Between 1946 and 1958 the atolls of the Marshall Islands in the Pacific Ocean were testing ground for the United States nuclear arsenal. The first bomb, called Able, was detonated July 25, 1946, on Bikini Atoll. The first-ever American hydrogen bomb, with the code name Ivy Mike, was tested on Enewetak in 1951. The 1954 Castle Bravo hydrogen bomb was 1,000 times more powerful than Little Boy, the uranium bomb that destroyed the Japanese city of Hiroshima. In 12 years the U.S. tested 67 nuclear weapons on the Bikini and Enewetak Atolls. The craters formed by the explosions are visible from space; however, less obvious is the radioactive contamination of the entire area.
A survey conducted in 2015 found concentrations of radioactive plutonium-239 and -240 in the soil of Bikini and Enewetak almost ten times higher than levels in the Chernobyl exclusion zone, where thirty-three years ago the reactor experienced a catastrophic core meltdown, exploded and parts of the nuclear fuel were released. Levels of gamma radiation were also higher than previously reported on Bikini and significantly elevated on sites tested on Enewetak and Rongelap Atolls.. Radioactive fallout from the Castle Bravo test on March 1, 1954, also contaminated the nearby Rongelap and Utirik Atolls, prompting the evacuation of the local population. Still today some sites surpass the maximum exposure for radiation considered safe by experts. Apart the 67 tests, also a leaking nuclear waste repository is contributing to the radioactive pollution of the area.
On Runit Island, one of forty islands forming the Enewetak Atoll, sits “The Dome” – a 100 meters wide crater filled with 85,000 cubic meters of radioactive debris and waste and covered with half a meter of concrete. The dome sits on permeable rocks and in 2013 leaks of radioactive water were noted at the base of the structure. As sea levels are rising the entire site will be flooded, potentially causing widespread radioactive contamination, including plutonium-239.