RU78002U1 - NUCLEAR POWER PLANT - Google Patents

Abstract

The solution relates to nuclear engineering and can be used in reactor plants with heavy liquid metal coolants. It is proposed in the input device of the gas mixture to create a pressure chamber, in the wall of which holes are made connecting it with a drain chamber in communication with the supply line of the gas mixture and with the volume of the gas system above the free level of the coolant. Increases the efficiency of cleaning from deposits of impurities, oxides of the coolant of the surfaces of the reactor block, heat transfer surfaces of the active zone and steam generators. 1 s.p. f-ly, 2 ill.

Description

The solution relates to nuclear engineering and can be used in reactor plants with heavy liquid metal coolants.

Known nuclear power plant containing a reactor with liquid metal lead coolant or its alloys, placed below the free level of the active zone, steam generators, circulation means and a protective gas system including a gas purification filter, a gas compressor equipped with a gas mixture input device in the coolant path, one or more pipes with nozzle nozzles connected to the pressure line of the gas compressor, the suction line of which is connected to the gas reactor cavity and with gas cylinders with a reducing mixture (patent for the invention of the Russian Federation No. 2192052 G21C 9/016, 19/31 from 10.27.2002).

The disadvantage of this technical solution is that upon expiration from the nozzle nozzles, the gas phase bubbles have a size equal to or larger than the size of the outlet holes in the nozzle nozzles. Flow holes in nozzle nozzles with dimensions less than 1.0-3.0 mm are permissible, due to their possible clogging with impurities contained in the coolant and is technically difficult. The speed of bubble movement of the indicated sizes exceeds 0.5 m / s. The delivery of bubbles of the reducing gas phase to all surfaces at the lower sections of the branched reactor loop with coolant velocities of 0.5 m / s or less is not provided. For such sections of the circuit, cleaning with a known solution is not effective.

The problems solved by the invention are improving the design of a nuclear power plant, increasing the resource and increasing its safety.

The technical result is an increase in the efficiency of purification from deposits of impurities - oxides of the coolant surfaces of the reactor block, heat transfer surfaces of the active zone, heat transfer surfaces of the steam generators.

The technical result is achieved by the fact that a nuclear installation containing a reactor with liquid metal lead coolant or its alloys, with an active zone, steam generators, circulating means (pumps) placed under a free level, a protective gas system, a device for introducing gas sweep into the coolant path at the entrance to the core and steam generators, equipped with a pressure chamber connected to the pressure line of the pumps, in one of its walls are made

openings connecting the cavity of the pressure chamber with a drain chamber in communication with the gas mixture supply line and having a free coolant level. The cavity of the drain chamber is in communication with the volume of the gas system above the free level of the coolant.

Figure 1 presents a diagram of a nuclear power plant that implements the proposed technical solution, figure 2 is a structural diagram of a node of a device for introducing gas mixtures into sections of the circuit.

In a nuclear reactor with a lead or lead-bismuth coolant 1, with an active zone 3 located under the free level 2 of the coolant, a steam generator 4, circulation means, for example, pumps 5, a protective gas system including gas purification filters 6, a condenser cooler 7 with an exhaust line condensate 8. Water vapor condensers 9 are placed in the gas volume of the reactor, connected by a condensate drain line 10 to the “dirty water” tank. The nuclear power plant is equipped with a gas mixture input device 11 in the vicinity of the steam generator 4. The gas mixture input device 11 is equipped with a pressure chamber 12 connected to the pressure line 13 of the pumps. Openings 15 are made in one of the walls 14 of the pressure chamber 12, connecting the cavity of the pressure chamber 12 with the drain chamber 16. The latter is connected to the supply line 17 of the gas mixture and has its free level of coolant 18, onto which the coolant jets 19 flow from the pressure chamber 12. the drain chamber 16 is in communication with the cavity of the gas system 20 above the free level 2 of the coolant, a line with controlled valves 21. Line 17 is connected to a gas cylinder 22 with a reducing mixture, with a cylinder 23 with hydrogen and a cylinder 24 with argon.

