RISK-INFORMED METHOD FOR QUALIFYING STRATEGIES FOR OPERATION CONTROL OF METAL OF SAFETY RELATED SYSTEMS OF NUCLEAR POWER PLANTS

Abstract

The optimization of strategies for organizing operation control of metal of equipment and pipelines of safety related systems of nuclear power plants is a pressing issue in ensuring the operation safety and efficiency of nuclear power plants with VVERs. An analysis of regulatory and operational documentation, as well as well-known scientific developments, showed that the optimizing strategies for operation control of metal of safety related systems have not been sufficiently studied. Known strategies for organizing and planning operation control of metal of safety related systems do not take into account many years of experience in operating nuclear power plants with VVER (about 1000 reactor-years), the results of annual monitoring of the technical condition and reliability of equipment and pipelines of safety related systems (including continuous metal monitoring systems), as well as the influence of individual systems on the safety indicators of nuclear power plants and other relevant factors of reliable and safe operation. A risk-informed method has been developed for qualifying modernizations and optimizing strategies for organizing operation control of metal of safety related systems of nuclear power plants. The method is based on an analysis of the results of monitoring metal integrity of equipment and systems, as well as the probability of destruction (failure) of equipment and/or pipelines of safety related systems. Based on the developed risk-informed method for qualifying optimization of the strategy for organizing metal monitoring, the possibility to reduce the control frequency and scope for metal of the emergency feedwater pipeline of steam generators of nuclear power plants with VVER-1000 is substantiated. Further directions for the development of the practical application of the risk-informed method presented in this paper for the calculation qualification of strategies for operation control of metal of safety related systems of nuclear power plants can be related to experimental qualification of the method, as well as the improvement of deterministic methods for modelling processes of degradation/destruction of metal structures in transitional/emergency operating modes of nuclear power plants.