field phase u1 the operation to include shot Quince, and this participation is
covered in the portion of this report relating to that detonation. To make
the necessary measurements, threshold activation and fission detectors were
exposed at various distances from the Yellowwood and Walnut. zero
points.
These detectors included
ince land masses of sufficient size were
not available for displaying tNe detectors at desired distances, a buoy line
was used. The line extended from 917 to 4100 yd from Ground Zero for
both shots. Due to the radiological situation that existed after these detonatlons, recovery could not be effected until D+1 day. As a result, only limited
neutron flux and dose data were obtained.
Early results indicate that the
neutron dose for shot Yellowwood was lower than predicted by a factor of
2.3 and the Walnut dose was low by a factor of 2.0.
Fallout Sampling. The objectives were to determine the relative contribution of certain isotopes to both local and world-wide fallout and to use
this information, if possible, to determine the fraction of total bomb debris
deposited in the local area. The project was divided {nto two separate efforts: (1) the collection of early cloud samples by means of newly developed
rocket samplers, and (2) the collection of residual cloud samples and fallout
debris by aircraft.
The rocket sampling was to have been accomplished with rockets de-
veloped by UCRL Project 21.3. Gas and particulate sampling of the residual
cloud was accomplished by B-57D aircraft under the technical supervision of
LASL personnel. Fallout samples were collected at various times after the
detonation, based on predictions furnished by the Fallout Prediction Unit.
These collections were made at an altitude of 1000 ft by WB-50 aircraft.
The fallout collection was supervised by personnel of the U.S. Naval Radio-
logical Defense Laboratory.
The project participated during shots Koa, Walnut, and Oak, as it was
desired to obtain a comparison between the fallout from land surface and
water surface detonations in the megaton range. Because of various technical
problems, satisfactory rocket samples were not collected from shots Koa and
Walnut, and this portion of the project was canceled prior to Oak. Successful
B-57D and WB-50 samplings of the Koa fallout were made; however, early
analysis of the samples indicated they had been contaminated by debris from
shot Fir, fired the previous day at Bikini.
For this reason, project partici-
pation was extended to include Oak. Successful sampling was accomplished
during Walnut and Oak. Collected samples were returned to the continental
laboratories for analysis, and the resultant data were not available at the
time this report was written.
Program 3, Structures and Equipment
The objective of this program was to provide information on the effects
“of nuclear bursts on ship structures and equipment, and on various land
structures, under certain conditions that had not been heretofore investigated.
Five of the eight projects were concerned with the response of ship structures
and equipment to underwater bursts, and three were concerned with the re-~
sponse of land structures to air blast.
Prior to Operation Hardtack a series of tests was run employing HE
charges against the destroyer DD-592 off Santa Cruz Island, Calif., in Jan~uary 1958. A series of four large, specially shaped (tapered) HE charges
29
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