JPH01269094A - Water level controller for nuclear reactor - Google Patents

Abstract

PURPOSE:To suppress a variation of a water level of a nuclear reactor to a narrow range when a sudden variation of a furnace water temperature has been generated by providing a nuclear reactor water level detector, a furnace water temperature detector, a nuclear reactor water level setting device, a nuclear reactor water level controller and a flow rate regulator. CONSTITUTION:A furnace water temperature detector 31 detects a temperature of a coolant in a nuclear reactor 1 and outputs a furnace water temperature signal 39 to a nuclear reactor water level controller 34. A nuclear reactor water level detector 32 detects a water level of the coolant in the nuclear reactor 1, and outputs a nuclear reactor water level signal 40 to the controller 34. A nuclear reactor water level setting device 41 outputs a nuclear reactor water level setting signal 42 to the controller 34. A dump flow rate regulating valve 33 inputs a nuclear reactor water level control signal 43 from the controller 34, and adjusts a discharge of the coolant of the nuclear reactor 1. According to this constitution, by preceding a variation of a water level of the nuclear reactor caused by a sudden variation of a furnace water temperature, a water level correcting signal is outputted from a compensating part of the controller 34, and an opening of the regulating valve 33 is adjusted, therefore, comparing with a conventional one, a suppressing operation against a water level fluctuation is executed in advance, and safety and controllability of the nuclear reactor can be improved.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a nuclear reactor water level control device.

(Prior Art) In a boiling water nuclear reactor, controlling the water level of the coolant in the reactor is one of the important controls in terms of reactor safety and protection.

Reactor water level control during normal operation detects the coolant water level in the H subreactor, compares this water level with a pre-programmed water level, and increases or decreases the water supply to correct the excess or deficiency. It is being done.

Water level control at times of low output, such as during reactor startup and transitional shutdown periods, reduces the amount of water supplied to the reactor due to the small amount of steam generated. This is done by increasing or decreasing the amount. Even during such low-power operation, water level rises due to drive water flowing into the reactor from the control rod drive system, expansion and contraction due to temperature changes in the coolant, and fluctuations in reactor pressure before and after depressurized boiling. Appropriate water level control is required due to water level changes.

A conventional nuclear reactor water level control system will be explained with reference to the system diagram shown in FIG.

A reactor core 2 to which fuel (not shown) is loaded is installed in the center of the nuclear reactor 1 . This core 2.

A control rod (not shown) is inserted or withdrawn from below. The control rods are connected to a control rod drive system (CRD) 3 that drives the control rods via control rod guide tubes 18. Inside the 1M slave reactor 1, the coolant inside the reactor 1 is forced to circulate. A jet pump 4 is arranged to This jet pump 4 is connected to a reactor coolant recirculation system 6 comprising a recirculation pump 5 . A reactor water temperature detector 8 is attached to the piping 7 of the reactor coolant recirculation system 6 . A main steam pipe 9 is connected to the nuclear reactor 1 . This main steam pipe 9 is connected to a turbine (not shown) via an isolation valve 10. A water supply pump (not shown) is connected to the nuclear reactor 1 via a water supply pipe 11. The reactor recirculation system 6 includes a reactor coolant purification system (CUW).
)12 are connected. This reactor coolant purification system 12
is connected to the water supply pipe 11. A dump flow rate regulating valve 15 is connected to the pipe 13 of the reactor coolant purification system 12 via a pipe 14 . This dump flow rate adjustment valve 15
is connected to a condenser (not shown). A reactor pressure detector 16 is attached to the nuclear reactor 1 .

The reactor water level controller 21 receives signals from the reactor water level detector 17 and the reactor water level setter 22 and outputs a signal to the dump flow rate adjustment valve 15 . A comparison section 23 and a main control section 24 are set within the reactor water level controller 21.

The coolant is supplied to the reactor 1 from the water supply pipe 11.

It is fed into the reactor core 2 by the reactor coolant recirculation system 6.

The coolant that removes heat from the fuel loaded in the reactor core 2 becomes steam and is supplied to the turbine through the main steam pipe 9. The steam that has worked in the turbine is condensed in a condenser, and is again supplied to the reactor 1 through the water supply pipe 11 by the water supply pump.

In addition, the reactor coolant recirculation system 6 to the reactor coolant purification system 1
After being purified, the coolant taken into the water supply pipe 1
1 to the nuclear reactor 1 again.

The reactor water level detector 17 detects the water level of the coolant in the nuclear reactor 1 and outputs a reactor water level signal 25.

The reactor water level setter 22 is programmed with the water level in the reactor 1 in advance, and outputs a reactor water level setting signal 26. The comparator 23 subtracts the reactor water level signal 25 and the reactor water level setting signal 26 and outputs a water level deviation signal 27. The main control unit 24 performs proportional and integral operations on the water level deviation signal 27 and outputs a reactor water level control signal 28 .

