MISTY PICTURE

On May 14, 1987, the Defense Nuclear Agency [DNA], exploded 4,685 tons of ammonium nitrate and fuel oil (ANFO) about 12,000 feet (or two-plus miles) from the McDonald ranch house. Called "MISTY PICTURE," the test recorded the effects of the air blast and ground motion of an 8-KT [kiloton] free-air nuclear detonation. Fortunately no serious damage occurred to the $300,000 rehabilitation work at the ranch house, but the experience followed upon Superintendent Harper's request that SWR personnel examine monument structures for cracking and repair.

The MISTY PICTURE surface burst was detonated at the White Sands Missle range in May of 1987. The Los Alamos National Laboratory dust characterization program was expanded to help correlate and interrelate aspects of the overall MISTY PICTURE dust and ejecta characterization program. Pre-shot sampling of the test bed included composite samples from 15 to 75 m distance from Surface Ground Zero (SGZ) representing depths down to 2.5 m, interval samples from 15 to 25 m from SGZ representing depths down to 3m, and samples of surface material (top 0.5 cm) out to distances of 190 m from SGZ. Sweep-up samples were collected in GREG/SNOB gages located within the DPR. All samples were dry-sieved between 8.0 mm and 0.045 mm (16 size fractures); selected samples were analyzed for fines by a contrifugal settling technique. The size distributions were analyzed using spectral decomposition based upon a sequential fragmentation model. Results suggest that the same particle size subpopulations are present in the ejecta, fallout, and sweep-up samples as are present in the pre-shot test bed. The particle size distribution in post-shot environments apparently can be modelled taking into account heterogeneities in the pre-shot test bed and dominant wind direction during and following the shot.