Publications

Exploring integrated safety/security dynamic probabilistic risk assessments (DPRA) for nuclear power plants

Cohn, Brian C.; Williams, Adam D.; Aldemir, Tunc

Security at nuclear power plants (NPPs) in the United States is currently based on vital area identification (VAI)-a procedure to determine locations within a nuclear facility that need to be defended from adversaries in order to avoid damage to the facility and/or release of radionuclides to the environment. This procedure heavily leverages a Level 1 probabilistic risk assessment (PRA) which identifies combinations of events that can lead to core damage. Current approaches to VAI for NPPs, however, are determined on a “snapshot-in-time,” and therefore unable to include the time-dependent effects of safety systems within a NPP A novel “leading simulator (LS) / trailing simulator (TS)” methodology is proposed to integrate the thermal hydraulic-based safety analysis of a NPP with a physical security analytical tool to model vital area boundaries and related potential consequences. The methodology will use dynamic event trees to systematically explore the uncertainties in an adversary attack scenario at a hypothetical NPP while incorporating the timing and repair effects that are not captured using the available modeling approaches to physical security practices. Ultimately, the LS/TS methodology will enable NPPs to incorporate the full complement of safety systems and procedures when performing security analyses.