The 18-kiloton atomic bomb test “Cactus” detonated at Enewetak Atoll in May 1958 was, by all accounts, unremarkable. At 18 kilotons, it was smaller than the atomic bombs that had leveled Hiroshima and Nagasaki at the end of World War Two, and paled in contrast to the massive hydrogen bomb tests that were conducted by the United States before and after it in the Marshall Islands.
It did, however, carve out a crater 106 meters (347 feet) in diameter and 9.5 meters (31 feet) deep in the coral island of Runit. Twenty years later, as part of a partial clean up of the former nuclear test site to allow displaced islanders to return home, US Army soldiers turned the crater into a radioactive waste storage dump for plutonium-contaminated soil and debris, capping it with a concrete dome.
The Army clean up team packed its bags in 1980, and left Enewetak and the Runit Dome to the 1,000 returning residents who had lived in exile since they had been forcibly removed from Enewetak in 1947 to make way for the first weapons tests at the atoll the following year. No fence was erected around the Runit Dome nuclear waste facility, and there was little indication for the public of the dangers posed by the dome save for a sign or two noting a radiation hazard on the island — signs that rusted away within a few years.
The Cactus nuclear test was one of 67 conducted by the US from 1946 to 1958 at Enewetak and Bikini atolls.
In recent years, the Runit Dome has come to symbolize the lingering United States nuclear weapons test legacy — and more, a nexus of atomic bomb test damage and climate-induced sea level rise that imperils these low-lying coral islands and their small populations.
In mid-May, United Nations Secretary General Antonio Guterres catapulted the Runit Dome into world headlines with his comment that the Runit Dome is “a kind of coffin” that is leaking radioactive waste into the Pacific.“But it’s worse than a coffin because Runit Dome doesn’t just contain the remains of a loved one,” said Jack Ading, Enewetak’s Nitijela representative and a member of the government’s Cabinet, commenting on Guterres’ remarks. “It is stuffed with radioactive contaminants that include plutonium-239, one of the most toxic substances known to man.”An irony not lost on Marshall Islanders is the fact that the US government built the radioactive waste storage facility on Enewetak and then left, wiping its hands of ongoing responsibility for the Runit Dome.
“If the Cactus crater concrete containment structure on Runit Island were located in the United States, it would be formally classified as a Low-Level Radioactive Waste Disposal Site and be subject of stringent site management and monitoring practices,” wrote Dr. Terry Hamilton, the lead US government scientist working for the Lawrence Livermore National Laboratory in California who began the first monitoring of the dome over 30 years after it was constructed. “A long-term groundwater monitoring program would almost certainly form an integral part of these activities,” Hamilton added in a report on the dome issued in early 2014 as he began to study the dome for the first time, following passage of a law by the US Congress mandating regular monitoring of the Runit Dome. Photographs from the construction of the Runit Dome in the 1978-1980 period show that the Cactus crater acted as a large swimming pool, filled with ocean water that went up and down with the tides. The porous nature of a coral atoll allows ocean water to seep in and out during daily high and low tides.
As construction started, the sediment on the floor of the crater was laced with plutonium left from the weapons test. “The bottom sediments and crater water formed a source-term for transfer of plutonium isotopes and other radionuclides into the nearby lagoon,” said a recent report on the Runit Dome prepared by Lawrence Livermore National Laboratory. This contaminated sediment was left in the crater as additional contaminated sand, dirt, and other materials scraped off Runit and other islands in the atoll was dumped into the crater on top of it the existing contaminated material. “It was believed that filling the crater with solid debris would prevent ‘washout’ of contamination from the crater to the lagoon, and actually reduce the migration of fallout radionuclides into the near-surface marine environment,” said the US government report.
Although US authorities said that filling and capping the crater would reduce contamination to the atoll and ocean, the porous crater bottom was not lined when it was built in the 1970s and until 2013, the issue of leakage was not checked.
In the meantime, said Ading, “the coffin is leaking its poison into the surrounding environment. And to make matters even worse, we’re told not to worry about this leakage because the radioactivity outside of the dome is at least as bad as the radioactivity inside of it.”
Ading called the Runit Dome a “monstrosity” that is “a constant source of anxiety for the people of Enewetak.” About 800 islanders now live on islands at the southern part of Enewetak, 20 km (12 miles) from Runit. Ading and Marshall Islands Foreign Minister John Silk said they appreciated the UN Secretary General bringing the Runit Dome to world attention with this comments earlier this month. “We are pleased that the Secretary General made these statements since so often it seems that these ongoing legacy issues that continue to impact our people are forgotten by the international community,” Silk said.
Although noting that the US Congress passed legislation to establish a monitoring program for the Runit Dome, Silk said “our government also believes that an outside independent study of the Runit Dome’s current status would be helpful.”
“A lot needs to be done in relation to the explosions that took place in French Polynesia and the Marshall Islands,” Guterres said while in Fiji recently. “The consequences of these (tests) have been quite dramatic, in relation to health, in relation to poisoning of waters in some areas.”
Rhea Moss-Christian, who chairs the Marshall Islands National Nuclear Commission, welcomed Guterres’ comments about Enewetak. The Marshall Islands “needs the support of the international community to address the staggering health and environmental challenges across the Pacific,” she said.
“The people of Enewetak are gratified that the Secretary General has called attention to our predicament, living in the shadow of a massive nuclear waste dump that he aptly calls a ‘coffin,’” said Ading.
Still, while the Runit Dome catches international interest, in reality it is but a small part of the overall radiation contamination problem at Enewetak Atoll. The level of radioactivity entombed in the Runit Dome “is dwarfed by the current inventory of fallout radionuclides in atoll lagoon sediments,” said Hamilton. “Consequently, catastrophic failure of the concrete dome façade covering the debris mound and instantaneous release of all its contents into the lagoon will not necessarily lead to any significant change in the radiation dose deliver to the local resident population.”
But, added Hamilton, because daily tides push groundwater up and down under the dome, “the potential does exist for contaminated groundwater from Runit Dome to flow into the nearby, subsurface marine environment.” “We pray,” Ading observed, “that Runit Dome does not eventually become our coffin.”
Read more about this in the May 31, 2019 edition of the Marshall Islands Journal.