EVALUATION OF NUCLEAR WEAPON THERMAL THREAT.

Abstract : The threat to urban areas from fires produced by the detonation of a nuclear weapon may be measured in terms of the proportion of structures that will contain one or more significant fires, i.e., fires producing a flashover. In the study, this proportion is determined for uncrushed structures in which the ignition of an interior fuel by thermal radiation from a nuclear weapon results in at least one significant fire. The proportions of structures containing a significant fire in different land-use areas are expressed as functions of the radiant exposure outside structures. The functions depend on such parameters as the weapon yield, height of burst, atmospheric conditions, number of fuels, and exposure of fuels. Scaling relationships for determining parameter values are given. Atmospheric transmission factors for completely overcast skies are given for different elevation angles of the fireball. In addition, a preliminary estimate is made of the conditions under which clouds will be burned out by thermal radiation. (Author)