JP7374140B2 - Control rod automatic control device and control rod automatic control method - Google Patents

Description

The present invention relates to an automatic control rod control device and an automatic control rod control method.

Patent Document 1 relates to a nuclear reactor power control device, and states, “A reactor power control device that controls a nuclear reactor calculates local reactivity based on the neutron flux detected by each of a plurality of neutron detectors arranged in the reactor core. The reactor is equipped with a reactivity estimation unit that estimates the local reactivity and determines that the reactor is in near-critical mode if the maximum value exceeds a predetermined value, and that the reactor is in subcritical mode otherwise.Control rod withdrawal The quantity calculation unit calculates the control rod withdrawal amount deviation, which is the amount of control rods to be withdrawn per unit time, from the difference between the reactivity and the target reactivity. Generates a command to withdraw the rod by the amount determined based on the reactor cycle, or in subcritical mode, generates a command to withdraw the control rod by the amount determined based on the control rod withdrawal amount deviation, and operates the control rod. commands to the control rod drive controller.''

Japanese Patent Application Publication No. 2008-122094

When starting up a boiling water reactor in a boiling water nuclear power plant, the control rods inserted into the reactor core are gradually withdrawn one after another to add reactivity to the reactor. reach a critical state. Methods have been devised to automate such control rod operations in order to save labor and shorten start-up time, or to output appropriate instructions.

For example, Patent Document 1 describes the control rod withdrawal mode as a near-critical mode in which the control rod is withdrawn by the amount of withdrawal determined based on the reactor cycle, and a near-critical mode in which the control rod is withdrawn by the amount of withdrawal determined based on the reactor cycle, and a near-critical mode in which the control rod is withdrawn by the amount of withdrawal determined based on the reactor cycle, and a near-critical mode in which the control rod is withdrawn by the amount of withdrawal determined based on the reactor cycle, and a mode in which the control rod is withdrawn based on the difference between the reactivity at that point and the target reactivity. A technique related to a subcritical mode in which a control rod is withdrawn by a determined withdrawal amount is disclosed. Specifically, the technology in the same document switches the mode when the reactivity estimated based on the neutron flux reaches a predetermined value, thereby maintaining the critical state of the reactor while controlling the input reactivity. Achieved.

However, during high-temperature startup immediately after reactor shutdown, the xenon concentration in the reactor core changes transiently, so negative reactivity due to xenon build-up may be added to the reactor. If this reactivity is large, it will take a long time to reach criticality even if the control rod is withdrawn, so unless the input reactivity is increased by withdrawing the control rod, the time required to reach criticality will increase. The technique described in Patent Document 1 uses the fact that the core parameters reach a predetermined value to determine whether to switch the control rod drive mode, and does not take into account temporal changes in the core parameters. Therefore, it may not be possible to determine that a negative reactivity is being added due to the build-up of the xenon concentration, and the drive mode may be switched to a drive mode in which the input reactivity is smaller. In that case, even if the control rod is pulled out, it takes time to reach criticality, making it difficult to shorten the start-up time.

The present invention has been made in view of the above problems, and an object of the present invention is to shorten the startup time of a nuclear reactor by switching the control rod drive mode at a more appropriate timing.

The present application includes a plurality of means for solving at least part of the above problems, examples of which are as follows. A control rod automatic control device according to one aspect of the present invention that solves the above problems has a high-speed drive mode in which the control rods in the core of a nuclear reactor are operated at high speed and a block drive mode in which the control rod is operated in units of a block amount defined in the drawing direction of the control rod, and a step drive mode in which the control rod is operated in steps of one step, which is the minimum operation unit amount of the control rod, The switching of the drive mode and the operation of the control rod are performed based on the value of the effective multiplication factor of neutrons and the tendency of increase/decrease in the effective multiplication factor of neutrons within a predetermined time.

According to the present invention, the start-up time of a nuclear reactor can be shortened by switching the control rod drive mode at a more appropriate timing.

FIG. 2 is a graph showing the relationship between the drive mode and the change over time in the effective multiplication factor of neutrons from subcriticality to criticality in the core. 1 is a diagram showing a schematic configuration of a control rod automatic control device. FIG. 7 is a flow diagram showing a process for determining whether control rod operation is permitted or not. FIG. 3 is a flow diagram showing a determination process for determining a drive mode. FIG. 2 is a diagram showing an example of the hardware configuration of a control rod operation calculation device, a control rod operation instruction device, and a control rod drive control device.

Embodiments of the present invention will be described below with reference to the drawings. First, the principle of the present invention will be explained.

