The S9G reactor is a naval reactor

United States Naval reactor

United States Naval reactor refers to nuclear reactors used by the United States Navy aboard certain ships to produce power for propulsion, electric power, catapulting airplanes in aircraft carriers, and a few more minor uses. Such Naval nuclear reactors have a complete power plant associated with...

 used by the United States Navy

United States Navy

The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...

 to provide electricity generation

Electricity generation

Electricity generation is the process of generating electric energy from other forms of energy.The fundamental principles of electricity generation were discovered during the 1820s and early 1830s by the British scientist Michael Faraday...

 and propulsion

Nuclear marine propulsion

Nuclear marine propulsion is propulsion of a ship by a nuclear reactor. Naval nuclear propulsion is propulsion that specifically refers to naval warships...

 on Virginia class submarine

Virginia class submarine

The Virginia class is a class of nuclear-powered fast attack submarines in service with the United States Navy. The submarines are designed for a broad spectrum of open-ocean and littoral missions...

s. The S9G designation stands for:

• S = Submarine
  Submarine
  A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...
  
   platform
• 9 = Ninth generation core
  Nuclear reactor core
  A nuclear reactor core is the portion of a nuclear reactor containing the nuclear fuel components where the nuclear reactions take place.- Description :...
  
   designed by the contractor
• G = General Electric
  General Electric
  General Electric Company , or GE, is an American multinational conglomerate corporation incorporated in Schenectady, New York and headquartered in Fairfield, Connecticut, United States...
  
   was the contracted designer

This pressurized water reactor

Pressurized water reactor

Pressurized water reactors constitute a large majority of all western nuclear power plants and are one of three types of light water reactor , the other types being boiling water reactors and supercritical water reactors...

 style nuclear reactor

Nuclear reactor

A nuclear reactor is a device to initiate and control a sustained nuclear chain reaction. Most commonly they are used for generating electricity and for the propulsion of ships. Usually heat from nuclear fission is passed to a working fluid , which runs through turbines that power either ship's...

, designed by Knolls Atomic Power Laboratory

Knolls Atomic Power Laboratory

Knolls Atomic Power Laboratory is a research and development facility dedicated to the support of the US Naval Nuclear Propulsion Program. KAPL is a government-owned, contractor operated laboratory run by Bechtel Marine Propulsion Corporation for the United States Department of Energy. KAPL is...

(then managed by General Electric), is designed to have increased energy density, and new plant components, including a new steam generator design featuring improved corrosion resistance and reduced life-cycle costs. This steam generator will alleviate the corrosion concerns encountered in existing designs of steam generators, while reducing component size and weight and providing greater flexibility in overall arrangement.

This reactor is designed to operate for 33 years without refueling.