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To reduce the concentration of Pu-240 in the plutonium produced, weapons program plutonium production reactors (e.g. B Reactor) irradiate the uranium for a far shorter time than is normal for a nuclear power reactor. More precisely, weapons-grade plutonium is obtained from uranium irradiated to a low burnup.
The two fissile materials used in nuclear weapons are: 235 U, also known as highly enriched uranium (HEU), "oralloy" meaning "Oak Ridge alloy", [12] or "25" (a combination of the last digit of the atomic number of uranium-235, which is 92, and the last digit of its mass number, which is 235); and 239 Pu, also known as plutonium-239, or "49 ...
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.
Gun type uranium-235 fission bomb (the first of the two nuclear weapons that have been used in warfare). 64 kg of Uranium-235, about 1.38% of the uranium fissioned Nagasaki's "Fat Man" gravity bomb 19–23 79–96 Implosion type plutonium-239 fission bomb (the second of the two nuclear weapons used in warfare).
The first time gun-type fission weapons were discussed was as part of the British Tube Alloys nuclear bomb development program, the world's first nuclear bomb development program. [1] The British MAUD Report [ 2 ] of 1941 laid out how "an effective uranium bomb which, containing some 25 lb of active material, would be equivalent as regards ...
Apr. 14—It's been almost 80 years since the first atomic bomb was detonated, and scientists say there's still much to learn about how nuclear devices function as they reach the point of ...
The "Thin Man" design was an early nuclear weapon design proposed before plutonium had been successfully bred in a nuclear reactor from the irradiation of uranium-238. It was assumed that plutonium, like uranium-235 , could be assembled into a critical mass by a gun-type method, which involved shooting one sub-critical piece into another.
Feb. 19—Los Alamos National Laboratory reached what federal officials say is a key milestone in developing its first plutonium pit that can be placed in a nuclear warhead as it seeks to produce ...