Development of a Potential Facility Risk Index for Radiological Security

Abstract

Given the threat of radiological and nuclear terrorism, it is imperative to understand and evaluate the security risk of radioactive sources. In this context, risk assessment is a function of threat, vulnerability, and consequences. Currently, no broad risk index exists for radiological facilities, such as healthcare centers and universities. This study aims to develop and demonstrate a methodology to compute a potential facility risk index (PFRI) based on a probable loss event (LE) and loss magnitude (LM) resulting from a radiological dispersal device (RDD) attack. The threat component of the PFRI is devised as a utility function weighing the threat group attributes and RDD radioactive material preference. The principles of probabilistic risk assessment and pathway analysis are implemented to account for RDD radioactive material theft probabilities in different attack scenarios. Locational hazards and nuclear security culture are measured as a function of radiological facility vulnerability for LE. The LM of the attack, in the form of loss of life and economic damage, is then estimated to construct the PFRI. The methodology is applied to a hypothetical healthcare facility with a single radioactive material asset. For this example, the PFRI resulted in a value of 2.0 (on a scale of 1–10), showing low risk to the facility. The development of the PFRI provides a risk analysis tool that may be useful in making decisions for radiological security improvements.

Quantification of a Facility Radiological Security Risk Index With a Graphical User Interface Tool

“…The survey was divided into categories of “general,” “technical,” and a “combination of general and technical.” Each survey category reflected the impact of security culture on the facility’s vulnerability from the above defined threat groups of G1, G2, and G3. The survey questionnaire characteristics and categories are elaborated and presented in greater detail in Rane and Harris (2020). Each survey questionnaire was formatted with a seven-point Likert scale.…”

“…The panel of “Expected Utility” computes the expected utility of each scenario. The expected utility is computed as a product of the overall success probability, P s (M i X j ) t , and the total utility, U tot (M i X j ), for each threat scenario, t (Rane and Harris 2020). A simplifying assumption is made that each terrorist group only plans one type of attack for each time period analyzed.…”

“…This study uses the economic theory of preference and utility functions (eqns 1-3) to rank the utilities that a group of adversaries would derive from the assets with respect to attractiveness and form. The utility function for the relative attractiveness of the radiological material is based on the International Atomic Energy Agency (IAEA) categorization system (2005a), and the utility function for physical form is derived from the innate physical properties (metallic or powdered salt) of the radioactive materials (Rane and Harris, 2020):…”

“…The PFRI, unique to the facility, can be used by practitioners to conduct self-assessments. The theoretical framework of the PFRI is formally introduced and explained by Rane and Harris (2020). This paper focuses on implementing the PFRI methodology to an RDD incident from three radionuclides of concern: 137 Cs, 60 Co, and 192 Ir.…”

“…Since this paper is a continuation of previous work (Rane and Harris 2020), the same notation and terminology used previously is retained in this work. The layout of St. Benedict Healthcare, a hypothetical facility, is outlined here.…”