S5G reactor
Encyclopedia
The S5G reactor was a prototype naval reactor
designed for the United States Navy
to provide electricity generation
and propulsion
on submarine
s. The S5G designation stands for:
The S5G was a pressurized water reactor
plant with two coolant loops and two steam generators
. The design featured a reactor vessel
situated low in the boat and the steam generators
located high in the boat to support natural circulation
of the primary coolant.
This nuclear reactor
was installed both as a land-based prototype at the Nuclear Power Training Unit
, Idaho National Laboratory
near Arco, Idaho
, and on board the USS Narwhal (SSN-671)
; both have been decommissioned. It was intended to test the potential contribution of natural circulation
technology to submarine
quieting.
Reactor primary coolant pumps are a main source of noise from submarines. The elimination of coolant pumps and associated equipment would also reduce mechanical complexity and the space required by propulsion equipment. Its design was the direct ancestor of the S8G reactor
used on the Ohio class ballistic missile submarines
, another very quiet submarine
.
The S5G had primary coolant pumps, but they were only needed for very high speeds. And since the reactor core was designed with very smooth paths for the coolant, the coolant pumps were smaller and quieter than the pumps used by the competing S5W
core. In most cases, the submarine could be operated without using coolant pumps at all. The reduction in electrical requirements enabled this design to use two lower-capacity, but quieter electrical turbine generators. The quiet design resulted in a larger hull diameter and a larger primary coolant intake pipe than the competing S5W reactor. Due to the larger size, the S5G was not used in subsequent attack submarines, but was a precursor to the S8G reactor used in the larger Ohio class submarines.
To further reduce engine plant noise, the typical propulsion setup of two steam turbine
s driving the screw through a reduction gear
unit was changed instead to one large propulsion turbine with no reduction gears. This eliminated the noise from the main reduction gears, but at the cost of requiring a huge main propulsion turbine. The turbine was cylindrical, about 12 feet in diameter, and about 30 feet long. The massive size was a result of the slow rotations needed to directly drive the screw. The same propulsion setup was used for both the USS Narwhal and the land-based prototype.
The concept of a natural circulation
plant was relatively new when the Navy requested this design. The prototype plant in Idaho was therefore given quite a rigorous performance shakedown to determine if such a design would work for the U.S. Navy. It was largely a success, although the design never became the basis for any more fast-attack submarines besides the Narwhal. The prototype testing included the simulation of the entire engine room of a submarine. Floating the plant in a large pool of water allowed the prototype to be rotated on its long axis by torquing large flywheels mounted ahead of the reactor compartment to simulate a hard turn. The effects on natural circulation were evaluated at various angles and during simulated hard maneuvers.
The S5G prototype was permanently shut down in May 1995.
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...
designed for 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 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...
s. The S5G designation stands for:
- S = Submarine platform
- 5 = Fifth generation coreNuclear reactor coreA 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 ElectricGeneral ElectricGeneral 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
The S5G was a 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...
plant with two coolant loops and two steam generators
Steam generator (nuclear power)
Steam generators are heat exchangers used to convert water into steam from heat produced in a nuclear reactor core. They are used in pressurized water reactors between the primary and secondary coolant loops....
. The design featured a reactor vessel
Reactor vessel
In a nuclear power plant, the reactor vessel is a pressure vessel containing the Nuclear reactor coolant and reactor core.Not all power reactors have a reactor vessel. Power reactors are generally classified by the type of coolant rather than by the configuration of the reactor vessel used to...
situated low in the boat and the steam generators
Steam generator (nuclear power)
Steam generators are heat exchangers used to convert water into steam from heat produced in a nuclear reactor core. They are used in pressurized water reactors between the primary and secondary coolant loops....
located high in the boat to support natural circulation
Natural circulation
Natural circulation refers to the ability of a fluid in a system to circulate continuously, with gravity and changes in heat energy being the only driving force. This force is known as "thermal head" or "thermal driving head."...
of the primary coolant.
This 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...
was installed both as a land-based prototype at the Nuclear Power Training Unit
Naval Reactors Facility
Naval Reactors Facility is located 52 miles northwest of Idaho Falls. The NRF is a United States Department of Energy-Naval Reactors facility where three nuclear propulsion prototypes A1W, S1W and S5G were located...
