The OK-150 reactor (1st generation) and its successor, the OK-900 reactor (2nd generation) are

Soviet The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen nation ...

marine nuclear reactors used to power ships at sea. They are

pressurized water reactor A pressurized water reactor (PWR) is a type of light-water nuclear reactor. PWRs constitute the large majority of the world's nuclear power plants (with notable exceptions being the UK, Japan and Canada). In a PWR, the primary coolant (water) i ...

s (PWRs) that use enriched

uranium-235 Uranium-235 (235U or U-235) is an isotope of uranium making up about 0.72% of natural uranium. Unlike the predominant isotope uranium-238, it is fissile, i.e., it can sustain a nuclear chain reaction. It is the only fissile isotope that exi ...

fuel. They have been used in various

Russia Russia (, , ), or the Russian Federation, is a transcontinental country spanning Eastern Europe and Northern Asia. It is the largest country in the world, with its internationally recognised territory covering , and encompassing one-eig ...

nuclear-powered icebreaker A nuclear-powered icebreaker is an icebreaker with an onboard nuclear power plant that produces power for the vessel's propulsion system. , Russia is the only country that builds and operates nuclear-powered icebreakers, having built a number of ...

ships. The reactor was developed by

OKBM OKBM Afrikantov (full name: OAO I. I. Afrikantov OKB Mechanical Engineering, russian: Опытное конструкторское бюро машиностроения им. И. И. Африкантова) is a nuclear engineering com ...

. OK-150 specifications: *Fuel: 5% enriched uranium in the form of

ceramic A ceramic is any of the various hard, brittle, heat-resistant and corrosion-resistant materials made by shaping and then firing an inorganic, nonmetallic material, such as clay, at a high temperature. Common examples are earthenware, porcelain ...

uranium dioxide Uranium dioxide or uranium(IV) oxide (), also known as urania or uranous oxide, is an oxide of uranium, and is a black, radioactive, crystalline powder that naturally occurs in the mineral uraninite. It is used in nuclear fuel rods in nuclear re ...

() fuel elements with a cladding. Different cladding materials were used; initially

zirconium Zirconium is a chemical element with the symbol Zr and atomic number 40. The name ''zirconium'' is taken from the name of the mineral zircon, the most important source of zirconium. The word is related to Persian '' zargun'' (zircon; ''zar-gun'' ...

, later on, stainless steel as well as a zirconium- niobium alloy were tried. *Fuel load: 75 to 85 kilograms *Power production: 90 megawatts Distilled water was used for heat transfer and as a moderator. The core was 1.6 m high by 1 m diameter. It consisted of 219 fuel assemblies, totalling 7,704 fuel pins. There was a biological shield made of

concrete Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most wid ...

mixed with metal shavings. OK-900A specifications: *Fuel: 90% enriched uranium in the form of

metal A metal (from Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typicall ...

lic uranium-zirconium alloy fuel elements *Fuel load: 150.7 kg *Power production: 171 megawatts Three OK-150s were used to power the Soviet icebreaker ''Lenin'' at the time of its launch in 1957. Later, after damage caused by nuclear accidents in 1965 and 1967, these were removed and replaced with two OK-900s.

External links

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Bellona Foundation: Nuclear icebreaker LeninBellona Foundation: Nuclear icebreaker Lenin decommissioning
Soviet naval reactors Pressurized water reactors {{nuclear-energy-stub