An intelligent system by fuzzy reliability algorithm in fault tree analysis for nuclear power plant probabilistic safety assessment

© Imperial College Press. Fault tree analysis for nuclear power plant probabilistic safety assessment is an intricate process. Personal computer-based software systems have therefore been developed to conduct this analysis. However, all existing fault tree analysis software systems only accept quantitative data to characterized basic event reliabilities. In real-world applications, basic event reliabilities may not be represented by quantitative data but by qualitative justifications. The motivation of this work is to develop an intelligent system by fuzzy reliability algorithm in fault tree analysis, which can accept not only quantitative data but also qualitative information to characterized reliabilities of basic events. In this paper, a newly-developed system called InFaTAS-NuSA is presented and its main features and capabilities are discussed. To benchmark the applicability of the intelligent concept implemented in InFaTAS-NuSA, a case study is performed and the analysis results are compared to the results obtained from a well-known fault tree analysis software package. The results confirm that the intelligent concept implemented in InFaTAS-NuSA can be very useful to complement conventional fault tree analysis software systems

The Implementation of Importance Measure Approaches for Criticality Analysis in Fault Tree Analysis: A Review

THE IMPLEMENTATION OF IMPORTANCE MEASURE APPROACHES FOR CRITICALITY ANALYSIS IN FAULT TREE ANALYSIS: A REVIEW.Fault tree analysis (FTA) has been widely applied in nuclear power plant (NPP) probabilistic safety assessment to evaluate the reliability of a safety system. In FTA, criticality analysis is performed to identify the weakest paths in the system designs and components. For this purpose, an importance measure approach can be applied. Risk managers can apply information obtained from this analysis to improve safety by implementing risk reduction measure into the new design or build a more innovative design. Various importance measure approaches have been developed and proposed for criticality analysis in FTA. Each important measure approach offers specific purposes and advantages but has limitations. Therefore, it is necessary to understand characteristics of each approach in order to select the most appropriate approach to reach the purpose of the study. The objective of this study is to review the current implementations of importance measure approaches to rank individual basic events and/or minimal cut sets regarding their contributions to the unreliability or unavailability of NPP safety systems. This study classified importance measure approaches into two groups, i.e. probability–based importance measure approaches and fuzzy–based importance measure approaches. This study concluded that clear understanding of the purpose of the study, the type of reliability data at hands, and the uncertainty in the calculation need to be considered prior to the selection of the appropriate importance measure approach to the study of interest.

Integrated methodology for analyzing highly enriched uranium production scenarios at gas centrifuge enrichment plants

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2010.Cataloged from PDF version of thesis.Includes bibliographical references (p. 399-417).The dramatic change in the international security environment after the collapse of the bipolar system has had a negative impact on the effectiveness of the existing nuclear non-proliferation regime. Furthermore, the success of the Pakistani Gas Centrifuge Enrichment Technology (GCET)- based nuclear weapons program has imposed a great challenge on the Nuclear Nonproliferation Treaty (NPT) regime. In this context, this study tried to answer two questions: (a) what is the probability of proliferators successfully producing Highly Enriched Uranium (HEU) at Gas Centrifuge Enrichment Plants (GCEPs) and (b) how effective is the current NPT regime in dealing with this issue. In order to tackle these two questions, an integrated methodology is used that reflects all factors affecting the nuclear proliferation on the front-end of the nuclear fuel cycle. A quantitative assessment of the proliferation risks of producing HEU for multiple scenarios is presented using success tree models, uncertainty analysis, sensitivity analysis, importance measures, and expert opinion. This assessment identifies the factors that can reduce the proliferators' success of producing HEU, which will be helpful in prioritizing the use of the IAEA's limited resources.(cont.) The study found that legal capabilities of the NPT regime are more problematic than technological capabilities in preventing proliferators from producing HEU at GCEPs, since the United Nations Security Council (UNSC) is the only NPT regime component that has compliance-enforcing resources. This study recommends three approaches as follows: First, the NPT regime should take a multi-faceted approach that incorporates all NPT regime components into each step of nuclear weapons program development. Second, the NPT regime should impose nuclear elements control via Multilateral Export Control Regimes (MECRs). Third, the NPT regime should develop an approach that challenges HEU production from both technological- and legal points of view. Since law governs technological capability, a multidimensional approach that includes this relationship would be more effective than an approach that focuses on either aspect individually.by Taeshin Kwak.Ph.D

Safety and Reliability - Safe Societies in a Changing World

The contributions cover a wide range of methodologies and application areas for safety and reliability that contribute to safe societies in a changing world. These methodologies and applications include: - foundations of risk and reliability assessment and management - mathematical methods in reliability and safety - risk assessment - risk management - system reliability - uncertainty analysis - digitalization and big data - prognostics and system health management - occupational safety - accident and incident modeling - maintenance modeling and applications - simulation for safety and reliability analysis - dynamic risk and barrier management - organizational factors and safety culture - human factors and human reliability - resilience engineering - structural reliability - natural hazards - security - economic analysis in risk managemen

Federal Register

Daily publication of the U.S. Office of the Federal Register contains rules and regulations, proposed legislation and rule changes, and other notices, including "Presidential proclamations and Executive Orders, Federal agency documents having general applicability and legal effect, documents required to be published by act of Congress, and other Federal agency documents of public interest" (p. ii). Table of Contents starts on page iii

Ohio State University Bulletin

Classes available for students to enroll in during the 1974-1975 academic year for The Ohio State University