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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]
Peierls also attempted to simplify the problem by using the fast neutrons produced by fission, thus omitting consideration of moderator. He then calculated the critical mass of a sphere of uranium metal in a theoretical paper written in 1939. [33] [34] He later recalled that the size of the critical mass "was of the order of tons. It therefore ...
The tamper had a radius of 17.5 centimetres (6.9 in) and a thickness of 11.3 centimetres (4.4 in), for a mass of 317 kilograms (699 lb). This was about 3.5 times the mass of the fissile material used. Tungsten carbide has a high density and a low neutron absorbency cross section.
The Mod 11 variant of the B61 replaced the B53 in the bunker busting role. The W53 warhead from the weapon was used on the Titan II Missile until the system was decommissioned in 1987. Castle Bravo device 15,000 63,000 Most powerful US test. [4] Never deployed. 400 kg of Lithium-6 deuteride EC17/Mk-17, the EC24/Mk-24, and the B41 (Mk-41) 25,000 ...
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.
Little Boy was a type of atomic bomb created by the United States as part of the Manhattan Project during World War II.The name is also often used to describe the specific bomb (L-11) used in the bombing of the Japanese city of Hiroshima by the Boeing B-29 Superfortress Enola Gay on 6 August 1945, making it the first nuclear weapon used in warfare, and the second nuclear explosion in history ...
The W25 was a small nuclear warhead that was developed by the Los Alamos Scientific Laboratory for air-defense use. It was a fission device with a nominal yield of 1.7 kt. [ 1 ] The W25 was used for the MB-1 "Ding Dong" , an unguided air-to-air rocket used by US Northrop F-89 Scorpion , F-101 Voodoo , and F-106 Delta Dart interceptor aircraft ...
For every 1,000 neutrons released by fission, a small number, typically no more than about 7, are delayed neutrons which are emitted from the fission product precursors, called delayed neutron emitters. This delayed neutron fraction, on the order of 0.007 for uranium, is crucial for the control of the neutron chain reaction in reactors.