S5W reactor

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The S5W reactor is a nuclear reactor used by the United States Navy to generate electrical energy and propulsion power for warships . The designation "S5W" ​​stands for:

S = submarine platform

5 = A fifth generation reactor core

W = Westinghouse (the manufacturer / developer)

The simplicity of this pressurized water reactor, its oversizing and redundancy aimed at simple operation and good tolerance in the event of damage in combat. These characteristics were responsible for the good reputation, durability and high level of safety of this type of reactor. The S5W was the standard reactor for submarines in the United States Navy from its first use in 1959 on USS Skipjack (SSN-585) until the introduction of the Los Angeles-class which used an S6G reactor in the 1970s. An S5W was also used by the UK in the Royal Navy's first nuclear powered submarine , the HMS Dreadnought (S101).

Shortly before 1971 (not exactly known), the S5W reactor replaced the older S1W reactor at the S1W prototype test facilities. Although the S5W reactor was now used, the facility was still called the S1W. In order to utilize the additional energy generated by the S5W reactor at higher power levels, steam release valves were constructed in the same S1W building, but outside of the original shell (with the appearance of a submarine).

Two S5W reactors have remained in operation since 2012: Used on MTS-626 (formerly SSBN-626 USS Daniel Webster) and MTS-635 (formerly SSBN-635 USS Sam Rayburn) . These ships are now moored training ships, which are used to train nuclear operators of the US Navy on the former “Naval Weapons Station” in Charleston . Both training ships are equipped with diesel-powered supplemental water injection systems (SWIS) in order to provide sufficient emergency cooling water in the event of an accident.

Later model S5W reactors are often "refilled" with S3G-3 cores, the third version of the S3G core .


  • US Nuclear Propulsion. Forecast International. August 2000 (archived 8/2001). Retrieved September 14, 2008.