viously used on Operations Tumbler and Jangle:
Wianko balanced variable reluctance transducer type,
connected to oscillograph recorders. All instrumentation functioned; good records were obtained, although the magnitude of the data was much less than
predicted because of the low yield of Shot 3.
The average values of the recorded free field data
were: peak pressure at structure, 3.53 pai; dynamic
pressure, 0.38 psi; and positive-phase duration, 1.52
seconds.
Although the data obtained proved of considerable
value as a check on the loading theory and the conclusions of related Upshot-Knothole Project 3.1, the
immediate objective of the project was not met because the yield of Shot 3 was only 130 kt instead of
the expected value of approximately 1 Mt. Nevertheless, the blast-loading data obtained was evaluated in
the project reports, and loading-prediction methods
derived from Upshot-Knothole Project 3.1—both the
AFSWP-226 and ARF prediction procedures——can be
considered to have been generally checked by this
noted that depth-of~penetration measurements were
highly dependent upon the reliability of estimates of
fallout below the ocean surface: the rate of descent of
the fallout into the mixed layer must be slow enough
to allow accessibility for measurement at the time of
the survey. It appeared that for both Shots 5 and 6
this requirement was met, since (1) other fallout observations indicated a very-small particle size which
could be expected to settle slowly and (2) from the
depth-cast data of Shot 5, the descent of the radioactive material into the water mass comprising the
mixed layer was of such a rate and uniformity as to
make depth-of-penetration calculations feasible.
Project 2.7a “Radioactivity of Open-Sea Plankton
Samples” (WT~954), Scripps Institution of Oceanography; T. R. Folsom, Project Officer.
This was not a formal Castle project, but represents work done incidental to Project 2.7 but of sufficient interest to warrant publication in the Castle
WTseries.
The objective of this study was to ascertain the
experiment.
general relationship pertinent to the uptake of fission
Project 3.2 “Crater Survey’ (WT-920), Stanford
products by marine organisms, in order to form a
background for more-extensive tests that were to be
conducted on Operation Wigwam. Samples of zooplankton were collected, and gross beta activities,
ResearchInstitute (Assisted by Army Map Service);
R. B. Vaile, Jr., Project Officer.
The objective was to obtain dimensional] data on
craters formed by nuclear detonations for use in developing a generalized theoretical-empirical means
beta-absorption curves, und gamma spectra were
analyzed after identification of the orgumisms. A
radiochemical analysis was performed by the U. S.
Naval Radiological Defense Laboratory. It was found
that (1) the feeding mechanism of the organism determined the amotat of activity assimilated, (2) solid
of predicting crater dimensions.
In the preliminary planning for this project, consideration was given to determining the dimensions
of the true crater as well as those of the apparent
crater. No feasible method of obtaining dependable
data on the true crater—-other than employing drilling or coring operations—-was developed. The cost
and operational problems involved outweighed the
probable value of any data so obtained. Therefore,
measurements were limited to those of the apparent
phases in the water were concentrated in preference
to the non-particulate phases, and (3) there was evidence of fractionation of isotopes by different groups
of organisms.
PROGRAM 3: EFFECTS ON STRUCTURES
crater.
Project 3.1 “Air Pressure Measurements”
(WT-919), Stanford Research Institute; L. M. Swift,
Project Officer.
The objective was to obtain the air-blast loading
pattern (as a function of time, in the 10-to-15-pai
overpressure region) imposed upon a rigid, rectangular parallelepiped by a megaton-range detonaticn.
This data was desired as an extension of that obtained
by Upshot-Knothole Project 3.1 on target structures
of the same type and to develop techniques of prediction that could be applied to the calculations of structure loading, response, and consequent damage from
air blast from large-~yield nuclear devices.
The test structure was a 6-by--by-12-foot rigid
concrete cubicle, with the 12-foot dimension normal
to the path of the shock wave, located 9,500 feet from
ground zero.
A total of 46 gages were installed on the target
structure; 12 pairs (24, total) were duplicates to
ensure usable results. The gages were the type pre-
111
The craters formed by Shots 1, 3, and 4 were
measured. No measurements were made for other
shots because they were detonated at the sites of
prior shot events.
The measurement techniques emp'oyed werc fathometer traverses, lead-line soundings, and photo
interpretation:
A Navy NK-6 fathometer operating at 14.25 kc/sec
was mounted in an LCU which traversed the craters,
with horizontal control for these hydrograph surveys
monitored by a combination of Raydist electronicpositioning equipment loaned by Navy Bureau of Aer-~
onautics, Sextants, Alidades combined with gyrocompass, and anchored taut-wire equipment.
Aerial-photography missions were flown to obtain
pictures suitable for employment of stereoscopic
photogrammetry techniques by the Army Map Service
to provide detail of any above-water crater phenom-
ena.
The body of knowledge regarding craters was ma-