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Monitoring Nuclear Weapons and Nuclear Explosive Materials

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Previous studies by the National Academy of Sciences’ Committee on International Security and Arms Control (CISAC) emphasized the key role of transparency, monitoring and verification, both for the future of arms limitations among the nuclear-weapon states and for keeping nuclearexplosive materials (NEM) 4 away from proliferation-prone states and terrorists. In 2000, the U.S. Department of Energy requested that CISAC study the potential for a more comprehensive approach to nuclear-arms control. The report, Monitoring Nuclear Warheads and Nuclear Explosive Materials, explores the extent to which current and foreseeable approaches to transparency and monitoring can support verification for all categories of nuclear weapons – strategic and non-strategic, deployed and nondeployed – as well as for the nuclear explosive components and materials that are their essential ingredients. Increasing the categories of items subject to transparency and monitoring would be valuable – and may ultimately be essential – as the United States and the world attempt to address the urgent and interrelated goals of reducing the dangers from existing nuclear arsenals, minimizing the spread of nuclear weaponry to additional states, and preventing the acquisition of nuclear weapons by terrorists. In addition to understanding the transparency and monitoring possibilities and requirements for more ambitious arms control regimes, the study also focuses on potential applications to the continuing challenges of keeping nuclear weapons out of the hands of proliferant states and terrorists. To give one prominent example, the United States has emphasized the need for verification as part of an agreement to eliminate North Korea’s nuclear weapons program. Likewise, as the United States continues to work with Russia to ensure that nuclear materials are adequately protected and accounted for, the partners will continue to require transparency measures to facilitate the process. 1 The paper is adapted from the Executive Summary of Monitoring Nuclear Weapons and Nuclear-Explosive Materials: An Assessment of Methods and Capabilities, Committee on International Security and Arms Control (2005). Available at: 2 Steve Fetter is Professor and Dean of the School of Public Policy at the University of Maryland, a member of the National Academy of Sciences’ Committee on International Security and Arms Control (CISAC), and co-chair of the study. Ben Rusek is a Research Associate with CISAC. 4 A “nuclear-explosive material” is a mixture of fissionable nuclides in which the proportions of these are such as to support an explosively growing fission chain reaction when the material is present in suitable quantity, density, configuration, and chemical form and purity. Uranium containing more than 20 percent U-235 or more than 12 percent U-233 (or an equivalent combination of proportions of these two nuclides) is considered NEM, as are all mixtures of plutonium isotopes containing less than 80 percent Pu-238. The study addresses the technical and institutional approaches and capabilities in transparency and monitoring that could be applied to declared stocks of nuclear weapons, nuclear weapons components, and nuclear-explosive materials. The study also evaluates methods that could be used to detect clandestine stocks or covert production of nuclear weapons or NEM. Although the study does not make recommendations about U.S. arms control and nonproliferation policies, such policy choices will continue to shape the context within which monitoring approaches and capabilities might be applied.

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