The OK-650 reactor is the nuclear fission reactor used for powering the Soviet Navy's Project 685 ÃÂûðòýøú/Plavnik (Mike), Project 971 éÃÂúð-ÃÂ/Shchuka-B (Akula), and Project 945 ÃÂðÃÂÃÂðúÃÂôð/Barrakuda, ÃÂþýôþÃÂ/Kondor, and ÃÂðÃÂÃÂ/Mars (Sierra) submarines, and in pairs to power the Project 941 ÃÂúÃÂûð/Akula (Typhoon) and Project 949 ÃÂÃÂðýøÃÂ/Granit and ÃÂýÃÂõù/Antei (Oscar) third generation submarines.
This pressurized water reactor (PWR) uses 20-45% enriched uranium-235 fuel to produce 190 MW of thermal power. Developed during the 1970s, these reactors were designed with the aim of minimizing accidents and malfunctions. Monitoring subsystems, designed for rapid detection of leaks, were included, along with newer-generation emergency cooling systems for the main reactor core. The reactor is now also used to power the new Project 955 Borei submarines. It was developed by OKBM Afrikantov.