ACR AG |
5 April 1984
Fact
daa
Defense Nuclear Agency
S h eet
Public Affairs Office
4.
Washington, D.C. 20305
Operation CROSSROADS
Operation CROSSROADS was an atmospheric nuclear weapon test series conducted in
summer of 1946. The series consisted of two detonations, each with a yield of 23 KT:
o
ABLE -- detonated at an altitude of 520 feet (158 meters) on 1 July
o
BAKER -- detonated 90 feet (27 meters) underwater on 25 July.
the
It was the first nuclear test held in the Marshal Islands.
The
material.
series
was
to
stuay
the
effects
of
nuclear
weapons
on
ships,
equipment,
and
A fleet of more than SO vessels was assembled in Bikini Lagoon as a target.
This target fleet consisted of older U.S. capital ships, three captured German and Japanese
ships, surplus U.S. cruisers, destroyers and submarines, and a large number of auxiliary
and amphibious vessels.
Military equipment was arrayea on some of the ships as well as
amphibious craft that were beached on Bikini Island.
ducted to study nuclear weapon explosion phenomena.
live animals.
Technical experiments were also conSome experiments included the use of
The support fleet of more than 150 ships provided quarters, experimental stations, and
workshops for most of the 42,000 men (more than 37,000 of whom were Navy personnel) of Joint
Task Force 1 (JTF 1), the organization that conducted the tests. Additional personnel were
located on nearby atolls such as Enewetak and Kwajalein.
The islands of the Bikini Atoll
were used primarily as recreation and instrumentation sites.
Before the first test, all
Atoll.
These men were
personnel were evacuated from the target fleet and Bikini
placed on
units of the
support
fleet,
which sortied
Lagoon and took safe positions at least 10 nmi (18.5 km) east of the atoll.
from Bikini
In the ABLE test, the weapon was dropped from a B-29 and burst over the target fleet.
In BAKER, the weapon was suspended beneath an auxiliary craft anchored in the midst of the
target fleet.
ABLE operations went smoothly except that the test weapon was dropped between 1,500 and
2,000 feet (457 and 610 meters) off target.
only a transient effect,
The radioactivity created by the burst had
and within a day nearly all
the surviving target ships had been
safely reboarded. The ship inspections, instrument recoveries, and remooring necessary for
the BAKER test proceeded on schedule. Five ships were sunk as a result of the test.
The crews of the target ships that had been remanned following ABLE were evacuated prior
to BAKER to the support fleet east of the atoll. BAKER sank eight ships and damaged more
ships than ABLE. The detonation caused most of the target fleet to be bathed in radioactive
water spray and radioactive debris from the lagcon bottom. With the exception of 12 target
vessels anchored in the array and the landing craft beached on Bikini Island, the target
fleet remained too
on-board activities.
radiclogically
contaminated
for
several
weeks
for
more
than
brief
The inability to complete inspections on much of the target fleet threatened the success
of the operation after BAKER.
A program of target vessel decontamination was begun in
earnest about 1 August.
This involved washing the ships’ exteriors using work crews drawn