Calculation of the Probabilistic Safety Analysis and Reliability by the Fault Trees and Event Trees Methods

One of the main requirements for ensuring a high level of safety and economic efficiency of nuclear power units at all stages of the life cycle - designing new ones, operating existing power units and decommissioning them - is a probabilistic safety analysis of nuclear power units. The most widely used method for probabilistic safety analysis is the fault tree method. NPP power units are a complex system consisting of a large number of units of equipment, systems and units that are interconnected functionally and affect each other. In addition, to increase the adequacy of the developed probabilistic model of a power unit, it is necessary to take into account equipment failures for general reasons and the human factor. The resulting in-depth probabilistic models of power units can contain tens of thousands of fault trees and, as a result, hundreds or more of thousands of minimum sections and require lengthy calculations to obtain acceptable accuracy of the results. This complicates the application of this method, especially when monitoring risk in real time, when it is necessary to promptly make changes to the model and assess the impact of these changes on the current risk. The novelty of the project is the use of a modified modularization method, which significantly accelerates the generation of many minimal sections.