S5G reactor
The
S5G nuclear reactor, the fifth submarine reactor designed by
General Electric, was installed as a land based prototype at the
Nuclear Power Training Unit,
Idaho National Engineering Laboratory near
Idaho Falls, Idaho and on
Narwhal (SSN-671). It was intended to test the potential contribution of
natural circulation technology to submarine quieting.
Reactor primary coolant pumps are one of the primary sources of noise from submarines, and the elimination of coolant pumps and associated equipment would also reduce mechanical complexity and the volume required by propulsion equipment. Its design was the direct ancestor of the
S8G reactor used in the
Ohio-class submarines.
To further reduce engine plant noise, the normal propulsion setup of two steam turbines driving the screw through a reduction gear unit was changed to one large propulsion turbine with no reduction gears. This would eliminate the noise from the main reduction gears, but the cost was to have a huge main propulsion turbine. It was cylindrical, about 12 feet in diameter, and about 30 feet long. This size was necessary to allow it to turn slow enough to directly drive the screw and be fairly efficient in doing so. The same propulsion setup was used on USS Narwhal.
