and amplitudes was uncertain. The air-induced signal propagated with a velocity of the air-blast wave,
radiation cxposure is of little significance at distance;
beyond 16,900 fect for surface bursty of yieias up to
15 Mt, .4) the decay vate is affected by the capture
decreasing with increasing ground range, while the
ground~transmitted shock propagated with a velocity
of about 8,700 ft/sec. The determination of velocities
products of the thermonuclear devices fired, and (3,
the .nitial-gamma- radiation spectr.m for Shot 3 ap-
and displacements by means of integration of the acceleration traces was not aftempted—the precision
of the data was too poor to support such an analysis.
pears harder thanthat obtained from fission devices.
Project 1.8 “Dynamic Pressure Investigation”
(WT-911), Ballistic Research Laboratories; E. J.
Bryant, Project Officer
The objective was to evaluate dynamic pressure as
a damage parameter. in addition, some information
seegarding the damage effect of long positive-phase
duration was to be obtained. A total of 27 jeeps were
exposed on Shots 3 and 6, the ground ranges were
Signal Corps Engineering Laborutorics: Peter Brown,
Project 22 “Gamma Rate versus Time” (WT-913),
Pro;ect Officer.
The objective was to document the gamm -radiation
rate from the detonation of high-v'eld thermun:.clear
devices. Two types of measurements were .nade:
(1) initial-gamma rate versus timne at various fixed
distance; from ground zero and, .n particular, the
effect on the initial-gamma rate due to the passage
of the shock from ground zero through the detector
selected to obtain dynamic pressures comparable in
magnitude to those acting upon the jeeps experiencing
light to severe damcge on Shot 10, Upshot~Knothole.
station, and (2) gamma-radiation time-intensity datz,
which gives information on fallout rate of arrival anJ
gamma-field radiation-decay rate during the period
up to 36 hours after the detonation
Ali measurements were made using scintillation
detector techniques. The instrument stations were
self-contained and required no outside facilities other
The yield of Shot 3 was too low to give any significant results. The limited results of Shot 6 were not
conclusive enough to permit an evaluation of dynamic
pressure as a damage parameter to be applied to the
jeep as a drag-sensitive target. Further, the results
did not allow a separation of the effect of dynamic
than timing signals to turn the stations on at a pre-
pressure on damage from the effect of the long
positive-phase duration.
Based on a comparison of
Castle and Upahot-Knothole data, Project 1.: proposed
cube-root scaling for vehicle damage.
determined time prior to the detonation.
The expanding fireball an the passage of the shock
However, a
composite AFSWP report, TAR 514 “Damage to MIltary Field Equipment from Nuclear Bursts” was subsequently prepared which included the Castle, UpshotKnothole, and all other nuclear-test data. This
front from ground zero thraugh the detector station
had a marked effect on the initial-gamma rale and
hence on the integrated expesure.
In general, the
initfal-gamuna rate decreased relatively slowly after
report concluded that wé scaling was the most ap-
reaching its peak value immediateiy after the detonation, began to rise siow!y, and then rose rapidly to
the same value as the peak received at time of dein-
propriate method for predicting damage to military
field equipment.
rate decreased rapidly toward zero value.
nation.
After reaching the second peak value, the
The initial decrease in rate was attributed to the
natural decay of the fission products, the slow rise
PROGRAM 2: NUCLEAR RADIATION
STUDIES
Project 2.1 “Gamma Radiation Dosimetry”
(WT-912), Signal Corps Engineering Laboratory;
Robert Dempsey, Major, USA, Project Officer.
The objectives were to documentthe in‘tial and
residual gamma radiation exposure from high-yield
bursts in order to asaist in the evaluation of the resultant gamma radiation hazards, provide data for
the correlation of results for other projects, and extend the use of gamma-radtation dosimetry techniques
to higher gamma-exposure ranges.
Radiation exposure from a series of nuclear detonations was measured by photographic films and
chemical-dosimetry vials of various sensitivity
ranges. The film and chemical detectors were placed
in protective detector stations at positions from 1 to
15 miles from ground zero for Shots 1, 2, 3, 4, and
6. Calibrated exposure range of dosimeters used extended from 1 to 60,000 r.
In general, it was concluded that (1) initial-gamma-
108
to the expanding of the freball and approach of the
shock front, and the rapid rise to the passage of the
shock front through the detector station. These effects were also evidenced in the integrated exposure
prior and subsequent to the arrivai of the shock front.
The average velocity of the shock front was found
to vary with distance from ground zero, decreasing |
rapidly with distance.
The decay exponent from the residual contamination and fallout was found to vary with distance and
direction from ground zero. In general, the decay
exponent appeared to increase rather abruptly several
hours after the detonation. This can be attributed to
the presence of shurt-lived {sotcpes in the residua!
contamination and fallout.
In general, it was indicated that the magnitude of
gamma radiation emitted from high-yield thermonuclear devices is considerably lower than the predictions in the Super Effects Handbook (Reference 11).
At approximately 2,390-yard range, this handbook
indicates the exposure from initi.’ gamma from a