Project 4.1
In 1994, a 1953 "Castle Bravo" program prospectus was found which included reference to Project 4.1 apparently written before the "Bravo" shot had occurred. The U.S. government responded that someone had gone back into the project list after the "Bravo" test to insert Project 4.1; thus, according to the U.S. government, the acts were not premeditated. All other U.S. documents point to Project 4.1 having been established after the "Bravo" test—most sources point to its having been organized on March 7, 1954. The final Project 4.1 report began in its preface with the statement that "Operation CASTLE did not include a biomedical program" (it mentions this in discussing the ad hoc nature by which the project personnel were assembled). All official and mainstream historical accounts of the "Bravo" test indicate that its high level of fallout was a result of a miscalculation in relation to its design and was not deliberate (see the Castle Bravo article for more information on the alleged accident).
Radiophobia
March 1, 1954, the operation Castle Bravo testing of a then, first of its kind, experimental thermonuclear "Shrimp" device, overshot its predicted yield of 4–6 megatons and instead produced 15 megatons; this resulted in an unanticipated amount of "Bikini snow" or visible particles of nuclear fallout being produced, fallout which caught the Japanese fishing boat the Daigo Fukuryū Maru or "Lucky Dragon" in its plume, even though it was fishing outside the initially predicted ~5 megaton fallout area which had been cordoned off for the Castle Bravo test. Approximately 2 weeks after the test and fallout exposure, the 23-member fishing crew began to fall ill, with acute radiation sickness, largely brought on by beta burns that were caused by direct contact between the "Bikini snow" fallout and their skin, through their practice of scooping the "Bikini snow" into bags with their bare hands. One member of the crew, Kuboyama Aikichi the boat's chief radioman, died 7 months later, on September 23, 1954. It was later estimated that about a hundred fishing boats were contaminated to some degree by fallout from the test. Inhabitants of the Marshall Islands were also exposed to fallout, and a number of islands had to be evacuated.