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.
Contents |
The first British naval reactor, the PWR1, utilising a core based on a Westinghouse design (though built entirely by Rolls-Royce) and a larger reactor assembly of purely British design[1] 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.[2]
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.
The latest design of the PWR2 is the "Core H", which removes the need for refuelling, allowing a submarine to avoid two reactor refits in its service life. HMS Vanguard will be fitted with the new core during its refit, followed by its three sister ships. The Astute-class submarines will have this full-life core installed. As they were developed for SSBNs, the reactors are considerably larger than those of current British SSNs. The diameter of Astute class hulls have therefore been increased to accommodate the PWR2.
Rolls-Royce Marine Power Operations Ltd claim that the Core H PWR2 can deliver six times the power of the original PWR1 and last four times as long.
In March 2011 a safety assessment of the PWR2 design, by the Defence Nuclear Safety Regulator in November 2009, was released under a Freedom of Information request.[3] The Regulator identified two major areas where UK practice fell significantly short of comparable good practice, loss-of-coolant accident and control of submarine depth following emergency reactor shutdown.[4][5] For the British replacement of the Trident system the option of developing a PWR3 plant based on current US design was under consideration, and in March 2011 Defence Secretary Liam Fox indicated this was the preferred option "because those reactors give us a better safety outlook".[6][7]
In May 2011 the Ministry of Defence announced that the US design had been selected for the PWR3, at a cost of about £3 billion.[8][9]