The decision on whether or not to continue with the UK’s nuclear deterrent has been contentious since the need was first raised in 2006. This has a lot to do with the price tag for a fleet of ballistic missile submarines to replace the ageing Trident-carrying Vanguard vessels – between £11 billion and £14 billion. But the development of a complex nuclear weapons system can be kicked into the long grass only for so long. The go-ahead to proceed with the full design of the Successor-class submarines was given by the government in 2011.
Despite the political prevarication, the grass has not been allowed to grow long at BAE Systems’ Barrow shipyard in Cumbria. The government’s 2011 decision, the ‘initial gate’, was a signal that the shipyard still had a future making submarines. Since then, and as work on the last of the Astute ‘hunter-killer’ class of submarines completes, the site has been readying itself to build the UK’s next generation of ‘continuous-at-sea-deterrent’ submarines, Successor. The ‘main gate’, when the project is fully approved and manufacturing starts, is expected for Successor at the end of 2016.
Physically, the preparation has included an extension to the Devonshire Dock Hall, where final assembly of the submarines takes place. The company is also increasing the size of another yard so more assembly can be done outside the Devonshire Dock Hall, to increase efficiency. In addition, Barrow has been recruiting 150 professional engineers, every year, for the past five years. The site’s total workforce is 6,900. There are 1,400 people working on the Successor programme at the shipyard. Around 900 of these were recruited last year alone, and hundreds more will be employed this year.
According to sources at the site, the bulk of the recruits are design and engineering staff, and the increase in recruitment has resulted in “a real buzz” at Barrow. Most of the staff are working to ‘mature’ the design of the Successor submarines. Tony Johns, managing director of the submarines division of BAE Systems Maritime, is pleased with progress on the design so far. According to a parliamentary briefing published earlier this year, around 70% of the design should be complete before the main gate approval next year.
“We’re four years into a five-and-a-half-year process,” says Johns. “The design has progressed well, and we’re working well with the ministry and our partners Rolls-Royce and Babcock. There was a major design review before Christmas, and we’re on track to start manufacturing at the back end of 2016.”
The starting point for the design is the Ministry of Defence’s high-level requirement, he says. Pre-concept work then helps the engineers to understand the technology challenges and decide which development programmes need to be put in place. The programme’s requirements are gradually refined as this concept work progresses. Once a viable concept design exists, it is assessed against the requirements to see if it is achievable within budget and to schedule, which is the aim of the concept design phase. All of this happened on the Successor programme in the five years before the 2011 initial gate decision.
“You then move into the full design, which is about maturing it,” says Johns. “When that is more or less complete, you move into production.”
‘Maturing’ is a catch-all term used to describe how the various sub-systems and components will be incorporated into the overall design and for the production of detailed technical drawings. It does not, though, mean that engineers just fill out the blanks with more detail, says Johns. “It’s not just detail; it’s whether that detail is provident. For example, we need information back from the supply chain to know we can manufacture the way we want. We gradually iterate towards that.
“There’s also no point in designing one bit first. Everything else has to work around it. You need to make sure the design progresses in a measured way. You look at it by compartment and by system. It has to work as a system, but also with each compartment the system passes through,” he says.
Gearing up: The main gate decision, when Successor manufacture can start, is due at the end of 2016
As the submarine’s design goes through iterations, engineers continue to check whether it will still meet the MoD’s requirements on schedule and budget. During design reviews, the MoD decides on what will be included and what won’t. The requirements describe things such as the number of people the submarine can carry, and its speed. These aspects are traded off against how long it will take to develop and build, and cost.
“Those are the key design drivers, and you are trying to reach that compromise all the time,” says Johns. “In that respect, it’s no different from any other project; it’s just that it is a complex set of parameters to manage.”
The progressive design process allows engineers to procure long lead items earlier than would otherwise be possible. A total of £588 million of orders for long lead items will be placed before the main gate decision in 2016. These items include parts of the propulsion system, weapons handling and launch system, gearbox components and equipment, material for manufacturing the missile tubes, and material for the tube and hull fixtures. Other parts ordered before 2016 include lubrication oil pumps, the main shaft bearings, hull fittings, pressure plate and stiffeners, the main engines and condensers, electrical distribution and fibre-optic components.
One challenge is that with such a long project, it’s difficult for engineers to ensure that the technology they are specifying for the submarine is, and remains, the best available. It’s important for the designers to keep abreast of technological developments relevant to the programme, says Johns. “Four years into the full design process is too late. They have to be abreast of what could be used, understand the technology, its level of maturity, and if it is something we would want to incorporate.”
Another area where the Barrow site has invested heavily in preparation for Successor is CAD and simulation software and hardware. There has been substantial investment in these technologies to ensure “beyond a shadow of a doubt” that its engineers are working with the latest technology, says Johns. “There are about 100 people working on making sure that the right toolsets are ready and capable of doing what needs to be done, as well as contractual support.
