- Author
-
Wiersma, S. J.
|
Martin, S. B.
- Title
- Evaluation of the Nuclear Fire Threat to Urban Areas. Annual Report. August 1972-September 1973.
- Coporate
- Stanford Research Institute, Menlo Park, CA
- Sponsor
- Defense Civil Preparedness Agency, Washington, DC
- Report
-
DCPA Work Unit 2561A; SRI Project PYU-8150,
September 1973,
138 p.
- Contract
- DAHC20-70-C-0219
- Keywords
-
nuclear warfare
|
urban fires
|
blast effects
|
overpressure
|
detonation
|
building fires
|
fire behavior
|
structural design
- Identifiers
- nuclear fire threat; dynamic behavior of fires; structural fire behavior; attack environment following a nuclear detonation; structural response to blast waves; fire spread in debris; simulating air blast effects; blast-fire interaction; influence of air blast
- Abstract
- The nuclear fire threat to urban areas was evaluated in a four-task program. During three previous years of experiments the dynamic behavior of fires in full-scale structures and the nature and magnitude of behavioral changes that result from variations in both structural and environmental factors were studied. This year an attempt was made to integrate the present structural fire bheavior knowledge with blast knowledge and to predict the combined blash-fire responses of an urban area to a nuclear attack. In Task 1 a problem definition and sensitivity analysis was conducted to identify the blash damage and fire situations that are important to study and then a description of an attack environment following a nuclear detonation was attempted. Further analysis of the structural response to blast waves and of the interaction between blast and fire is found necessary before a reliable description of the attack environment can be accomplished. In Task 2, three field tests of fire development in full-scale structures were made in response to questions raised in the problem definition. In the first field test fire was found not to spread to the interior of a building from a neighboring burning structure so rapidly as expected because induced air currents were drawn toward the initial fire. In the second and third field tests the environment in an improvised basement shelter beneath a burning building and the fire spread in debris were measured. In Task 3, a method of simulating air blast effects on structures was investigated. The scale model experiment showed promise for simulating room filling by a blast wave; however, simulating the collase of a structure by a blast wave using the vacuum-air bag technique is not feasible. In Task 4, a blast-fire interaction experiment was attempted to determine the influence of air blast and its effects on the incendiary responses of combustible target areas. At Mixed Company, a 500-ton TNT blast and shock experiment, test plots of burning liquid fuels contained by a series of pans of varying lengths were located at each of three stations at 5-, 2-, and 1-psi peak overpressures. It was anticipated that the flames on some of the smaller pans would be displaced sufficiently by the shoch wave to extinguish the flames, but that the larger pans at each staion would remain burning and thus the dependence of the size of threshold fires that are extinguished by air shocks on characteristics of shock and flow could be computed. However, no fire at any of the three stations was extinguished by the shock wave, a result that seemingly contradicts the conclusion of a previous experiment.