Subsurface detonation

The following discussion gives an example of the data treatment required to characterize the population for three cases—a land surface burst, a land subsurface detonation, and an airburst detonation. These three examples cover the complete range of types of solutions to the characterization problem. 

Graphs of rA vs. r89 for several isotopes are shown in Figure 1. It is important to note that all the normalized isotopic ratios are equal to unity when the cesium-137/refractory ratio is unity. This fact implies quite clearly that the samples analyzed are representative of the complete particle population. The linearity of the rA values relative to r137 indicates that there are two and only two isotopic compositions present in the particle population and that the isotopic composition of any arbitrary particle sample is a linear combination of these. In the case of subsurface detonations where a third particle class is observed, the normalized isotopic ratios for the other isotopes are not equal to unity when the cesium-137 ratio is. A minimum conclusion is that for this particular Coral Island... 

The over-all distribution function consists of a linear combination of two lognormal functions. This is based on the observation that size distribution from very early aerial clouds samples from subsurface detonations are described accurately by the lognormal form of distribution. (This is shown below in connection with subsurface detonation analyses.) It is also supported by the work of particle analysts in industry, who find that particle population produced by crushing or grinding are described by lognormal distributions. 

A subsurface detonation in the low kiloton yield range which produced an aboveground fireball and a three component particle population is treated in this section. 

Table IV. Normalized Atom Ratios (Subsurface Detonation)...

Figure 4. Land subsurface detonation. Aerial filter samples.

As in the case of the land surface burst, complete characterization of the particle population requires only that particle mass, a volatile species, and a refractory species distribution with particle size be determined. All other isotopic distributions may be deduced from the istotope partition calculations described above. In the subsurface detonation, the earliest aerial cloud sample was obtained in the cloud 15 minutes after detonation. The early sample was, therefore, completely representative of the aerial cloud particle population. In Figure 5 the results of the size analysis on a weight basis are shown. Included for comparison is a size distribution for the early, local fallout material. The local fallout population and the aerial cloud population are separated completely from the time of their formation. 

Detonations which produce particle populations of the first category are land surface bursts, land subsurface bursts, vented underground bursts, and tower bursts. 

The utility of explosives lay in the strongly energetic and exothermic reaction initiated upon detonation or ignition. Most modem explosives are reasonably stable and require percussive shock or other triggering devices for detonation. Fortunately, subsurface Explosives-Associated Compounds (XAC) contamination usually occurs as dilute, aqueous solutions and thus presents no explosion hazard. However, masses of pure crystalline explosive material have been encountered in soils associated with wastewater lagoons, leach pits, bum pits, and perhaps firing ranges. 

Upon detecting a possible subsurface UXO, the UXO specialist will mark the spot with a pin flag or spot of spray paint. A team of two UXO specialists then will excavate the marked items when the magnetometer survey team had advanced beyond the area that would be hazardous in the event of an accidental detonation caused by the excavation team. 

Castle Air Force Base, California FY 1995 Air Force base closure. Open bum/open detonation area. Research and development and applied technology testing-demonstration for contaminated media and subsurface unexploded ordnance detection, identification, and remediation in an uncontrolled test environment. This would also be a DOIT Committee process demonstration site. 

Types of Bursts. The altitude at which the weapon is detonated will largely determine the relative effects of blast, heat, and nuclear radiation. Nuclear explosions are generally classified as airbursts, surface bursts, subsurface bursts, or high altitude bursts. 

C. Subsurface Burst. A subsurface burst weapon is detonated beneath the surface of land or water. Cratering will generally result from an underground burst, just as for a surface burst. If the burst does not penetrate the surface, the only other hazard will be from ground or water shock. If the burst is shallow enough to penetrate the surface, blast, thermal, and initial nuclear radiation effects will be present, but will be less than for a surface burst of comparable yield. Local fallout will be very heavy if penetration occurs. 

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