Given the strength of the case that has been made against new nuclear build (see box), we are surely not alone in wondering whether other factors may have persuaded the Prime Minister that nuclear is necessary. Here are two candidates: military links and influence from the Bush administration.
But first, a short history lesson. In June 1955, just months after the publication of the original UK white paper on nuclear power, the first Anglo-American bilateral atomic energy agreement was signed. Ironically, it was a complementary military atomic cooperation agreement, the US/UK Mutual Defence Agreement (MDA) of 1958 that led to the decision in the late 1950s that the old Central Electricity Generating Board (CEGB) should go for Magnox reactors.
This was critically influenced by the fact that these reactors produce significant amounts of weapons grade plutonium in early years of operation. There was a need for more plutonium than the dedicated military reactors could produce to fulfill the conditions of an amendment to the 1958 MDA, under which plutonium from the UK civil and military reactors was exchanged for highly enriched uranium for Polaris submarines and tritium for warheads.
The full implications of this treaty did not emerge until the 1980s by which time the UK government was a sponsor of the Non-Proliferation Treaty (NPT) which aims to separate civil and military nuclear activities. The government tried to draw a line under this past history by claiming to Parliament in 1983 that “No Plutonium produced in any of the CEGB’s nuclear power stations has ever been used for military purposes…” . However, at the Sizewell B Inquiry in 1983-4 CND obtained the admissions that civil and military origin plutonium was still being reprocessed together at Sellafield, and that there was no longer any weapons grade plutonium in the civil stockpile. In 1986 the parliamentary record was modified by the addition of the get-out clause “during the period of the current administration” .
All subsequent governments have stuck to this line, even following the remarkable admission by the Ministry of Defence (MoD) in 2000 that “figures show that the weapon cycle stockpile is in fact some 0.3 tonnes larger than the amount of plutonium the records indicate as available”. The quantity involved agrees very well  with calculations published 15 years earlier of the civil origin weapons grade plutonium. The simplest explanation for the excess is that all the plutonium from the early years of the civil programme went into the military stockpile. In addition 5.4 te of, mainly civil-origin, non-weapons grade plutonium was sent the US as part of the MDA barter .
A further example of the benefit to military activities of an active civil nuclear programme surfaced in 2000 when the government admitted that in the 1980’s 1000s of tonnes of depleted U were removed from the safeguarded civil nuclear programme for munitions and armour used in both Gulf wars and for tritium production for nuclear warheads .
This brief historical summary suggests that when looking for links between civil and military activities in the UK the special relationship with the US is the place to start. Indeed the US/UK MDA was renewed in 2004. The reasons remain secret. However, a fair assumption is they relate to the Trident replacement (see Trident – we’ve been conned again, Dan Plesch, New Statesman, 27 March 2006). Exchanges of nuclear materials may be involved, although further use of civil plutonium in the exchanges is unlikely. However, the tritium in warheads needs replenishing and the Chapelcross military reactors that produce tritium are ceasing operation . Also, where is the highly enriched uranium for submarine reactors to come from?
A new US/UK civil nuclear link was revealed in a little reported speech by President Bush in Milwaukee, Wisconsin on 20 February this year, when he said that the US had UK support for the initiative he launched following the last G8 meeting July 2005 at Gleneagles - the ‘Global Nuclear Energy Partnership’ - involving countries that have got advanced nuclear energy programmes, or civilian nuclear energy programmes "like France and Great Britain and Japan and Russia". British involvement was confirmed month later in a written Parliamentary answer . That such a link could influence Blair is suggested by his increasing support for the Asia-Pacific Partnership (AP6) in which the US, Australia, India, China, Japan and South Korea pledge to cooperate on energy technologies outside the Kyoto Protocol .
There have been questions in Parliament to try ascertain how much the MoD spends supporting nuclear fission energy research, and why. The only answer so far regards departmental spend on “nuclear related research”, which was £79m in 2005 . What is clear is that the MoD and the Atomic Weapons Establishment (AWE) are stakeholders in the UK Research Council’s “Keep the Nuclear Option Open” project . It is likely that the military interest is in submarine reactor technology plus their wish to ensure a plentiful supply of recruits for the weapons programme with relevant expertise.
External factors affecting the UK government decision on a new civil nuclear build have changed from those which so strongly influenced the choice of the first UK reactors, but the US/UK special relationship remains a common factor. Does it matter that there may still be links between the military and civil nuclear activities in the UK? We believe it would strengthen the UK government’s attempts to get countries such as Iran to adhere to the NPT were all such links in the UK to be clarified and/or scrupulously avoided. After all, both Whitehall and the White House would have more chance of positively influencing Tehran if their own nuclear activities are whiter than white.
Keith Barnham is emeritus professor of physics at Imperial College, London. Dr David Lowry is an independent environmental policy consultant, specialising in nuclear issues
 Environmental Audit Select Committee, Session 2005-06, sixth report, vol. III, ‘Keeping the lights on: Nuclear, Renewables and Climate Change’, evidence from Open University Energy and Environment Research Unit, pp 607-11, (16 April 2006).
 K.W.J.Barnham, J. Nelson and R.A.Stevens, Nature, 407, 833, (2000)
 “Historical Accounting and Plutonium” (Ministry of Defence, London, 2000) www.fas.org/news/uk000414-uk3.htm (2000)
 K.W.J.Barnham, J. Nelson, and R.A.Stevens, R. A., Nature 395, 739 (1998).
 “Withdrawals from Safeguards pursuant to the UK safeguards agreement with the International Atomic Energy Agency (IAEA) and EURATOM" DTI, Dep. 00/1261 House of Commons Library, (July 2000).
 Consultation on draft Magnox decision document, (October 2005)
 Advance Energy Initiative
 Hansard, 20 March 2006 : Column 35W
 Blair speech to Australian Parliament "Global alliance for global values", 27 March 2006, www.number-10.gov.uk/output/Page9245.asp
 Hansard, 14 December 2005 : Column 2041W
 Engineering and Physical Sciences Research Council, “Keeping the Nuclear Option Open”, (April 2006).