CHAPTER 17
can be expressed in terms of yield and burst depth:
max
_ 1500 y2/3
{e + 33/3
(The number 33 represents atmospheric preare at the surface in ft of
water; thus, d + 33 represents hydrostatic pressure. )
Values of scaled base-surge radius and scaled time for the four
underwater test ahots, based on visual extent of the surge, are given
in Table 17-3, reproduced from Ref. 47 , which contains a discussion
of the principles of scaling used. The following expressions for
ecaled radius were developed by graphical methods of fitting to the
values of Table 17-3, and the application of correction factors to
bring calculated dose rates into agreement with observed ones.
Very Shallow and Shellow: Rye -[5-8 10819 (tye + 0-73) + 0-802)°.
Deep: Re. =
16.7 logyo tee * 4,54
Cy,
Very Deep: Rg, = [7-32 logig (tye - 1) + 1.83] c.
7-4)
The term C, which has the value 0.8 is the correction factor applied
to bring calculated dose rates into agreement with cbserved ones. The
value indicates that the "radiological” redius of the surge is less than
the visual photographic radius.
E.
Radiological Aspects of the Model
1.
General Characteristics
The radiological characteristics specified for the model include source strength, activity distribution, and air-atteriation
behavior. In the model, the source is homogeneous. Source strength
is proportional to yield, Y. Energy emission rate is that of un-
fractionated fisaion products. An "effective attenuation factor"
it, for air attenuation is used in dose-rate computation. Dose-rate
ee om
we
computations for a given point are made at 15-sec intervals, starting
at 30 sec after burst. Dose is camputed from these dose rates in
15-sec increments. The model predicts excessively high dose rates at
times earlier than 30 sec because only air attemuation is considered.
At these early times, attemuation by water thrown up by the explosion,
or inhomogeneities in the distribution of radioactivity, which have
been ignored, probably accounts for much of the difference. These early
dose rates probably make a significant contribution to the total dose
only in the region near surface zero where other weapon effects,
especially underwater shock, are of dominating importance.
C
Cort
E
L
B
A
L
I
A
V
A
BEST
17-47
wee mene oe eee er eee ee