Review and summary of some project gnome results

Abstract

A summary of some results of the Gnome underground nuclear explosion in bedded salt is presented. The report deals primarily with the environment produced by the explosion, touches also on isotope production feasibility, feasibility of power production, seismic measurements, shock studies, and neutron experimentation, and discusses the venting which accompanied the explosion.

Understanding and constructively using the effects of underground nuclear explosions

“…At later times, when the cavity is nearing its maximum size, the equationof-state problem is one associated with high-temperature chemistry. The chemistry of the Gnome (89• NaC1) [Rawson, 1963] and Salmon (90% l•aC1) [Rawson et al, 1967] cavity gases is relatively simple compared to that for most other rocks. Silicate rocks, in general, contain 50 to 70 wt • SiOn, the remainder consisting primarily of oxides of aluminum, magnesium, calcium, and iron [Birch, 1942].…”

“…It is therefore inferred that the heat deposited in and conducted into the cavity walls vaporized the water (15% by weight) in the tuff, and the walls imploded into the cavity when the cavity pressure dropped below that of the steam in the walls (after cavity expansion and before collapse) [Kennedy and Higgins, 1958]. There is evidence of the same phenomenon in Gnome, where steam pressure (from a water content of 1 or 2%) may have been suftieient to contribute to the implosion, deerepitation, or spalling of about 13,000 tons of salt that was intimately mixed with about 2400 tons of melt [Rawson, 1963]. The Salmon salt contained only 0.001% water, and the implosion phenomenon was not the data points is such that the variation of permeability versus radial distance from the shot point (shown in Figure 25) is not perceptibly different from a plot of permeability versus horizontal distance from the chimney axis [Boardman and Skrove, 1966].…”

“…Chimney formation. Of all the contained underground nuclear explosions detonated by the United States, only two are known to have produced permanent cavities: Salmon [Rawson et al, 1967], which remained standing (Figure 29), and Gnome [Rawson, 1963], which partially collapsed (Figure 30)…”

Inelastic processes in seismic wave generation by underground explosions

“…The only known exceptions are cavities in salt formations; e.g., those produced by the 3-kt Gnome (Rawson 1963 Cavity collapse forms a "chimney" which may or may not extend to the surface, forming a subsidence crater (Boarctaan, Rabb, and McArthur 1964). Springer andKinnaman (1971, 1975) list surface collapse intervals that have been observed following US nuclear explosions; the intervals range from minutes to hours-and even years in a few exceptional cases.…”

Proceedings of the Third Plowshare Symposium Engineering With Nuclear Explosives, April 21-23, 1964

“…Thus a relatively simple, and in some cases a well-known, equation of state exists for the high-explosive cavity gas for an appropriate range of pressures. However, nuclear explosives a r e known to vaporize a great deal of surrounding rock o r soil during the early part of the cavity life history (Nuckolls, 1959, Rawson, 1962. This vaporized material is believed to condense late in the life history of the cavity (Knox and Terhune, 1963), and prior to vent of the cavity gas to the d\ atmosphere, such that the latent heat of condenapplying Newton's second low with o simple frictional force (calibrated on the Scooter event) t o each mass element, and by assuming thot the cavity gas behaves adiabatically, the cavity evolution, mound development, and the formation of the l i p through up-thrust are numerically simulated.…”