Project 22220 icebreaker  Project 22220, also known through the Russian type size series designation LK-60Ya, is a series of Russian nuclear-powered icebreakers. , three vessels have been launched at Baltic Shipyard in Saint Petersburg, fourth has been laid down, and fifth is on order. Project22220 icebreakers are currently the largest and most powerful icebreakers under construction, surpassing their predecessors of the . After the Second World War, the Soviet Union launched an ambitious marine transportation development program with the intention of turning the ice-covered Northern Sea Route into a navigable shipping route which could be then used to extract natural resources from the Arctic. This included replacing the obsolete steam-powered icebreakers with more powerful diesel-electric vessels and culminated with the construction of the first nuclear-powered icebreaker in the late 1950s. The second phase, which began in the early 1970s and continued until the dissolution of the Soviet Union, further expanded the Soviet icebreaker fleet with new nuclear- and diesel-powered icebreakers that enabled uninterrupted year-round operation in the western part of the Northern Sea Route as well as extended the navigating season in the eastern sector. While traffic volumes along the Northern Sea Route declined drastically in the early 1990s due to the slowdown of the Russian economy, a new fleet renewal program was nonetheless initiated. Studies by the Central Marine Research and Design Institute (CNIIMF) and the Central Design Bureau "Iceberg" resulted in "icebreaker type size series" ranging from 7-megawatt auxiliary icebreakers (LK-7) to a 110-megawatt nuclear-powered "icebreaker-leaders" (LK-110Ya). One of the proposed new icebreaker classes, LK-60Ya, was developed as a direct replacement for the previous-generation "Arktika"-class nuclear-powered icebreakers which had entered service in the late 1970s and seen widespread use in the Russian Arctic for decades. On the Dudinka–Murmansk route, they were also intended to replace the shallow-draft nuclear-powered icebreakers "Taymyr" and "Vaygach" which operated primarily in the Yenisei River estuary. This was made possible by the dual-draft functionality of the new icebreakers, ability to de-ballast the vessel when approaching coastal areas. During the summer-autumn navigation season, the icebreakers would be used along the full length of the Northern Sea Route from Murmansk all the way to the Bering Strait.