On April 7, 1989, the Soviet nuclear submarine K-278 Komsomolets sank in the Norwegian Sea after an uncontrolled fire fruit probably short circuit in the electrical panels of compartment 7, which led to a massive and uncontrollable deflagration because the atmosphere was critically enriched with oxygen due to failures in the air regeneration system. Of the 69 people on board, only 27 survived.
It wasn’t just any submarine: it had a double titanium helmet that allowed him descend to unreachable depths for his rivals of the time. Its cutting-edge technology hid a dangerous core: a nuclear reactor and two plutonium warheads that have since lain at the bottom of the sea, 180 kilometers southwest of Bear Island, in the Svalbard archipelago. And according to the most complete study carried out to date, published a few days ago in the scientific journal PNASthe Komsomolets remains an active source of radioactive contamination in the Arctic.
The discovery. In 2019, a Norwegian research team went down with the Ægir 6000 underwater robot to thoroughly inspect the submarine using cutting-edge technology. As they approached the ventilation tube they found a visibly distorted column of water, as if it were smoke, as you can see in the video immediately after this block. It is a leak with intermittent behavior.
They took samples and the results were overwhelming: concentrations of Cesium-137 800,000 times the normal radiation of seawater in the area and Strontium-90 400,000 times. Both isotopes are direct products of nuclear reactor fission. The analysis shows that the radiation comes from the propulsion system (the nuclear reactor) and that the reactor fuel is in the process of corrosion with the environment.
Why is it important. The good news is that this radioactive leak does not come from the nuclear warheads: two torpedoes with atomic warheads. For now, that threat is under control: the Soviets sealed the torpedo compartment with titanium plates in the early 1990s and judging by analysis, the sealing continues to work because they have not detected weapons-grade plutonium in the marine environment.
The bad news is the reactor. It does not explode or disappear, but simply the zirconium cylinders that protect the uranium and plutonium are corroding, leaking these isotopes into the sea in a slow and invisible leak that is diluted in the ocean. Fortunately, samples taken in relatively close areas show that dilution is rapid, as they return values close to normal. In fact, the hull is full of sponges, corals and anemones and its samples contain low traces of cesium-137, but without detectable damage.
Context. Man-made radioactivity in the oceans has three main sources according to the International Atomic Energy Agency: the atmospheric nuclear tests of the 60s and 70s, the Chernobyl accident and the authorized discharges from the Sellafield and La Hague reprocessing plants, in the United Kingdom and France respectively. The sunken nuclear submarines, where the Komsomolets would enter, have a marginal contribution. Their importance is more qualitative than quantitative: they are point sources, localized and that tend to worsen over time.
After the Chernobyl disaster in 1986, the Soviet Union came under great international pressure. When the Komsomolets sank three years later, Moscow organized inspection missions with MIR submersibles. When he confirmed that the warheads had been in contact with sea water, he acted: in 1994, with the economy in free fall and western funds involvedRussian technicians they sealed the cracks of the torpedo compartment with titanium plates. Since 2007, Norway has undertaken regular monitoring of the wreck as part of its nuclear safety responsibilities in the Arctic.
Current risk status. For now the nuclear warheads are contained, their sealing works and there are no signs of weapons-grade plutonium in the water. The reactor is the active problem now: the fuel is corroding, the emissions are real, and the research team does not understand why they are intermittent or what the rate is. Any attempt to recover or physically manipulate the submarine would probably be more dangerous than leaving it where it is, since if the radioactive materials reached the atmosphere, the contamination could reach land with worse consequences than today. .
A nuclear laboratory under the sea. The research team has two goals ahead: to understand why the leak is intermittent and whether that corrosion rate is accelerating over time. Inadvertently, the Komsomolets is now a natural laboratory to study what happens to submerged nuclear reactors in the long term. Information that is not trivial, given the number of nuclear devices that sleep on the seabed.
Cover | Karina Victoria
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