Select Committee on Defence Fourth Report


2  The UK's nuclear deterrent

The deterrent

8. The UK's current strategic nuclear deterrent is based upon the Trident weapons system. Trident was introduced into service in the UK over a six-year period beginning in December 1994 and has a projected life span of up to 30 years. It is the UK's sole nuclear weapons system.

9. The UK's Trident system has three main components: the Vanguard-class nuclear-powered submarine, the submarine-launched Trident D5 missile and the nuclear warhead fitted to the tip of that missile. As we highlighted in our first report on the deterrent, it is the operational life of the Vanguard submarines which is the critical factor driving the timetable of decision-making on the future of the UK's strategic nuclear deterrent. During the course of our first inquiry, it became apparent that the maintenance of onshore infrastructure and the domestic UK skills base would be of paramount importance if the UK wished to keep open the option of maintaining a submarine-based deterrent.[3]

The submarine fleet

10. The Royal Navy submarine fleet currently comprises 4 Swiftsure-class nuclear-powered attack submarines (SSNs), 7 Trafalgar-class SSNs, and 4 Vanguard-class nuclear-armed and nuclear-powered submarines (SSBNs). The Swiftsure-class boats are due to be retired within the next 5 years. The Trafalgar-class boats are expected to be withdrawn progressively as the new Astute-class submarines enter service.

11. The target launch for the first of the Astute-class is June 2007, with delivery to the Royal Navy scheduled for August 2008. The later boats in the class are expected to enter Service at 22-month intervals. A total of 7 Astute-class boats is expected to be ordered, though orders beyond Boat 3 are yet to be placed by the Ministry of Defence.

Table: The Royal Navy's submarine fleet
   In-service date  Approximate out-of-service date  
Swiftsure Class SSNs  SUPERB 1976  2008 
 SCEPTRE  1978 2010  
Trafalgar Class SSNs  TRAFALGAR 1983  2008 
 TURBULENT  1984 2011  
 TIRELESS  1985 2013  
 TORBAY  1987 2015  
 TRENCHANT  1989 2017  
 TALENT  1990 2019  
 TRIUMPH  1991 2022  
Vanguard Class SSBNs  VANGUARD 1993  2022 
 VICTORIOUS  1995 2024  
 VIGILANT  1996 2025  
 VENGEANCE  1999 2028  
Astute Class SSNs  ASTUTE Planned 2009   
 AMBUSH  Planned 2010   
 ARTFUL  Planned 2012   

Source: Ministry of Defence[4]

The onshore infrastructure

12. The submarine fleet is supported by an extensive onshore infrastructure.


13. The Vanguard SSBNs and the Swiftsure SSNs are based at HM Naval Base Clyde at Faslane. The new Astute-class SSNs will also be based at Faslane. At present, the Trafalgar-class submarines have their base port at HM Naval Base Devonport, in Plymouth, Devon.


14. Routine maintenance of the submarines is carried out at their base ports. For the Vanguard SSBNs, maintenance is carried out at the HM Naval Base Clyde at Faslane by Royal Navy and civilian personnel. Faslane is managed under a partnership arrangement involving the Royal Navy and Babcock Naval Services. HM Naval Base Clyde—which includes the Royal Naval Armaments Depot (RNAD) Coulport as well as Faslane—employs around 6,500 people.


15. Refit and maintenance of nuclear-powered submarines is carried out by Devonport Management Limited (DML) at Devonport in Plymouth. DML has £1 billion worth of dedicated, and unique, facilities which are essential for submarine refuelling and refitting. It has five basins for submarine refit, with a dedicated section for the Trident SSBNs. It is currently involved in two submarine refit streams, for the Vanguard and Trafalgar classes. It is also involved in upkeep work and capability upgrades on surface ships and in providing onsite support and fleet management to the Royal Navy.

16. Devonport currently employs 5,200 staff, of which 4,700 are permanent staff. DML is owned by KBR (a subsidiary of Halliburton) which holds a 51% controlling stake, the Weir Group and Balfour Beatty.


17. The UK's nuclear-powered submarines are designed and built by BAE Systems Submarines at Barrow-in-Furness, in Cumbria. Barrow is the only UK nuclear-licensed site for the construction, testing and commissioning of nuclear-powered submarines. Barrow (then under the ownership of VSEL) built the Vanguard class submarines, and is currently involved in the design and build of the first batch of Astute-class SSN submarines. It also carries out design, build and conversion of surface ships for the Royal Navy (recently HMS Albion, Bulwark, Ocean) and it is planned that it will build a section of the future aircraft carriers. It employs around 3,500 people, and dominates the local economy.

Supply chain

18. Fifty per cent of the prime contract value for a nuclear powered submarine is subcontracted to the supply chain. The top 10 companies, including BAE Systems, account for around 80% by value of a nuclear-powered submarine.[5] Key suppliers include Rolls- Royce, Alsthom, L3, MacTaggart Scott, Sheffield Forgemasters, Thales, Wellman, Weir Strachan and Henshaw, and York.

Nuclear reactor

19. The Nuclear Steam Raising Plants, or reactors, as well as a range of other equipment, for nuclear-powered submarines (both SSNs and SSBNs) are built by Rolls-Royce at Raynesway in Derbyshire. Rolls-Royce is currently involved in designing and manufacturing the Nuclear Steam Raising Plant (NSRP), fuel cores, propulsors, flexible couplings and turbogenerators for the Astute-class submarine. It also provides in-service support to the existing fleet, including the Vanguard-class submarine, and is responsible for design improvements, inspection, refurbishment, condition monitoring and continuous safety review of the NSRP. Rolls-Royce is involved in concept design and assessment of future submarine propulsion options. It also manages the Royal Navy's Vulcan Shore Test Facility at Thurso in northern Scotland. Rolls-Royce employs 910 staff in its submarine business.

Nuclear warheads

20. The nuclear warheads for the Trident D5 missiles are manufactured by the Atomic Weapons Establishment (AWE) at Aldermaston and Burghfield, in Berkshire. The AWE also carries out scientific research, stockpile management and warhead decommissioning, and seismological research in support of the verification of the Comprehensive Test Ban Treaty. The AWE is managed under a Government-owned, contractor-operated arrangement by AWE plc. It employs around 4,000 people.

21. The nuclear warheads are fitted to the UK's Trident D5 missiles at RNAD Coulport, at the HM Naval Base Clyde. The Trident D5 missiles, which carry the UK-built warhead, are procured from the United States.

The Naval Base Review

22. The Ministry of Defence is currently conducting a review of UK naval bases and this may significantly affect the submarine onshore infrastructure. The recommendations from the review, which is being undertaken by the Defence Logistics Organisation, are expected to be finalised in Spring 2007.[6]

3   HC (2005-06) 986, paras 126-138 Back

4   For Vanguard class out-of-service dates, see Cm 6994, paras 1-3. For Trafalgar class, see HL Deb, 14 March 2005, col WA116. For Swiftsure class, see HC Deb, 7 January 2004, col 414W. For in-service dates, see HC Deb, 26 January 2005, col 335W. For Astute class, see HC Deb, 20 April 2006, col 769W and HC Deb, 9 December 2004, col 687W. Back

5   Ev 53 Back

6   HC Deb, 18 September 2006, col 134WS Back


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Prepared 19 December 2006