The United Kingdom is one of three countries in the world that operates only nuclear submarines; the US and France are the other two. The choice was deliberate and was premised on the firm belief that the operational advantages that the nuclear submarine gave over the conventional diesel-electric outweighed the additional costs and technological demands generated by nuclear propulsion.

Conventional submarines in the past always had to contend with a number of operational constraints, primarily because they had to recharge their batteries at frequent intervals. This involved rising near to the surface to snorkel, or snort, that is to say to run their diesel engines to generate electricity to recharge the batteries. This had always been a source of frustration to the Royal Navy almost from the time that submarines entered service in 1901 because it meant their submarines were severely limited by either range or speed, when submerged. To stop and snorkel also rendered the submarine vulnerable to attack, the more so when the range of enemy radar expanded and signatures of the submarine's snorkel pipes became easier to detect.

After World War II, much technological effort was put into overcoming these practical problems. Initially, there were grounds for optimism from the work that the Germans had been engaged in with the development of the Type XVIIB submarine powered by a closed-cycle hydrogen-peroxide-fuelled Walter or HTP engine. One of these was captured at the end of the war and brought to Britain for evaluation, subsequently entering the Royal Navy as HMS Meteorite.

The HTP engine offered the promise of higher speeds and reduced substantially the need to snorkel. However, HMS Meteorite had several serious design faults, even though the engine offered great promise. The panacea of a submarine with endurance, range, speed and without the requirement to snorkel was still to be found. For a while the UK concentrated on conventional patrol submarines of the Oberon and Porpoise classes, developing what were considered at the time to be the finest of their type anywhere in the world.

The Americans very quickly abandoned HTP; they had the resources and the scientific know-how to explore nuclear power as a solution. The problem then was that it was believed the nuclear reactor would be too large to be accommodated in a submarine, but these initial constraints were soon overcome. The first US nuclear-powered submarine, USS Nautilus, was launched in 1955. Three years later, the US Navy finally abandoned conventional SSK submarines all together, concentrating on SSNs only and later SSBNs.

With a common concern for the security of the northern Atlantic in the face of the Soviet navy's ever-mounting submarine capability, the US made its nuclear-reactor technology available to the Royal Navy. The Vickers shipyard demonstrated its construction skills by marrying the reactor to a British hull, producing the first UK nuclear attack, or fleet, SSN submarine in 1960, the HMS Dreadnought. The Churchill, Swiftsure and Trafalgar classes of SSN followed soon afterwards.

The nuclear-powered SSN attack submarine was ideal for blue-water operations in the north Atlantic. It had all that the submariner wanted in terms of speed, endurance, range and capability to accomplish its anti-submarine role. Meanwhile, the Royal Navy retained its conventional patrol submarine programme, ordering in the early 1980s the Type 2400 Upholder class SSK to replace the O and P-class submarines.

The end of the cold war ended the emphasis on blue-water operations in the north Atlantic and the Royal Navy was left with a difficult choice in the early 1990s: either it should scrap the SSN programme, or the Upholder SSK, of which originally 12 had been envisaged. To run two programmes, one nuclear and one conventional, was too expensive. The casualties were in fact the Upholder submarines that subsequently were leased to Canada.

UK deterrent

One persuasive reason for retaining the SSNs, aside from the navy's preference for their manifest greater capabilities over distances compared to the SSK, was that the UK deterrent was entrusted to the Royal Navy; initially to the Polaris missile resolution class, and subsequently the Trident missile vanguard class SSBNs. If both ballistic missile boats involved nuclear propulsion, and the capital costs in creating the necessary construction and testing facilities, together with their safety features and licences, had already been spent, it also made sense to share the costs with the Fleet SSNs.

What now is the future of UK nuclear submarines if their operational environments are no longer the blue-water operations to which they are best suited? The answer is that the UK SSN will continue to have a promising future for the following reasons. First, even though the SSK promises greater capability, less vulnerability and is better suited to the littoral operational environment, it still has to get to wherever the theatre of operations is likely to be. This may well be thousands of miles away where there is an absence of local support, for which reason submarines that are self sufficient for prolonged periods of time have the advantage.

Rapid-reaction capability

The future operational environment, coupled with UK defence policy to be engaged in defence diplomacy and preventative diplomacy intervention operation roles, is one where the UK must have the capability of rapid reaction and the means to conduct joint operations with amphibious and land forces as well as supporting aircraft. By equipping Britain's SSNs with the Tomahawk cruise missiles, the UK government has done just that.

Nevertheless, there is one final commanding reason why the SSN is likely to remain Britain's principal submarine force; this is the matter of cost. Although the SSN is vastly more expensive than the SSK, the UK can afford to have fewer of them. Indeed, the total number of SSNs is scheduled to be reduced to ten from the 12 currently in the submarine flotilla. This compares sharply with the 145 or so that were in the fleet in 1945, the 60 that were around at Suez in 1956 or even the 32 at the time of the Falklands in 1982.

The last of the most recent class of submarine, the Trafalgar-class boat has been completed and delivered to the navy. So also, incidentally, has the last of the Trident missile boats, HMS Vengeance that entered service in the summer of 2000. Leaving the question of the safety of the Trafalgar- class nuclear-reactor cooling system to one side - a problem that confined the whole SSN fleet to harbour in the autumn of 2000 - the future of the UK nuclear submarine programme rests currently with the batch two Trafalgar class, renamed the Astute class. Three of these were ordered in 1997 for delivery originally in 2001 but this has been revised to 2005. There is an option for two more, though contracts have not been awarded.

The particular significance of the Astute boat is in part the nature of the contract that required the prime contractor to provide support for eight submarines years after commission for a fixed price, and in part the design of the boat. Though a Trafalgar batch two in origin, the Astute bears little resemblance in size and shape. In fact Astute is substantially larger and its hull shape is parallel, not the more familiar tear-shaped. This has enabled the contractor to reduce manufacturing and build costs by up to 35 per cent. Indeed, the whole Astute programme has embraced the smart procurement, integrated project team and integrated logistic support principles that are designed to drive costs down and deliver the product in line with the government's procurement objectives of faster, better, cheaper.

Eight-year gap

After Astute, that has been under design and construction for over three years, comes the future attack submarine scheduled to be ordered in 2008. This means that there will be an eight-year gap between the end of Astute design work and the start of detailed design work on FASM. The implications of this for the design teams at BAE systems at Barrow and Frimley are serious, and whether or not the company will be prepared to pay for them to do nothing in effect for up to five out of a possible eight years is a moot point.

There is no respite on the horizon with work on a replacement for the SSBNs because the current deterrent fleet is not due to retire until around 2025-2030.

All of which leaves the situation regarding the future of Britain's nuclear submarines and with them, that of the Royal Navy submarine service, in something of a quandary. Already, BAE systems at Barrow has allowed its nuclear site licence to lapse because there is no work requiring it to remain current for a further three years.

Perhaps this is the clearest indication of the future: if there is no significant return on capital from building submarines, and the throughput of work and the resulting cash flow are not there, then we may well see the demise of the British submarine manufacturing base in the not-too-distant future.

But then there may be a renaissance of the SSK where there does appear to be something of an international demand. Already, BAE systems is working with Germany on future SSK designs, and because they are cheaper and their performance is improving, their marginal worth to the Royal Navy might increase.

However, the most informed judgement at present is that nuclear navies will remain nuclear with fewer boats, non-nuclear AIP submarines will be acquired by navies with short-range operational requirements, and non-AIP diesel electric submarines will have a role but with improved competitiveness made possible by the use of advanced batteries.

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