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OTHER MAJOR ACTIVITIES
will be the means used to look for new elements and newisotopes of
known heavy elements. Second, in order to recoversignificant quantities of transplutonium elements, the special nuclear device must be
detonated in a medium that facilitates mining recovery operations.
Salt is one such media, therefore the same area that had been previously used for Project Gnomewasselected for Project Coach. Material from the Gnome cavity has been studied as a part of the work to
determine possible mining and chemical processing techniques.
Hardhat
The Department of Defense experiment Hardhat (4.5 kiloton
military effects test detonated 950 feet underground on February
15, 1962, at the NTS) was of particular interest to the Plowshare
program because the granodiorite in which the explosion took place
is typical of the media in many miningsituations. This explosion
formed a cavity about 63 feet in radius which collapsed about 11 hours
after the detonation. Oncollapse rock above the cavity fractured
by the explosion caved progressively upward forming a chimney of
broken rubble,to 280 feet above the detonation point.
About 220,000
tons of granodiorite were fractured.
Early in 1963, a Plowshare mining experiment at the Hardhat site
was successfully completed. The experiment provided informatioy
on the use of nuclear explosives to break and crush mineral deposits
preparatory to extracting the ore by conventional, block-caving techniques. There-entry drift was driven completely through the rubblefilled chimneyat a level 90 feet above the shot point. Two standard
mining draw-points were installed and more than 2,700 tons of broken
rock were withdrawn in a simulated mining operation. No hazardous amounts of radioactivity were encountered. The results are considered sufficient to allow undertaking an industrial scale project
next.
Shoal
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Project Shoal was a contained 12 kiloton nuclear explosion conducted 1,200 feet underground in granite near Fallon, Nev., on October 26, 1963. Shoal was conducted as part of the Vela program
which is directed by the Advanced Research Projects Agency of the
Department of Defense to improve the capability of detecting, locating, and identifying underground nuclear detonations. The phenomena of this explosion will be of great interest to the Plowshare
program.
The Plowshare program sponsored a U.S. Bureau of Mines add-on
experiment to the Shoal detonation to measure the extent and type