Study On Organizational Factors Related To Safety Of Nuclear Power Plant

For the root causes of an accident in a nuclear power plant (NPP), technical errors and human errors of operators are not the final answer. Organizational factors commit significantly. However, how organizational factors influence upon the safety of an NPP, e.g. which organizational factors are involved in an accident? How do they interact with each other to cause mistakes? What are the main contributors? Therefore we must conduct in-depth research work and systematically and overally reveal the impacts of organizational factors upon NPP safety.The purpose of the dissertation is to probe into the influences of organizational factors upon NPP safety, analyze their impact force, construct an assessment and identification system and catch the leading factors to support efficiently the probabilistic safety assessment (PSA) and set forth the corresponding countermeasures to secure the critical organizational factors uninfluenced to strengthen the NPP operation safety and ultimately sharpen the competition edge and enlarge the development of a NPP.The significance of the study is reflected in three aspects. The first is to systematically study the generation and transmission mechanism of NPP accidents caused by organizational factors. The causes of their growing, route and barrier failure are explained. Then a theoretical model and technique is constructed to analyze and identify the safety-related organizational factors. It provides a theoretical basis, technique and assessment standard to observe the symptoms of organizational failures and the relationship between the leading factors and other ones. Finally the organizational factors are combined with PSA through investigation into ultra accident samples. It makes an assessment and analysis on the organizational behaviors of the existing social-technical system of a NPP and benefits its safety and economical performance.At the beginning the dissertation makes a brief review and comment on the related theories and documents. On the basis of a review on the 940 operation event reports form WANO, a conclusion of organizational factors being a leading contributor to human errors is drawn out. Then on the basis of the definition and categorization of organizational factors, the internal meaning and the elements which impact upon these factors are focused. In the data collection, the study adopts various methods to guarantee their reliability and availability. It uses structural equation to testify the influences of organization strategy, structure and factors upon safety performance. On the basis of the above, Bayesian net is used to simulate the influences of the organizational factors upon reliability of operators. The internal relationship among organizational factors, situation awareness and individual factors is well modeled. Furthermore, in case of given proofs, cause-effect deduction and diagnosis deduction can be employed to calculate the reliability value of operators. The most possible organizational factors leading to human errors are identified to prevent those caused by organizational factors. Studies have found that "training","procedures","available time","work organizations" and "personnel assignment" are sensitive to the safety of nuclear power plant. Therefore special attention should be paid to thoses key factors. The paper puts forward measures to improve safety-related organizational factors in connection with severe accident management, procedures, operator screening and promotion, main control room area management and safety culture construction. Finally the dissertation discusses the limitation and future work of the study.