Published online 4 November 2010 | Nature | doi:10.1038/news.2010.583

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Weapons research crosses the Channel

Joint facility at the heart of Anglo-French nuclear cooperation.

turbulenceComputer simulations similar to these play a crucial role in nuclear-weapons research.University of Chicago Center for Astrophysical Thermonuclear Flashes

Nuclear-weapons data is among the most closely guarded information there is. But in the wake of a major defence agreement, it seems that crucial data needed to maintain the nuclear stockpiles of both the United Kingdom and France will be coming from a single shared facility.

The two nations have agreed to build a joint test facility that will image dummy bombs as they explode. The facility, known as EPURE, will be based at France's main nuclear-weapons laboratory in Valduc, 45 kilometres northwest of Dijon, and will be built in part using technology developed at the UK Atomic Weapons Establishment at Aldermaston in Berkshire. The data from EPURE will be used to determine whether warheads remain reliable as they age — an essential part of maintaining nuclear weapons without testing them directly.

The decision to share such a sensitive facility is a marked shift for both countries, and has left some arms-control experts scratching their heads. "I'm frankly effing baffled by this," says Jeffrey Lewis, an arms-control expert with the James Martin Center for Nonproliferation Studies in Washington DC. But Bruno Tertrais at the Foundation for Strategic Research in Paris says that the motivation is "extremely simple: to save money".

Bridging the divide

Until now, the two nations' programmes have stood apart. From its inception, the United Kingdom's nuclear programme has been closely tied to that of the United States. British weapons closely resemble US equivalents, and UK scientists are regularly found on the campuses of US weapons laboratories. France, by contrast, has prided itself on an independent nuclear programme, often avoiding public cooperation agreements with other countries.

But both the United Kingdom and France have similar needs for weapons research. Since the mid-1990s, both nations have had moratoriums on nuclear testing. To maintain their weapons in the absence of tests, both have turned to computer simulations supported by smaller-scale explosions.

“I'm frankly effing baffled by this.”

Jeffrey Lewis
James Martin Center for Nonproliferation Studies in Washington, DC

Among the most crucial studies needed are those that look at the moment of detonation. At the heart of modern nuclear weapons is a small sphere of plutonium or uranium, surrounded by conventional explosives. The explosives detonate simultaneously, compressing the radioactive material and triggering the blast, which is then used to explode a second, more powerful stage.

Modelling that first moment of detonation is a complicated affair. The high energies liquefy the materials, which mix as they compress. Scientists fear that ageing explosives and old nuclear material could change the conditions of the compression and make warheads unreliable.

The role of EPURE will be to feed computer models with real-world data from dummy blasts. Although neither government has yet released details of the new facility, it could look somewhat similar to the Dual Axis Radiographic Hydrotest facility at Los Alamos National Laboratory in New Mexico. That facility uses two electron particle accelerators to create X-rays that can image explosions from multiple angles, allowing scientists a detailed view of the moment of detonation.

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Climate of trust

At US$350 million to construct, the Los Alamos facility didn't come cheap. The United Kingdom and France will save "considerable sums of money" building EPURE together, according to a UK Ministry of Defence spokesperson.

Whether the data from the facility will also be shared is another matter. The collaboration will include exchanges of nuclear researchers between the two labs, and, according to a press release from the office of French President Nicolas Sarkozy, create "a climate of trust" between scientists in the two countries. "However, EPURE is designed to allow both countries to keep, for each experiment, full sovereignty over the results," the statement adds.

Lewis is sceptical that the facility can be shared without some details of each nation's bombs being revealed. "Unless you say 'On Mondays, Wednesdays and Fridays only French are allowed in the building, and on Tuesdays, Thursdays and Saturdays only Brits and we all take Sunday off to have a party,' I don't know how you don't share information," he says. 

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