Use of logical-graphic methods of analysis of risks in the water supply systems of thermal power plants

Today's urgent issues in the water supply of thermal power plants are increasing the efficiency of production processes, reducing energy costs, introducing innovative technologies, as well as ensuring environmental safety and sustainable development. The analysis of the causes of industrial accidents and damages shows that the occurrence and development of accidents, as a rule, is characterized by a combination of random local events that occur with different frequency at different stages of the accident. Logical-graphic methods of fault trees and events are used to identify cause-and-effect relationships between these events. In order to investigate the identification and analysis of cause-and-effect relationships that contribute to the occurrence of failures in the water treatment system using a fault tree for the further development of effective measures to minimize risks and increase the reliability and safety of the water supply systems of thermal power plants, it is proposed to use logical-graphic methods on the previous stage of identification and assessment of technogenic risks. The analysis of the obtained results showed that: 1) the fault tree is an instantaneous display of the system at a certain moment in time t and is a graphical representation of the cause-and-effect relationships obtained as a result of identifying dangerous situations in the system in a forward and reverse order in order to find possible causes of their occurrence; 2) a complex final event should be determined using the so-called «tree top». The top of the tree consists of the final event and additional undesirable events, including potential accidents and dangerous conditions that are direct causes of the final event. The final event and additional events must be carefully defined and all the most important causes of the final event identified. Therefore, the first five heuristic rules must be used when building a rejection tree; 3) construction of a fault tree using heuristic rules can be used when considering any element of the system, however, to simplify cumbersome constructions, it is more appropriate to build trees only for the main elements that cause emergency situations and have a negative impact on people's lives and health, as well as on environment; 4) when building a fault trees for the technological scheme of water treatment, it is possible to specify and quantify events, to find events with a very high probability and a very low probability, to limit the further development of the fault trees and to establish the causes of failures at each stage of the water treatment process; 5) the rejection tree can be used for quantitative assessments using Markov models.