MOSCOW — The Russian military submersible that suffered a deadly fire in the Arctic has a nuclear-powered engine, President Vladimir V. Putin revealed on Thursday, but his defense minister said the power unit was not seriously affected by the accident.

The fire erupted on Monday aboard what Russian officials described as a deep-sea research vessel in the Barents Sea, killing 14 Russian Navy officers. The vessel was able to return to port.

Speaking before reporters in the Kremlin on Thursday, Mr. Putin asked Defense Minister Sergei K. Shoigu, “What about the nuclear power unit?” according to a transcript released by the government.

The unit “has been sealed off and all personnel have been removed,” Mr. Shoigu replied. The crew, he said, took “the necessary measures to save the unit, which is in working order. This means we can repair the submersible quickly.”