The Runit Dome is a containment structure on Runit Island, located on Enewetak Atoll. Enewetak Atoll is a former U.S. atmospheric nuclear weapons test site located approximately 2,300 miles west of Hawaii in the northwest Pacific Ocean. The Runit Dome, which was built in the late 1970s, contains over 100,000 cubic yards of contaminated soil and debris [from the US nuclear weapons testing] that were encapsulated in concrete inside an unlined nuclear test crater, the Cactus Crater, on the north end of Runit Island. The site has remained a concern to the people of Enewetak.
The Runit Dome is not in any immediate danger of collapse or failure, and the exterior concrete covering the containment structure is still serving its intended purpose, effectively reducing the natural erosion of the waste pile below by wind and water. Visual surveys of the exterior concrete of the Cactus Crater containment structure have revealed the presence of cracks and spalls in the concrete cap. However, these cracks and spalls in the exterior concrete cap do not form sites for external or internal radiation exposure that impact or endanger human health or
the environment, or wildlife.
DOE has performed preventative maintenance on exterior surfaces of the containment structure, which will aid in the determination of any changes that
may occur in the condition of the concrete in the future. Any concerns about the imminent failure or collapse of the structure are unfounded.
The main safety concern to humans associated with leakage of radioactive waste from the Cactus Crater containment structure is the uptake of fallout radioactivity in marine foods. There are no data to suggest that the Cactus Crater containment structure, or more specifically, the radioactive material encapsulated in Cactus Crater, is currently having a measurable adverse effect on the surrounding environment or on the health of the people of Enewetak. However, DOE is in the process of establishing a groundwater radiochemical analysis program that is designed to provide scientifically substantiated data that can be used to determine what, if any, effects the dome contents are having, or will have, on the surrounding environment now
and in the future.
Long-term trends in the concentration of Pu in lagoon waters derived from retrospective analysis of a coral core collected off Runit Island show levels of Pu in lagoon waters are systematically decreasing. These data provide compelling evidence that the construction of the Runit Dome has had, and continues to have, a negligible impact on the wider marine environment….
The Cactus Crater containment structure remains vulnerable to wave driven over wash and flooding caused by storm surge and potential effects of sea level rise… It is
anticipated that any measured or modeled effects of storm events may help provide a better understanding of the long-term consequences of sea-level rise on mass-transport of dome derived radionuclides.