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The temperature of the fuel varies as a function of the distance from the center to the rim. At distance x from the center the temperature (T x) is described by the equation where ρ is the power density (W m −3) and K f is the thermal conductivity. T x = T Rim + ρ (r pellet ² – x²) (4 K f) −1
A critical mass is a mass of fissile material that self-sustains a fission chain reaction. In this case, known as criticality, k = 1. A steady rate of spontaneous fission causes a proportionally steady level of neutron activity. A supercritical mass is a mass which, once fission has started, will proceed at an increasing rate. [1]
[39] Using modern values he found that to be "equal to about a microsecond, which makes the point about the rapidity of fission with fact [sic] neutrons". [39] In the original memorandum, if the neutrons had velocities of 10 9 cm/s, then they would have an average time between fission collisions of 2.6 × 10 −9 s. Therefore, Bernstein's time ...
The pits of the first nuclear weapons were solid, with an urchin neutron initiator in their center. The Gadget and Fat Man used pits made of 6.2 kg of solid hot pressed plutonium-gallium alloy (at 400 °C and 200 MPa in steel dies – 750 °F and 29,000 psi) half-spheres of 9.2 cm (3.6 in) diameter, with a 2.5 cm (1 in) internal cavity for the initiator.
Nuclear cross sections are used in determining the nuclear reaction rate, and are governed by the reaction rate equation for a particular set of particles (usually viewed as a "beam and target" thought experiment where one particle or nucleus is the "target", which is typically at rest, and the other is treated as a "beam", which is a projectile with a given energy).
Quantity (common name/s) (Common) symbol/s Defining equation SI units Dimension Number of atoms N = Number of atoms remaining at time t. N 0 = Initial number of atoms at time t = 0
The central portion of the star is now crushed into a neutron core with the temperature soaring further to 100 GK (8.6 MeV) [8] that quickly cools down [9] into a neutron star if the mass of the star is below 20 M ☉. [7] Between 20 M ☉ and 40–50 M ☉, fallback of the material will make the neutron core collapse further into a black hole ...
6.95: Ammonal (Al+NH 4 NO 3 oxidizer) [citation needed] 6.9: 12.7: Tetranitromethane + hydrazine bipropellant - computed [citation needed] 6.6: Nitroglycerin: 6.38 [9] 10.2 [10] ANFO-ANNM [citation needed] 6.26: battery, Lithium–air: 6.12: Octogen (HMX) 5.7 [9] 10.8 [11] TNT [12] 4.610: 6.92: Copper Thermite (Al + CuO as oxidizer) [citation ...