SU719341A1 - Nuclear reactor control device - Google Patents

Description

/ :. L

The invention relates to the field of nuclear energy and is mainly intended to control the shape of axial energy distributed on nuclear reactors of the type VVER, RVMK and to suppress azimuthal disturbances in the RBMK reactor.

A device for controlling a reactor is known, which is a closed Channel with a liquid absorber occupying 5-10% of its volume. the remainder of the channel is filled with the gaseous phase of the absorber l. The lower part of the channel is washed by a coolant, so the change in reactor power affects the temperature of the liquid absorber and the pressure of its gaseous phase. This results in an auto-adjusting effect.

The drawbacks of the device are inertia, which is caused by the large heat capacity of the heated medium. A significant disadvantage is that the effective operation of the device is possible only at one given level. The latter deficiency is deprived of the gas control system of indirect action.

A device for controlling a nuclear reactor is known, the control volume of which is directly connected through the pressure collector to the preheater tank. However, the known liquid neutron absorbers, especially in the vapor phase) cause severe corrosion of communications, which reduces nuclear safety. This device is inertial and uneconomical due to the high heat capacity of the Adhesion medium and the inefficient use of heater i operating in an uninterrupted manner.

The closest in technical essence is a device for controlling a nuclear reactor, containing

The burning partitioned enclosed volume with gas is absorbed by a neutron body and at least one gas heater.

In the prototype, the closed volume is divided into two sections by bellows. One section is in the neutron flux and is filled with CO gas, which is weakly neutron-absorbing, and the other is outside of it in the output flow of the coolant, which serves as a gas heater. This section contains neutron-strong BF gas. The bellows changes the amount of absorbing gas in the active zone. .

The device works as follows.

An increase in nuclear reactor power above a predetermined level leads to an increase in the temperature of the coolant, which heats the neutron absorbing gas. The gas expands and, acting on the bellows, enters the active zone, displaced by the CPS. . This leads to an increase in the absorption capacity of a part of the volume in the active zone and a decrease in the power of tees. Reverse breakouts (essy occur when the power decreases below a predetermined level. Thus, the device stabilizes the power at a given level, but is not able to change it.

An indirect device, free from this disadvantage, contains an autonomous gas heater. Such a device requires Continuous heater operation, therefore uneconomical. Especially important for this device is to control the axial distribution of energy release in the active zone for the device. It contains several heaters and needs intensive cooling. The more powerful the heater and the more intense the cooling, the wider the dynamic range of the device and the greater the speed. But increasing the heater in the device is limited by the cooling conditions, since if the heat balance of the device is disturbed, the device case will be heated, which will reduce the dynamic characteristics. That is, these characteristics in the “autotype” are limited by cooling conditions. Improving the cooling of this device is not only due to technical difficulties, but is also not economically viable because of the increased 1. four

energy loss of the heater

into the cooling medium.

The aim of the invention is to improve the dynamic characteristics and increase the economy through the use of the a-neutron absorber in the pulsed mode, which allows an increase in the power of the heater without increasing the cooling intensity.

This goal is achieved by the fact that high-speed shut-off valves are installed on the gas supply tubes of the sections, which are synchronized with the heater of the corresponding section by the synchronization unit.

So-hay, so, is a partitioned closed volume with a neutron absorber gas, containing at least one gas heater, on the gas supply lines of the sections of which high-speed shut-off valves are installed, for example, electric, connected to the control heater through sync block.

The control signal for opening the solenoid valves is given with a small (fraction of a second) delay after the heater is turned on. A powerful, high-temperature heater during this time heats the gas in the section and creates a large excess pressure in it. When the valve opens, the gas which absorbs the neutrons, under the action of a pressure difference, begins to move from the section where the heater is turned on to the others. The absorbing capacity of this section is reduced until it reaches the desired value.

