JANUARY—DECEMBER 1963
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surface layers, followed by: two, the expansion of the cavity containing high pressure gases to the point where it intercepts the surface,
increasing the amount of material leaving the crater and boosting that
already freed by the spalling action of the shock wave. This material
then assumes trajectories in which a part of it falls outside the immediate area, thus forming a crater.
Mathematical models to simulate these effects and computer codes
are under development, and increased success was achieved in matching this theory to results obtained from field experiments. Among
effects to be studied are the differences caused by the type of earth
media, especially its particle structure, the effect of the chemical
composition of the earth media, and the entrapmentof radioactivity.
Additional data are needed from field experiments in different media
and at different yields in order to provide input for further theoretical
treatments. In particular, it is necessary to obtain data which will
allow theoretical understanding of the physics of the simultaneous
explosion of a row of charges. Among the most important phenomena
in a row of simultaneously detonated charges is the manner in which
the cavities created by the individual charges in a rowcoalesce and
the gas pressure from them acts upon the material being thrown out
of the crater.
Sedan
Sedan was a project in which a 100-kiloton thermonuclear explosive
was detonated 635 feet undergroundin alluvium at the Nevada Test
Site (NTS) on July 6, 1962. The project was described extensively
-
in the Commission’s 1962 Annual Report During the year. additional data became available and were published with 23 technical
reports out of a total of 31 planned having been issued? As indicated above, these data were available for use in the theoretical studies
which are underway.
Post-shot exploration of the Sedan crater was begun in February
by LRL and the Corps of Engineers’ Nuclear Cratering Group. Men,
trucks, equipment, and drilling rigs were lowered to the floor of the
crater to obtain measurements of the fallback material, radioactivity,
porosity, and permeability of the crater. On May 7, 18 representatives of 14 news media organizations visited the Sedan crater. The
feasibility of re-entering and working in a crater made by nuclear
explosives was conclusively demonstrated in the course of these
activities.
2 See pp. 247-250 of AEC Annual Report to Congress for 1965.
3 Copies of these reports are available from the Office of Technical Services, U.S. De-
partment of Commerce. Washington, D.C.. 20230.