Arktika Class Icebreaker - Propulsion

Propulsion

Both the OK-150 and OK-900(A) are Pressurized water reactors, meaning that cooling water is continually pumped under pressure through the reactor to remove heat, keeping the cores and the reactor cool. The heated water is pumped from the reactor to a Boiler (4 boilers per reactor), where it transfers its heat into another body of water, producing steam at a rate of 30 kg/cm3. Each set of four boilers drives two Steam turbines, which turn three Dynamos. One kilovolt of Direct current is then delivered to three double-wound motors directly connected to the Propeller, providing an average screw velocity of 120-180 rpm. Five auxiliary steam turbines are tied into the plant to provide electricity, turning dynamos which develop 30 MW. Three fixed-pitch propellers provide the Arktika with its thrust, power, and maneuverability. The starboard and amidships propellers turn clockwise while the port turns counter clockwise to compensate. Each propeller sits at the end of a 20 meter (65.6 ft) shaft and has four blades, which weigh seven tons and are attached by nine bolts to the hub which is 5.7 meters (18.7 ft) in diameter and weighs 50 tonnes. The Arktika also carries four spare blades along with the appropriate diving equipment and tools so that propeller repairs may be made at sea; the operation can take anywhere from 1–4 days depending on the extent of the damage. Each propeller can deliver a propulsive force of 480 tons with 18-43 MW (25,000 shaft horsepower) . This amounts to a maximum speed of 22 knots (44 km/h, 27 mph) on open water, full speed of 19 knots (35 km/h, 22 mph), and an average speed of 3 knots (5.5 km/h, 3.5 mph) while icebreaking 2-3m thick ice.