The analysis of emergency cooling system for the active zone of the VVER-1000 reactor in order to increase reliability of its operation.
Students Name: Gumeniuk Vitalii
Qualification Level: magister
Speciality: Heat and Power Engineering
Institute: Institute of Power Engineering and Control Systems
Mode of Study: part
Academic Year: 2022-2023 н.р.
Language of Defence: ukrainian
Abstract: Humenyuk V.Yu., Lys S.S. (head). The analysis of emergency cooling system for the active zone of the VVER-1000 reactor in order to increase reliability of its operation. Master’s thesis. - Lviv Polytechnic National University, Lviv, 2022. The system of emergency cooling of the core of the low pressure reactor is designed for: 1. emergency cooling of the reactor core and subsequent long-term removal of residual heat from the core in accidents involving the disintegration of the first circuit, including rupture of the main circulation circuit Du 850 full cross section with unobstructed bilateral termination of the coolant (emergency mode; 2. scheduled cooling of the first circuit at a given speed (300C / h) during shutdown of the reactor unit and removal of residual heat from the core during overload of the core (mode of planned cooling of the first circuit and removal of residual heat from the core during PPR and / or overload of the core ); 3. removal of residual heat from the core during repair work on equipment of the I circuit, associated with the need to reduce the level of coolant in the reactor below the axis of "hot" nozzles (mark 25,700) up to the axis of "cold" nozzles fcc (mark 23,900) drainage zone in the reverse circulation of the coolant I circuit). The object of research is the emergency cooling system of the WWER-1000 reactor core. The subject of research is the reliability of the emergency cooling system of the core of the WWER-1000 reactor. The purpose and objectives of research. The aim of the work is to analyze the emergency cooling system of the core of the WWER-1000 reactor. To achieve this goal it was necessary to perform the following tasks: - conduct a technical description of the SAOZ; - analyze the composition of the SAOZ system; - to analyze the device and operation of the SAOZ system; - analyze violations of normal operation and emergency modes; - to carry out the analysis of emergency modes of supply of rbk by SAOZ pumps from ГА-201. In this master’s qualification work it is shown that the emergency cooling system of the core is a system important for safety, and belongs to the protective safety systems, as well as combines the functions of normal operation systems in terms of planned cooling. As a protective safety system, the system provides heat removal from the core in emergency modes, as a system of normal operation - provides heat removal from the core in the mode of scheduled and repair cooling. It is established that the system of emergency cooling of the core of the low pressure reactor must take into account the requirements of the reactor unit: 1. in all modes to ensure the consumption of cold water 250 ? 300 m3 / h, at a pressure in the I circuit 21 kgf / cm2, and a flow rate of 700 ? 750 m3 / h, at a pressure in the I circuit 1 kgf / cm2 and a temperature not lower than 200C; 2. ensure, at the initial moment of the accident, the supply to the circuit of water with a concentration of at least 16 g / dm3 of boric acid; 3. to provide water supply in emergency situations not later than in 35 ? 40 sec. from the moment of reaching the pressure of the I circuit 21 kgf / cm2; 4. ensure the possibility of periodic testing and testing of systems within the channel of security systems, as well as testing of its components and elements, without violating the conditions of normal operation; 5. to provide work both during emergency modes, and in the post-accident period (during all period of finding of fuel in an active zone); 6. to provide the possibility of putting into repair its elements as part of one channel when working at capacity for up to 72 hours. The criterion for performing the functions of the system is to meet the requirements of the reactor unit to ensure the supply of boric acid solution in the I circuit with the flow rate: 1. not less than 230 m3 / h at a pressure of the I circuit of 21 kgf / cm2; 2. not less than 750 m3 / h at a pressure of the I circuit of 1 kgf / cm2. The design of the system is based on the following criteria and requirements for it from the reactor unit: 1. to provide supply to the I circuit of boric acid solution with a flow rate of 6 m3 / h, concentration 39.5 ? 44.5 g / dm3 in the pressure range from 160 to 0 kgf / cm2; 2. to ensure the supply to the I circuit of boric acid solution with a flow rate of not less than 130 m3 / h and an initial concentration of 40 g / dm3 in the pressure range in the I circuit 90 ? 15 kgf / cm2 and not less than 100 m3 / h in the pressure range in the I circuit 90 ? 100 kgf / cm2; 3. to provide the possibility of long-term work with the tank-pit ГА-201; 4. ensure the temperature of the water supplied in all modes is not less than 200C; 5. the system must allow the possibility of per-channel testing during operation of the power unit at power without loss of functional properties; 6. to provide in an emergency situation supply of boron solution I contour not later than in 35 ? 40 sec. since reaching 90 kgf / cm2 in the I circuit. The criterion for performing the functions assigned to the system is to prevent uncontrolled increase in reactor power and reliable cooling of the reactor core. In the economic part, the calculation of technical and economic indicators for NPPs was carried out. The automation of the turbine installation was carried out. Since it is impossible to measure the vapor pressure by directly connecting the manometer to the steam line due to the high temperature of the medium, therefore a condensing vessel should be provided. Secondary intermediate devices are selected taking into account their unified input / output signals. Actuators must ensure appropriate speed of regulation. Key words: power unit, boric acid solution, emergency cooling system, WWER-1000 reactor.