Quantitative Model of a Facility -Level Radiological Security Risk Index

The safety and security of a radiological facility shares a common objective which is to ensure the protection of the population and the environment from an undue radiological hazard. Adapting and extending risk assessment to security applications has been limited because of the adaptive nature of the sub-state actors and the lack of historical data of terrorist attacks on radiological facilities. Currently, no broad risk index exists for radiological facilities, such as healthcare centers and universities. This study develops a quantitative risk-based methodology that radiological facilities can employ to conduct self-assessments and gain better understanding of the threat they face. The computation of the Potential Facility Risk Index (PFRI) is based on the triplet definition (threat, vulnerability, and consequences) of risk. The threat component of the PFRI is devised as a utility function weighing the threat group attributes and asset preference. The principles of probabilistic risk assessment and pathway analysis are implemented to account for radioactive material theft probabilities in different attack scenarios. Locational hazards and nuclear security culture are measured as a function of radiological facility vulnerability. The consequences of loss of life and economic loss are computed, as a result of an attack from the radiological dispersal device (RDD). The methodology is applied to a hypothetical healthcare facility a single radioactive with three material assets (⁶⁰Co, ¹³⁷Cs, ¹⁹²Ir). The representation of the PFRI value on a qualitative scale-ranging from “very low risk” (1) to “very high risk” (10) presents a holistic view of the state of the facility risk to RDD. The PFRI may be used by decision makers to evaluate any security upgrades and justify security investments. The RDD game, developed as an extension to PFRI, provides the healthcare facility (defender) with strategic options to budget scarce security resources and make optimal choices under severe uncertainty about the terrorist adversary (attacker) theat.