RU2013812C1 - Ventilation system of block of auxiliary systems of nuclear reactor - Google Patents

Abstract

FIELD: nuclear power engineering. SUBSTANCE: ventilation system of block of auxiliary systems of nuclear reactor includes circulation and dump tanks coupled with connection. Moisture separator which condensate outlet is coupled to trap system through vessel-hydro seal is installed at outlet of circulation tank. Moisture separator is connected through shut-off fixture to two contact apparatuses which outlets are coupled to inlets of two coolers. Rotational gas blowers are mounted beyond coolers which are connected through shut-off fixture to dump tank. Apart from this coolers are coupled through shut-off fixture, decay chamber and ventilation duct to ventilation pipe. When system operates multiple forced circulation of gases occurs over closed circuit which leads to reduction of radioactive discharges into environment. EFFECT: reduced radioactive discharge into environment. 1 dwg, 1 tbl

Description

 The invention relates to nuclear energy, in particular to structures of the cooling circuit of the channels of the control and protection systems of RBMK and other types of reactors for venting collection tanks for leaks and drains containing radiolysis gases.

 The closest technical solution (prototype) is a tank ventilation system for auxiliary systems of a nuclear reactor, containing circulation and drain tanks, connecting pipelines, a gas removal pipeline and a ventilation pipe.

 The disadvantage of this system is the design complexity of the possibility of radioactive releases into the environment.

 The aim of the invention is to reduce radioactive emissions through the use of multiple forced circulation in a closed loop.

 The goal is achieved by the fact that the ventilation system of the tanks of the auxiliary systems of the nuclear reactor, containing circulation and drain tanks, connecting pipelines, the pipeline for the removal of the gaseous medium and the ventilation pipe, further comprises a water separator, two contact apparatuses, two refrigerators, three rotational gas blowers, a holding chamber, a ventilation duct, a drainage system and a water trap, moreover, a water separator is installed at the outlet of the circulation tank and is connected to two contact valves through the stop valves apparatuses whose exits are connected to the inlets of two refrigerators, the exits of which through shut-off valves are connected to the inlet of three rotary gas blowers connected through shut-off valves to a drain tank, the outlet of which is connected to a circulation tank through a jumper, in addition, refrigerators through shut-off valves, a holding chamber and the ventilation duct is connected to the ventilation pipe, and the exits of the dehumidifier and condensers are connected via condensate to the drain system through a water trap.

 The invention is illustrated in the drawing, which shows a General view of the ventilation system of the tanks of the cooling circuit of the control system and protection of the reactor type RBMK-1000, RBMK-1500.

 The ventilation system of the tanks of the cooling circuit of the RBMK-1000, RBMK-1500 type reactor control and protection system contains a circulation tank 1, a drain tank 2, a moisture separator 3, two contact devices 4, two refrigerators 5, three rotary gas blowers 6, connecting piping 7, shutoff valves 8, a holding chamber 9, a water trap 10, a ventilation duct 11, a ventilation pipe 12. The tanks are connected by a jumper 13.

 The ventilation system of the tanks of the cooling circuit of the control and protection systems of the RBMK-1000, RBMK-1500 reactors works as follows.

 In nominal mode, process water passes through the circulation 1 and drain 2 tanks after cooling the actuators of the control and protection system, containing dissolved radiolysis gases. In addition, the gas-water mixture is discharged into the drain tank 2 after cooling the actuators of the quick emergency protection channels (BAZ). The process water passing through the tanks and the gas-water mixture discharged contains argon-41, which is formed in the reactor core from argon-40, which, in turn, is contained in the process water as an air component. Before using this invention, the saturation of process water with air, and accordingly, argon-40, occurred in the tanks when they were purged with air in order to dilute to a safe concentration and further blow off the radiolysis hydrogen and oxygen. Ventilation of the circulation 1 and drain 2 tanks was carried out forcibly through compressed air pipelines with an air flow rate of 150-300 m3 / h, with blowing through the ventilation duct 11 and ventilation pipe 12 into the environment.

 At the same time, along with radiolysis gases, radioactive argon-41 was blown into the atmosphere; and purging the tanks with air led to saturation of the process water with argon-40, which, in turn, led to the arrival of a new "portion" of argon-40 in the reactor core. In addition, saturation of the process water of the circuit with atmospheric oxygen leads to a decrease in pH (increase in acidity).

