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Volcanic activity
Published in F.G. Bell, Geological Hazards, 1999
The size of pyroclasts varies enormously. It is dependent upon the viscosity of the magma, the violence of the explosive activity, the amount of gas coming out of solution during the flight of the pyroclast, and the height to which it is thrown. The largest blocks thrown into the air may weight over 100 tonnes, whereas the smallest consist of very fine ash, which may take years to fall back to the Earth’s surface. The largest pyroclasts are referred to as volcanic bombs. These consist of clots of lava or fragments of wall rock. They may fall in significant quantities within a 5 km radius of the eruption. The bombs may destroy structures on which they fall, and incandescent bombs may ignite homes, crops or woodlands.
Trinity by the Numbers: The Computing Effort that Made Trinity Possible
Published in Nuclear Technology, 2021
Through the end of 1941, the U.S. atomic bomb program, then under the auspices of the Office of Scientific Research and Development (OSRD), had focused primarily on slow-neutron fission research. The purpose of this focus was to develop techniques for generating the needed isotopes of uranium and plutonium in sufficient quantities for an atomic weapon. Without a reasonable confidence in the project’s ability to produce the needed fissile materials, there would have been little purpose in developing the weapon itself. In late 1941, Arthur Compton, the Nobel laureate and head of the Chicago Metallurgical Laboratory (Met Lab), provided encouraging progress reports to the OSRD and to the National Academy of Sciences about the multiple methods being pursued to produce fissile materials. He also provided critical mass estimates that pointed toward the feasibility of a weapon. The reports resulted in an increased project focus on the issues of atomic bomb design and construction. Engineering the weapon itself meant expanding on the relatively small amount of research on fast neutrons—neutrons with high kinetic energies needed to drive the detonation of an atomic weapon—conducted up to that point.4–9
Development of a new ammonium nitrate composition: an attempt to prevent misuse of explosives for antisocial activities
Published in Journal of the Chinese Institute of Engineers, 2020
Ahmet Ozan Gezerman, Burcu Didem Çorbacıoğlu
The reaction heats for different concentrations of FBC ash, calcium carbonate, and dolomite in AN solution are shown in Table 1. A steel vessel with an inner volume of 5.6 dm3 was used for the calorimetric tests. The spherical volume of the bomb is filled with 2.0 MPa compressed Ar gas, and the detonation velocity and heat of explosion are determined. However, the gaseous products formed by AN decomposition can react with the FBC ash. For the detonation test, 80 mg of the AN sample was fired by using a standard fuse and 670 mg-RDX (Electric Detonator DYNAWELL, 0015 FDB RDX 1.4S). Two trials were performed for each mixture. The average of the obtained explosion heats is shown in Table 1. Shock waves that are reflected toward the bomb wall can trigger a heat explosion to increase the reaction heat. The final heat measured in the calorimetric system decreased with an increase in the FBC ash content in the AN mixture.
Manhattan Project: The Story of the Century, by Bruce Cameron Reed. Springer Nature Switzerland AG, 2020,
Published in Technometrics, 2022
Pre-detonation characteristics were studied, the problem of uranium or plutonium premature alpha-decay by neutron bombardment was solved with help of devices called initiators filled with polonium and beryllium within the bomb core, carried out by chemists and metallurgists Ch. Thomas and C. Smith, and the problem of spontaneous fission was cracked as well. Responsibility for the design, engineering, drop tests, and assembly of the uranium gun bomb lay with the Gun Group of the Ordnance Division, directed by A.F. Birch. The final Little Boy bomb was 10 feet long, 28 inches in diameter, and weighed about 9700 lb, the gun barrel itself was six feet long and weighed 1000 lb. A more efficient spherical weapon of plutonium bomb with inward initial implosion crushing the radioactive core to critical density was suggested by S. Neddermeyer who estimated the needed critical size and weight. With help of famous mathematician J. von Neumann who analyzed shaped-charged explosives, explosive expertise by G. Kistiakowsky, R. Christy, L. Alvarez, D. Hornig, J. Tuck from British Mission, and many other specialists, the progress was reached in building the Trinity and Fat Man devices. The bomb was a hand-assembled three-dimensional jigsaw puzzle with explosive pieces precisely fit together, with total weight above 10,000 lb, and the high-explosive assembly alone just over half of the weight. The first full-scale experimental test on Trinity plutonium bomb explosion was performed at Alamogordo Army Air Field located at 160 miles from Los Alamos, on July 16, 1945, and this dramatic event is recalled in many observers’ memoirs.