JPS625200A - Controller for operation of nuclear power plant - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an apparatus for operating a nuclear power plant.

(Technical background of the invention and its problems) In general, in power systems where nuclear power plants are used together, the nuclear power plants operate at a constant load, and the hydropower/thermal power plants respond to fluctuations in power demand throughout the day and night. Load following operation is being performed.

In this constant load operation of a nuclear power plant, the load is set to a constant value using a manual load setting device, and the reactor power control system controls the reactor recirculation flow rate based on this set value.
This is done by keeping the reactor's output constant.゛However, in recent years, in order to operate the power system flexibly, nuclear power plants have also been
There is a growing demand for load-following operation that changes the load as needed. However, if the load following operation performed in thermal power plants, etc. is applied directly to nuclear power plants, the minimum critical power ratio of the reactor will fall below the minimum critical power ratio limit IE [(0-LMCPR) during operation. There is. Considering this phenomenon using the operating characteristic diagram of the Ill water reactor shown in the m4 diagram, the operating point A of the reactor moves in a zigzag manner during the load following operation of the reactor, and the thermal υ1 limit line B is It is to overcome. Under this phenomenon, boiling IIM migration occurs in the reactor core, damaging the fuel rods, and there is a risk that safe operation of the reactor cannot be ensured.

[Purpose of the invention]

This invention has been made in consideration of the above facts, and an object of the present invention is to provide an operation control device for a nuclear power plant that can perform load following operation while maintaining the integrity of the reactor core in the nuclear power plant. .

[Summary of the invention]

In order to achieve the above object, the operation control device for a nuclear power plant according to the present invention includes an output regulator that requests reactor output according to load fluctuations, and a recirculation outflow that varies based on an output request signal. An output control system that controls the output of the nuclear reactor, and is arranged between the output regulator and the output control system,
A load operation switch that inputs the output request signal from the output regulator to the output control system during load following operation, and inputs the output request signal from the manual load setting device to the output control system during constant load operation, and It is connected to the reactor thermal margin monitoring device that monitors the thermal margin in time series and the load operation switching device, and when the thermal margin falls below a certain value, the load operation switching device is connected from the output regulator side. This includes a determination device that switches to the manual load setting device side.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the operation control device for a nuclear power plant according to the present invention. Nuclear power plant operation IIJ tl equipment mainly consists of reactor power regulator 3, load operation switch 5, and reactor power! ,1
Connect the 1 control system 7 in sequence - 1 and the reactor thermal margin monitoring device! It is configured by connecting i9 to the load operation switching PJ5 via the determiner 11. The manual load setting device 15 is connected to the manual setting point 13 of the load operation switching device 15, and the reactor power regulator 3 is connected to the automatic setting point 1f of the load operation switching device 5.

The reactor output JlI device 3 detects frequency fluctuations in the power system, and when the frequency falls below a specified frequency, it sends a load request signal to increase the reactor output in accordance with the increase in load, and also outputs a power When the frequency of the system rises above the specified frequency, a load request signal is output that reduces the output of the reactor in response to the reduction in load. Further, the load operation switching device 5 outputs a signal requesting a constant load by operating the operation 0.

The reactor power control system 7 varies the recirculation rate of the boiling water reactor based on the load request signal from the reactor power control system 3 and the manual load setting device 15, thereby increasing the recirculation rate in a relatively small range and at high speed. It changes the output of a nuclear reactor.

The load operation switching 15 is the reactor power control terminal 1 on the spotlight 7 side.
8 is selectively connected to either the manual setting point 13 or the self-first stage fixed point 17. That is, during load following operation, the terminal 18 is connected to the automatic set point 17 to input the load request signal from the reactor power control system 3 to the reactor power control system 7. Also, during constant load operation,
Terminal 18 is connected to manual set point 13 to input the load request signal from manual load setter 15 to the reactor power control system.

The determiner 11 is connected to the load operation switching device 5 and also to the manual load setting device 15 .

Then, the evaluation value of the atomic thermal margin is inputted to this judger 11 from the reactor thermal margin monitoring system R9 at each operating point, and this judger 11 inputs the evaluation value of the thermal margin by -1. When the value falls below a certain value, terminal 1 of the load operation switch 5
8 to manual set point 13. At the same time, determiner 1
1 outputs the load value to be set to the load hand Q regulator 15.

