The United States military conducted a series of nuclear tests in the Marshall Islands from 1946 to 1958, including the 1954 hydrogen bomb that sent a massive mushroom cloud over Bikini Atoll and covered nearby inhabited islands in radioactive ash. The US built a "kind of coffin" in the islands to contain the radioactive debris—but the structure was not intended to last, and is now in danger of being breached, UN Secretary General António Guterres said during a recent tour of the Pacific islands last week, per CBS News. Per Guterres, a combination of disrepair and rising sea tides due to climate change has made the dome vulnerable. If it was breached, perhaps by a strong storm, deadly debris could be released, the Washington Post reports. Experts warn that the Marshallese government does not have the necessary funds to make the repairs and improvements that are needed.
The Defense Nuclear Agency started cleaning up the nuclear debris in 1977, with 4,000 US service members collecting an estimated 73,000 cubic meters of tainted surface soil from across the islands and transporting it to a 328-foot crater that had been created on Runit Island by one of the test explosions. The material was dumped in the crater—dubbed by locals as "The Tomb" due to six men reportedly dying during the work—and, in 1980, an 18-inch-thick concrete dome was placed over it and sealed off. The site was intended to be temporary, but the more permanent containment site that was planned never came about. In 1983, when the Marshall Islands gained the right to govern itself rather than continuing to be under US administration, care for the dome was transferred to the island government, and cracks have started to appear. Thanks to the fact that the crater is just soil, and was never lined, experts say seawater is already inside and radioactive material may have already started to leak from it. See the Post for more. (Read more Marshall Islands stories.)