explosive energy from the fusion, or joining, of hydrogen atoms. These explosive devices were
developed by the AEC, the civilian agency authorized to perform this activity by the Atomic
Energy Act of 1946.
The devices were tested at the PPG by a joint military and civilian organization
designated as Joint Task Force 7 (JTF 7).
This was a military organization in form, but was
populated by military, civil service and contractor personnel of the Department of Defense
(DOD) and AEC. The commander of this force was the appointed representative of the AEC and
reported also to the Joint Chiefs of Staff (JCS) and the Commander in Chief, Pacific
(CINCPAC).
The peak DOD numerical strength of CASTLE was approximately as follows:
Uniformed military
DOD civil service
DOD contractors
Total personnel
9,800
250
60
10, 110
Numerous technical experiments were carried out in conjunction with each of the six
detonations.
These experiments measured the power and efficiency of the devices and attempted
to gauge the military effects of the explosions.
DOD personnel participated in this test
operation as individuals whose duty stations were at the AEC design laboratories, as units
performing separate experiments, and as units performing various support roles.
The CASTLE
operations placed almost all of the Navy support group at Bikini, where its ships provided
living space for personnel who were evacuated from the islands for the first test and then
could not return to live there because of the potential radiation exposure.
An extensive radiological safety program was instituted wnose objectives were:
1.
Maintenance
of
personnel
radiation
exposure
at
the
lowest
possible
level
consistent with medical knowledge of radiation effects and the importance of the
test series.
2.
Avoidance
shipping.
of
inadvertant
contamination
of
populated
islands
or
transient
The program established an organization to provide radiological safety (radsafe) expertise and
services to the separate components of the task force who were responsible for personnel
safety within their commands.
Personnel were trained in radiological safety and standards
governing maximum permissible exposures (MPE) were established. Film badges were provided to
a large portion of the participating personnel.
Persons likely to be exposed to radiation
were badged as well as a representative group of the remainder.
An extensive weather
forecasting group was established
fallout.
in order to predict wind directions and areas of potential
Personnel were evacuated from danger areas before each detonation,
and reentry to
contaminated areas was restricted to the personnel required to retrieve important data.
amount of radiation exposure for these personnel was monitored.
The
TEST ‘OPERATIONS AND EXPOSURES
The first event of this series, designated BRAVO, had a yield of 15 MT and was the largest
device ever detonated in atmospheric nuclear testing by the U.S. Government.
Significantly
exceeding its expected yield, BRAVO, detonated at Bikini Atoll, released large quantities of
radioactive materials into the atmosphere, which were caught up in winds that spread the
particles over a much larger area than anticipated.
This resulted in the contamination and
exposure of some individuals either stationed or residing on distant atolls or aboard various
vessels.
Acute radiation effects were observed among some of these people.
A limited number of JTF 7 personnel] received radiation exposures considerably in excess of
the initially established CASTLE MPE. This operational limit was established at 3.9 roentgens
(R) gamma within.any 13-week period of the operation.
In particular, three members of the
U.S. Navy Bikini Boat Pool had heavily exposed badges with readings from 85 to $6 R, and 28
Army and Air Force personne] had film badge exposures that read as high as 78 R.
All these
men were medically evaluated at Kwajalein.
Subsequently, follow-up on 29 of them was
done
at