Russia says the main cause of the deadly incident on board a submersible which killed 14 crew on Monday was a fire in the battery compartment.
Defense Minister Sergei Shoigu also said the top-secret military craft was nuclear-powered but the reactor had been isolated from the fire.
Fourteen crew members died of smoke inhalation as a result of the fire on the submersible in the Barents Sea.
The craft is now at Severomorsk, the main base of Russia’s Northern Fleet.
“The main cause has been established, it was a fire in the battery compartment, and then it spread,” Mr Shoigu told President Vladimir Putin in a meeting on July 4.
“The nuclear power unit on the vessel has been fully isolated and nobody is in that section. The crew took all the necessary measures to protect the unit, and it is in full working condition. This leads to us to hope that in quite a short time the vessel can be put back into service.”
Severomorsk was also home to the Russian Kursk nuclear submarine, which sank in 2000 killing 118 sailors.
The Kremlin had previously kept details about the vessel confidential, adding that it was in “the interests of the state and state security”.
The crew on board were involved in exploring the Arctic seabed.
In 2000, Mr Putin was heavily criticised for the way he handled the Kursk submarine disaster. Media reports at the time showed the president enjoying a holiday at a Black Sea villa as families of the victims demanded information about their relatives.