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Probabilistic basis and assessment methodology for effectiveness of protecting nuclear materials
textSafeguards and security (S&S) systems for nuclear facilities include material control and accounting (MC&A) and a physical protection system (PPS) to protect nuclear materials from theft, sabotage and other malevolent human acts. The PPS for a facility is evaluated using probabilistic analysis of adversary paths on the basis of detection, delay, and response timelines to determine timely detection. The path analysis methodology focuses on systematic, quantitative evaluation of the physical protection component for potential external threats, and often calculates the probability that the PPS is effective (PE) in defeating an adversary who uses that attack path. By monitoring and tracking critical materials, MC&A activities provide additional protection against inside adversaries, but have been difficult to characterize in ways that are compatible with the existing path analysis methods that are used to systematically evaluate the effectiveness of a site’s protection system. This research describes and demonstrates a new method to incorporate MC&A protection elements explicitly within the existing probabilistic path analysis methodology. MC&A activities, from monitoring to inventory measurements, provide many, often recurring opportunities to determine the status of critical items, including detection of missing materials. Human reliability analysis methods are applied to determine human error probabilities to characterize the detection capabilities of MC&A activities. An object-based state machine paradigm was developed to characterize the path elements and timing of an insider theft scenario as a race against MC&A activities that can move a facility from a normal state to a heightened alert state having additional detection opportunities. This paradigm is coupled with nuclear power plant probabilistic risk assessment techniques to incorporate the evaluation of MC&A activities in the existing path analysis methodology. Event sequence diagrams describe insider paths through the PPS and also incorporate MC&A activities as path elements. This work establishes a probabilistic basis for incorporating MC&A activities explicitly within the existing path analysis methodology to extend it to address insider threats. The analysis results for this new method provide an integrated effectiveness measure for a safeguards and security system that addresses threats from both outside and inside adversaries.Mechanical Engineerin
Quantitative Methodology for Assessing State-Level Nuclear Security Measures
The international community faces a growing threat from nuclear terrorism. The complexity of the threats of nuclear terrorism, the variety of nuclear security measures that States can devote resources towards to address the threats, and the limited resources States have to invest in these nuclear security measures make it imperative that resources are applied in the most effective way possible. In this dissertation, we develop a quantitative, risk-based methodology that States can employ to gain a better understanding of the nuclear threat they face, assist them in determining what nuclear security measures they should invest in, and facilitate communication to stake-holders to request and justify investment in these measures.
The risk-based methodology has been developed employing a combination of pathways analysis, game-theory, multiple-attribute utility analysis, decision theory and risk analysis. The methodology was designed to account for the wide variety of nuclear security measures that States can invest in, the range of possible consequences from different nuclear threats, and the severity of these consequences to the State. In addition, the methodology models the adversary's strategic decision making while accounting for the capabilities, motivations, and disincentives that may influence which nuclear threat a terrorist group will attempt.
The methodology is introduced into a Visual Basic for Applications code, which we demonstrate through verification and qualitative validation tests. We then develop three State nuclear infrastructures with varying levels of complexity, meant to provide a realistic representation of real-world States. We then utilize the code to evaluate the risk of nuclear terrorism against terrorist threats that have different motivations for nuclear terrorism to demonstrate how different motivations for nuclear terrorism may affect both State-level risk and the State's optimal risk-reduction strategy. These risk analyses are then used to both evaluate various nuclear security strategies and determine which nuclear security measures will have the greatest risk-reduction value. Finally, we conduct a sensitivity analysis on capabilities of terrorist groups to understand how changes in these capabilities affect the State-level risk from nuclear terrorism