, Idaho National Laboratory
Idaho National Laboratory
Idaho National Laboratory is an complex located in the high desert of eastern Idaho, between the town of Arco to the west and the cities of Idaho Falls and Blackfoot to the east. It lies within Butte, Bingham, Bonneville and Jefferson counties...
near Arco, Idaho
Arco, Idaho
Arco is a city in Butte County, Idaho, United States. The population was 995 at the 2010 census. The city is the county seat of Butte County.Craters of the Moon National Monument is located along U.S. Route 20, southwest of the city. The Idaho National Laboratory is located east of Arco...
, and on board the USS Narwhal (SSN-671)
USS Narwhal (SSN-671)
USS Narwhal , a unique submarine, was the third ship of the United States Navy to be named for the narwhal, a gray and white arctic whale....
; both have been decommissioned. It was intended to test the potential contribution of natural circulation
Natural circulation
Natural circulation refers to the ability of a fluid in a system to circulate continuously, with gravity and changes in heat energy being the only driving force. This force is known as "thermal head" or "thermal driving head."...
technology to 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...
quieting.
Reactor primary coolant pumps are a main source of noise from submarines. The elimination of coolant pumps and associated equipment would also reduce mechanical complexity and the space required by propulsion equipment. Its design was the direct ancestor of the S8G reactor
S8G reactor
The S8G reactor is a naval reactor used by the United States Navy to provide electricity generation and propulsion on warships. The S8G designation stands for:* S = Submarine platform* 8 = Eighth generation core designed by the contractor...
used on the Ohio class ballistic missile submarines
Ohio class submarine
The Ohio class is a class of nuclear-powered submarines used by the United States Navy. The United States has 18 Ohio-class submarines:...
, another very quiet 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...
.
The S5G had primary coolant pumps, but they were only needed for very high speeds. And since the reactor core was designed with very smooth paths for the coolant, the coolant pumps were smaller and quieter than the pumps used by the competing S5W
S5W reactor
The S5W reactor is a nuclear reactor used by the United States Navy to provide electricity generation and propulsion on warships. The S5W designation stands for:* S = Submarine platform* 5 = Fifth generation core designed by the contractor...
core. In most cases, the submarine could be operated without using coolant pumps at all. The reduction in electrical requirements enabled this design to use two lower-capacity, but quieter electrical turbine generators. The quiet design resulted in a larger hull diameter and a larger primary coolant intake pipe than the competing S5W reactor. Due to the larger size, the S5G was not used in subsequent attack submarines, but was a precursor to the S8G reactor used in the larger Ohio class submarines.
To further reduce engine plant noise, the typical propulsion setup of two steam turbine
Steam turbine
A steam turbine is a mechanical device that extracts thermal energy from pressurized steam, and converts it into rotary motion. Its modern manifestation was invented by Sir Charles Parsons in 1884....
s driving the screw through a reduction gear
Gear
A gear is a rotating machine part having cut teeth, or cogs, which mesh with another toothed part in order to transmit torque. Two or more gears working in tandem are called a transmission and can produce a mechanical advantage through a gear ratio and thus may be considered a simple machine....
unit was changed instead to one large propulsion turbine with no reduction gears. This eliminated the noise from the main reduction gears, but at the cost of requiring a huge main propulsion turbine. The turbine was cylindrical, about 12 feet in diameter, and about 30 feet long. The massive size was a result of the slow rotations needed to directly drive the screw. The same propulsion setup was used for both the USS Narwhal and the land-based prototype.
The concept of a natural circulation
Natural circulation
Natural circulation refers to the ability of a fluid in a system to circulate continuously, with gravity and changes in heat energy being the only driving force. This force is known as "thermal head" or "thermal driving head."...
plant was relatively new when the Navy requested this design. The prototype plant in Idaho was therefore given quite a rigorous performance shakedown to determine if such a design would work for the U.S. Navy. It was largely a success, although the design never became the basis for any more fast-attack submarines besides the Narwhal. The prototype testing included the simulation of the entire engine room of a submarine. Floating the plant in a large pool of water allowed the prototype to be rotated on its long axis by torquing large flywheels mounted ahead of the reactor compartment to simulate a hard turn. The effects on natural circulation were evaluated at various angles and during simulated hard maneuvers.
The S5G prototype was permanently shut down in May 1995.
External links
- Stacy, Susan M (2000). "Proving the Principle, A History of The Idaho National Engineering and Environmental Laboratory, 1949-1999", (Chapter 10) http://www.inl.gov/proving-the-principle/chapter_10.pdf