Today, the most important issues in the national economy of Ukraine are the issues of continuous, reliable and safe operation of reversible water supply systems, namely power units of thermal electric stations and heating plants of industrial enterprises. Trouble-free and reliable operation of water supply systems ensures the normal operation of social and household and industrial enterprises, as well as the safe operation of fire protection systems, which can be disrupted when the supply of a quality product to the consumer is stopped. For the purpose of research to determine the conditions of the reliability of reversible water supply systems in thermal power engineering, as well as the impact of risks in these systems on the reliability of reversible water supply systems, it is proposed to determine the states in which any water treatment system can be and the risks in water treatment systems that are technogenic in origin, and the consequences are ecological. The analysis of the obtained results showed that the states in which the water treatment system can be divided into three classes in accordance with the regulatory documents on the definition of technogenic risks in water treatment systems: class 1 (limit state) - the system works in normal mode, all blocks and elements work without failures and crashes; class 2 (critical state) - the system works in offline mode, some units or elements of the system work in partial failure mode; class 3 (dangerous state) - the system practically does not work and does not purify water, some blocks or elements of the system are in a state of failure. The risks that arise during the operation of water treatment systems and which can be used to assess their technogenic safety can be defined as: a) the probability of this system supplying raw water to the consumer as a result of the failure of blocks and elements of this system - state 3 - dangerous; b) the probability of this system supplying the consumer with poor-quality water as a result of partial failures and freelance work of units and elements of this system - state 2 - critical; c) the probability of this system supplying raw water to the consumer when the system is in state 1 - limiting, due to the natural inertia inherent in the specific physical and chemical processes on which the actual system operates.

Ensuring uninterrupted and reliable operation of water treatment systems is a priority task of the industrial complex of Ukraine. For effective reliability management in water treatment systems, it is necessary to analyze potential failures and determine the probability of their occurrence. For the purpose of research to determine the probability of the occurrence of risks as a result of failures of various units of the water purification system, using the example of the operation of a column-type electrocoagulator, it is proposed to use the structural and functional block diagram of water purification systems to obtain generalized patterns, which makes it possible to reduce the entire system to several interdependent units, namely: 1) fine-cleaning filtration unit; 2) a unit for cleaning from soluble impurities; 3) a unit for cleaning coarse impurities; 4) pipe-pump unit. When the water treatment system is operating, taking into account the ranking of the reliability of the units, it can be stated that the 1st unit may fail at the beginning, followed by the 2nd, 3rd and 4th units. It is established that if all the units of the system are working, the system is in the S0 state. When other blocks fail, in the same sequence, the system will be in states S1, S2, S3 and S4. The most interesting are the states of the system, in which block failures do not cause shutdown of the entire system, but only its off-duty operation, which is manifested only as a result of the deterioration of the quality of treated water. Analyzing the obtained results, it can be asserted that during the operation of the water treatment system, the highest probability of failure is in unit 1. After the unit is restored and during further operation of the system, the highest probability of failure is unit 2, then unit 4 and unit 3. The failure probabilities of the units are the probabilities of risks, moreover, the physical value generated by these risks (the amount of polluted water that entered the ecosystem or the boiler unit) will be greater, the longer the unit failure detection period. When the water treatment system operates for a long enough time, a probabilistic constant mode of transition from state to state is established in it according to the scheme «working state of all blocks - failure of one or several blocks - repair - working state of all blocks». The probability of the sequence and duration of these events can be determined, which makes it possible, on the one hand, to assess the risks arising during operation and to determine a management strategy to minimize these risks.

Protection and security of energy systems from all types of threats, including threats of a complex nature, are of primary importance in Ukraine today. Therefore, the management of technogenic risks in energy systems related to critical infrastructure and, first of all, in thermal energy systems of thermal power plants and thermal power plants, the failure of which can lead to the impossibility of living in the specified territory or object, carrying out economic activities there, loss of life or significant material damage is important and relevant. In order to justify the use of reversible water supply systems of thermal power facilities to increase the reliability and safety of their operation, a generalized algorithm of optimal quality management during water purification was proposed in order to minimize technogenic risk for any water purification system. The analysis of the obtained results showed that the generalized algorithm of optimal quality management during water treatment in order to minimize technogenic risk for any water treatment system can be obtained in the case of using the following methodology: drawing up a structural and functional block diagram of the water treatment system; analysis of technological modes affecting quality; technical and economic analysis of the values that limit the values of the regimes that give minimal pollution; obtaining mathematical expressions that reflect the dependence of the amount of pollution and the amount of restrictions on specific technological modes; entering data into the computerized control system, the input port of which is supplied with the current value of stiffness, at the output of the water treatment plant, from the output port of which the specific values of the technological modes supported by the control bodies of the water treatment plant are taken.

Purpose. To determine and evaluate technogenic risks within the water purification systems of TSs and TPSs during normal operation in terms of electrocoagulation plant. Methodology. It is proposed to apply a fault tree method for the analysis of various operation failures of water purification facilities in the heat power industry. Additional analysis method, applied at stages one and two of technogenic risk determination, is suggested for its use. The method is based upon the construction of matrix combining states of the system elements. Findings. The aggregation of the combination matrix and fault tree method makes it possible to derive a new grapho-analytical procedure to analyse probabilities of technogenic risk initiation in the context of any water purification system operation both at the stage of its design and at the stage of its work. Originality. Non-routine operation of a water purification system may depend upon certain internal reasons as well the external ones. The reasons pose risks to a situation that at the output of the system, water will turn out being insufficiently purified. It has been identified that in terms of the non-routine operation of water purification system, risk probability is worth analysing with the help of the fault tree serving as graphical representation of causal relationships obtained while considering dangerous situations in reverse order to determine probabilities for their initiation. Practical value. The procedure helps obtain quantitative, qualitative, and causal-consequential indicatorsfacilitating control of technogenic risk initiation in water purification systems. Software has been developed to calculate rapidly the probabilities of running of block elements or water purification system elements in an operation mode or in a failure mode, and see clearly the poorest combinations in terms of an electrocoagulation water purification system.