In 1982, a US government task force raised concern about a probable breach if a severe typhoon were to hit the island.[6] In 2013, a report by the US Department of Energy[7] found that the concrete dome had weathered with minor cracking of the structure.[8]
However, the soil around the dome was found to be more contaminated than its contents, so a breach could not increase the radiation levels by any means. Because the cleaning operation in the 1970s only removed an estimated 0.8 percent of the total transuranic waste in the Enewetak atoll,[9]: 2 the soil and the lagoon water surrounding the structure now contain a higher level of radioactivity than the debris of the dome itself, so even in the event of a total collapse, the radiation dose delivered to the local resident population or marine environment should not change significantly.
Concern primarily lies in the rapid tidal response to the height of the water beneath the debris pile, with the potential for contamination of the groundwater supply with radionuclides. One particular concern is that, in order to save costs, the original plan to line the porous bottom crater with concrete was abandoned.[3] Since the bottom of the crater consists of permeable soil, there is seawater inside the dome.[3]
However, as the Department of Energy report stated, the released radionuclides will be very rapidly diluted and should not cause any elevated radioactive risk for the marine environment, compared to what is already experienced.[7] Leaking and breaching of the dome could however disperse plutonium, a radioactive element that is also a toxic heavy metal.[10][11]
Last sentence about "disperse plutonium" appears to be the concern. Unclear how accurate Wikipedia information is at this point, but good jumping off point for verification (if possible).
https://en.wikipedia.org/wiki/Runit_Island
Last sentence about "disperse plutonium" appears to be the concern. Unclear how accurate Wikipedia information is at this point, but good jumping off point for verification (if possible).