Safety Functions in the Software Quality Assurance of NPP Safety Important Systems

One of the most important tasks in the software complexes quality assurance is the procedure of forming requirements to a developed or modified system and their subsequent verification. The most essential errors are done at the first life cycle stages - these are errors in determining requirements, selecting the architecture, high-level design. The faults of safety critical software may considerably damage the equipment or properties, as well as to lead to essential detriment of the environment and human victims. Increasing requirements to the software quality of NPP (nuclear power plant) safety important systems at all stages of the life cycle is concerned with increasing the software complexity and functionality and has led to the necessity of developing approaches to justify both the system's safety and the safety of software involved in the systems make-up. The paper considers an approach based on the "safety functions" the implementing of which is verified in sequel. This approach is used under the software verification of upper level systems of automated process control systems and may be applied for the fault tolerance analysis, information- and cyber- security of soft- and hardware complexes.