_ 0.3549
v~ a
Where:
CL(h, 8) R/hr
(1.2)
C = curies per cubic meter
L{h, 6)
a polynormal, dependent on the altitude of the aircraft, h; and half angle, @
which Subtends the diameter at the surface contamination.
The gamma rays from the fission products are assumed to have an effective gamma energy of
0.5 Mev when 1 to 6 days old (Reference 5).
This reference states quantitatively that gamma
curies and beta curies are nearly equivalent in this period.
Estimates based on this assumption indicate that contamination with a beta activity of 4.43 x
10°(dis/min)/liter at the surface should produce a 1 mr/hr gamma flux at 3 feet from the surface,
when the diameter of the contamination is large enough to appear infinite (@ = 90 deg).
psinOa p
Figure 1.1 Coordinate system of gamma radiation from a water volume.
Fallout of 0.404 megacurie per naut mi* deposited in the sea, uniformly mixed to a depth of
60 meters (Reference 3 and Section 3.4.2), would produce a 1 mr/hr gammafield at 3 feet above
the surface.
The gamma dose rate at anyaltitude f,, related to the 3-foot value is expressed by the ratio
of the polynomials L(h, 90 deg). The altitude absorption 1/f, is plotted in Figure 1.2.
1.3.2 Fallout Contamination of a Land Surface.
or,
When fallout is deposited on land, the con-
taminated area appears as a large plane source. At any point in the radiation field, the gamma
intensity will include contribution from a circle whose radius is determined by the absorption of
the gamma photons in air. The dose rate (L)) above such a plane is given by the following equa-
tion (Appendix A, Equation A.15).
Ib = 3.4427 Cp J(h, 8) x R/hr
Where:
C = curies per square meter
HIVES
J(h, 6) = a polynomial similar in construction to that in Section 1.3.1.
DOE ARC
With the same assumptions as for the water case (Eo = 0.5 Mev and the ratio of beta and
gamma curies equal to 1), 2.1 x 10’(dis/min)/ft? of beta activity will result ina 1 mr/hr gamma
field at 3 feet fram the surface, when the Source Giameter is proportional to 6=90 deg. A
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