OPERATION CROSSROADS
Bikini Atoll (July 1946)
Events: Postscript -- The
Nuclear Age, 1945-present
Even after the Trinity test and
the bombings of Hiroshima and Nagasaki,
military officials still knew far less than they would have liked about the
effects, especially on naval targets, of nuclear weapons. Accordingly, the
Joint Chiefs of Staff requested and received presidential approval to conduct a
series of tests during summer 1946. Vice Admiral W. H. P. Blandy,
head of the test series task force, proposed calling the series Operation
"Crossroads." "It was apparent," he noted, "that
warfare, perhaps civilization itself, had been brought to a turning point by
this revolutionary weapon."
Experience with the radiological
hazards of Trinity and the two bombs dropped on Japan strongly
influenced the decision to locate Crossroads at Bikini Atoll in the Marshall
Islands of the central Pacific, far from major population centers. Bikini
was a typical coral atoll. With a reef
surrounding a lagoon of well over 200 square miles, Bikini offered ample
protected anchorage for both a target fleet and support ships. As a test
site, the atoll held two drawbacks: the distance from the continental United
States imposed extraordinary logistical demands, and the humid climate created
numerous problems for sophisticated electronic and photographic equipment.
The military removed the native population of 162 to another atoll and brought
in a large, invited audience of journalists, scientists, military officers,
congressmen, and foreign observers.
The first test, Shot "Able"
(right), a plutonium bomb dropped
from a B–29 on July 1, performed as well as the plutonium devices used at Trinity and
Nagasaki. Able nonetheless failed to fulfill
its pre-test publicity buildup. Partly this was because expectations had
been too extravagant and observers were so far from the test area that they
could not see the target array. Partly it was because the drop had missed
the anticipated ground zero by some distance and the blast sank only three
ships. In any event, the general conclusion reached by the media at Bikini
was that the "atomic bomb was, after all, just another weapon."
(Click here for a video clip of
the Able test.)
The second test, Shot "Baker," proved much more impressive.
Detonated ninety feet underwater on the morning of July 25, Baker produced a
spectacular display as it wreaked havoc on a seventy–four–vessel fleet of
empty ships and spewed thousands of tons of water into the air. As with
Able, the test yielded explosions equivalent to 21,000 tons of TNT. Baker,
as one historian notes, "helped restore respect for the power of the
bomb." (Click here for
a video clip of the Baker test.)
Baker also created a major radiation problem. The test
produced a radioactive mist that deposited active products on the target fleet
in amounts far greater than had been predicted. As the Joint Chiefs of
Staff evaluation board later noted, the contaminated ships "became
radioactive stoves, and would have burned all living things aboard them with
invisible and painless but deadly radiation." Decontamination
presented a significant radiation hazard, and, as a result, over a period of
several weeks personnel exposure levels began to climb. A worried Stafford
Warren (right), who headed the testing task force's radiological safety section,
concluded that the task force faced "great risks of harm to personnel
engaged in decontamination and survey work unless such work ceases within the
very near future." With exposure data in hand, Warren prevailed and
decontamination operations ceased. A planned third shot, to be detonated
on the bottom of the lagoon, was canceled. Able and Baker were the final weapon tests conducted by the Manhattan Project
and the last American tests until the Atomic Energy Commission's Sandstone
series began in spring 1948.
Click here to
view sources and notes for this page.