DRAFT PLEASE DO NOT CITE WITHOUT PERMISSION Protecting Critical Nuclear Infrastructure: Strategies for Security

The safety and security of a nuclear facility share a common objective – ensure the protection of the local population, society at large, and the environment. The gradual transition in reactor safety regulation from highly deterministic requirements toward a more riskinformed framework provides a useful analogue for reactor security and ensuring effective resource allocation. However, there are some important differences between the way security and safety risks are quantified and managed. A cornerstone of the National Strategy for Homeland Security and the National Infrastructure Protection Plan is that terrorists pose a strategic threat to key assets and critical infrastructure. Unlike hurricanes, tornadoes, earthquakes, or equipment failures, terrorists do not act randomly and instead try to strike where the defenses are weak and the expected gains are large. As a result, protecting one target may simply shift the risk of attack to another target. Failing to treat threats as fully strategic can lead to significant misallocations of defensive resources. The current Design Basis Threat (DBT) approach to allocating defensive resources generally requires the defender to attain a high probability of successfully defending against a specific threat or small number of specific threats and is typically highly prescriptive. This paper integrates fully strategic threats and elements of risk analysis by modeling the interaction between a defender and attacker as a game. Additionally, an alternative theoretical framework for characterizing and managing the risks posed by security threats is developed.