PWR2 reactor

The Rolls-Royce pressurised water reactor (PWR) series has powered British nuclear submarines since the Valiant class, commissioned in 1966. The first British nuclear submarine, HMS Dreadnought, was powered by a Westinghouse S5W reactor.

The first British naval reactor, the PWR1, utilising a core and reactor assembly of purely British design went critical in 1965. Technology transfers under the 1958 US-UK Mutual Defence Agreement eventually made Rolls-Royce entirely self-sufficient in reactor design in exchange for a "considerable amount" of information regarding submarine design and quietening techniques being passed on to the United States.

Rolls Royce and Associates at Derby became the centre for design and manufacture of the reactors. The Ministry of Defence's Vulcan Naval Reactor Test Establishment, at Dounreay, tested each reactor prior to its installation in nuclear submarines.

PWR2 is the latest nuclear reactor designed to power the Royal Navy's submarines. The PWR2 was developed for the Vanguard-class Trident missile submarines and is a development of the PWR1. The first PWR2 reactor was completed in 1985 with testing beginning in August 1987 at the Vulcan Naval Reactor Test Establishment.

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