The National Academies will advise the Department of Energy (DOE) on the augmentation of its current risk-based approach, the Design Basis Threat, for securing the nuclear weapons complex, specifically for securing nuclear weapons usable materials and facilities. The study will examine the augmentation of cyber security as well, while recognizing that cyber security and physical security present different challenges. The National Academies will: 1. Evaluate the potential applicability and feasibility of risk-based approaches, including probabilistic approaches, for securing the DOE nuclear weapons complex and document their potential strengths and weaknesses, cost effectiveness, and impediments to implementation. As part of this task, the National Academies will consider the experiences of DOE and its national laboratories, other federal agencies (e.g., Department of Defense, Department of Homeland Security, Nuclear Regulatory Commission), and the private sector (e.g., nuclear power industry) on the use of risk-based approaches for securing complex technological systems. 2. Evaluate whether and how dissuasion (i.e., deterrence and prevention) concepts can be incorporated into risk-based approaches to enhance security, both in terms of effectiveness and cost efficiency. 3. Provide practical and actionable findings and recommendations on the use of risk-based approaches to (i) balance physical and cyber security; and (ii) communicate within the government and with the public about security risks and costs.The project is sponsored by the National Nuclear Security Administration, U.S. Department of EnergyThe contractural start date for the project was September 9, 2008.A report will be issued at the end of the project.Note: The project duration has been extended through December 31, 2010.