Concrete dome not watertight

A concrete dome on the Enewetak atoll in the Marshall Islands, built in 1980 to contain radioactive soil from U.S. nuclear tests, was never designed to prevent seawater from circulating underneath it.

Radioactive material and seawater interaction

The structure, known as the Runit dome, covers approximately 85,000 cubic meters of radioactive material, but the U.S. Department of Energy has acknowledged that seawater has been entering the area under the dome since its construction. This occurs at the pace of the tides, releasing radioactive contaminants into the surrounding lagoon twice daily.

Construction details of the dome

The dome, which measures approximately 115 meters in diameter, was constructed using 358 concrete panels assembled like a giant puzzle, forming a cover about 46 centimeters thick. However, it was never intended to be a watertight seal.

Original crater and environmental concerns

The crater left by the 1958 nuclear test named Cactus was not waterproofed, and the bottom of the excavation remained porous. The U.S. Department of Energy report notes that radioactive groundwater under the structure rises and falls with the tides, releasing contaminants directly into the lagoon.

Climate change and structural degradation

This process is exacerbated by climate change, which weakens the concrete and increases seawater pressure on the structure. The dome contains only about 1 percent of the plutonium spilled on the atoll during nuclear tests, with the remaining 99 percent already present in the lagoon sediments outside any containment structure.

Broader environmental impact

The Runit dome, therefore, represents only a visible part of a broader environmental issue affecting the entire marine ecosystem near the atoll. The situation raises questions about the long-term consequences of decisions made during the Cold War, as radioactive materials continue to flow into the ocean, impacting the future of the region and its inhabitants.