ooane0
chim
ret) =
Kk, Ge (t) x
(15)
bh
Equation 15 suggests that, for the stated assumptions,
vary inversely with distance.
-
wv
M(t) shoulda
For small particles where the falling
velocity is preportional to the square of the diemeter, the masé con-
tour ratio for those particles is given by
7
,
vee) = 2el ye
|
kx
k G
in which k,
is a constant.
(6)
3
For these assumed conditions, Me(t) decreases
with the square root of the distance.
For the second case, the average specific activity is given by
(a,/m,) = k,
in which k), is‘a constant.
(17)
For this case where the specific activity is
independent of the particle diameter, M2(t)is independent of the dis-
tance and is given by
W(t) = —
kK, G,
(18)
Although Eq. 18 does not contain a distance term and in that sense is
not a point function, the region of its applicability is, of course,
restricted to the area within which the particles with a constant speci-
fic activity fall.
DOE /NW
In addition to the distance, x, Eqs. 15 and 16 suggest that the
value of
M°(t) depends on the wind velocity and the height from which
the particles fall. The latter depends on weapon yield. If the bottom
of the clouds is used as a reference point with respect to the measure
~
-
.