Dangerous discovery on the Atlantic Ocean floor – what scientists found

Scientists on the French NODSSUM expedition have for the first time in decades thoroughly examined barrels of radioactive waste submerged on the Atlantic Ocean floor. Many containers have corroded, their contents partially leaked into the sediment, and elevated radiation levels have been recorded. The barrels have become artificial reefs, and biologists are studying the accumulation of radionuclides in marine organisms.

The French expedition under the NODSSUM project in May-June 2026 conducted the first detailed inspection in decades of submerged radioactive waste on the northeastern Atlantic Ocean floor. About thirty researchers aboard the deep-sea submersible Nautilus made twenty dives to depths exceeding 4.5 km. The survey targeted metal barrels dumped in the second half of the 20th century — over 200,000 containers in total. The results were alarming: many barrels were heavily rusted, their contents partially leaked into the bottom sediment. Measurements recorded a significant increase above natural background radiation, with the main markers of leakage being isotopes cobalt-60 and niobium-94. The metal casings have turned into artificial reefs, colonized by anemones, sponges, and crabs. Biologists are collecting tissue, water, and sediment samples to determine whether organisms accumulate radioactive elements. Historians note that the buried materials were classified as low-level waste and sealed in concrete or bitumen. France alone dumped 46,000 barrels in 1967 and 1969. Prior mapping of the seafloor by the robot Ulyx identified over three thousand objects.