Study finds Soviet submarine Komsomolets still leaking radioactive material three decades after sinking

A new peer‑reviewed study in the Proceedings of the National Academy of Sciences (PNAS) finds that the Soviet nuclear attack submarine Komsomolets, which sank in the Norwegian Sea in 1989, continues to leak radioactive material from its reactor more than 30 years later. The vessel went to the bottom with its nuclear reactor and two nuclear warheads; its titanium hull allowed it to descend much deeper than most submarines of its era. The headline: the reactor fuel is corroding and intermittent radioactive plumes were observed during a 2019 robotic survey.

Survey and key findings

In 2019 remotely operated vehicles (ROVs) carried out four independent dives to map the wreck, record video and sonar, and collect seawater, sediment and biological samples. The PNAS team reported clear video evidence of intermittent plumes emerging from the reactor area and ventilation ducts. Water sampled after visible plumes showed cesium‑137 activity roughly 1,000 times higher than pre‑leak samples. Near a metal grating on the wreck, measured strontium‑90 and cesium‑137 concentrations reached as much as 400,000 and 800,000 times typical Norwegian Sea background levels, respectively — though those hot spots dilute rapidly once they enter the surrounding seawater. Analyses also show elevated plutonium and uranium near the same grating, consistent with ongoing corrosion of reactor fuel.

Environmental assessment and safety status

Reassuringly, the study reports that the two nuclear warheads appear intact with no detectable leakage, and the 1994 plugging work on the forward torpedo room remains effective. Samples from sediments and marine life around the wreck show very low accumulation of radionuclides, and Norway’s long‑running monitoring programs in the Norwegian Sea and Barents Sea have not detected anomalies at coastal or basin scales. In short: detectable, large localized leaks exist at the wreck, but so far there is no evidence of a wider environmental impact.

Geopolitical and policy implications

What now? The wreck sits at great depth and belongs to Russia, so any remediation would be technically demanding and politically sensitive. It has been reported that Russia and Norway have cooperated on monitoring since 1989, but current geopolitical tensions and sanctions complicate multinational recovery or mitigation efforts. The PNAS authors call for continued monitoring and further investigation to clarify leak mechanisms, the corrosion timeline of remaining fuel, and the eventual fate of the radioactive material — questions that are as much political as they are scientific.