Description

The effects of fire on shelter occupants, caused either by the explosion of a nuclear weapon or by subsequent events, has been of concern to the Defense Civil Preparedness Agency (DCPA) for many years. Both the designer attempting to provide greater protection from weapon effects in new construction and the planner trying to provide guidance for local civil defense operations suffer from the lack of an adequate description of the threat from fire. In order to plan the use of existing shelters with certainty and to optimally design new ones, one must fully understand the threat from fire.

The inability to completely define fire environments is not unique to a shelter situation. In general the state-of-the-art of fire research has many areas of uncertainty. Because of these uncertainties, many of the questions that arise depend on large-scale experimentation for practical answers. These include (1) better characterization of fire environments, particularly debris fires, and the significance of these to shelter heating; (2) the location and size of shelter vent systems; (3) the evaluation of simple countermeasures and fire control methods; (4) the behavior of shelterees during the period of fire threat; and (5) the effects of superimposed blast damage to the shelter envelope.

The studies reported herein center around large-scale fire experiments conducted in a reusable two-story fire test facility which provides a 60-man (600 ft²) basement shelter, fully instrumented for assessment of the flow of heat and fire gases. By providing for full-scale experiments under laboratory conditions, the facility is adaptable to a systematic study of the effects of variable parameters, as well as to spot check applicability of designs based on theoretical or small-scale laboratory studies.

This program was developed to provide more information so that slanting of new construction (i.e., incorporation of modifications during the design stage) would provide shelters with enhanced resistance to the combined effects of nuclear weapons: blast, fire, and fallout. There is little question that below-grade shelters of concrete construction, designed to withstand 10 psi or more overpressure, can also maintain structural integrity under all imaginable fire exposures. For life safety, the shelter~envelope must protect occupants from the penetration of significant heat and fire gases into the shelter space from external fires. Obviously, fires originating in the shelter must be quickly detected and extinguished. The fire environments of concern to this study are both those determined by fire load and the level of blast damage and those modified by various conceptual countermeasure activities. Obviously, the results of the studies are applicable, for the most part, to NFSS shelters too, although some interpretation may be required.

Product Details

Published:

1975

Number of Pages:

9

File Size:

1 file , 620 KB

Product Code(s):

D-AC-75-02-2

Note:

This product is unavailable in Russia, Belarus