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Project 92M Lenin

Even the best ice-breakers with a diesel power plant carry fuel for no more than 30-40 days. In the harsh conditions of the Arctic it is clearly not enough: the fight against ice requires a great deal of fuel. During an hour a powerful icebreaker often burns up to three tons of oil. While fuel accounted for nearly one-third the weight of the ice in the Arctic period, a ship would have to repeatedly enter the base to take fuel. There have been cases where caravans of ships winter in the polar ice only because fuel for ledokolah faded away early.

Launched by the Soviet Union during the Cold War, the World's first nuclear-powered surface ship never fired a shot in anger: it had no guns, missiles, depth charges or weapons of any kind. This was the progressive solution: to ice-breaker is necessary the unlimited independence, i.e., the ability for long to be located in the sea without the replenishment of supplies of fuel, and large installed power, since in the duel ship - ice chances to the victory will belong to the vessel, which will prove to be stronger than the element. All this is guaranteed by the nuclear engine.

The decision to build the world's first nuclear icebreaker was passed by the Cabinet of Ministers of the USSR on Nov 20 1953. The icebreaker was launched on Dec 5 1957 in Leningrad. Built in the Admiralty Shipyards of what was then Leningrad, the Soviet icebreaker Lenin was launched on December 5, 1957. On Sept 15 1959 it sailed out for its first voyage. The designer of the ship is Anatoly Alexandrov, the first captain was Pavel Ponomaryov.

The icebreaker is of turboelectric type with a continuous navigation time of 1 year. The length of the icebreaker is 134 m, the width 26.7 m, the shaft horsepower 44,000, the tonnage 16,000, a maximum speed in deep quiet water of 18 knots, and a continuous speed in 2.4 m thick ice of 2 knots. The icebreaker has three screw propellers. The maximum number of revolutions at maximum speed of the center propeller is 185 rot/ min and of the board propellers 205 rot/min. The height of the board at the middle is 16.1 m, and the draft is 9.2 m. The screw propeller thrust accelerated at the front speed at mooring is 330 tons.

The weight of the power plant including the shielding (total) is 3017 tons, or (specific) 68.5 ton/hp. The shield weight is 1963 tons, and the total weight of the mechanical installation (including the electric motors for propellers and power plant but without nuclear power plant) is 2750 tons. The total steam capacity is 360 toas/hr. The steam parameters are (temperature) 310 C and (pressure) 28 atm. The steam consumption for main generators is 204 tons /hr. The efficiency of the auxiliary steam boiler is 10 tons/hr, and the capacity of the auxiliary power plant is 6200 kw.

The icebreaker was powered by three individual reactors; there is a lOO% reserve for circulating the pumps. The power plant is divided into two separate units located at the prow and stern of the ship. The third reactur is used only in an emergency. The reactor characteristics are: diameter, 1 m; height, 1.6 m; fuel, sintered uranium dioxide 5% enriched with U/sup 235/; loading (with U/sup 235/; sheath materia), zirconium alloy or stainless steel; burnout control material, a natural mixture of boron isotopes; the thermal capacity, 90 Mw; the maximum thermal load (considering the curve of the energy losses) - 106 kcal/m/sup 2/.hr; the inlet water temperature, 248'C; and the outiet water temperature, 825 C.

Lenin is said to have suffered one, if not two, major radiation accidents. The date and details remain a hazy, and it is unclear whether these are two separate events or [far more likely] garbled accounts of a single event. According to the U.S. Navy, "There is strong evidence that this ship experienced a nuclearrelated casualty in the 1960s, requiring the ship to be abandoned for over a year before work was begun to replace the three reactors with two."

By one telling, in February 1965 the icebreaker Lenin suffered a reactor accident when the reactor was starved of cooling water. It is said that thirty crew were fatally irradiated, and 60% of the nuclear fuel rods are damaged. By another telling, in late 1966 or early 1967 Lenin was said to have suffered a nuclear reactor accident that killed several [possibly 27 to 30] crew members, with some reports citing a "reactor meltdown". Other crew member were said to ahve received powerful irradiation resulting in radiation sickness.

By the mid-1990s Russian information had become available on the NS Lenin accident in the autumn of 1966. "At this time the three reactors of the Lenin nuclear power plant were undergoing their second refueling. Due to an operator error the water was drained from the core of the second reactor hefore the refueling, and the core was left without water for some time. The decay heat of the core and the lack of cooling caused partial melting of part of the core. When after the accident the fuel was to be removed, it was possible to remove only 94 of the irradiated fuel elements. The remaining 125 elements could not be withdrawn from the core. The damaged fuel had to be removed from the reactor tank by removal of the core insert or basket consisting of the bottom grid plate and the cylindrical thermal shield. No information has so far been made available on the details of the accident or on the number of casualties, if any." "The loss-of-coolant accident which NS Lenin suffered may have to do with the fact that unlike modern pressurized water reactors the OK-150 reactors had only the coolant outlet (and not the coolant inlet) placed above the top of the core. In OK-150 the inlet is placed at the bottom of the pressure vessel. Thus the draining cif the core could be due to the opening of a valve in the inlet tube."

There were also rumors that NS Lenin had been disposed of by sinking following the accident; these were of course untrue since NS Lenin continued its operation with the new reactors from 1970/71 until 1989. In the West it had been claimed that NS Lenin was towed to the position of dumping, and that here the whole reactor compartment was cut out of the hul1 by use of explosives and dumped directly to the sea bottom. This claim is not correct. The damaged power plant was cut out in Severodvinsk. Since the damaged fuel could not be removed from the core basket, it was filled by a furfurol-based mixture, lifted out of the reactor tank and placed in a reimforced concrete container with a steel casing. The container was then disposed of by dumping in the sea, close to the dumping place of the Lenin power plant.

Lenin was said to have been laid up in an Arctic for a period that might have lasted for as long as five years. The ship was said to have abandoned for over one year before replacement of the old reactors could begin. The vessel was repaired and the three OK-150 reactors replaced. The ship's three reactors were removed and dumped into Tsivolko Fjord on the eastern side of Novaya Zemlya in 1967, without spent fuel. It is reported that 60% of the fuel elements from the reactors packed in a container and dumped at the same location. It is known that two new KLT-40 reactors were installed and the ship again entered service in 1970.

The inherent safety characteristics of the KLT-40 [used in subsequent atomic icebreakers] include a large negative temperature coefficient for the reactor core, where increasing core temperature lowers core power. This is achieved in the KLT-40 design without the use of soluble boron in the coolant water. Instead, a large quantity of burnable poison is used in the fuel and more control rods are incorporated in the design to ensure a cold shutdown. The reactor safety system is designed as an active system that relies on gravitational acceleration of spring-loaded control rods in response to an initiating event. After the reactor is shutdown, the residual heat in the core can be removed from the primary coolant through the secondary system. An emergency core coolant system provides water in case of a LOCA. A feedwater system with three pumps is also provided to compensate for small leaks and, if necessary, to inject a liquid absorber into the core. Since the reactor core is maintained under water, however, the design has the capacity to remove the residual heat passively following a primary circuit break.

Lenin retired in 1989, having completed three decades of service. During its 30-year life the icebreaker passed 654,400 sea miles (560,600 through the ice) and towed 3,741 ships. The first nuclear-powered icebreaker was converted into a museum, but it has descendents. Soviet ship-builders were not mistaken, after placing nuclear reactor on the ice-breaker vessel.

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