Operation Castle
Quick Summary
The goal of Operation Castle was to produce a practical, deliverable thermonuclear bomb. The United States' Mike thermonuclear device—detonated November 1, 1952, at Enewetak, an atoll in the Marshall Islands—had weighed some 82 tons and took up the space of a small building to hold the cryogenic equipment that kept its deuterium fuel in liquid form. In contrast, Bravo, the first test of the Operation Castle series, used solid lithium deuteride, forgoing the need for cryogenic equipment. Detonated on March 1, 1954, at Bikini, another atoll in the Marshall Islands, the Bravo bomb produced a 15-megaton explosion—three times the expected yield. The large blast produced considerable unexpected radiation, which resulted in widespread contamination that forced the U.S. government to make restitution to various injured parties.
Operation Castle was a series of American nuclear weapons tests conducted in the Marshall Islands between March and May 1954. The most significant test, Castle Bravo, on March 1, 1954, was a thermonuclear bomb detonation that yielded 15 megatons, far exceeding the expected 6 megatons. This explosion was approximately 1,000 times more powerful than the bomb dropped on Hiroshima and remains the most powerful nuclear device ever tested by the U.S.. The blast vaporized islands, created a massive fireball and mushroom cloud, and scattered radioactive debris over a wide area, affecting nearby atolls and a Japanese fishing boat. Despite the devastating consequences, the U.S. continued with nuclear testing in the region for several more years.1
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