Nuclear warhead is being made more destructive and more accurate while an entirely new one is being developed, say researchers

Work is under way in secret at Britain’s nuclear bomb factory to upgrade the existing Trident arsenal and to develop an entirely new warhead, according to a report from the Nuclear Information Service.

The Atomic Weapons Establishment (AWE) at Aldermaston and Burghfield in Berkshire is working on a programme to upgrade the current UK Trident warhead to produce the “Mark 4A”, which will be more accurate and have greater destructive power, the report says. The costs and timetable of the programme have not been revealed to parliament.



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The modified, upgraded warhead is mentioned in a little-noticed letter on the Ministry of Defence website, dated 2 July 2014. In it, Jon Thompson, then top civil servant at the Ministry of Defence, confirms that Dr Paul Hollinshead had been appointed senior official responsible for the “nuclear warhead capability sustainment programme”.



The letter says Hollinshead will be responsible for “commencement of Mk4A production in accordance with the Trident Manufacture Plan”.

Tuesday’s report, published by Nuclear Information Service (NIS), an independent research body, says £85m has already been spent by the AWE on new nuclear warhead design studies.



The government later this year is expected to table a Commons motion in favour of replacing the existing fleet of Trident submarines with four new boats. The government says they will cost £31bn, but has set up a £10bn contingency fund in the event of overruns.

The MoD has declined to answer questions on the costs of the overall Trident programme on the ground that the information is classified. The Campaign for Nuclear Disarmament has estimated it will cost £205bn.



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Debate so far has focused on the construction of new nuclear-armed submarines. The Mark 4A warhead upgrade programme is going ahead in tandem with a US programme aimed at improving the performance and extending the life of the W76 warhead, the NIS says. A joint US-UK working group to allow collaboration on the programmes has been set up, and new warheads have been tested at Sandia National Laboratories in the US.

Peter Burt of the NIS said: “The Mark 4A warhead modification programme will allow Trident nuclear warheads to remain in service until the middle of this century, and plenty of money is being spent to pave the way for developing a new generation warhead which will remain in service for even longer.”



The report acknowledges that AWE is an important national resource in terms of its scientific expertise and equipment, and a big local employer that makes a significant contribution to the local economy. AWE employs around 4,900 people directly and a further 890 contractors.



The report says that if the Trident programme was to be cancelled, the likelihood of outright closure of the establishment would be “low”. Decommissioning radioactive facilities would be likely to last into the 2040s and 2050s and AWE’s expertise on disarmament verification and nuclear threat reduction would most likely be retained by the government regardless of any decision to cease warhead production.



An MoD spokesperson said: “The government is committed to maintaining minimum continuous at-sea deterrence to deter the most extreme threats to the UK and to protect our vital interests; a decision on replacing the warhead will be taken when necessary.”