Dreadnought prototype review exposes flaws in naval reactor programme

Artist's impression of Dreadnought submarine credit BAE Systems

Senior academics highlighted serious concerns about the capabilities and culture of the naval nuclear propulsion programme in a document recently released in response to a Freedom of Information request. The concerns were raised in a review commissioned by Vernon Gibson, the Chief Scientific Advisor to the Ministry of Defence (MoD), into the decision not to build a prototype of the reactor design that will be used in the new Dreadnought nuclear powered and nuclear armed submarines.

The PWR3 reactor is a new reactor design, the successor to the PWR2 reactors which power the Vanguard and Astute class submarines. PWR stands for Pressurised Water Reactor. In the review it is described as an adaptation of proven technologies, though it differs from the PWR2 design in a number of ways. In other government documents it has been described as being based on a US design but using British reactor technology and modern secondary propulsion systems.

For the two previous generations of naval reactors a prototype has been built and operated at the the Vulcan Naval Reactor Test Establishment at Dounreay. This arrangement allowed problems with the reactor design to be identified at an early stage, before they became evident on the reactors in the submarines themselves.

This approach paid dividends when a fuel element breach was identified in the the PWR2 reactor in the Shore Test Facility (STF) at Dounreay in 2012. As a consequence a decision was taken to undertake an unscheduled refuelling of HMS Vanguard, the oldest Vanguard class submarine. A decision had been taken several years previously not to produce a prototype of the PWR3 reactor and the Chief Scientific Advisor commissioned a review of this decision in light of the fuel element breach.

The review was carried out in 2014 by Professor Robin Grimes, Professor Dame Sue Ion and Professor Andrew Sherry. They supported the decision not to run a prototype reactor, despite the fuel element breach. Part of the justification for this was that they felt that a non-nuclear verification, validation and testing regime would provide sufficient reassurance. But another factor was that it would not actually be possible to set up a test facility in time for the reactor to have a sufficient lead time before the Dreadnought submarines come into service. As such the test facility would not be able to provide an early warning of future problems.

The review also identified long-term risks to the naval nuclear propulsion programme and recommended remedies. It said the programme needed to address a loss of contingency and the fact that long-term activities had been deferred, that an ongoing research programme needed to be put in place, and that engagement with and learning from the civil nuclear sector also needed to be better.

In some of the most damning comments, the review criticised what it called a 'culture of optimism' in the naval nuclear propulsion programme, “that assumes success within the tight confines of the required timescales and is then caught unawares when a problem arises”.


The prototype decision
The PWR3 design work began in 2006, and was approved in the 2010 Successor Initial Business Case. According to the review it was the first new nuclear steam rising plant design for over 20 years. The PWR reactors are steam cooled, unlike the gas cooling technology that is predominant in civil nuclear reactors. Since the UK first imported a nuclear reactor from the US to power the original HMS Dreadnought the Navy has operated around 80 reactor cores at sea and on land.

The prototypes that were built of the first and second generation of PWR reactors (PWR1 and PWR2) were not built during the design phase in order to inform design and manufacture. Instead their primary use was as ‘lead cores’ - reactors operating several years ahead of those deployed in the submarines, primarily to monitor performance of the reactor and burn up of fuel in the core.

The review concluded that even a lead core prototype would not be able to be operational far enough ahead of the Dreadnought submarines to provide valuable information. It would have to go through a similar regulatory process to be licensed to operate, and as the Dounreay site is being decommissioned a new location would need to be found. The review estimated that the cost of setting up a new facility would be £1bn, with additional funds being required to run the facility throughout its lifetime – the cost of running the previous site was £30m a year.
Instead of building a prototype reactor, the design for the PWR3 reactor was supported by a non-nuclear verification, validation and testing programme. The report endorsed this process, saying it was easier to push the boundaries of equipment in a programme of this sort than in a prototype reactor with the attendant nuclear risks. It also recommended that a plan be put in place for verification, validation and testing of the PWR3 through its whole in-service life, using a suite of test rigs.


Non-nuclear verification, validation and testing programme
The verification, validation and testing programme used for the PWR3 reactor involved breaking its functions down into 45 subsystems, analysing and testing them separately before bringing them all together in a computer model. The methods used included extrapolating from current reactor designs and testing individual components and systems using a mix of existing, modified and all-new test rigs

The review did not examine at all the details of verification, validation and testing programme, but the authors had confidence in the programme based on the elements that they looked at. However, the review implies that they perceived a risk that work to verify the PWR3 reactors through their whole in-service life could have its funding cut, and they emphasised that the programme would need to be run for a very long time in order to confirm the modelling assumptions used in the PWR3 design. The lack of funding for such a programme is described as a “worry”.

