The VT-1 reactor was the nuclear fission reactor used in a pair to power Soviet submarine K-27 as part of the Soviet Navy's Project 645 Кит-ЖМТ. It is a liquid metal cooled reactor (LMR), using highly enriched uranium-235 fuel to produce 73 MW of power.
K-27 was a November class first generation nuclear submarine, and the only one of its class fitted with liquid metal cooled reactors. However the seven-member Alfa class were subsequently fitted with liquid metal cooled reactors.
It was developed by OKB Gidropress in cooperation with IPPE.