Nuclear decoupling, full and partial

Abstract

An underground explosion in a cavity is said to be fully decoupled if the cavity is large enough for the explosion to produce only elastic motion in the walls; in a smaller cavity where the wall motion is elastoplastic, the explosion is said to be partially decoupled. In this report, the pressure histories on the walls of cavities in salt of suitable size for decoupling sources are calculated and used in computing the motions of the walls, including the effect of elastoplastic behavior of salt. From the motion of the cavity walls, seismic displacement potentials are calculated and compared with the measured close‐in displacement potentials for the Salmon event (5 kt) and the Gnome event (3.1 kt) scaled to 5 kt, both tamped (tightly coupled) nuclear detonations in salt. The close‐in decoupling ratios for salt thus obtained are 350 for Gnome data and 200 for Salmon data. The reduced displacement potential based on the Gnome measurement at 298 m and scaled to the 5‐kt size of Salmon is found to be 40% above the measured Salmon value at 300 m; the Gnome measurement may have been in the inelastic region or it may have been influenced by stronger horizontal propagation due to bedding planes. Reduced displacement potentials are also calculated for shots of 100 tons, 0.5 kt, and 1 kt, all in a cavity volume for 100‐ton decoupling. They are 0.47, 5.0, and 45 m3, respectively, as compared with 80 m3 for a 100‐ton fully tamped shot.

Symposium on Engineering With Nuclear Explosives, Las Vegas, Nevada, January 14--16, 1970. Proceedings.

“…Reduction of the device yield would reduce the initial concentrations of radioactivity correspondingly. Costs quoted in Table V-b are based on [9,12,46,47].…”

“…Copper extraction coefficients were 10 or higher in all tests. Ruthenium-106, the most troublesome radiocontaminant in the cementation process, had extraction coefficients of less than 0.005 over this pH range, as did 134 Cs, 85 Sr, 6°C o, 46 Sc, 6 Zn, and 144 Ce. Further study of the extraction of 95 Zr-Nb, 5 Fe, and 110 Ag showed extractions of the first two to be time dependent (Fig.…”

“…Less than 2$ of 134 Cs, 51 Cr, 46 Sc, 59 Fe, 144 Ce, that appears important with respect to radiocontamination of the cement copper. Attempts were made to remove 10 Ru from the leach liquor with various types of ion exchange and other adsorbents but none of these were very effective.…”

“…A comprehensive experimental-theoretical study of an underground nuclear event from explosive detonation to distant seismic signal has been published for only one experiment, Salmon. 45,46,47 This work concerned only the first P-wave arrival in the first zone, the head wave that is critically refracted at the Mohorovicic discontinuity. Other experimental-theoretical studies beginning with the measured reduced displacement potential (instead of the explosive detonation) and ending with the head wave arrival have been made.°>28 Toksoz et al4° used R-wave measurements from several nuclear explosions together with an appropriate layered geological model to calculate a seismic source function (equivalent to a reduced displacement potential) for the explosion.…”

“…•P (n/y)' 46 Ar, 31 P (n,p) (n, 7 The target that was exposed to the intense neutron flux produced by the Hutch device consisted of 17.8 g of 238^ and 8.8 g of 232rph. Neutron capture was expected to take place in four separate chains-"the uranium chain starting from 238-Q^ the protactinium chain from 238p a^ the thorium chain from 23 2rph, and the actinium chain from 23 2^c.…”