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Literature Survey of Blast and Fire Effects of Nuclear Weapons on Urban Areas The American literature of the past 30 years on fire and blast effects of nuclear weapons on urban areas has been surveyed. The relevant work in the categories of thermal radiation and blast-wave propagation, ignition, structural response, and firespread is sketched and areas where information is apparently lacking are noted. One purpose of this report is to provide entry into the literature for researchers. Over 850 references are given, arranged alphabetically by first author. Accession numbers are given wherever possible to facilitate ordering from DTIC or NTIS. The main prupose of this report is to provide the basis for suggesting Sixty-two research priorities in fire and blast effects for civil defense. component problems are identified and assigned to one of three rankings according to their perceived relative state of knowledge. Without implying any relative importance by their order, we list below those areas where knowledge appears to be the most deficient. Ignition criteria for newer materials and for all materials under typical use conditions. Effects of complex geometry or mixed fuel on ignition criteria. Enclosure effects on flashover. Conditions under which blast.prornotes incipient fires. Effects of blast damage on the burn characteristics of structures. Debris production and distribution from individual building elements and buildings, especially residential. Fire spread rates between relatively intact structures for many simultaneous ignitions and through debris fields for various wind and weather conditions. Conditions for the existence of mass fires and conditions within and near them. Methodology for thermal radiation propagation through incompletely specified atmospheres. Methodology for efficient representation of an urban area in a realistic fashion. Methodology for calculating shadowing and shielding effects of a specified urban area. Methodology for calculating dynamic response and collapse of entire buildings. Multiple-burst effects on thermal radiation and blast-wave loading of targets; effects of blast on established fires; and structural response of structures previously damaged by blast or fire. Since the assignment of priorities depends on long-term goals and budget information, priorities are not suggested in this report.

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Hafnia-silica multilayer polarizers were deposited by e-beam evaporation onto BK7 glass substrates. The polarizers were designed to operate at a wavelength of 1064 nm at Brewster's angle (56°). The polarizers were tested with a 3-ns laser pulse at 45°, 56°, and 65° incidence angle in order to vary the electric field distribution in the multilayer, study their effects on the damage morphology, and investigate the possible advantages of off-use angle laser conditioning. The morphology of the laser-induced damage was characterized by optical and scanning electron microscopy. Four distinct damage morphologies (pit, flat bottom pit, scald, and outer layer delamination) were observed.These damage morphologies were found to depend strongly on the angle of incidence of the laser beam. In particular, massive delamination observed at 45° and 56° incidence, did not occur at 65°. Instead, large and deep pits were found at 65°. The electric field distribution, the temperature rise and the change in stress in the multilayer were calculated to attempt to better understand the relationship between damage morphology, electric field peak locations, and maximum thermal stress gradients. The calculations showed a two-fold increase in stress change in the hafnia top layers depending on the incidence angle. The stress gradient in the first hafnia-silica interface was found to be highest for 45°, 56°, and 65°, respectively. Finally, the maximum stress was deeper in the multilayer at 65°. Although the limitations of such simple thermal mechanical model are obvious, the results can explain that outer layer delamination is more likely at 45° and 56° than 65° and that damage sites are expected to be deeper at 65°.

The fundamental mechanisms of material removal by fluidjet machining have been theoretically and experimentally investigated as a potential method for dismantling nuclear weapons with efficiency and safety. Preliminary I experiments and analyses have revealed that at small standoff distances between the nozzle exit and the target workpiece there is no mass removal from the workpiece, but that far from the nozzle there exists an optimum standoff distance at which the jet impact removes mass from the workpiece at a maximum rate. Such results suggest a mass-removal process due to the droplets and ligaments impinging on the material that cause sudden pressure increases in the impact regions. This proposed material-removal mechanism has been addressed theoretically by considering a series of multiple droplet impacts on a material. The calculated results display a series of pressure peaks at the target surface as each of these droplets strikes the material, supporting the plausibility of the proposed mass-removal scenario at the optimum standoff distance. Although plausible further experiments and analyses are needed to verify the proposed jet-induced mass removal mechanism.