350 KNOX resulting base surge has approximately the same radius as the base surge from a large single shot of the same total yield and emplaced at the same scaled depth. The base-surge height for a five-charge row shot is reaSonably well approximated by scaling the height of the base surge for a Single-charge event by the 0.2 power of the total yield of the row-charge shot. A first approximation to the geometries of the individual main cloud may be obtained by treating each main cloud independently and estimating the top and the radius of each cloud from the work of Day.® Examination of the high-explosive row-charge documentary photographs of the Rowboat, the Dugout, and the Pre-Buggy shots indicates that such an approximation is reasonable, This approximation can, of course, be in error if main-cloud interactions occur. There is a need to evaluate the uncertainty in fallout prediction for multiple-charge shots in cases where cloud interactions lead to the injection of radioactivity at levels higher in the atmosphere than predicted. Concerning the F, for row-charge shots, preliminary experimental results for high-explosive single- and row-charge shots have been reported previously," In this study, results of the measured vented frac- tion of °La tracer from single- and row-charge high-explosive shots were given. The experimental evidence suggests that the vented fraction from row-charge shots may be about twice that from single- charge shots. One of the most pressing needs for fallout prediction from row-charge shots is the establishment, through either experiment or theory, of the dependencyof the F, on yield, depth of burial, or charge spacing, The development of computer aids for the row-charge fallout- prediction problem, however, can proceed independently of the solution of the two previously cited problems: (1) the specification of initial cloud geometry and (2) the specification of F,. Therefore the capability of plotting fallout patterns for multicloud and/or multidetonation events has been developed. Figures 11 and 12 show, respectively, the (H + 1)hr dose-rate patterns computed for 10 Danny Boy detonations on an east to west line with charge centers separated by 33.5 m and for 10 Danny Boy detonations on a north to south line with charge centers separated by 33.5 m. For the purpose of these calculations, each deto- nation is assumed to vent 5% (e.g., F, = 0.05), each cloud is assumed to be the same as that for Danny Boy, and the input wind for each cloud fallout problem is assumed to be the same as the shot-time wind for Danny Boy. These two row-charge fallout patterns, although detectably different as determined from the printout, appear to be very similar. Calculational results suggest that the fallout pattern from a smallscale row-charge shot is not sensitive to the orientation of the wind to the alignment of the charges.