Performing complicated engineering analyses of a nuclear power plant requires storage and manipulation of a large amount of information, both data and knowledge. This information is characterized by its multidisciplinary nature, complexity, and diversity. The problems caused by inefficient and lengthy manual operations involving the data flow management within the framework of the safety-related analysis of a power plant can be solved by applying the computer aided engineering principles. These principles are the basis of the design of an integrated information storage system (IRIS). The basic idea is to create a computerized environment, which includes both database and functional capabilities. Consideration and analysis of the data types and required data manipulation capabilities as well as operational requirements, resulted in the choice of an object-oriented database management system (OODBMS) as a development platform for solving the software engineering problems. Several advantages of OODBMSs over conventional relations database systems were found of crucial importance, especially providing the necessary flexibility for different data types and extensibility potential. A detailed design of a data model is produced for the plant technical data and for the storage of analysis results. The overall system architecture was designed to assure the feasibility of integrating database capabilities with procedures and functions written in conventional algorithmic programming languages.