Runit Atoll's radioactive dome is cracking—and the Pacific faces a silent crisis

A crumbling concrete dome on Runit Atoll in the Marshall Islands holds thousands of tons of radioactive waste from past U.S. nuclear tests. Built in the 1980s, the structure was meant to contain the contamination—but now, cracks and rising sea levels are raising fears of a wider environmental disaster.

The waste was buried under the dome after the U.S. military attempted to clean up the site following decades of nuclear testing. By the 1980s, the area was declared habitable again, though concerns lingered. Over time, the dome's condition worsened, and in 2013, the U.S. Department of Energy confirmed radiation was already escaping.

The main risk does not come from the dome collapsing but from the porous limestone beneath it. This bedrock allows radioactive material to seep into the surrounding ocean and groundwater. Experts warn that climate change is accelerating the problem, as rising seas threaten to destabilise the structure further. Initially, the U.S. downplayed the dangers, focusing on monitoring rather than action. But pressure grew after a 2019 inspection confirmed ongoing leaks. By 2023, Washington agreed to a $6.5 million aid package to help the Marshall Islands track radiation levels. Talks under the Compact of Free Association have since included discussions on dome repairs and health programmes for affected communities. Still, as of 2026, no full cleanup has been promised. The Marshall Islands, home to just 53,000 people, lacks the resources to manage a potential radioactive crisis alone. While the U.S. maintains it has met its obligations, the island nation continues to push for greater support—arguing that the waste, and its consequences, were never theirs to inherit.

The dome remains a ticking environmental hazard, with radiation already escaping through the island's bedrock. Though funding for monitoring has increased, no long-term solution has been finalised. For now, the Marshall Islands must rely on limited aid while negotiations over responsibility—and the risk to its people—continue.