precondition, acceptance of IAEA full-scope safeguards and internationally legally binding commitments not to acquire nuclear weapons or other nuclear explosive devices. 

It is obvious that the neutron energy spectrum of a reactor plays an essential role. Figure 19.4 shows the prompt (unmoderated) fission neutron spectrum with 2 MeV. In a nuclear explosive device almost all fission is caused by fast neutrons. Nuclear reactors can be designed so that fission mainly occurs with fast neutrons or with slow neutrons (by moderating the neutrons to thermal energies before they encounter fuel). This leads to two different reactor concepts - the fast reactor and the thermal reactor. The approximate neutron spectra for both reactor types are shown in Figure 19.4. Because thermal reactors are more important at present, we discuss this type of reactors first. 

Indigenous development of nuclear weapons is possible for countries with industrial bases no greater than that of Iraq in 1990. Given a source of fissile material, even terrorist groups could construct their own nuclear explosive devices. 

An important practical limitation is that each laser medium requires a minimum volumetric pump rate to begin lasing and a somewhat greater volumetric pump rate to convert the pumping power to laser light efii-ciently. One limitation of RPLs is that reactors tend to produce lower volumetric pump rates (no more than 3000 MW/m ) than can be obtained with some conventional laser excitation methods. This limit is set by temperature limitations of the reactor structure itself. In the case of nuclear explosive devices used as pump sources, much higher pump rates can be obtained, since the survival of the nuclear device and its immediate surroundings is not required. 

The fuel in most nuclear reactors is in the form of a heat-resistant ceramic. The main use of the metallic forms of the special nuclear materials is as fuel in nuclear explosive devices. Consequently, interdiction of a metal sample is the smoking gun that points to a weapons application. 

To set a target for the quantification of the inspection goal, the IAEA currently adopts the following quantities (O Table 63.1) called significant quantities (SQs) as estimates of the amount of material that would be sufficient to manufacture a nuclear explosive device. 

A minimum time necessary for manufacturing a nuclear explosive device has been defined according to the material category, its irradiation status and suitability for conversion into components of nuclear explosive devices. Direct use material (such as Pu containing less than 80% Pu, HEU and can be used without transmutation or finther enrichment. 

Unirradiated material does not contain substantial amounts of fission products thus it requires less time and effort to be converted to components of nuclear explosive devices than irradiated direct use material like spent reactor fuel. Indirect use material (DU, NU, LEU and Th) must be further processed to produce direct use material. 

Proliferation resistance is that characteristic of a nuclear energy system that impedes the diversion or undeclared production of nuclear material, or misuse of technology, by States in order to acquire nuclear weapons or other nuclear explosive devices. 

Other nuclear explosive devices. For their part, the nuclear weapon possessor states that are signatories—China, France, Russia, the United Kingdom, and the United States, referred to as the P-5 —are obliged to work in good faith toward complete and final nuclear disarmament. These five nations have periodically reiterated their commitment to work toward achieving this goal. 

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