5.7 KiB
| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Castle Bravo | 7/9 | https://en.wikipedia.org/wiki/Castle_Bravo | reference | science, encyclopedia | 2026-05-05T13:10:17.178423+00:00 | kb-cron |
=== Bomb test personnel take shelter === Unanticipated fallout and the radiation emitted by it also affected many of the vessels and personnel involved in the test, in some cases forcing them into bunkers for several hours. In contrast to the crew of the Lucky Dragon No. 5, who did not anticipate the hazard and therefore did not take shelter in the hold of their ship, or refrain from inhaling the fallout dust, the firing crew that triggered the explosion safely sheltered in their firing station when they noticed the wind was carrying the fallout in the unanticipated direction towards the island of Enyu on the Bikini Atoll where they were located, with the fire crew sheltering in place ("buttoning up") for several hours until outside radiation decayed to safer levels. "25 roentgens per hour" was recorded above the bunker.
=== US Navy ships affected === The US Navy tanker USS Patapsco was at Enewetak Atoll in late February 1954. Patapsco lacked a decontamination washdown system, and was therefore ordered on 27 February, to return to Pearl Harbor at the highest possible speed. A breakdown in her engine systems, namely a cracked cylinder liner, slowed Patapsco to one-third of her full speed, and when the Castle Bravo detonation took place, she was still about 180 to 195 nautical miles east of Bikini. Patapsco was in the range of nuclear fallout, which began landing on the ship in the mid-afternoon of 2 March. By this time Patapsco was 565 to 586 nautical miles from ground zero. The fallout was at first thought to be harmless and there were no radiation detectors aboard, so no decontamination measures were taken. Measurements taken after Patapsco had returned to Pearl Harbor suggested an exposure range of 0.18 to 0.62 R/hr. Total exposure estimates range from 3.3 R to 18 R of whole-body radiation, taking into account the effects of natural washdown from rain, and variations between above- and below-deck exposure.
=== International incident === The fallout spread traces of radioactive material as far as Australia, India and Japan, and even the United States and parts of Europe. Though organized as a secret test, Castle Bravo quickly became an international incident, prompting calls for a ban on the atmospheric testing of thermonuclear devices. A worldwide network of gummed film stations was established to monitor fallout following Operation Castle. Although meteorological data was poor, a general connection of tropospheric flow patterns with observed fallout was evident. There was a tendency for fallout/debris to remain in tropical latitudes, with incursions into the temperate regions associated with meteorological disturbances of the predominantly zonal flow. Outside of the tropics, the Southwestern United States received the greatest total fallout, about five times that received in Japan. Stratospheric fallout particles of strontium-90 from the test were later captured with balloon-borne air filters used to sample the air at stratospheric altitudes; the research (Project Ashcan) was conducted to better understand the stratosphere and fallout times, and arrive at more accurate meteorological models after hindcasting. The fallout from Castle Bravo and other testing on the atoll also affected islanders who had previously inhabited the atoll, and who returned there some time after the tests. This was due to the presence of radioactive caesium-137 in locally grown coconut milk. Plants and trees absorb potassium as part of the normal biological process, but will also readily absorb caesium if present, being of the same group on the periodic table, and therefore very similar chemically. Islanders consuming contaminated coconut milk were found to have abnormally high concentrations of caesium in their bodies and so had to be evacuated from the atoll a second time. The American magazine Consumer Reports warned of the contamination of milk with strontium-90.
== Impact on US policy == The test caused a reassessment of US policies towards nuclear weapons and energy in order to contend with massive international backlash that declared the disaster "intolerable". The following year's Russell–Einstein Manifesto explicitly focused on the hydrogen bomb's threat to human existence demonstrated by the test:
No doubt in an H-bomb war great cities would be obliterated ... If everybody in London, New York and Moscow were exterminated the world might, in the course of a few centuries, recover from the blow. But we now know, especially since the Bikini test, that nuclear bombs can gradually spread destruction over a very much wider area than had been supposed. It is stated on very good authority that a bomb can now be manufactured which will be 2,500 times as powerful (37.5 megatons) as that which destroyed Hiroshima (15 kilotons). Such a bomb, if exploded near the ground or under water, sends radio-active particles into the upper air. They sink gradually and reach the surface of the earth in the form of a deadly dust or rain. It was this dust which infected the Japanese fishermen and their catch of fish. In May 1954 National Security Council meeting, President Dwight D. Eisenhower said "everybody seems to think that we are skunks, saber-rattlers, and warmongers." Secretary of State John Foster Dulles said "comparisons are now being made between ours and Hitler's military machine." Attempts to repair this image included the yield and fallout limiting of all future tests, and an emphasis on peaceful nuclear energy production, from both nascent fission reactor plants and speculative fusion implosion facilities.
=== Nuclear testing policies ===