Sedan Nuclear Test, Operation Plowshare, Nevada Test Site, Yucca Flats 1962 US Department of Energy

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more at http://scitech.quickfound.net "Project Sedan, a 100-kiloton nuclear cratering detonation, recently executed as part of the Atomic Energy Commission's Plowshare Program. Plowshare envisages many uses for nuclear explosives..." A test of a nuclear weapon for simple dirt excavation purposes. Public domain film from the US Government, slightly cropped to remove uneven edges, with the aspect ratio corrected, and mild video noise reduction applied. The soundtrack was also processed with volume normalization, noise reduction, clipping reduction, and/or equalization (the resulting sound, though not perfect, is far less noisy than the original). http://creativecommons.org/licenses/by-sa/3.0/ http://en.wikipedia.org/wiki/Sedan_(nuclear_test) Storax Sedan was a shallow underground nuclear test conducted in Area 10 of Yucca Flat at the Nevada National Security Site on 6 July 1962 as part of Operation Plowshare, a program to investigate the use of nuclear weapons for mining, cratering, and other civilian purposes. The radioactive fallout from the test contaminated more US residents than any other nuclear test. The Sedan Crater is the largest man-made crater in the United States, and is listed on the National Register of Historic Places... Sedan was a thermonuclear device with a fission yield less than 30% and a fusion yield about 70%. The timing of the test put it within the Operation Storax fiscal year, but Sedan was functionally part of Operation Plowshare, and the test protocol was sponsored and conducted by Lawrence Livermore National Laboratory with minimal involvement by the United States Department of Defense. The explosive device was lowered into a shaft drilled into the desert alluvium 194 m (636 ft) deep. The fusion-fission blast had a yield equivalent to 104 kilotons of TNT (435 terajoules) and lifted a dome of earth 90 m (300 ft) above the desert floor before it vented at three seconds after detonation, exploding upward and outward displacing more than 11,000,000 t (11,000,000 long tons; 12,000,000 short tons) of soil. The resulting crater is 100 m (330 ft) deep with a diameter of about 390 m (1,280 ft). A circular area of the desert floor five miles across was obscured by fast-expanding dust clouds moving out horizontally from the base surge, akin to pyroclastic surge. The blast caused seismic waves equivalent to an earthquake of 4.75 on the Richter scale. The radiation level on the crater lip at 1 hour after burst was 500 R per hour (130 mC/(kg·h)). Within 7 months of the excavation, the bottom of the crater could be safely walked upon with no protective clothing. The Sedan shot resulted in a radioactive cloud that separated into two plumes, rising to 3.0 km and 4.9 km (10,000 ft and 16,000 ft). The two plumes headed northeast and then east in roughly parallel paths towards the Atlantic Ocean. Nuclear fallout was dropped along the way, narrowly dispersed in a relatively small number of United States counties. Detected radioactivity was especially high in eight counties in Iowa and one county each in Nebraska, South Dakota and Illinois. Most heavily affected counties were Howard, Mitchell and Worth counties in Iowa, as well as Washabaugh County in South Dakota, an area that has since been incorporated into Jackson County and is wholly within Pine Ridge Indian Reservation. These four counties measured maximum levels higher than 6,000 microcuries per square meter (220 MBq/m2). Of all the nuclear tests conducted in the USA, Sedan ranked highest in overall activity of radionuclides in fallout... Conclusions The Plowshare project developed the Sedan test in order to determine the feasibility of using nuclear detonations to quickly and economically excavate large amounts of earth and rock. Proposed applications included the creation of harbors, canals, open pit mines, railroad and highway cuts through mountainous terrain and the construction of dams. Assessment of the full effects of the Sedan shot showed that the radioactive fallout from such uses would be extensive. Public concerns about the health effects and a lack of political support eventually led to abandonment of the concept. No such nuclear excavation has since been undertaken by the US, though the Soviet Union continued to pursue the concept through their program Nuclear Explosions for the National Economy, particularly with their 140 kiloton Chagan (nuclear test), which created an artificial lake reservoir(see Lake Chagan)...