The various types of the VM reactor series are nuclear pressurized water reactors (PWR). They are used singly or in pairs to power the Soviet Navy's submarines.
- The VM-A reactor was the nuclear fission reactor used in pairs to power the Soviet Navy's Project 658 and 701 (Hotel), Project 659 and 675 (Echo), and Project 627 Кит (November) first-generation submarines. It was a pressurized water reactor (PWR), using 20% enriched uranium-235 fuel to produce 70 MW of power. This is the reactor that powered the K-19.
- The VM-4 reactor is a nuclear fission reactor using 20% enriched uranium-235 fuel to produce 70-90 MW of power. It is used:
- singly to power the Project 670 Скат and Чайка-Б (Charlie) submarines
- in pairs to power the Project 671 Ёрш and Щука (Victor), Project 667 Мурена, Кальмар, and Дельфин (Delta), and Project 667 Навага, Налим, Груша, and Андромеда (Yankee) second-generation submarines.
- The VM-5 reactor was the nuclear fission reactor used in a pair to power the Soviet Navy's Project 661 Анчар (Papa) second-generation submarine. It was a pressurized water reactor (PWR) using enriched uranium-235 fuel to produce 177 MW of power.