Path of <a href="https://en.wikipedia.org/wiki/Nuclear_fallout" class="extiw" title="en:Nuclear fallout">nuclear fallout</a> plume after U.S. nuclear weapons test Bravo (yield 15 Mt) on <a href="https://en.wikipedia.org/wiki/Bikini_Atoll" class="extiw" title="en:Bikini Atoll">Bikini Atoll</a>. It is the single worst contamination accident in U.S. nuclear history. The test was part of the <a href="https://en.wikipedia.org/wiki/Operation_Castle" class="extiw" title="en:Operation Castle">Operation Castle</a>. The Bravo event was an experimental thermonuclear device surface event. The numbers correspond with estimated total (accumulated) dose contours (<a href="https://en.wikipedia.org/wiki/Rad_(unit)" class="extiw" title="en:Rad (unit)">rad</a>).
<a href="https://en.wikipedia.org/wiki/United_States_Department_of_Energy" class="extiw" title="en:United States Department of Energy">United States Department of Energy</a>
1954
Samuel Glasstone and Phillip J. Dolan, eds., <i>The Effects of Nuclear Weapons</i>, 3rd. edn. (Washington, D.C.: DOD and DOE, 1977): 437.  [Gamma doses are Roentgens from arrival time to 96 hours (4 days) after detonation, outside on land.  Glasstone and Dolan mention that because data from the ocean was not obtained in this particular test, <i>Bravo</i>, the fallout contours to the north of the islands are uncertain and some other fallout patterns for the same test ascribe the high levels measured on Rongelap to a "hotspot" of the sort measured in the ocean downwind in later tests.