According to this invention, purging of the tanks with air is excluded. Gas with a flow rate of 300 m ³ / h is taken from the circulation tank 1 and enters the moisture separator 3. In the moisture separator 3, the gas stream is cleaned of water droplets, the condensate of water vapor is discharged into the drain system through a water trap 10. The gas separated from moisture enters the contact device 4 of one of the technological threads (the second thread may be in reserve or repair), in which it is first heated in electric heaters, and then fed to the catalyst, where it is oxidized by radiolytic and atmospheric oxygen. After contact apparatus 4 gas with a temperature of 80 ^{° C} arrives in a refridgerator 5. Refrigerator 5, two functions are performed: off gas to prevent overheating blowers and condenses water vapor formed during the combustion of hydrogen. The condensate is discharged to the water trap 10. The gas then enters the intake manifold of the blower 6 to the inlet of the working blower 6 and through the pressure collector flows through the pipeline into the gas volume of the drain tank 2. From the drain tank 2 into the circulation tank 1, gas flows through the jumper 13.

Nitrogen with a flow rate of 6-7 m ³ / h is supplied to the closed ventilation system from the gas-water mixture of quick emergency protection channels, therefore it is necessary to discharge part of the gases with the same flow rate from the system. For this purpose, a communication pipeline is designed for the outlet pipeline of the refrigerator 5 and the holding chamber 9 with shutoff valves 8. The holding chamber 9 is designed to suppress the activity of unbalanced gas discharged from the tank ventilation system. From the holding chamber 9, gas is discharged through the connecting pipe 7 to the ventilation duct 11 and to the ventilation pipe 12.

1+

× 10³;

, где А - активность выброса аргона-41 в окружающую среду, Ки/ч;
К - постоянная выброса после камеры выдержки (10^-4 Ки/л);
G_д - расход дебалансного газа, сбрасываемого в окружающую среду после камеры выдержки, м³/м;
G_в - расход сжатого воздуха на продувку баков СУЗ, м³/ч;
G_баз - расход азота на продувку исполнительных механизмов каналов БАЗ, м³/ч;
10³ - переводной коэффициент размерностей.The volume of the exposure chamber 9 is about 140 m ³ . In this case, the dependence is realized:
A = K × lnG

1+

× 10 ³ ;

where A is the activity of the release of argon-41 into the environment, Ki / h;
K is the ejection constant after the holding chamber (10 ^-4 Ci / l);
G _d - the flow rate of unbalanced gas discharged into the environment after the holding chamber, m ³ / m;
G _in - the flow of compressed air to purge the tanks CPS, m ³ / h;
G _bases - nitrogen consumption for purging actuators of BAZ channels, m ³ / h;
10 ³ - conversion coefficient of dimensions.

.In this invention, in the absence of purging the tanks with air (G _in = 0), the mathematical expression takes the form
A = K × lnG _d × 1 × 10 ³

.

 Pilot operation of the tank ventilation system has begun; its results are presented in the table.

From the above data it follows that the release of radioactive argon-41 into the environment is almost completely excluded. This is confirmed by analyzes of samples of the activity of gases taken from the ventilation pipe system. Moreover, the analysis of the nuclide composition of the emissions shows the absence of argon isotopes within the sensitivity of the measuring device (1 x 10 ^-12 Ci / l). The hydrogen content in the atmosphere of the circuit tanks decreased due to the operation of the contact apparatus 3, and the pH value of the process water increased (acidity decreased) due to the replacement of the air atmosphere of the tanks with nitrogen.

 The operation of the CPS tank ventilation system has shown the reliability of its operation, simplicity and accessibility in maintenance. In addition, a slight decrease in the acidity of the medium (water of the CPS cooling circuit) due to a decrease in the oxygen content dissolved in water due to the replacement of the air atmosphere of the tanks with nitrogen, in turn leads to an improvement in the operating conditions of the metal of the CPS cooling system, increases the operating time of the filters used to maintain water quality in predetermined normalized limits, i.e., increasing the filter cycle. Emissions of tritium to the atmosphere are reduced due to its oxidation by oxygen in the contact apparatus and the discharge of the heavy water formed in this way through a water trap into a special water treatment system.

Claims (1)

 SYSTEM OF VENTILATION OF TANKS OF AUXILIARY SYSTEMS OF THE NUCLEAR REACTOR, containing circulation and drain tanks, connecting pipelines, gas removal pipe and ventilation pipe, characterized in that it further comprises a dehumidifier, two contact apparatuses, two refrigerators, three rotational gas blowers, an exposure chamber, a ventilation chamber a drainage system and a water trap vessel, and a water separator is installed at the outlet of the circulation tank and is connected to two contact devices through shutoff valves, the outlets of which are connected to the inlets of two refrigerators, the outlets of which through the shutoff valves are connected to the inlets of three rotary gas blowers connected through the shutoff valves to a drain tank, the outlet of which is connected via a jumper to the circulation tank, in addition, the refrigerators are through the shutoff valves, a holding chamber and a ventilation duct connected to the ventilation pipe, and the exits of the dehumidifier and condensers are connected via condensate to the drain system through a water trap.

Images