The heater is then turned off, and at the same time the valve, the compartment gas in the section, is closed from the rest of the volume. The amount of absorbing gas in the section will now remain constant, maintaining the required absorbing capacity of the section until further manipulation. Since the powerful heater is turned on for a short time, it does not have time to warm up the heat-absorbing body of the device, cooled from the outside by coolant, therefore the gas in the section quickly rises and its pressure decreases. If it is now necessary to increase the absorption capacity of the section, then the valve must be opened, then under the action of the pressure difference, the section will begin to fill with gas to the original level. To establish the absorption capacity at a different level, it is necessary to close the valve again. The absorptive capacity of the section is determined by the amount of neutron absorber gas in it and is controlled in the device by the coordinated operation of the heater and the shut-off valve. Moreover, the heater is turned on only for a short time (seconds to maintain the overpressure in the section by heating the gas. This allows it to increase its power without changing the cooling conditions to improve the dynamic performance of the device and saves a significant amount of energy, which is especially important azimuthal harmonics suppression topics at RBMK, energy management systems, where the heater is off most of the time the device has been running. The device does not require intensive for example, water cooling, which simplifies its maintenance, makes it much simpler. The device does not contain mobile NfexaHH3MOBs, such as pumps, motors, bellows. This allows it to remain operable at any position in space, for example, in a flying space. Fig. 1 shows a device designed to control the axial distribution of the energy Lenin and a control circuit of this device; Fig. 2 shows a device designed to suppress azimuthal harmonics to the reactor RBMK; Fig. 3 is a top view of a part of the active zone in which the device for controlling a nuclear reactor is located. The device (Fig. 1) is a partitioned closed volume 1 filled with a gas - absorber i of neutrons 2. As such a gas helium-3 is selected - inert Gas with a microscopic cross section of 5,400 barn. Inside each section 3,4,5 contains a heater. 6,7,8. The sections communicate 416. through gas supply tubes 9.10P, on which shut-off solenoid valves 12, 13, 14 and a variable cross section choke 15 are installed to adjust the gas flow. The gas flow rate from the sections located in the E core 16 is limited by the requirement of nuclear safety. The device control system includes neutron flux detectors 17, comparison elements 18.19, synchronization unit 20, and power amplifier unit 21, supplying heaters. The synchronization unit performs the functions of coordinating the operation of valves and heaters. It consists of threshold elements that, when input signals exceed permissible limits, control keys in the supply circuit of shut-off valves and control circuits of power amplifiers and a signal delay circuit for switching on shut-off valves. Power amplifier blocks are made on thyristors controlled by keys from a synchronization unit . Comparison element 19 generates an error signal for the difference in the magnitude of the neutron flux in the upper and lower half of the active zone, which determines the shape of the axial energy release, from the desired difference, which is specified by the setpoint. If the mismatch is within acceptable limits, then all valves are closed and heaters are turned off. As soon as the mismatch exceeds the allowable value, the synchronization unit turns on (depending on the mismatch sign) one of the two heaters located in the active zone and after some time opens valves 12 and 13 During this time, the heater will heat the gas in the section, creating a high pressure area in it. After the valves are exhausted, the gas under the action of the difference in pressure in the sections passes from one to another, redistributing their absorption capacity. This will continue until the error signal is again within acceptable limits. Then the synchronization unit closes the valves 12 and 13 will turn off the heater. If the alignment signal changes the sign and exceeds the permissible limits, the other heater already operates, and it moves in the opposite direction, redistributing the absorptive capacity of the sections so as to establish the necessary form of axial energy release again.

This is the way that Energy Management is controlled by s Bttcote active reactor zone. The valve 14 is always closed and the heater, located outside the active zone, does not work. That is, the neutron-absorbing gas does not enter from the active zone and does not enter it, but only

W) p | -distributed along its height. This means that such a control is not a BOSI of the integral and integral power of the chopper. 15

If it is required to use this device to control the integral ratio, then sections with a heater that is outside the active zone and valve 14 are used. In 2Q of this case, the synchronization unit operates on a signal from comparison element J 8. Comparison element 18 forms the cnlrWan mismatch of the measured 25 integral power (determined by the sum of the upper and lower sensor readings) of the desired value. When it is necessary to increase the power, the synchronization unit turns on the heaters 30 located in the active zone and through From time to time opens all valves. The gas leaves the core until the power reaches the desired value, and the signal 35 from the reference element 18 is within acceptable limits. Then the valves close and the heaters turn off. To reduce the power, it is hardly possible to turn on the heater 6. All three work synchronously at power control. The rate of change of reactivity is set with the help of drossel 15. "-.

Figure 2 shows an application example 5 of the proposed device for suppressing azimuthal harmonics on a RBMK. Control sections 4.5 here are located in diametrically opposite channels. Fig. 3 shows a top view 50 of the active zone 16, in katiguiax 22,2,3., In which this device is installed. The device is similar to the above. Shut-off valve 14 is always closed. It is used in conjunction with a heater 55 6 only to compensate for the burnt-out absorber gas in the channels, when it is necessary to add this gas to the control. sections or when an absorber needs to be replaced. The control sections are cooled by a coolant 24. The synchronization unit is not shown in this example for simplicity.

An important advantage of such a device is that it does not disturb the integrated power and does not distort the axial distribution of the neutron flux, since the absorber does not leave the active zone and is not redistributed along the zone height.

The device provides an increase in the dynamic range (greater maximum pressure difference in the sections) and speed due to the use of the heater in a pulsed mode, which allows an increase in the power of the heater without changing the cooling conditions. The device economically consumes the energy of the heater, which, most of the time, the device is off.

The device is reliable because it does not contain moving mechanisms such as pumps, engines, bellows. This allows it to maintain its performance at any position in space, which can be important on aircraft.

Invention Formula

A device for controlling a nuclear reactor containing a partitioned enclosed volume with a gas neutron absorber and at least one gas heater, characterized in that, in order to improve dynamic performance and increase efficiency, gas-operated section tubes are equipped with high-speed shut-off valves that are controlled synchronously with the heater of the corresponding section of the synchronization unit.

.., The source of information taken into account in the examination

1. Patent FR.G№ 1200451, cl. 21 a 21/31, pub. 1966.

2. US patent number 2990358, VP. 176-21, published. 1961.

3.Patent of England No. 1042315,

cl. G 6c, pub. 1966 (prototype.

Claims (3)

The invention is a device for controlling a nuclear reactor containing a partitioned closed volume with a gas neutron absorber and at least one gas heater, characterized in that, in order to improve dynamic performance and increase efficiency, quick shut-off valves are installed on the gas tubes of the sections controlled synchronously with the heater of the corresponding section by the synchronization unit. Source of information taken into account during the examination 1. Germany patent No. 1200451, class 21 g 21/31, published. 1966. 2. US patent 'No. 2990358, CL. 176-21, published. 1961. 3. Patent of England No. 1042315, cl. G 6c, published. 1966 (prototype). Fig ί VNIIIPI__Order5901 / h9__ Circulation 476 Subscribed _____ Branch of the PPP Patent, Uzhgorod, Project 4,