A concrete dome containing radioactive waste from Cold War-era atomic bomb tests may be leaking into the Pacific Ocean, according to United Nations Secretary-General Antonio Guterres.
The AFP reported that Guterres spoke to students in Fiji on Thursday and raised concerns about the structure, which is known as the Runit Dome on Enewetak Atoll in the Marshall Islands. The area was the spot for 67 American nuclear weapons tests between 1946 and 1958.
The tests included the 1954 "Bravo" hydrogen bomb, which is the most powerful bomb ever detonated by the U.S., according to AFP.
"I've just been with the president of the Marshall Islands, who is very worried because there is a risk of leaking of radioactive materials that are contained in a kind of coffin in the area," Guterres said, according to AFP.
When testing came to an end, the U.S. Defense Nuclear Agency spent eight years cleaning up the area, but Congress did not provide funding for a decontamination program, according to The Guardian.
The concrete dome was built in the 1970s as a dumping ground for the radioactive soil and ash from test explosions. The material was tipped into the crater and topped with an 18-inch thick layer of concrete. It was seen as a temporary fix and the bottom of the crater was never lined with anything.
In the 1980s, the Marshall Islands signed a contract to be free from association with the United States, according to The Guardian, but that contract also meant that anything related to the U.S. nuclear programs was left under the responsibility of the Marshallese government.
Cracks are forming in the concrete after years of exposure, and AFP reports there are concerns the structure could break apart if hit with a strong enough tropical cyclone.
A 2013 report released by the U.S. Department of Energy showed that soil around the dome is more contaminated than the waste within the structure, according to The Guardian.
Guterres did not provide any solutions on how to fix the situation during his speech.