Operation Redwing: Yuma
The United States’ Operation Redwing was a series of 17 nuclear weapons tests in 1956
named after Native American tribes.
It was designed to assess second-generation thermonuclear weapons or H-bombs.
But when it was dropped on the Pacific, the nuclear blast that the tiny device produced
was not what the military initially intended...
The fourth tryout during Operation Redwing was carried out with the smallest and lightest
nuclear warhead on the project.
The weapon was named Yuma after the Indian Reservation in the Southwestern United States.
With a 5-inch diameter and weighing only 96 pounds, Yuma was intended to fit inside an
air-to-air defense missile.
It was also among the first tests of the boosted fusion technology used to miniaturize and
increase the yields of bombs.
In contrast, a smaller, initial fusion blast triggers an immense fission reaction that
brings the devastation associated with standard nuclear weapons.
On May 27, 1956, Yuma was dropped on the Pacific Island of Aomon.
Instead of igniting a full plutonium-fueled explosion, the initial blast failed to detonate
the second reaction.
The tiny nuclear blast, known as a fizzle, was only 190 tons, or about 1.2% of the force
of the bomb dropped on Hiroshima.
The detonation was captured on camera and has been equated with the power to destroy
just a couple of city blocks.
One year after the failed Yuma explosion, the military finally succeeded in developing
its first air-to-air nuke.
The AIR-2 Genie would remain in service until 1985, with over 3,000 manufactured models.
Castle Bravo
Castle Bravo was the first of several tests of a brand-new series of high-yield thermonuclear
weapons conducted by the US military in the Marshall Islands under Operation Castle.
The detonation was the first atmospheric test of a nuke fueled by lithium-deuteride.
It was expected to yield a 6 megaton blast, but nuclear engineers were astonished by its
ultimate power.
On March 1, 1954, the Castle Bravo detonation produced a 15 megaton yield.
In terms of energy released, it was about 1,000 times more potent than the Hiroshima
and Nagasaki bombs.
The incident became the most powerful nuclear explosion that the United States has ever
detonated.
The miscalculation occurred because engineers only considered the lithium-6 isotope to be
reactive.
This isotope accounted for 40% of the lithium content.
The remaining 60% was lithium-7 isotope, which produced a larger neutron flux than expected
and contributed to the detonation’s increased yield.
The explosion sent a giant mushroom cloud nearly 22 miles into the air, leaving an enormous
250-foot-deep crater.
The radioactive fallout from the blast covered over 7,000 square miles, including the inhabited
Rongelap and Utirik atolls.
It also spread over the seas, damaging countless maritime flora and fauna.
Evacuation efforts organized by the United States and the United Nations proved too slow
to prevent lethal radiation exposure.
In the Rongelap atoll, white powder resembling snow fell from the skies while young children
played with it.
An hour and a half after the detonation, the radiation remnants reached the Japanese fishing
vessel Lucky Dragon No. 5, which was 80 miles east of the test site in the middle of the
ocean.
23 crewmembers suffered acute radiation syndrome, and the Japanese government expressed their
outrage not long after.
The gaseous fallout continued to spread beyond the Atolls and around the world.
Some radioactive material traces were discovered in India, Australia, Europe, Japan, and the
United States.
The blast incited international outrage over the morality of atmospheric thermonuclear
testing.
The fallout from Castle Bravo has also been linked to a bout of several types of cancer
such as leukemia and thyroid cancer in the Atolls residents.
Despite the indignation, Castle Bravo's tragic miscalculation did not stop thermonuclear
testing.
Operation Castle continued with a series of nuclear tests on the Marshall Islands.
During 12 years, between 1946 and 1958, the United States conducted 67 nuclear weapons
experiments in the Pacific Ocean.
Bluegill Prime
In 1962, the United States carried out Operation Fishbowl, a series of high-altitude nuclear
tests from Johnson Island in the Pacific Ocean.
The test failed spectacularly when the Thor ballistic missile carrying the bomb suffered
a stuck valve, causing it to lose thrust and spill fuel into the searing thrust chamber,
where it ignited and engulfed the rocket in flames.
Military officers immediately sent a command to destroy it, but their efforts quickly backfired...
According to the initial Operation Fishbowl plan, the high-altitude nuclear tests were
to be named Bluegill, Starfish, and Urraca.
If one of the tests failed, the next attempt would take over its name while adding the
word “prime.”
When Bluegill went off trajectory on June 2, 1962, a second attempt was planned for
the following month.
Bluegill Prime was launched on July 25 but failed again when its Thor launch vehicle
suffered a stuck valve and blocked the flow of rocket propellant through the combustion
chamber.
The engine then lost thrust, and unburned RP-1 fuel spilled onto the hot thrust chamber,
igniting it and starting a massive fire at the missile base.