The dump flow rate adjustment valve 15 receives a reactor water level control signal 28 and controls the valve opening degree. Dump flow rate adjustment valve 1
5 controls the water level of the reactor 1 by adjusting the amount of coolant discharged by adjusting the valve opening degree.

By the way, as mentioned above, there are three factors that cause the water level of a boiling water reactor operated at low output to change. In other words, the water level rises due to drive water flowing into the reactor from the control rod drive system.

These are changes in the water level before and after boiling under reduced pressure, which are caused by the expansion and contraction of the coolant due to temperature changes and fluctuations in the pressure inside the furnace. Of these, the increase in water level due to the coolant flowing in as high-pressure working water from the control rod drive system has a small amount of change and is easy to grasp, so corresponding water level control is also relatively easy.

On the other hand, changes in water level due to changes in coolant temperature and pressure inside the reactor are relatively large, especially when the rate of temperature change is large, such as when the reactor becomes critical and the temperature begins to rise while the reactor water temperature is falling. It is known that the width of water level disturbance is extremely large.

Figure 4 shows the temporal changes in the reactor water level when the reactor becomes critical while the reactor water temperature is falling and the temperature begins to rise. Figure 4 (A) is a graph of reactor water temperature changes with time on the horizontal axis and reactor water temperature on the vertical axis. Figure 4 (B) is a graph of reactor water temperature changes with time on the horizontal axis and reactor water temperature on the vertical axis. It is a graph showing changes in reactor water level based on the water level. As shown in curve a in Figure 4 (A), if the reactor becomes critical during the temperature drop and the reactor water temperature begins to rise, the result of water level control is shown in the solid curve in Figure 4 (CB). It becomes like this. That is, the reactor water level rises rapidly due to a sudden change in the reactor water temperature. At this time, the reactor water level control signal increases the valve opening of the dump flow control valve to lower the reactor water level only after detecting an increase in the reactor water level, but the water level rises due to the rapid change in the water level. cannot be suppressed. After that, the water level changes significantly to the lower side, and then gradually returns to the original water level.

In this way, conventional reactor water level control devices change the reactor water level control signal only after detecting changes in the reactor water level, adjust the valve opening of the dump flow rate adjustment valve, and prevent disturbances to the reactor water level. Acts to suppress.

(Problem to be solved by the invention) When a nuclear reactor becomes critical during a temperature drop and a sudden change in water level occurs due to a large temperature change that causes the temperature to rise, it is not possible to sufficiently suppress the water level fluctuation. There wasn't.

Therefore, when such a situation occurs, there is a risk that a reactor water level alarm will be activated, and operators will have to take necessary actions in response to this alarm.

An object of the present invention is to obtain a reactor water level control device that can suppress changes in reactor water level within a narrow range when a sudden change in reactor water temperature occurs.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention includes a reactor water level detector that detects the water level of the coolant in a nuclear reactor and outputs a reactor water level signal, and a reactor water temperature detector that detects the temperature of the coolant and outputs a reactor water temperature signal; a reactor water level setting device that sets the water level of the coolant and outputs a reactor water level setting signal; a reactor water level controller that inputs a reactor water temperature signal and the reactor water level setting signal and outputs a reactor water level control signal; and a reactor water level controller that inputs the reactor water level control signal and discharges the coolant water from the reactor. Provided is a nuclear reactor water level control device characterized by comprising a flow rate regulator that adjusts the flow rate.

(Function) In a device configured in this way, the reactor water level control signal changes depending on changes in reactor water temperature, so it is possible to suppress changes in reactor water level due to changes in reactor water temperature to a narrow range. becomes.

(Example) Hereinafter, an example of a nuclear reactor water level control device according to the present invention will be described with reference to FIGS. 1 and 2.

Figure 1 is a system diagram, and Figure 2 is a professional diagram showing the main parts. Note that the same parts and locations as in FIG. 3 are designated by the same reference numerals, and explanations of their configurations will be omitted.

As shown in FIG. 1, the reactor water temperature detector 31 is attached to the piping 7 of the reactor coolant recirculation system 6.

Reactor water level detector 32 is attached to nuclear reactor 1 .

A dump flow rate adjustment valve 33, which is a flow rate regulator, is installed between the reactor coolant purification system 12 and the condenser. As shown in FIG. 2, the reactor water level controller 34 is composed of two main parts: a reactor water volume change compensator 35 and a main control part 36, and is also provided with a comparison part 37 and an integration part 38.