‘“The technology has moved on brilliantly since we designed Astute. We now have mature tools that are really useful. It allows us to iterate the design more quickly than we could have done in the days of drawings. You don’t have to have mock-ups to prove a design.”
3D visualisation tools enable a designer to look around as if they are in the submarine, allowing them to understand what the design will look like for the person that builds the submarine, the operator and the maintainer.
Johns says he is confident that Successor will be better than its predecessor submarines. “We have the experience of Astute behind us. We’ve got additional capability through the tools and processes, and we can use improved technology in various aspects that allows us to improve the overall design. In many ways with submarines, you are trying to solve the same problem in a different context. As an ex-mariner, I can look at things and say ‘I would have liked to have gone to sea with that’.”
Johns’ background is in propulsion. He was director of nuclear propulsion for the Royal Navy, and was responsible for the procurement, support and operational safety of its 14 reactors. While in this role, he also authorised the £1 billion contract with Rolls-Royce to develop the PWR3 nuclear reactor, which will be used for the first time on Successor. It’s this technology that he is most excited about with Successor. “We’ve got a new reactor plant, and it’s a great innovation,” he says.
Innovation on the project comes from the engineers, the ministry and suppliers, he says. “The majority of innovation comes from the engineers who design the submarine. It also comes from the MoD. The supply chain also tells us when its products have moved on.”
Young engineers have been particularly innovative, he adds. “Innovation is also coming from the high calibre of the young engineers we are getting. They are not as constrained by the history, and approach the design with a fresh pair of eyes. They’ve learnt quickly and have added substantial value. We need that challenge, or we become a very closed community.”
Another significant aspect of Successor is project management. BAE Systems has worked across its organisation in recent years to improve the way big projects are managed, so as to avoid delays and cost overruns, and the Barrow yard is no exception. Core to this process for Successor is an integrated master schedule that links stakeholders and their contributions. It pays dividends to manage these relationships and the things that happen outside the shipyard with the MoD and with different programmes such as the missile compartments, which are being developed in partnership with the US, with a clear system from the start, says Johns.
“It’s a demanding programme with a lot of technical complexity. It’s a question of managing the interface between the key elements of the programme more effectively than we have done in the past. But the real challenge is often when you don’t think you are going to be on time or on budget – what do you do? All big programmes have their problems. It’s how you manage them that is the key.”
Johns compares designing and making a 17,000-tonne ballistic missile submarine to projects such as Crossrail, the Thames Tideway Tunnel and the Olympics. “Successor tones the UK’s ability to do complex engineering programmes. It helps keep engineering capability match-fit; ensures we’re right up there at the high-technology end of manufacturing and engineering design.”
Whatever your opinion on the merit of a UK nuclear deterrent in the 21st century, there’s little argument to be had over the complexity of a nuclear submarine. The sheer engineering achievement – in designing, making, and managing the making of one – is colossal. By 2028, when the first Successor-class nuclear submarine enters service for the Royal Navy, it will have taken thousands of people more than 20 years to produce. Engineering and manufacturing firms involved in its supply chain throughout the UK will have benefited, and what grass there is on BAE Systems’ Barrow shipyard will still be short.
What we know about the design for Successor
The specification and capabilities of the next generation of ballistic missile submarine are a closely guarded secret. But from information in the public domain, some basics and a few clues can be gleaned.
Four boats are planned. Each will weigh 17,000 tonnes. This is slightly more than its Vanguard predecessor, which is about the same size as, but more than double the weight of the Astute hunter-killers, which each weigh 7,400 tonnes.
According to the latest parliamentary briefing document, Successor will use the PWR3 reactor as its propulsion, because it is considered easier to operate, has a longer lifetime and costs less to maintain. Rolls-Royce pressurised water reactors have powered the Royal Navy’s nuclear submarines since 1966, and the PWR2 is used on the Astute submarines. The choice to use the PWR3, which is based on a US design but uses UK reactor technology, was made at the time of Successor’s ‘initial gate’ announcement. The reactor is widely reported as using ‘passive cooling’ and as allowing extra ways to inject coolant into the reactor compared with earlier versions.
The missile tubes of Successor will use a design shared with the US and supplied by defence firm General Dynamics. The 2010 defence review recommended a reduction in the number of Trident warheads. Nevertheless, an order was placed in October last year for units with 12 tubes instead of the necessary eight. Work is ongoing to adjust the design.
The other certainty is that large sections of the submarine will be based on, and in some cases identical to, those of Astute. Tony Johns, managing director of the submarines division of BAE Systems Maritime, says: “If a technology solution is well-proven, why change it?”
Parts of the submarine that will feature new technology have, therefore, already been planned and identified. These include communications, tactical weapons systems, batteries and structural materials.
Johns says the adoption of this technology depends on its source: “It depends how ready the technology is. If it’s well-proven elsewhere, that’s easy. If it’s something novel, we have to de-risk it.”