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. == pwr1 == thumb|250px|hms valiant, the first british nuclear submarine to be powered by a british built reactor the first british naval reactor, the pwr1, utilising a core and reactor assembly of purely british designdaniels, r.j, p.135-136, the end of an era: the memoirs of a naval constructor, periscope publishing ltd, 2004, isbn 1-904381-18-9 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 usa.p.529, conway's all the world's fighting ships, us naval institute press, annapolis, 1996, isbn 1-55750-132-7 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. ===pwr1 submarines=== *prototype ** vulcan naval reactor test establishment, dounreay *core 1 ** valiant-class ssn *** *** ** resolution-class ssbn *** *** *** *** *core 2 ** churchill-class ssn *** *** *** *core 3 ** swiftsure-class ssn *** *** *** *** *** *** ** trafalgar-class ssn *** *** *** *** *** *** *** == pwr2 == 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. the latest design of the pwr2 is the "core h", which removes 
Naval_reactors Nuclear_reactors Nuclear_technology_in_the_United_Kingdom Rolls-Royce UK_Trident_programme