With the Thor launch vehicle now engulfed in flames, the Range Safety Officer sent a
specialized team to destroy it.
The commanders split the rocket in two and ruptured both of its fuel tanks, completely
destroying the missile and damaging the launch pad.
The warhead charges also exploded asymmetrically, spraying the area with radioactive substances.
Although the nuclear warhead did not explode, some radioactive materials from its core contaminated
Johnston Island.
Burning rocket fuel flowed through the cable trenches, causing extensive chemical contamination
in the area.
The US government ordered the military to decontaminate the atoll before the severely-damaged
Thor launch pad could be rebuilt.
A hasty effort ensued, and the contaminated top layer of soil was scraped and dumped into
a lagoon.
But only two years later, the radioactive sediment would be added back to the atoll
when it was used as a landfill to expand Johnston Island…
Operation Upshot-Knothole
Operation Upshot-Knothole was a series of 1953 nuclear tests in the Nevada Proving Ground.
The operation included the first test of a device known as Hydride 1, a fission bomb
fueled by enriched uranium hydride.
The exercise was supposed to produce a lower yield than other thermonuclear weapons, but
also used more efficient fissile material.
Still, the test ultimately failed when it produced a much smaller yield than originally
planned...
An estimated 18,000 Department of Defense personnel and members of all four armed services
participated in the Operation Upshot-Knothole program as observers and tactical maneuvers
to support activities and scientific studies.
The Hydride 1 “Ruth” shot was fired on March 31, 1953.
Even though it produced a slow-motion fireball, the test ultimately failed and fizzled, resulting
in a small 200-ton yield, a much lower fraction of its predicted 1.5-3 kiloton blast.
To add to the failure, the weapon only vaporized the top third of the 300-foot tower from which
it was detonated.
Parts of it scattered across the sea, and the remaining lower core was left standing.
A second Hydride 1 was tested two weeks later using deuterium and a different concentration
of enriched uranium in its solid spherical pit.
It had the same weight and dimensions as its predecessor, with only a different pit fuel
mix.
The “Ray” test was fired atop a shorter 100-foot tower on April 11.
Although it fared slightly better than the Ruth tryout, it still performed way below
expectations.
The detonation produced a 220-ton yield, about a tenth of its predicted 0.5-1 kiloton blast.
Though regarded as total failures, Ruth and Ray contributed very little fallout contamination
to the surrounding environment.
Operation Upshot-Knothole, however, dosed the more than 20,000 soldiers with dangerous
levels of radiation.
It also released about 35,000 kilocuries of radioiodine into the atmosphere, resulting
in civilian radiation exposure that amounted to 89 million person-rads of thyroid tissue
exposure.
The Baneberry Incident
After the 1963 Partial Test Ban Treaty banned all above-ground nuclear explosions, many
countries took their detonations underground.
In one such test at the Nevada Test Site in 1970, the military detonated a 10-kiloton
nuke 850-feet underground that could not be contained, resulting in disastrous consequences...
The Partial Test Ban Treaty, signed by the United States and other 120 nations, banned
nuclear weapons testing in the atmosphere, outer space, and underwater.
The treaty was meant to stop the spread of nuclear materials into the atmosphere and
limit human exposure to dangerous radioactive fallout.
Consequently, many countries resorted to dangerous underground testing conduction.
On December 18, 1970, the United States carried out an underground trial that later became
known as the Baneberry Incident.
During the Baneberry test at the Nevada Test Site, a nuclear bomb was lowered into a small
7-foot diameter hole.
Once the device was 900-feet underground, the atomic bomb was detonated.
About 300 feet away from the explosion, a fissure opened in the ground and an enormous
cloud of radioactive dust poured skyward.
The cloud mushroom could be seen as far away as Las Vegas, and the fallout spread all the
way to California.
For a relatively small bomb, Baneberry had an unexpectedly significant impact on the
atmosphere.
Although government workers operating in the area were evacuated, hundreds were exposed
to radiation.
In an official report, the Atomic Energy Commission noted that almost 500 cars were contaminated
and had to be sprayed down and vacuumed with a special device before being returned to
their owners.
The investigation also established that the human exposure was within the established
safety rules and limitations.
But two men with high radiation exposure eventually contracted leukemia, and their families spent
years fighting for compensation and advocating against underground nuclear testing.
The courts eventually ruled that the government's handling of the situation was negligent but
not liable, and no damages were awarded.
The test site and subsequent nuclear tests were shut down for six months while authorities
investigated the cause of the accident, ultimately attributing it to abnormally high water content
in the medium surrounding the detonation point.
New rules were eventually put in place to limit the workers' potential exposure to radiation
fallout.