The S6G reactor plant consists of the reactor coolant, steam generating and other support systems that supplies steam to the engine room of United States Navy's Los Angeles-class submarines. The 688-class engine room powers two steam turbines that propel a single shaft rated at 30,000 horsepower (33,000 horsepower for USS Chicago (SSN-721) and later) plus the electrical generation system. The S6G reactor plant was originally designed to use the D1G core 2 reactor first used on the Bainbridge-class guided missile cruisers rated at 148 MW. All submarines following (and including) USS Providence (SSN-719) were built with a D2W reactor rated at 165 MW. The D1G-2 reactors are being replaced with D2W reactors when the ships are refueled. The United States Navy (USN) is the branch of the United States armed forces responsible for naval operations. ... The Los Angeles-class attack submarines (SSN) is the most numerous class of nuclear powered submarines built by any nation, and forms the bulk of the U.S. attack submarine force as of 2004. ... A steam turbine extracts the energy of pressurized superheated steam as mechanical movement. ... USS Chicago (SSN-721), a Los Angeles-class submarine, was the fourth ship of the United States Navy to be named for Chicago, Illinois. ... USS Bainbridge (DLGN/CGN-25) was a nuclear-powered version of the Leahy-class guided missile frigate/cruiser (DLG/CG-16 class). ... USS Providence (SSN-719), a Los Angeles-class submarine, was the fifth ship of the United States Navy to be named for Providence, Rhode Island. ...

U.S. Naval reactors are assigned three-character designations consisting of a letter representing the ship type the reactor is designed for, a consecutive generation number, and a letter indicating the reactor's designer.

The ship types are: "A" for aircraft carrier, "C" for cruiser, "D" for destroyer, or "S" for submarine. An aircraft carrier is a warship whose main role is to deploy and recover aircraft—in effect acting as a sea-going airbase. ... USS Port Royal, a Ticonderoga-class guided missile cruiser, launched in 1994. ... USS Lassen, an Arleigh Burke-class destroyer In naval terminology, a destroyer is a fast and maneuverable yet long-endurance warship intended to escort larger vessels in a fleet or battle group and defend them against smaller, short-range attackers (originally torpedo boats, later submarines and aircraft). ... USS Los Angeles A submarine is a specialized watercraft that can operate underwater. ...

The designers are: "W" for Westinghouse, "G" for General Electric, and "C" for Combustion Engineering. Westinghouse logo (designed by Paul Rand) The Westinghouse Electric Company, headquartered in Monroeville, Pennsylvania, is an organization founded by George Westinghouse in 1886. ... The General Electric Company, or GE, NYSE: GE is a multinational technology and services company. ...

Specifications are classified, but the S6G can propel a Los Angeles-class submarine at over 25 knots when surfaced and over 30 knots while submerged.