Study on the evolution process of nuclear accident consequence assessment system

Nuclear accident consequence assessment is used to predict the total distribution of all the consequences of the release of radioactive material in the environment. Due to the development of computer technology and technology of computer simulation of atmospheric dispersion, the nuclear accident consequence assessment software system, which is designed and constructed on the basic of computerized model of atmospheric dispersion and dose calculation, is widely used in the realm of emergency response in nuclear power plants. As an E-type software system, nuclear accident consequence assessment system focuses on solving practical issues and needs in the field of accident consequence assessment. The evolution of the system follows the laws of software evolution. This paper introduces the background knowledge and basic concepts of nuclear accident consequence assessment system. Spiral model is used in the whole life cycle of evolution process according to the characteristic and complexity of the system. The initial version of the system is designed and constructed on the basic of the requirements of nuclear power plant and universal technology and model in the realm of nuclear accident consequence assessment. According to the practice of system reengineering, the evolution process of nuclear accident consequence assessment system is divided into three main phases or cycles in this paper. The main process of three-phase evolution is studied on the basic of spiral model. In each phase, the details of requirements change and application scenarios are studied and discussed deeply. Then, the key issues including impact analysis, system reengineering and CASE tools of evolution process are discussed separately in the paper. The nuclear accident consequence assessment system discussed in this paper has been applied in Ningde Nuclear Power Plant, Taishan Nuclear Power Plant, Sanmen Nuclear Power Plant in China. The practical application and improvement process of the system are discussed from the standpoint of software evolution. Moreover, the specific process, method, technologies, tools and issues are studied deeply in the paper. The research contents have great significance for software design, construction and evolution of nuclear accident consequence assessment system or other related software.