Chopter |
INTROOUCTION
1.1 OBJECTIVES
The primary objective of this project was to measure nuclear radiation from a very-lowyield detonation, specifically: (1) initial gamma dose rate, (2) total initial gamma dose, (3) total
neutron dose in low-dose regions, and (4) rate of induced-activity decay of Nevada Test Site
soil.
A secondary objective of this project was to field-test a prototype of the standard Air Force
fallout detector (designated MG-3).
1.2 BACKGROUND AND THEORY
In this report the initial nuclear radiation associated with a nuclear detonation is considered
to include the gammaand neutron radiation emitted during the first 20 seconds after an air
burst.
During the delivery of an air-to-air nuclear warhead, the air-crew dose is received essentially in two increments. The first increment, i.e., neutron dose, gammaradiation associated
with the fission process, and gammadose arising from the capture of neutrons by the nitrogen
in the air, is received within a fraction of a second after the detonation. This dose is solely a
‘function of the distance of the aircraft from the point of detonation and must be accepted for an
air-to-air delivery of any specific rocket.
The second, and final, portion of the dose is received
during the escape maneuver(the flight path of the aircraft subsequent to the delivery) and arises
from the fission-product gamma rays. Fora stationary observer the fission-product portion of
the total gamma dose is less than 20 percent of the total (depending on the range), but this fraction is increased considerably in the case of an aircraft moving toward a detonation after it has
taken place.
Consequently,. the escape maneuver is a critical parameter in the employmentof
air-to-air nuclear warheads.
With the increased speeds of modern supersonic interceptor air-
craft, optimum escape maneuver programming to minimize the air-crew radiation dose is es-
sential.
1.2.1 Initial-Gamma Dose Rate versus Time. Gamma rate versus time has been measured’
during Operations Buster-Jangle (Reference 1), Jangle (Reference 2), Redwing (Reference 3),
and Plumbbob (Reference 4). The data obtained during Operation Buster-Jangle are not directly
applicable to air bursts, as the measurements were made on a surface and for an underground
shot. The delivery rate of the initial gamma radiation and the total gamma doSe from anair
burst are significantly different when compared with surface or underground bursts. Operation
Redwing measurements were concerned primarily with megaton-range devices.
The data obtained from Operations Buster-Jangle and Plumbbob form the basis of existing
methods of predicting gamma doses received by aircrews during the escape maneuver subsequent
to the delivery of the air-to-air, nuclear-warhead, MB-1 rocket (References 5 and 6).
With the advent of fractional-kiloton nuclear warheads suitable for fighter delivery, the validity
of using existing dose-prediction techniques based on kiloton-range measurements must be sub-