The VT-1 reactor was the nuclear fission

Nuclear fission

In nuclear physics and nuclear chemistry, nuclear fission is a nuclear reaction in which the nucleus of an atom splits into smaller parts , often producing free neutrons and photons , and releasing a tremendous amount of energy...

 reactor

Nuclear reactor

A nuclear reactor is a device to initiate and control a sustained nuclear chain reaction. Most commonly they are used for generating electricity and for the propulsion of ships. Usually heat from nuclear fission is passed to a working fluid , which runs through turbines that power either ship's...

 used in a pair to power Soviet submarine K-27

Soviet submarine K-27

The K-27 was the only submarine of Projekt 645 in the Soviet Navy. Project 645 did not have or need its own NATO reporting name. That project produced just one test model nuclear submarine, one which incorporated a pair of experimental VT-1 nuclear reactors that used a liquid-metal coolant ,...

 as part of the Soviet Navy

Soviet Navy

The Soviet Navy was the naval arm of the Soviet Armed Forces. Often referred to as the Red Fleet, the Soviet Navy would have played an instrumental role in a Warsaw Pact war with NATO, where it would have attempted to prevent naval convoys from bringing reinforcements across the Atlantic Ocean...

's Project 645 Кит-ЖМТ. It is a liquid metal cooled reactor

Liquid metal cooled reactor

A liquid metal cooled nuclear reactor, liquid metal fast reactor or LMFR is an advanced type of nuclear reactor where the primary coolant is a liquid metal. Liquid metal cooled reactors were first adapted for nuclear submarine use but have also been extensively studied for power generation...

 (LMR), using highly enriched

Enriched uranium

Enriched uranium is a kind of uranium in which the percent composition of uranium-235 has been increased through the process of isotope separation. Natural uranium is 99.284% 238U isotope, with 235U only constituting about 0.711% of its weight...

 uranium-235

Uranium-235

- References :* .* DOE Fundamentals handbook: Nuclear Physics and Reactor theory , .* A piece of U-235 the size of a grain of rice can produce energy equal to that contained in three tons of coal or fourteen barrels of oil. -External links:* * * one of the earliest articles on U-235 for the...

 fuel to produce 73 MWt of power.

K-27 was a November class

November class submarine

The Project 627 class submarine was the Soviet Union's first class of nuclear-powered submarines. The North Atlantic Treaty Organization used the standard radio communication phonetic alphabet to denote submarine classes...

 first generation nuclear submarine, and the only one of its class fitted with liquid metal cooled reactors. However the seven-member Alfa class

Alfa class submarine

The Soviet Union/Russian Navy Project 705 was a class of hunter/killer nuclear powered submarines. The class is also known by the NATO reporting name of Alfa...

were subsequently fitted with liquid metal cooled reactors.