S2G reactor

The S2G reactor was a naval reactor used by the United States Navy to provide electricity generation and propulsion on warships, and the only liquid metal cooled reactor yet deployed by the US Navy. The S2G designation stands for:

* S = Submarine platform
* 2 = Second generation core designed by the contractor
* G = General Electric was the contracted designer

An S2G was the initial power plant of USS "Seawolf" (SSN-575). This was one of three sodium cooled fast reactors ordered for the "Seawolf" program at the same time as three PWR units were ordered to support the USS "Nautilus" (SSN-571) program; In each case, one reactor was land-based for training and research, one intended for installation on a submarine, and one spare. The land-based unit corresponding to S2G was S1G reactor.

Persistent superheater problems on "Seawolf" caused the superheaters to be bypassed, resulting in mediocre performance. This and concern for the dangers posed by liquid sodium coolant led to the PWR type being selected instead as the standard US naval reactor type, and the S2G on "Seawolf" was replaced by the spare S2Wa reactor from the "Nautilus" program.