The influence of a fire-induced convection column on radiological fallout patterns

Abstract

Since no nuclear devices have been detonated by the United States under conditions leading to both mass fires and radiological fallout, a theoretical and small-scale experimental study was undertaken to see if fire-induced convection columns could significantly affect fallout patterns. Experiments were conducted in a 6- by 6-foot low-velocity wind tunnel using full-scale fallout simulants. Values of characteristic parameters of fallout patterns were compared for experiments conducted with and without fire, all other factors being held constant. As predicted by theory, a fire upwind of the region of deposition introduced a further downwind movement and lateral dispersion of the fallout. In a few experiments in which the fire was located at the edge of the no-fire pattern, air flow into the convection column shifted the pattern peak upwind . These results suggest quite strongly that effects which can markedly alter civil defense planning will be found for large-scale fires. Since this effect can be significantly influenced by the air flow into and around the column, open air experiments on a larger scale should be performed so that such flow will not be affected by tunnel walls and ceiling.

Citation

Broido, A.; McMasters. A.W. 1959. The influence of a fire-induced convection column on radiological fallout patterns. Technical Paper Number 32. Berkeley, CA: USDA Forest Service, California Forest and Range Experiment Station. 45 p.