Chapter 2—The Nuclear Testing Program e 19 Figure 2-3—Drill-Back Operation Drill rig Surfaced ground zero <-- X-- ecer Photo credit: Department of Energy “ne of interest Emplacement Tower for Vertical Orilt Hole Test 1/2 up to 7 ft; while Livermore typically uses 8-ft diameter holes and an occasional 10-ft diameter hole.2° Livermore usually places its experimental devices above the watertable to avoid the additional time and expense required to case holes below the water table. Whenthe device is detonated at the bottom of a vertical drill hole, data from the test are transmitted through electrical and fiber-optic cables to trailers containing recording equipment. Performanceinformation is also determined from samplesof radioactive material that are recovered by drilling back into the solidified melt created by the explosion (figure 2-3). On rare occasions, vertical drill holes have been used for effects tests. One such test, ‘‘Huron King,’” used an initially open, vertical ‘‘line-of- sight’’ pipe that extended upwards to a large SOURCE: Modified from Michael W. Butier, Pastshot Dniling Handbook, Lawrence Livermore National Laboratory, Jan 19. 1984. enclosed chamberlocated at the surface. The chamber contained a satellite inside a vacuum to simulate the conditions of space. The radiation from the explosion was directed up the hole at thesatellite. The explosion was contained by a series of mechanical pipe closures that blocked the pipe immediately after the initial burst of radiation. The purposeof the test was to determine how satellites might be affected by the radiation produced by a nuclear explosion. Tunnel tests occur within horizontal tunnels that are drilled into the volcanic rock of Rainier or Aqueduct Mesa. From 1970 through 1988, there 20Livermore has considered the use of 12 ft diameter holes, but has not yet used one.