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USS ''Seawolf'' (SSN-575), a unique submarine, was the third ship of the United States Navy to be named for the seawolf, the second nuclear submarine, and the only US submarine built with a liquid metal cooled (sodium) nuclear reactor known as the Submarine Intermediate Reactor (SIR) or Liquid Metal Fast Reactor (LMFR), later designated S2G. Her overall design was a variant of , but with numerous detail changes, such as a conning tower, stepped sail, and the BQR-4 passive sonar mounted on top of the bow instead of below it. Her distinctive reactor was later replaced with a standard pressurized water reactor, the replacement process lasting from 12 December 1958 to 30 September 1960. ==Comparison to ''Nautilus''== ''Seawolf'' was the same basic "double hull" twin-screw submarine design as her predecessor , but her propulsion system was more technologically advanced. The Submarine Intermediate Reactor (SIR) nuclear plant was designed by General Electric's Knolls Atomic Power Laboratory and prototyped in West Milton, New York. The prototype plant was eventually designated S1G and ''Seawolf'' 's plant as S2G. Carrying a liquid sodium, epithermal, superheated, more powerful reactor and steam powerplant, rather than ''Nautilus alternative light water reactor and saturated steam plant, reduced the size of the machinery in the engineering spaces nearly 40%. Her liquid-sodium cooled epithermal reactor was more thermally efficient than a light water-cooled system, quieter, and presumably better system, but posed, presumably and arguably, several safety hazards for the ship and crew. Primary system pressure was and the only moving part in the primary system was the liquid sodium which was magnetically pumped by electromagnets external to primary piping. The phrase "Blue Haze" was often associated with the boat, which was Cherenkov radiation, visible on a dark night, in the sea water surrounding the hull, outboard of the reactor compartment, during the decay of radioactive 24Na (sodium-24) in the primary system over essentially the first half-life (15 hrs). There was only one coolant leak ever noted, and that was during fitting out in the yards. However the superheaters suffered from tube sheet welding cracks which allowed high pressure steam to leak into the low pressure primary system and react with the sodium to form sodium hydroxide and H2. Sodium also has a small fission capture cross section which formed 3H as a free gas in the primary system. This complicated system operation since 3H is radioactive, would mix with the H2 from Na-H2O reaction and had to be contained. The Atomic Energy Commission historians' account of the sodium-cooled reactor experience was: The S2G reactor was replaced with a pressurized water reactor similar to ''Nautilus'' and designated S2Wa, the replacement process lasting from 12 December 1958 to 30 September 1960. Although fully armed, ''Seawolf'', like the first nuclear submarine, ''Nautilus'', was primarily an experimental vessel. ''Seawolf'' was originally thought of publicly as a hunter-killer submarine, but in fact was intended to be a one-off test platform for the SIR (aka S2G) LMFR reactor and future sonar platforms. Her future uses, after the reactor plant was replaced with a light water system, included covert operations in foreign waters, for which she was converted January 1971-June 1973.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「USS Seawolf (SSN-575)」の詳細全文を読む スポンサード リンク
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