The reactor water temperature detector 31 detects the temperature of the coolant in the reactor 1 and outputs a reactor water temperature signal 39 to the reactor water level controller 34. The JM slave reactor water level detector 32 detects the water level of the coolant in the reactor 1 and outputs a reactor water level signal 40 to the reactor water level controller 34. The reactor water level setter 41 is
The water level is set in advance, and a reactor water level setting signal 42 is output to the reactor water level controller 34. The dump flow rate adjustment valve 33 inputs the reactor water level control signal 43 and controls the reactor 1.
The amount of coolant discharged is adjusted.

The reactor water temperature signal 39 is input to the reactor water volume change compensator 35 . The reactor water volume change compensator 35 branches the input reactor water temperature signal 39 and inputs it to the rate of change calculator 44 and the function generator 45 . The rate of change calculating section 44 calculates the rate of change of the reactor water temperature, and the reactor water temperature number 46 and the reactor water expansion coefficient signal 47 are input to the multiplier 48, where they are multiplied together to become the reactor water volume change signal 49. , gain 50, and is output from the reactor water volume change compensator 35 as a water level correction signal 51.

The reactor water level signal 40 and the reactor water level setting signal 42 are subtracted in the comparator 37, resulting in a water level deviation signal 52. This water level deviation signal 52 is added to the water level correction signal 51 in the integrating section 38 to form a corrected water level deviation signal 53 which is input to the main control section 36 . The main control unit 36 operates the corrected water level deviation signal 53 proportionally and integrally, and outputs the reactor water level control signal 43. This reactor water level control signal 43 is
It is output from the R child reactor water level controller 34 and adjusts the valve opening degree of the dump flow rate adjustment valve 33.

Figure 4 (B
), a water level correction signal is output from the reactor water volume change compensator before the reactor water level changes due to a sudden change in reactor water temperature, and the dump flow rate g [valve opening degree is adjusted, so compared to the conventional method, water level fluctuations are suppressed in advance.

In this embodiment, when a sudden change in reactor water temperature occurs, the range of fluctuation in the reactor water level can be significantly suppressed. Therefore, it is possible to prevent an alarm from being activated due to a high water level in the reactor, thereby reducing the number of operations required by the operator to respond to the alarm. In particular, in the case where the reactor water becomes critical while the reactor water temperature is decreasing, the reactor water level can be easily controlled and managed.

Ib.

Further, the time required for the water to return to a predetermined level after the moisture has fluctuated can be significantly shortened, so the stability of the nuclear reactor can be improved.

〔Effect of the invention〕

According to the present invention, fluctuations in water level due to reactor water temperature can be suppressed within a narrow range, so stability and controllability of the reactor can be improved.

[Brief explanation of the drawing]

1 and 2 show an embodiment of the reactor water level control system according to the present invention, FIG. 1 is its system diagram, FIG. 2 is a block diagram of the main parts, and FIG. 3 is a conventional nuclear reactor water level control system. System diagram of the water level control system, Figure 4 (A) is a graph of reactor water temperature changes, Figure 4 (B)
) is a graph of reactor water level changes. 1...Reactor 31...Reactor water temperature is falling 32...Reactor water level detector 33...Dump flow rate adjustment valve 34...Reactor water level controller 35...Reactor water volume change compensation Section 36... Main control section 37... Comparison section 38... Integration section 39... Reactor water temperature signal 40... Reactor water level signal 41... Reactor water level setter 42... Atomic Reactor water level setting signal 43...Reactor water level control signal 51...Water level correction signal 52...Water level deviation signal 53...Corrected water level deviation signal. Agent Patent Attorney Noriyuki Ken Yudo Daishimaru Ken Figure 1 Figure 3

Claims (2)

[Claims] (1) a reactor water level detector that detects the water level of the coolant in the reactor and outputs a reactor water level signal; a reactor water temperature detector that detects the temperature of the coolant and outputs the reactor water temperature signal; a reactor water level setter for setting the water level of the coolant and outputting a reactor water level setting signal; and a reactor water level control signal for inputting the reactor water level signal, the reactor water temperature signal, and the reactor water level setting signal. A nuclear reactor water level control device comprising: a reactor water level controller that outputs the reactor water level; and a flow rate regulator that receives the reactor water level control signal and adjusts the amount of water in the coolant discharged from the reactor. (2) The reactor water level controller includes a reactor water volume change compensator that inputs a reactor water temperature signal and outputs a water level correction signal from the rate of change in coolant temperature and an expansion coefficient corresponding to the temperature; a comparison unit that compares the water level signal and the reactor water level setting signal and outputs a water level deviation signal; an integration unit that adds the water level correction signal and the water level deviation signal and outputs a corrected water level deviation signal; and the corrected water level deviation 2. The reactor water level control system according to claim 1, further comprising a main control section that proportionally integrates a signal and outputs a reactor water level control signal.