COPENHAGEN, Denmark (AP) — Norwegian authorities say a joint Norwegian-Russian expedition will assess whether a Russian submarine that sank 30 years ago is leaking radioactive material.

The Radiation and Nuclear Safety Authority say a Norwegian research vessel will set off Saturday from Tromsoe, northern Norway, to the Arctic Barents Sea where the Komsomolets submarine sank in 1989.

Forty-two of its 69 crewmen died in a fire, and the submarine's nuclear reactor and two nuclear warheads are still on board.

The agency said Friday that a remote-controlled submersible would be used and the work "would be demanding" as "lies deep" at about 1,700 meters (5,610 feet)

Norway has found elevated concentrations of the radioactive substance cesium-137 around the wreck but said the levels were barely detectable and presented no danger.