Also, reactor thermal margin monitoring bag r! ! t9 is based on process calculation Ia19 and nuclear constant data 2, as shown in FIG.
A nuclear constant calculation device 23 that calculates nuclear constants based on various data from 1, and an abnormal transient analysis device 2F 25 that calculates overregion changes using the nuclear constant values calculated by this nuclear constant calculation device 23. υ1 limit value of small limit output ratio (OLMCP
The main part thereof consists of a transient limit output calculation device 27 that calculates R).

Process calculation 1119 calculates process computer data such as current core power, flow rate, control rod pattern, power distribution, burnup distribution, and plant data.

The nuclear constant data 21 is pre-calculated and stored data necessary for determining nuclear constants such as the density distribution of reactor water in the reactor core and the position of control rods.

The nuclear constant calculation device 23 receives process computer data from the process computer 19 and nuclear constant data from the nuclear constant data 3, and calculates the value of the nuclear constant.

The abnormal transient analysis device 25 analyzes large abnormal transient events between changes in the minimum critical power ratio (MCPR) using the nuclear constant calculated by the nuclear constant calculation bag ff23, and calculates the core flow m, Find transient changes in output, pressure, inlet enthalpy, etc.

The transient limit output calculation device 27 inputs the transient change determined by the abnormal transient analysis device 25, and based on this, calculates the initial value of the minimum critical power ratio (MCPR) and the minimum value of the minimum critical power ratio (MCPR) at the time of the transient change. Difference from value (ΔMCPR”)
is calculated, and the limit value of the minimum critical power ratio (OLMCPR) that reflects the core state at the time of monitoring is calculated as shown in the following equation.

Limit value of minimum output ratio (OLMCPR) - ΔMCPR
10 Safety limit power ratio Therefore, when evaluating the thermal margin during current operation using the reactor thermal margin monitoring device configured as above, the nuclear constant calculation bag H23 is used to calculate the reactor output from the process computer 1. ,
The flow rate, control rod pattern, power distribution, burnup distribution, plant data, and nuclear constant data from nuclear constant data 3 are inputted to calculate the nuclear constant.

Next, the nuclear constant calculated by this nuclear constant calculation device 23 is output to the abnormal transient analysis device f25, and in this abnormal transient analysis device 25, an analysis is performed for abnormal transient events with a large minimum critical power ratio (MCPR) change. Transient changes in flow rate, flow rate, output, pressure, inlet enthalpy, etc. are required.

This transient change is input to the transient limit output calculation device 27, and the transient limit output/calculation bag @27 calculates the initial value of the minimum critical power ratio (MCPR) and the minimum critical output ratio at the time of the transient change based on this transient change. The difference (Δ
MCPR) is determined, and the minimum critical power ratio limit value (OLMCPR) that reflects the core state at the current operating point is determined. And the minimum critical power ratio (MCPR) at the current operating point
1 of the minimum output ratio at the same operating point. II limit value (OL
MCPR) is output to the determiner 11 at each operating point as a thermal margin evaluation value of the reactor.

The thermal margin of this nuclear reactor will be explained using FIG. t111 limit value of the minimum output ratio at each operating point (OLM
The thermal limit line 29 is determined from the minimum output ratio limit value h at any operating point in time. Further, the operating point of the reactor is determined from the minimum power ratio, and the operating point 30 in the figure indicates the operating point at the same operating point as the thermal limit line 29.

If the evaluation value of the thermal margin at a certain operating point is positive, that is, if the minimum critical power ratio at a certain operating point is greater than the limit value of the minimum critical power ratio at the same operational point, the reactor calculated from the minimum critical power ratio The operating point 30 of is located below the thermal limit line 29 in the diagram. Further, when the evaluation value of the thermal margin is negative, the operating point of the nuclear reactor at a given operating point is located above the thermal limit line at the same point in time. If the evaluation value of the thermal margin at any operating point is positive and the value is large, the larger the value, the lower the operating point at that point is below the thermal limit line at the same point, The margin becomes expensive, expensive, expensive, etc.

