Nuclear fission definition

The binding-energy concept is essential to an understanding of the nuclear-fission process. A short summary of the idea is therefore in order. By definition, the total binding energy of a nucleus is given by the difference between the mass of the nucleus and the sum of the masses of its constituent nucleons (protons and neutrons). If M is the nuclear mass, A the mass number (number of nucleons), Nn the number of neutrons, and the masses of the neutron and proton, respectively, and c the velocity of light, then... 

High-level waste thus includes the concentrated wastes that arise from reprocessing of commercial or defense nuclear fuel that contain virtually all the fission products and transuranium radionuclides (except plutonium) in spent fuel. However, the definition does not mention the constituents of the waste, and it is only qualitative because concentrated is not quantified and the minimum fuel burnup that would yield high-level waste is not specified. Although the definition given above referred only to liquid (aqueous) waste, it is clear from further discussions in 10 CFR Part 50, Appendix F (AEC, 1970), that AEC intended that high-level waste also would include concentrated solid waste derived from liquid high-level waste that was suitable for permanent disposal. 

Special fissionable materials which fall within the definition of nuclear-weapon-usable materials are prohibited. 

Boyle s law the volume of a given sample of gas at constant temperature varies inversely with the pressure. (5.2) Breeder reactor a nuclear reactor in which fissionable fuel is produced while the reactor runs. (20.6) Bronsted-Lowry definition (model) a model proposing that an acid is a proton donoi and a hase is a proton acceptor (7.1)... 

The term unirradiated uranium is intended to exclude any uranium which has been irradiated in a nuclear reactor so as to transform some of the U-238 into Pu-239 and some of the U-235 into fission products. The definition could have prohibited the presence of any plutonium or fission products, but naturally occurring uranium may contain trace amounts of plutonium and fission products. In the 1985 edition of the Regulations, the limits of 10 g of plutonium per gram of U-235 and 9 MBq of fission products per gram of U-235 were intended to clearly prohibit any irradiated uranium while recognizing the presence of trace amounts of plutonium and fission products in natural uranium. 

S-12. NEA Group of Experts, Short Overview on the Definitions and Significance of the Late Phase Fission Product Aerosol/Vapour Source, NEA/CSNI/R(94)30, Committee on the Safety of Nuclear Installations, OECD Nuclear Energy Agency, Issy-les-Moulineaux, France, September 1994. 

As laid out in the Equation 21.1 definition of /c-effective, the basic neutron balance relationship is between fission neutron production and neutron loss mechanisms, the two neutron loss mechanisms being neutron absorption and neutron leakage. Nuclear reactors, for which criticality must be created and maintained for extended periods, tend to be large devices—both for neutron balance reasons and because of the large fuel inventory required to deliver substantial amounts of power for long periods of time. The result of this, from the point of view of the A -effective equation, is that neutron leakage is a relatively unimportant neutron... 

Radionuclides are, by definition, unstable and decay by one, or more, of the decay modes alpha, beta-minus, beta-plus, electron capture or spontaneous fission. Although strictly speaking a de-excitation rather than a nuclear decay process, we can include isomeric transition in that list from the mathematical point of view. The amount of a radionuclide in a sample is expressed in Becquerels -numerically equal to the rate of disintegration - the number of disintegrations per second. We refer to this amount as the activity of the sample. Because this amount will change with time we must always specify at what time the activity was measured. 

The term scattering has been included in these definitions to differentiate these nuclear events from other processes, such as fission reactions, which can yield neutrons at markedly different energies. 

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