Methodology for analyzing risk at nuclear facilities

Abstract

A methodology for evaluating risks at nuclear facilities is developed in this work. A series of measures is drawn from the analysis of factors that determine risks. Five measures are created to evaluate risks at nuclear facilities. These include the legal and institutional framework, material control, physical protection system effectiveness, human resources, and consequences. Evaluation attributes are developed for each measure and specific values are given in order to calculate the risk value quantitatively. Questionnaires are drawn up on whether or not a state has properly established a legal and regulatory framework (based on international standards). These questionnaires can be a useful measure for comparing the status of the physical protection regime between two countries. Analyzing an insider threat is not an easy task and no methodology has been developed for this purpose. In this study, attributes that could quantitatively evaluate an insider threat, in the case of an unauthorized removal of nuclear materials, are developed by adopting the Nuclear Material Accounting & Control (NMAC) system. The effectiveness of a physical protection system, P(E), could be analyzed by calculating the probability of interruption, P(I), and the probability of neutralization, P(N). In this study, the Tool for Evaluating Security System (TESS) code developed by KINAC is used to calculate P(I) and P(N). Consequence is an important measure used to analyze risks at nuclear facilities. This measure comprises radiological, economic, and social damage. Social and economic damages are difficult to evaluate. Therefore, radiation levels and theft of nuclear materials that could be quantified are adopted as attributes for analyzing the consequences. Awareness of the nuclear security culture and physical protection resources such as staffing, capabilities, and cost required to provide PP should be considered when evaluating risks. In this study, these attributes are included in the measure of human resources. Human resources include such factors as trustworthiness, degree of nuclear security culture awareness, and frequency of psychiatric testing of employees. A case study performed on hypothetical facilities demonstrates that the developed methodology could be used to analyze innovative nuclear systems as well as existing facilities.