Dynamic Risk Framework for Optimizing the Physical Security Postures of Nuclear Power Plants

This paper describes an ongoing effort within the Light Water Reactor Sustainability program at Idaho National Laboratory to optimize the security and costs of nuclear power plants (NPPs). It introduces Event Modeling Risk Assessment Using Linked Diagrams (EMRALD), a dynamic risk assessment tool developed at Idaho National Laboratory. EMRALD was leveraged to optimize NPP security postures by integrating force-on-force (FOF) simulations and operator mitigation actions, including dynamic and flexible coping strategies (FLEX). To illustrate the methodology, four attack scenarios were modeled via a commercially available FOF simulation tool, using a hypothetical NPP facility. The simulation results provided valuable insights into possible attack outcomes, as well as the probabilistic risk of core damage events given these outcomes. Safety mitigation procedures dependent on the attack outcomes were modeled in EMRALD by considering human operator uncertainties. The results demonstrate that the number of armed responders can be optimized while still affording the same level of protection as in the initial security posture. The proposed modeling and simulation framework created by integrating FLEX equipment with FOF models enables NPPs to credit portable FLEX equipment in their security postures, resulting in an efficient and optimized physical security system.