NIS Update: March 2011


UK nuclear weapon scientists are co-operating with colleagues in the USA to develop upgrades to a  US nuclear warhead design, according to budget documents prepared by the US Department of Energy.

The UK is participating in a development programme focusing on upgrading the arming, fusing, and firing (AF&F) system for one of the US Navy's warhead types.  The AF&F system controls where and when the weapon explodes and determines the power, impact, and level of radioactive fallout from the explosion, and improvements to the AF&F are an effective way of increasing a warhead's efficiency and extending its capability to destroy hardened targets.

The 2012 Congressional Budget Request for the Energy Department's National Nuclear Security Administration contains budget requests for development studies and capability improvements for the W88 nuclear warhead, including funds to continue work on “consideration of commonality with the W78 and collaboration with the United Kingdom”.  The W88 warhead is used to arm US Navy Trident II missiles, and is one of the most modern and sophisticated US warhead designs.  The process of designing, developing and testing a new fuse could extend over a decade and could cost over 1 billion.

New W88 warhead fuse technology is expected to form the basis for a new AF&F planned for the US Air Force's W78 warhead life extension programme, which according to analyst Hans Kristensen “is evolving into a whole new experiment with the plan to develop a 'common high-surety warhead'” – a modified warhead which would be deployed on both Air Force Minuteman missiles and the Navy's Trident.  Although UK Trident nuclear warheads are based on a different design, similar to the USA's W76 warhead, the UK government is keen to partner in the project to maintain its nuclear weapon design and stewardship capability and to keep abreast with developments in the US warhead programme.

The Atomic Weapons Establishment (AWE) is currently installing a US designed Mk-4A fuse to UK Trident warheads, but longer term co-operation on the US W88 development programme will enable AWE to maintain expertise on fuse technology that could contribute to an eventual programme to replace the current warhead design.

In response to a recent Parliamentary question asked by Paul Flynn MP, Peter Luff MP,  Defence Equipment, Support and Technology said: “Co-operation on a broad range of nuclear issues of mutual interest to the United Kingdom and the United States take place routinely under the auspices of the 1958 Mutual Defence Agreement. This includes collaboration with the US on its plans for the refurbishment or replacement of non-nuclear components within their W88 nuclear warhead which could have implications for the UK's consideration of its future warhead options”.

The answer provides further evidence that although the decision on a whether to design a new warhead to replace the current UK Trident design has been deferred until around 2019 (the Strategic Defence and Security Review announced that a replacement warhead would not be required until at least the late 2030s), research into new warhead options and designs is continuing at AWE regardless.


The government is looking to install a new US-designed nuclear reactor in the 'Successor' Trident replacement submarines to improve their "safety outlook", Defence Secretary Liam Fox has said.

Speaking in the Commons, the Defence Secretary said: "One decision in the Trident replacement will be whether we move to pressurised water reactor 3 for improved nuclear safety. The government's view is that that is the preferred option, because those reactors give us a better safety outlook.

"That is a debate on both sides of the Atlantic, but we believe that in terms of safety, the case is very clear-cut."

Fox's comments follow the publication of a report to the Defence Board, released to Scottish CND under the Freedom of Information Act, which highlights serious safety concerns with the existing second-generation pressurised water reactors (PWR) used on Astute class and earlier submarines.

Former head of the Defence Nuclear Safety Regulator Commodore Andrew MacFarlane wrote that current PWRs  fall "significantly short" of modern best practice for nuclear reactors and are "potentially vulnerable to a structural failure of the primary circuit".

The failure could cause a leak of "highly radioactive fission products" which could cause "multiple fatalities" among submarine crews and pose "a significant risk to life to those in close proximity and a public safety hazard out to 1.5km from the submarine".

Fox's announcement favours the PWR3, described as "a new propulsion plant based on a US design but using UK reactor technology", over the current PWR2 design used in Astute class submarines and refitted Vanguard class boats.   Like the stricken Fukushima power station in Japan, the PWR2 is believed to rely on back-up power supplies to provide emergency cooling in the event of an accident.  The newer PWR3 uses "passive" cooling, which makes it far less reliant on external power, and has additional methods of injecting coolant into the reactor.

The decision on which reactor type to opt for has delayed the initial gate decision on the successor to the Vanguard class submarines by around 18 months according to the Defence Board report, and has added a further £260.89 million to the project costs. Fox said an announcement on the initial gate for the Trident replacement project is due soon.

"The programme to replace the Vanguard submarine completed the initial concept studies, and we expect an announcement on initial gate approval in the coming weeks," he said.