The authors criticised the MoD’s record of investing in ‘world-class’ facilities, such as the test rigs used in the programme, then mothballing or closing them. They contrasted the stop-start funding of the navalnuclear propulsion programme with what they called the ‘holistic’ funding of the nuclear weapons programme, where AWE has an annual budget which allow it to continually run research, design and manufacture programmes. Their recommendation of work to verify the PWR3 through its in-service life was in part motivated by a desire to put these facilities on a secure financial footing.

A ‘culture of optimism’ and research priorities
The ‘culture of optimism’ criticised by the review meant problems, such as the fuel element breach, come as a surprise, even though such events are common in the civil nuclear sector. The authors of the review point out that optimism is probably misplaced in the light of the nuclear civil sector’s record of delivery projects on time and to budget.

They say that confidence in PWR3 design has resulted in a reduction of operational contingency, as has the desire to drive down costs. They also say that the drive for cost reductions has caused long-term activities to be differed or abandoned, and that this short-termism and desire for savings is likely to lead to a “fractured and unsustainable capability base”. Most ominously, they say that the potential risks inherent in this approach have not been addressed.

The research side of the naval nuclear propulsion programme depends upon Technical Working Groups, which are described as “overly orchestrated, defensive and closed” in the review. Overall introspection is still considered to be an issue in the programme, with a failure to maintain links with and learn from the civil nuclear programme, thought less so than in the past.

The budget for research and technology within the programme was reducing at the time of the review and was planned to be reduced further. This was compounded by the fact that short term investigations, presumably related to the fuel element breach, had crowded out longer term work. The review supported the decision to continue operating the STF to gain more understanding of PWR2 operations with a fuel element breach. However, work required to fully understand the condition of the PWR3 reactors throughout their working life had not been completed, and might not happen at all. Similarly the future of research on ‘husbandry’ of nuclear plant and future developments in nuclear propulsion was in doubt.

The decline of the civil nuclear sector was also highlighted as causing problems for the programme. Previous naval reactor projects could incorporate data from a number of research reactors which were operational in the UK at the time. These have all been shut down as the civil nuclear sector contracted, and one of the review’s recommendations is that the programme should seek access to other test reactors such as the University of Manchester's Dalton Cumbrian Facility and the National Nuclear User Facility.


Skills gap
A shortfall in skilled workers was also highlighted as an issue by the review. The length of time between the production of the Vanguard and Astute class submarines, coinciding with a decline in the civil nuclear sector was said to have significantly reduced the skills base for plant design, manufacture, support and repair.

Staffing levels were described as being at the bare minimum necessary to support the programme. This meant that the programme was overly reliant on individual experts and could soon face a “perfect storm” of an ageing expert community, an increased need for staff within the programme and greater competition for staff from a reviving civil nuclear sector and other industries such as oil and gas exploration.

Maintaining staff capacity within the programme was considered necessary not only to support the Dreadnought programme, but also to maintain capacity to build other submarines in the future, such as the ‘Marine Underwater Future Capability’, which will replace the Astute submarines when they come to the end of their life.

According to the review the programme’s staffing issues exist both within the MoD and its contractors. The MoD’s number of nuclear qualified posts has been reduced by civil service and navy staff cuts, and the MoD has outsourced so much technical expertise it was said to be in danger of failing to be an ‘intelligent consumer’.

Staffing issues within Rolls-Royce Submarines in Derby were also highlighted, with staff having been lost over the years in between building the Vanguard and Astute submarines. At the time the review was written the workforce there had been doubled but was working at full capacity with no ability to take on extra work. Furthermore, the new engineers and scientists were said to lack experience in designing and building nuclear plant, and there was also lack of middle management expertise in design and build projects. These problems were evident despite the government having agreed the £1.1bn Core Production Capability contract to regenerate the Derby site and put the facility on a sound financial footing.

While the decline in the civil nuclear sector is identified as a causal factor in the diminishing staffing pool, the report clearly considers that in the short term a revived civil sector is more likely to act as a further pressure on the programme, rather than an asset. While the civil nuclear programme could poach staff from the naval nuclear propulsion programme, flow in opposite direction is unlikely due to the relatively poor pay in the civil service and a lack of the right expertise in people who have worked in the civil sector.