Next, the effect will be explained. ``During normal operation, the nuclear power plant performs load following operation by connecting the terminal 18 of the load operation switch 5 to the automatic set point 17. That is, when the load on the power system changes, its frequency changes, and the reactor power regulator 3 detects this frequency change and sends a load request signal corresponding to the change to the reactor power control system 7. This reactor power control system 7 is
The recirculation flow rate of the reactor is controlled based on this load request signal, and the output of the reactor is adjusted to υ11 according to load fluctuations.
11. Roughly speaking, at each operating point during this load following operation, the reactor thermal margin is evaluated in time series by the reactor thermal margin monitoring system RA9, and each evaluation value is evaluated by the determiner 11 at each operating point. It will be judged.

During this load following operation, as shown in FIG. 3, the operating point 30 of the nuclear reactor fluctuates in a zigzag manner over a long period of time. and,
If the operating point 31 of the reactor at a certain point in time is expected to exceed the thermal limit line exposed at that point, i.e.
If the minimum limit output ratio at the same time decreases and approaches the limit value of the minimum limit output ratio at that time by a certain value or more, the judgment device 11 detects this and outputs a switching signal to the load operation switch 5. do.

When the load operation switch 5 is switched and the terminal 18 is connected to the start set point 13, the nuclear power plant is in constant load operation. The value of the load is set by the operator based on the load setting signal output from the determination device 11 to the manual load setting device 15.

In this way, by switching the nuclear power plant from load following operation to constant load operation when the evaluated value of the reactor's thermal margin falls below a certain value, the operating point of the reactor is thermally Boiling transition of the nuclear reactor that may occur due to exceeding the limit line can be avoided, and the integrity of the nuclear reactor can be maintained.

In this constant load operation, the operating point of the reactor moves to the left under constant output as shown in FIG. 3, and this movement further reduces the thermal margin of the reactor. Therefore,
Similar to conventional constant load operation, when the operating point of the reactor reaches point 33 in Figure 3, the control rods are inserted into the reactor core.
The operating point of the reactor will be returned from position 33 to position 30 to maintain the integrity of the reactor core.

(Effects of the Invention) As described above, according to the nuclear power plant operation u control device according to the present invention, the thermal margin i? Thermal margin is evaluated, and when this evaluation value is determined to be below a certain value, the load operation switch is activated and the reactor is switched from load following operation to constant load operation. Burning out of certain fuel rods can be avoided, and load-following operation can be performed while maintaining the integrity of the reactor core.This stable load-following operation of nuclear power plants also improves the elasticity of the power system. Operation can be planned.

[Brief explanation of the drawing]

Figure 1 shows the operation of the nuclear power plant according to the present invention.
Block diagram showing one embodiment of the IIJ control device, Part 2
The figure is a block diagram showing the reactor thermal margin monitoring device in this embodiment, Figure 3 is an operational characteristic diagram of a boiling water reactor to which this embodiment is applied, and Figure 4 is a block diagram showing the reactor thermal margin monitoring device in this embodiment. FIG. 2 is a diagram showing expected operating characteristics of a boiling water reactor when the applied load following operation is applied. 1... Nuclear power plant operation control device, 3...
Reactor power regulator, 5...Load operation switch, 7...
Reactor power control system, 9...Reactor thermal margin monitoring device,
11... Judgment device, 15... Load hand f1! I setting device. Applicant's agent Hisashi Hatano l Eincha 2 Figure

Claims (1)

[Scope of Claims] 1. An output regulator that requests reactor output in accordance with load fluctuations, an output control system that controls reactor output by varying recirculation flow rate based on an output request signal, and the above-mentioned It is installed between the output regulator and the output control system, and inputs the output request signal from the output regulator to the output control system during load following operation, and inputs the output request signal from the manual load setting device during constant load operation. A load operation switch that inputs input to the output control system, a reactor thermal margin monitoring device that monitors the thermal margin of the reactor in time series, and a load operation switch that is connected to the load operation switch to keep the thermal margin below a certain value. An operation control device for a nuclear power plant, comprising: a determination device that switches the load operation switching device from the output regulator side to the load manual setting device side when 2. The operation control device for a nuclear power plant according to claim 1, wherein the output regulator determines the output value of the nuclear reactor based on frequency fluctuations in the power system.