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Both the National Ignition Facility (NIF), now under construction at the Lawrence Livermore National Laboratory in California, and the Laser Megajoule project planned near Bordeaux, France, will violate the Comprehensive Test Ban Treaty (CTBT) and could open the way for the development of new, ‘pure fusion’ nuclear weapons, according to a study published this week.

The Institute for Energy and Environmental Research (IEER), a technically respected group based in Takoma Park, Maryland, calls on parties to the CTBT to issue a ruling on the treaty status of inertial confinement fusion research, which would be conducted at the two facilities. The IEER, which is consistently critical of US nuclear weapons policy, wants both projects halted.

The IEER's report, Dangerous Thermonuclear Quest, says that an operational NIF will lead to strong political demand for so-called ‘pure fusion’ weapons (see Nature 387, 439; 1997 ). These would yield fusion explosions without any need for the fission explosions that trigger fusion in existing thermonuclear weapons.

Both NIF and the Laser Megajoule will generate tiny thermonuclear explosions of a few kilogrammes TNT equivalent, triggered by massive and immobile banks of laser beams. “NIF will not, by itself, lead to pure fusion weapons,” says Arjun Makhijani, a plasma physicist who heads the IEER. “But it could play a crucial role by enabling the design of targets for other driven systems, which could be miniaturized.”

Makhijani also argues that NIF will create political pressure for the development of pure fusion weapons. “We must prevent the scientific feasibility of these weapons being established, because once it is, the pressure to build them will become irresistible,” he says.

David Crandall, director of the NIF office at the Department of Energy, says his department's non-proliferation office and the ‘Jasons’, a group of scientists who advise the government on complex issues, have confirmed that the machine poses no proliferation risk. Crandall says the signatories to the CTBT accept the definition of a nuclear explosion contained in the earlier Non-Proliferation Treaty (NPT). The NPT specifically permits inertial confinement fusion research.

Makhijani says the CTBT bans all nuclear explosions. “If they wanted a specific exemption for this, they should have asked for it.”

The NIF has been under construction for twelve months, has strong Congressional support, and, as Crandall confirms, there is no chance of it being halted in response to the report.