Concept of severe accident management for NPP-91 design with VVER-4000 reactor

After a brief description of the Nuclear Power Plant-91 concept, its main design features and safety design principles (main parameters of the power unit, reactor building, steam cell, safety building, control building, diesel building, safety system structure, protection systems, localizing systems, supporting systems, and control systems), the author discusses the strategy to assess and manage severe accidents. He outlines the design provisions against severe reactor accidents. He presents and comments the requirements for severe accident management: general approach, severe accident management measures, equipment and instrumentation for severe accident management, preventive measures and instructions, prevention of containment failure, and retention of fission products