A Bayesian Network Based Security Assessment Methodology for SMR Physical Protection Design

Small and Modular Reactor (SMRs) have several features that will improve the safety and security of the plant. However, the decrease in size and smaller facilities may cause undesirable consequences once a security incident happen. However, applying large-scale facilities physical protection systems that largely dependent on security guards may not be appropriate due to the simpler, safer, and other characteristics of SMR. As the cost of the security staffing and risk certainty of the physical protection system played a part in future SMR deployment, the purpose of this study is to develop risk assessment and security planning methodology. In this study, an influence diagram has been developed to model the SMR characteristics and cost-effective allocation of security countermeasures. The influence diagram used in this study is an extension of a Bayesian network that allows efficient modelling of SMR characteristics, threats, and attack consequences while accounting for interdependencies between each systems. The target preference and attack scenario also developed to represent vulnerabilities of the facilities relative to the adversaries’ preferences. The proposed method has shown to be able to identify the effective physical protection system to be established in a SMR Facility. The optimal value of defensive strategy and cost of security can be estimated by the expected utility value in the model.