TABLE 4,1 - Scaling Exponent, m, for Several Soils
Soil
Most Probable
Nevada
Minimum
Maximum
344
Dry Clay
2.9
Wet Clay
2.5
Sandstone
3.6
Dry Sand
2.7
“Tn:‘Fig. 4.11 the results for surface charges in various soils are
shown. .Far each soil the line drawn is that for the most probable value
of m. On.this curve also are shown the nuclear craters at Nevada and
in the Marshalls. In plotting the results of the nuclear explosions
on this figure, the value of efficiency found for the JANGLE surface
shot for the scaling exponent m * 3.4, namely 6per cent, has been
assumed to be applicable to the explosions in the Pacific. The logarithmic grid has been adjusted in the region of 1 KT to include this
efficiency for all ‘larger yields. Hence the graph can be entered di-
rectly with the value of radiochemical yield.
This graph gives a real-
istic indication of the uncertainty in crater prediction depending on
the properties of the soil.
All data that have: been used in the development of the extrapola-
tion method presented here. are summarized in Appendix A. This appendix
also includes data for ‘some TNT. shots, namely those in wet sand, as
well as some nuclear charges,> such as Trinity, which were not used in
the actual analyses presented,héere.*
4.3
COMMENTS ON THE EXTRAPOLATToftHETHOD
Ma
It should be noted explicit ihat the extrapolation method de-
scribed here is based on an empir ead qquation of the form
R = f(W, m). (4g)
1
or
Bo
~
R = (WE)™ . £(,)
where E is an efficiency which depends on nédiun, scaled charge depth,
and type of explosive.
As mentioned in section 1.5; this is not the
only form of equation which can be postulated, and:defended. The available data are so meager, and their scatter aroundthe curve representing
any specific equation is so great, that it is not possible at present
to establish unequivocally the relative validity of alternative forms of
io
the empirical equation.
* The wet sand TNT results were not used because data on only ‘one charge
size was found and hence a value of slope could not be established.
A value for Trinity was not used because the scaled height is greater
than that of interest in this report.
56