0021620 Ed and W. For W in KT (kilotons equivalent TNT) and ap in fissions, the value, 1.45 x 1023 fissions/KT, will be used for K. Eqs. 3, 4, 5, and 7 gives, for FDE(t) © me) - Combination of __t (8) 1.45 x 10°w (a(t) + iop(t) * in which FD°(t) is the idealized plane value of the fraction of device contour ratio. It may be noted that Eq. 8 has the units (r/br sq ft)72; this function has been given previously in a report? which discussed the CASTLE Shot Bravo fallout pattern and fallout pattermt summations in general. The expected specific activity, from auniform mixing of all the radionuclides produced, ap, with all the mass of soil removed from the crater, M,, is ap/M,. On an ideal plane, each fission/sq ft would give rise to G (t) r/hr, hence the mass contour ratio would be given by M(t) ———2— (9) ay & (t) ° The variation of M, with yield for surface detonation on clay-type soils may be estimated from M, = 1.79 x 1013 yo? (10) for My in mg and W in xn.® Substituting for M,, ap, and G, (t) in Eq. 9 gives, for the idealized plane value of M(t), M(t) = 1.23 x 10720 y-0-038 d [ig(t) + a(t] (11) por/NY For fallout in which the radionuclides are fused within or nixed uniformly throughout all the particles and in which the fractionation is also uniform, the mass contour ratio is a grand average function. However, if the specific activity of the fallout and the fractionation of the radionuclides changes from point-to-point, M,(+) becomes a point function. ° If