The operation of a nuclear power plant in the technological mode of purification from coolant oxides and surfaces of the reactor loop is carried out as follows.

The basis for the cleaning is either an unacceptable content of controlled oxygen impurities in the coolant and in the circuit, or routine cleaning (according to the established cleaning periods), or cleaning after decompression of the circuit due to an accident or during the repair period.

In the cylinder 22, a reducing gas mixture is prepared by supplying gas from the cylinders 23 and 24. If necessary, the protective gas in the gas cavity 20 of the reactor 1 is replaced with a reducing argon-hydrogen mixture. Pumps are introduced to ensure the supply of a liquid metal coolant to the pressure chamber 12 of device 11. A reducing gas mixture is supplied through

line 17 into the drain chamber 16 of the device 11. The coolant from the pressure chamber 12 through the holes 15 in its wall in the form of falling jets enters the drain chamber 16. The surface of the jets of liquid metal falling onto the free level of the coolant 18 in the device 11 capture and disperse the reducing gas phase, small bubbles of which are transported by the liquid metal coolant flow to the surface of the steam generator and other parts of the circuit, cleaning them from deposits of coolant oxides. Purification is carried out by reducing oxides to form a clean coolant and water vapor. The bubbles of the latter agglomerate, float and separate on the free surface 2 of the coolant in the reactor circuit. Steam due to the diffusion of convective currents in the volume of the gas cavity 20 enters the refrigerator-condensers 9 and through line 10 enters the tank of "dirty water". A cleaning mode is possible in which the reducing gas mixture through a line with controlled valves 21 enters from the volume of the gas cavity 20 into the drain chamber 16 of the device 11 due to ejection of jets of liquid metal flowing to a free level of the coolant 18 in the device 11. As the content decreases (" triggering ”) of hydrogen in the composition of the circulating reducing gas mixture, it is supplied to the gas system, maintaining the concentration of hydrogen in the mixture at about 30% by volume. After the completion of the cleaning process, controlled by reducing the rate of hydrogen loss in the gas mixture, stopping the accumulation of water condensate in the condensers 9, and according to the readings of the oxygen content sensors in the liquid metal coolant, the supply of the reducing gas mixture to the volume of the gas cavity 20 is stopped.

Thus, the coolant is cleaned of oxygen impurities due to the contact of the falling jets with the developed surface with the reducing gas mixture, and the surfaces, like steam generators and others, are cleaned by delivering small bubbles of the gas mixture to the coolant stream to them.

Application of the proposed technical solution will allow:

- increase the efficiency of cleaning heat exchange (steam generator, core) and isothermal surfaces of the reactor circuit with lead or lead-bismuth coolant from deposits of impurities - coolant oxides; to exclude the formation of deposits of significant thickness, "breakdowns" of deposits and clogging of the channels of the core,

- to increase the efficiency of the controlled content of oxygen impurities in the coolant of the reactor loop, if necessary, the deformation of protective

oxide coatings on the inner surfaces of the circuit by introducing oxidizing gas mixtures into the volume of the drain chamber;

- accelerate the regime of cleaning the coolant and the circuit from the oxides of the coolant;

- eliminate the possibility of failure of the cleaning devices with nozzle nozzles due to clogging of the gas outlets in the nozzles with impurities contained in the coolant.

Claims (1)

A nuclear power plant comprising a reactor with a liquid metal lead coolant or its alloys, with an active zone, steam generators, pumps and a protective gas system, devices for introducing a gas mixture into the coolant path at the entrance to the active zone and into the steam generators, characterized in that that the input device of the gas mixture is equipped with a pressure chamber connected to the pressure line of the pumps, holes are made in one of the walls of the pressure chamber connecting the cavity of the pressure chamber ry to the spill chamber communicating with a line for supplying the gaseous mixture and having a free level of the coolant and the volume of the gas system above the free level of the coolant.