The Rolls-Royce pressurised water reactor (PWR) series has powered the Royal Navy's nuclear submarines since the Valiant class, commissioned in 1966. [1]
Nuclear reactor designs, operating methods and performance standards are highly classified. [2]
The United Kingdom's first nuclear-powered submarine HMS Dreadnought, commissioned in 1963, was powered by an American Westinghouse S5W reactor, provided to Britain under the 1958 US-UK Mutual Defence Agreement. [3] [4]
The first British naval reactor was the PWR1. It was based on a core and reactor assembly of purely British design. The reactor first went critical in 1965, four years later than planned. [5] Technology transfers under the 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. [6] [7] [8] [9]
The reactor fuel was highly enriched uranium (HEU) enriched to between 93% and 97%. Each nuclear core had a life of about 10 years, so had to be refueled about twice during the lifetime of a submarine. [10] [11]
Rolls-Royce Marine Power Operations at Derby was the centre for design and manufacture of the UK's submarine reactors, and remains so today. The Ministry of Defence's Vulcan Naval Reactor Test Establishment (NRTE), at Dounreay, tested each reactor core design prior to its installation in nuclear 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 reactor fuel is highly enriched uranium (HEU) enriched to between 93% and 97%. The latest PWR2 reactor core design is "Core H", which has a life of about 30 years removing the need for refueling, allowing a submarine to avoid two reactor refits in its service life. [10] [11] HMS Vanguard was fitted with the new core during its refit, followed by her three sister boats. The Astute-class submarines have this full-life core installed. As they were developed for SSBNs, the reactors are considerably larger than those of then-current British fleet submarines. The diameter of then-forthcoming Astute-class hulls was therefore increased to accommodate the PWR2.
A safety assessment of the PWR2 design by the Defence Nuclear Safety Regulator in November 2009 was released under a Freedom of Information request in March 2011. [12] [13] 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. [14] [13] The regulator concluded that PWR2 was "potentially vulnerable to a structural failure of the primary circuit", which was a failure mode with significant safety hazards to crew and the public. [13] [15]
In January 2012 radiation was detected in the PWR2 test reactor's coolant water, caused by a microscopic breach in fuel cladding. This discovery led to HMS Vanguard being refueled early and contingency measures being applied to other Vanguard and Astute-class submarines, at a cost of £270 million. This was not revealed to the public until 2014. [16] [17]
In February 2013, the Ministry of Defence (MoD) awarded Rolls-Royce a £800 million ten year "foundation" contract to "deliver and maintain" the reactors of the Astute-class and the Vanguard-class replacement the Successor. [18] [19] In February 2019, the MoD awarded Rolls-Royce a £235 million three year contract for Nuclear Propulsion Lifetime Management for the Trafalgar, Vanguard and Astute classes. [20]
Three propulsion options were considered for the replacement of the Vanguard-class, the Successor: PWR2, PWR2b (derivative with improved performance) and PWR3. [21] PWR3 was a new system "based on a US design but using UK reactor technology". [22] [23] The Royal Institution of Naval Architects reported that it was likely that the UK was given access to the US Navy S9G reactor design used in their Virginia-class submarines. [24] The PWR3 was a simpler and safer design with a longer life and lower maintenance requirements than the PWR2 variants and cost roughly the same as the PWR2b. [21] The PWR3 has 30% fewer parts compared to the PWR2. [25]
In March 2011, Defence Secretary Liam Fox said the PWR3 was the preferred option "because those reactors give us a better safety outlook". [26] [27] In May 2011, the Ministry of Defence announced that PWR3 had been selected for the Successor (later named the Dreadnought-class in 2016). [21] [15] The PWR3 cost about £50 million more per boat to purchase and operate compared to PWR2 designs. This is offset by the PWR3's longer life over the 25-year life PWR2 designs. [21] The PWR3 does not require reactor core prototype tests; instead computational modelling is used. [28] [29] Consequently, the Shore Test Facility (STF) reactor located at Vulcan NRTE was shut down in 2015. [30]
In June 2012, the MoD awarded Rolls-Royce a £600 million contract to produce reactors for the Dreadnought-class and also for the final boat of the Astute-class HMS Agincourt. [31] The MoD also awarded Rolls-Royce a further £500 million to refurbish their Rolls-Royce Marine Power Operations reactor core manufacturing plant at Derby to manufacture the PWR3 and to extend the plant's operational life to 2056. [31] [32] In January 2020, the National Audit Office reported that the construction of the plant was five years behind schedule and was now forecast to be in service in 2026. [32] [33]
In 2025, the MoD awarded Rolls-Royce a £9 billion eight-year contract, named Unity, covering research, design, manufacture, and support for Royal Navy nuclear submarine reactors. Defence Secretary John Healey said "This investment in Britain’s defence will deliver a long-term boost to British business, jobs and national security." [34]
Rolls Royce is building the reactor for SSN-AUKUS, [35] which may be the PWR3, or a derivative. [36] [37]
The Trafalgar class was a class of nuclear-powered fleet submarines (SSNs) in service with the Royal Navy, and the successor to the Swiftsure class. Like the majority of Royal Navy nuclear submarines, all seven boats were constructed at Barrow-in-Furness shipyard, Cumbria. The class made up part of the Royal Navy's nuclear-powered ‘hunter-killer’ submarine force. The Trafalgar class was replaced by the larger and more capable Astute class, of which five are commissioned.
The Vanguard class is a class of nuclear-powered ballistic missile submarines (SSBNs) in service with the Royal Navy. The class was introduced in 1994 as part of the Trident nuclear programme, and comprises four vessels: Vanguard, Victorious, Vigilant and Vengeance, built between 1986 and 1999 at Barrow-in-Furness by Vickers Shipbuilding and Engineering, now owned by BAE Systems. All four boats are based at HM Naval Base Clyde , 40 km (25 mi) west of Glasgow, Scotland.
