6.5-Mt vicld to be approximately 4 x 10° r, whereas
(2) particle and drop-size rangcs of fallout and airborne materials at ground leve], (3) amount and
measurements for Shot 4 indicated that only 1.55 <
in! r were received. At approximately 4,500-yard
distribution of radioactive materials in fallout and
range. this handbook shows a prediction of about
airborne materials, and (4) gros3 gamma and beta-
$00 r; measurements showed that only about 84 r
gamma decay rates of radioactive materials (some
gamma field measurements were also made for cor-
were received.
\t would uppear that the {nitial-~gamma radiation
relation purposes).
ig of negligible significance, since the blast and thermai effects in the same range of distances are so
great that personnel could only survive tf they were
disposcd inside blast- and thermal-proof bunkers.
The distribution and intensity of fallout from all
shots was investigated. The residual gamma pattern
and some data on gamma decay and particle-size
distribution was established for Shot 1. The fallout
from Shot 1 was adr~-white particulate, irregular
in shape; many particles were flaky in nature.
Gamma levels of military significance were found to
exist at downwind distances to at least 280 nautical
miles. ‘The fallout from Shot 2 was more nearly
characteristic of an aerosol with no evidence of large
Project 2.3 “Neutron Flux Measurements”
(WT-914), Naval Research Laboratory; T
D. Hans-
coms, Project Officer.
This project was assigned the problem of meas-~
urtag tne neutron flux encountered in the detonation
of the nuclear devices at Castle, using the same
particulate.
Th. fragmentary data on the residual
gamma ficld show the level of activity 5 hours aftcr
techniques as used at Snapper and Upshot-Knothole.
detonation to be 145 r/hr at a downwind distance of
Gold, sulfur, and tantalum were used to measure
the flux in the thermal region and the regioa above
3 Mev. The fission detectors were used to measure
45 nautica] auics.
Project 2.5b ‘Fallout Studies” (WT~-916}, Chemi-
the 1-Mev region of the neutron spectrum and to give
an iaea of the shape of the spectrum above that point.
cal WarfareLaboratories, Army Chemical Center;
E. F. Wilscy, Project Officer.
Because of the short half tives of some of the in-~
cuced activities, it wag necessary to provide counting
facilities in the field: two trailers were installed on
(1) the characteristics of fallout from land-surface
and water-surface bursts, (2) the evaluation of the
hazards associated with the residual contamination
finec Igslacd for this purpose, and were equipped
from such bursts, (3) the evaluation of the contam-
nigm. The remaining samples were sent to the Naval
bursts, and (4) :nformation for the evaluation of mechanisms of particle formation and distribution. Inter-
The objectives of this project were to determine
to hancle the counting of gold,!
and pluto-
inating characteristics of fallout debris from such
Research Laboratcry for counting.
The plutonium. samples were included to provide
data in the region above 200 ev, the Oak Ridge National Laboratory supplicd these samples and the personnel to handle them.
Because of the unanticipated delays and shotschedule revisions after the firing of Shot 1, the participation of Project 2.3 was considerably modified.
Samples were exposed on the first two shots only,
and because of shifts in shot sitea and the modifica~
tion of the Shot 5 device, further participation was
curtailed.
The data acquired from Shots 1 and 2 indicated
that the neutron flux is relatively amal! outside the
mittent fallout collectors located at Bikini and Eniwetok Atolls were used to sample and collect the
fallout.
Most of the data, except the survey dala, were
obtained from Shot 1.
Shot 1 activities which were
sampled ranged up to 290 millicuries for areas of
0.6 in? at the downwind stations. The greatest amount
of radioactive fallout reached the downwindstation
east and southeast of ground zero atH + 5 to H + 15
minutes.
The main downwind stations received a
second wave from H + 25 to H + 60 minutes, and one
station sampled a third and smaller wave [rom H + 4
to H +5 hours. Fallout continued to occur in very
small quantities up to H + 12 hours.
radius of extreme damage caused by blast and ther-
The average Shot 1 decay slopes were ~1.69 for
mal radiation.
Project 2.5a “Distribution and Intensity of Fallout”
(WT-915), U. S. Naval Radiological Defense Labora-
tory; RL. Steton, Project Officer.
The gathering of fallout data at Castle was a logical
extension of previous fallout documentation. The
variation in yields as well as the opportunity to docu-
the period from H + 210 to H + 450 hours, and ~1 37
from H + 400 to H + 1,700 hours.
The Shot 1 fallout consisted primarily of particles
that appeared to be coral and salt. Most of the activity associated with the larger particles was located
near the particle surfaces, while for smaller particles
the activity appeared to be distributed regularly or
irregularly throughout the particle.
ment surface water detonations for the first time
made this study of fallout extremely important.
The specific objectives were to sample and analyze
fallout material to determine: (1) time and rate of
arrival of the fallout and its final distribution patterns,
109
Project 2.6a “Chemical, Physical, and Radio-
chemical Characteristics of the Contaminant”
(WT-917), U. S. Naval Radiological Defense Labora-