The Komsomolets sank during its first operational patrol on 7 April 1989, after a fire broke out onboard, killing 42 crew.

For the last 30 years, the wreck of the Komsomolets lies on the bottom of the Norwegian Sea at a depth of about 1,700 meters (5,577 feet).

Since then, authorities have conducted yearly expeditions to monitor radiation levels,

However, only this year’s inspection was the first to use a remotely operated vehicle called 'Aegir 6000', to film the wreckage and take samples which will be further analyzed.

Several samples, taken in and around a ventilation duct on the wreck of the submarine, contained far higher levels of radioactive caesium than one would normally find in the Norwegian Sea, up to 800,000 times higher than normal, said the Norwegian Radiation and Nuclear Safety Authority.

The levels the researchers found in the sample were around 100 Bq per litre, as opposed to around 0.001 Bq per litre elsewhere in the Norwegian Sea.

Over the past few days we have also taken samples a few metres above the duct. We didn’t find any measurable levels of radioactive caesium there, unlike in the duct itself,

...says Justin Gwynn, a researcher at the Norwegian Radiation and Nuclear Safety Authority (DSA).

Just before taking the first sample that gave a high reading, researchers noticed a kind of “cloud” rising up from the duct.

A “cloud” was also seen rising from a grille nearby, where the researchers again measured high levels.

The big question is whether this “cloud” may be related to the radioactivity the researchers observed inside the duct.

On 1st July 2019, 14 Russian sailors were killed aboard a nuclear submarine operating in the Arctic.