"There remain ongoing discussions, which have simply taken longer than it was anticipated a few months ago. It is important, given the size of the project, that we get the decision right."

Despite the concerns about their safety, PWR2 reactors are scheduled to be fitted in the seven new Astute-class submarines which have been ordered by the Navy and there are no plans to upgrade older reactors on submarines currently in service.


Mike Weightman, the Health and Safety Executive's Chief Inspector of Nuclear Installations, has been asked by the Secretary of State for Energy and Climate Change, Chris Huhne, to review the implications of the Fukushima nuclear emergency for the UK nuclear industry. The review will identify lessons to be learnt and is to be conducted in co-operation with national and international stakeholders.  Its scope will cover the following areas:


  • General background on nuclear power technology and the approach to nuclear safety and security regulation in the UK, internationally, and in Japan.


  • Events in Japan, including design provisions for resilience against natural hazards; actions taken to protect people; on-site factors including operator actions which contributed to the events; and off-site factors including emergency response provisions which affected the control and mitigation of events.
  • Lessons for the UK, including a comparison of UK nuclear power station designs with those at Fukushima; natural hazards and other potential threats to UK nuclear facilities; and potential lessons for the UK.

An interim report will be available by the middle of May 2011, with a final report published in September.

An expert technical advisory panel will be established to assist in the review and submissions have been invited from all those with technical information about the accident or views on lessons that can be learnt to enhance nuclear safety in the UK.


The annual summary of UK nuclear warhead convoy movements published by Nukewatch for 2010 shows that the UK's nuclear warhead programme is currently operating a baseline level, with a minimum number of warhead movements taking place over the year.  The number of movements is consistent with the maintenance and surveillance needs of the programme.  As well as convoy movements carrying nuclear weapons, a number of training exercises and vehicle familiarisation journeys also took place in 2010.

The Nukewatch report was compiled on the basis of spottings of nuclear convoys recorded by members of the organisation during 2010.  On the basis of these observations, Nukewatch judges that one loaded convoy carrying nuclear weapons travelled from the Coulport nuclear arms depot  at the Clyde submarine base to AWE Burghfield during the year, with a journey to return weapons to Coulport shortly afterwards.  Annual reports on convoy movements from Nukewatch are one of the few independent benchmarks which can be used to validate government statements on the size and status of the UK nuclear arsenal.

The Strategic Defence and Security Review published in October 2010 announced that the government intends to reduce both the number of nuclear warheads deployed on Vanguard class submarines and the size of the UK's nuclear warhead stockpile.  An upturn in warhead convoy numbers may be observed over the next couple of years as warheads are withdrawn from service and dismantled.

New specialist trucks for transporting nuclear warheads are scheduled to enter into service in summer 2011 after the safety case for the vehicles has been approved in June.  The new trucks will also be used to transport cargoes of special nuclear materials when the high security vehicles currently used for this purpose are retired from service in spring 2012.



West Berkshire Council has been forced to make repairs to Burnthouse Lane, a road leading to the Pingewood gate at the Atomic Weapons Establishment Burghfield, because of damage caused by heavy construction traffic travelling to the Project Mensa construction compound.  The road was closed for several weeks earlier this year for resurfacing.  According to the council the cost of repairing the road was £380,000, which was paid in full by AWE.


AWE has published its End of Year Review on the company's Environmental, Safety, and Health performance during 2010.  The review gives an upbeat picture, emphasising donations to charities made by the company in rewards for good performance, low levels of staff absence, and the low prevalence of work-related ill health.  Encouragingly, the annual objectives for individual and collective radiation dose for AWE workers were met and annual targets for waste production and electricity use were also achieved.  However, the review states that there is room for improvement in reducing work-related injuries, which now remain constant following recent decreases and do not appear to be falling further. The August 2010 fire at AWE Aldermaston, which is currently under investigation by the Health and Safety Executive, is not mentioned.

The report also mentions a number of recent abnormal events with the potential to impact upon safety, including an incident when a small quantity of explosive material was moved into a building where explosives are not permitted.  No further details are provided.


West Berkshire Council has set a date for determining the resubmitted planning application for a new conventional manufacturing rationalisation facility at AWE Burghfield.

The application is to be considered at the Council's Eastern Area Planning Committee meeting on 6 April 2011 at the Calcot Centre, Highview, Calcot.  The meeting commences at 6.30 pm and members of the public who have submitted comments on the application may speak at the meeting if they register in advance with the Council.

Officers have recommended approving planning permission, which was previously granted in August 2008 but will expire later this year unless renewed.

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