3. Evolution development of reactor engineering

The general trends in the PWR, BWR and LMFBR type reactors development and improvement are discussed. New concepts in power reactor design, which are the variants with exclusive utilization of inherent safety mechanisms, intermediate-power reactors combining the well known techniques with new passive safety systems preventing fuel damage during accidents and those developed taking into account the experience gained in the course of large-power nuclear power plant operation, are described in details. The main characteristics of the projects of the PWR, WWER, BWR, CANDU, RBMK and LMFBR type reactors of the new generation are given. The requirements and design variants of new containment shells applicable for underground NPPs as the way for increasing the efficiency of radiation containment and radioactive waste disposal cavity in the case of an accident are considered. It is shown that the main efforts are focused on standardization of the design and equipment; wider application of industrial manufacturing of the main components assuring better quality control; simplification of arrangement variants, operational and maintenance procedures and emergency conditions elimination; higher automation degree providing human factor influence decreasing; widening the role of containment shell during severe accidents; elimination of the risk of emergency conditions and sufficient decreasing accident probabilities; protection against sabotage; application of passive safety systems