The structural integrity of the Runit Dome in the Marshall Islands, described as a 115-meter-wide concrete ‘coffin,’ is endangered according to the United States Government Accountability Office (GAO). This dome was built over an unlined crater from a nuclear explosion that occurred in 1958 and contains over 120,000 tonnes of radioactive debris- much of which is made of plutonium-239 contaminated soil. Rising sea levels and increasing storm intensity in the Central Pacific have caused the 18-inch-thick concrete dome cap to be compromised by forces (e.g., both rising and falling tides) that were not anticipated when the dome was built and were never taken into account for its permanently stored design conditions. The porous nature of the coral substrate upon which the crater sits allows the radioactive waste to ‘float’ up and down with the tides and enables seawater to permeate the debris. The continued leakage of seawater from the degrading concrete cover, together with large visible surface cracks, has produced a ‘ticking time bomb’ environmental disaster that originated during the Cold War.
The ticking time bomb of Runit Dome: Cracks and a missing base let radioactive water flow
One of the dangerous aspect with Runit Dome is not only the fact that the outside is cracked, but that there is no bottom lining inside the dome. As described in the GAO report, the Defence Nuclear Agency (DNA), with support from the U.S. Army Corps of Engineers, used the ‘Cactus’ blast crater for radioactive soil disposal and did so without a concrete base to reduce costs when constructing the dome in the late 1970s. Therefore, radioactive waste is in constant contact with groundwater and rises and falls based on ocean tides. This causes what is commonly referred to as ‘pumping’ or the expulsion of radioactive isotopes into the lagoon surrounding Runit Dome daily.
How rising sea levels are breaking the Runit Dome
Runit Island is only 25 feet above sea level, according to the U.S. Department of Energy’s 2024 Climate Report. Sea level rise is currently pushing radioactive groundwater higher into the porous area. This is creating greater internal pressures and ‘base’ cracking on the surface of the structure. The cracks are allowing rain to enter the structure while carrying Plutonium-239 into the ground and into the water table surrounding the structure through existing channels over the area. The report indicates that a major typhoon surge could cause the internal contents to be washed out to Enewetak lagoon, as sediment and small particles will wash down through the channels into the lagoon.
Is the Runit Dome about to collapse
Today, Runit Dome’s cracking is a vista of structural failure, and a template of decaying nuclear history. The Government Accountability Office (GAO) and Department of Energy (DOE) reports have established that the ‘temporary’ 50-year design has reached design life. If no international action is taken to reinforce the unlined crater, the continually rising Pacific tide waters will continue to ‘pump’ Plutonium into the environment. Protecting the Marshall Islands from a catastrophic washout is now a matter of global environmental justice or the need for immediate climate action.