The Astute class is the latest class of nuclear-powered fleet submarines (SSNs) in service with the Royal Navy. The boats are being constructed by BAE Systems Submarines at Barrow-in-Furness. Seven boats will be constructed: the first of class, Astute, was launched by Camilla, Duchess of Cornwall, in 2007, commissioned in 2010, and declared fully operational in May 2014. The Astute class is the replacement for the Trafalgar-class fleet submarines in Royal Navy service.
Rolls-Royce Holdings plc is a British multinational aerospace and defence company incorporated in February 2011. The company owns Rolls-Royce, a business established in 1904 which today designs, manufactures and distributes power systems for aviation and other industries. Rolls-Royce is the world's second-largest maker of aircraft engines and has major businesses in the marine propulsion and energy sectors.
HMS Ambush is an Astute-class nuclear-powered attack submarine of the Royal Navy, the second boat of her class.
HMS Artful is the third Astute-class nuclear-powered fleet submarine of the British Royal Navy. She is the second submarine of the Royal Navy to bear this name. Artful was ordered from GEC's Marconi Marine on 17 March 1997, and was constructed at Barrow in Furness. She was named on 20 September 2013, was rolled out of the shipyard construction hall on 16 May 2014, and was due to start sea trials in early 2015. Artful made her first successful basin dive in October 2014, and sailed on 13 August 2015 for sea trials. Artful was handed over the Royal Navy on 14 December 2015, and commissioned on 18 March 2016.
The seventh Royal Navy ship to be named HMS Dreadnought was the United Kingdom's first nuclear-powered submarine, built by Vickers Armstrongs at Barrow-in-Furness. Launched by Queen Elizabeth II on Trafalgar Day 1960 and commissioned into service with the Royal Navy in April 1963, she continued in service until 1980. The submarine was powered by a S5W reactor, a design made available as a direct result of the 1958 US–UK Mutual Defence Agreement.
A nuclear submarine is a submarine powered by a nuclear reactor, but not necessarily nuclear-armed. In the US classification, nuclear-powered submarines are designated as SSxN, where the SS denotes submarine, x=G means that the submarine is equipped with guided missiles, x=B means that the submarine is equipped with ballistic missiles and the N means that the submarine is nuclear-powered. SSN refers to nuclear-powered attack submarines, which do not carry missiles.
The fifth HMS Sceptre is a Swiftsure-class submarine built by Vickers in Barrow-in-Furness. She was launched in 1976, with a bottle of cider against her hull. She was commissioned on 14 February 1978, by Lady Audrey White. She was the tenth nuclear fleet submarine to enter service with the Royal Navy. She was decommissioned on 10 December 2010, at which time she was the oldest commissioned vessel in the Royal Navy still available for service; in total around 1,500 men served aboard during her commission. In theory, she is replaced by the first Astute-class submarine in service, HMS Astute.
The eleventh HMS Vanguard of the Royal Navy is the lead boat of her class of Trident ballistic missile-armed submarines. The submarine is based at Faslane, HMNB Clyde, Argyll, Scotland.
His Majesty's Naval Base, Clyde, primarily sited at Faslane on the Gare Loch, is one of three operating bases in the United Kingdom for the Royal Navy. It is the navy's headquarters in Scotland and is best known as the home of Britain's nuclear weapons, in the form of nuclear submarines armed with Trident missiles.
The Royal Navy Submarine Service is one of the five fighting arms of the Royal Navy. It is sometimes known as the Silent Service, as submarines are generally required to operate undetected.
The Dreadnought class is the future replacement for the Royal Navy's Vanguard class of ballistic missile submarines. Like their predecessors they will carry Trident II D-5 missiles. The Vanguard submarines entered service in the United Kingdom in the 1990s with an intended service life of 25 years. Their replacement is necessary for maintaining a continuous at-sea deterrent (CASD), the principle of operation behind the Trident system.
Scotland has a long history of nuclear research and electricity generation. Work started on the Dounreay reactor in 1955.
HMS Achilles is an Astute-class nuclear-powered fleet submarine under construction for the Royal Navy and the seventh in her class. The boat has had its name changed twice, having previously held the in-work name of Ajax and Agincourt.
AUKUS, also styled as Aukus, is a trilateral security partnership between Australia, the United Kingdom, and the United States intended to "promote a free and open Indo-Pacific that is secure and stable." Initially announced on 15 September 2021, the partnership involves two lines of effort referred to as pillars. Pillar 1 focuses on Australia acquiring nuclear-powered attack submarines and the rotational basing of US and UK nuclear-powered attack submarines in Australia. Pillar 2 entails the collaborative development of advanced capabilities in six technological areas: undersea capabilities, quantum technologies, artificial intelligence and autonomy, advanced cyber, hypersonic and counter-hypersonic capabilities, and electronic warfare; and in two broader functional areas: innovation and information sharing.
The SSN-AUKUS, also known as the SSN-A, is a planned class of nuclear-powered fleet submarine (SSN) intended to enter service with the United Kingdom's Royal Navy in the late 2030s and Royal Australian Navy in the early 2040s. The class will replace the UK's Astute-class and Australia's Collins-class submarines.
Vulcan Naval Reactor Test Establishment (NRTE), formerly HMS Vulcan, is a UK Ministry of Defence (MoD) establishment in Scotland, operated by Rolls-Royce Submarines.
the British made important contributions to U.S. submarine design, such as the concept of rafting for silencing and initial types of pump-jets