FIG. 1 is a graph showing the relationship between the driving mode and the change over time in the effective multiplication factor of neutrons from subcriticality to criticality in the core. The horizontal axis indicates the time after the start of withdrawal of the control rod. Moreover, the vertical axis indicates the effective multiplication factor (Keff) of neutrons. Note that an effective multiplication factor of "1" indicates criticality, and an effective multiplication factor of less than "1" indicates subcriticality. Moreover, when the effective multiplication factor exceeds "1", a supercritical state occurs. The near-criticality mode realizes the operation from fully inserted control rods (point A) to criticality determination (point D).

The control rod automatic control device 100 according to this embodiment operates the control rods using three drive modes. Specifically, the drive modes include a high speed drive mode, a block drive mode, and a step drive mode.

The high-speed drive mode is a mode in which the control rod is pulled out (operated) at high speed. Further, the block drive mode is a mode in which the control rod is operated in block units so that the input reactivity of each block of the control rod is approximately equal. Further, the step drive mode is a drive mode in which the control rod is operated in the minimum operation unit amount (step).

In FIG. 1, points A to B indicate high-speed drive mode, points B to C indicate block drive mode, and points C to D indicate control rod operation in step drive mode. Moreover, the switching determination of each drive mode is performed based on the value of the effective multiplication factor of neutrons and its change over time.

The high-speed drive mode is a drive mode in which the control rod is pulled out at a relatively high speed when the degree of subcriticality is relatively large and there is little risk of exceeding criticality (points A to B). That is, from point A to point B, the period (furnace period) is not small, so the control rod is pulled out at a relatively high driving speed. The period signal is built into the reactor's safety system, and if it becomes shorter than a set value, it will prohibit withdrawal of the control rods or cause a scram.

Note that in a region where the high-speed drive mode is used, the period may become smaller when the control rod passes near a neutron detector and the neutron flux locally increases. Therefore, in the high-speed drive mode, the operation of the control rod is temporarily stopped at a position where the period is predicted to be short, and the control rod is otherwise controlled to be withdrawn at a relatively high drive speed.

The relationship between the period τ, the neutron flux φ, and the core reactivity ρ (ρ<0 in subcriticality) can be expressed by the following equation 1.

At the temporary stop position, withdrawal of the control rod is stopped for at least 10 seconds, for example. As a result, it can be seen that the input reactivity dρ/dt per unit time becomes smaller, and the period τ can be increased from Equation 1. Note that the position where the control rod is temporarily stopped is determined in advance.

Switching from the high-speed drive mode to the block drive mode is determined when the effective multiplication factor Keff reaches 0.995 (point B). Specifically, when the effective multiplication factor reaches 0.995, the control rod automatic control device 100 operates within a predetermined time period based on that point (for example, retroactively from the point in time when the effective multiplication factor reaches 0.995). 50 seconds) is at least a first predetermined value (for example, within a predetermined range between the first predetermined value as the lower limit and an arbitrary upper limit), the high-speed drive mode is activated. to block drive mode. Note that an example of the rate of increase in the effective multiplication factor will be described later.

On the other hand, when the effective multiplication factor reaches 0.995, the control rod automatic control device 100 operates within a predetermined period of time based on that point (for example, 50 seconds from the time when the effective multiplication factor reaches 0.995). ) is less than a first predetermined value (for example, less than a predetermined range between the first predetermined value as the lower limit value and an arbitrary upper limit value), the high-speed drive mode is continued. .

Note that the control rod automatic control device 100 monitors the rate of increase in the effective multiplication factor after that, and determines that the rate of increase in neutrons within a predetermined period of time (for example, every second, for 50 seconds retroactively) reaches the first rate. When it becomes a predetermined value or more (for example, within a predetermined range between the first predetermined value as the lower limit and an arbitrary upper limit), the high speed drive mode is switched to the block drive mode.

Note that the predetermined value regarding the rate of increase in the effective multiplication factor used to determine switching to the block drive mode is set with reference to the typical rate of increase when performing a pulling operation in the block drive mode during cold startup.

The block drive mode is a drive mode in which the control rod is pulled out by the amount of one block set so that the input reactivity of each block is approximately equal (points B to C). Note that one block amount is a unit indicating the amount of withdrawal set in the withdrawal direction of the control rod. The reactivity of a control rod varies greatly depending on the fuel characteristics and the position of the control rod, so one block may consist of one step, which is the minimum operating unit for the physical withdrawal amount of a control rod, or one block may consist of 20 steps. It may become a block. The amount of extraction corresponding to one block is calculated in advance. Note that the reactivity per block amount is, for example, about 0.05% Δk.

Switching from the block drive mode to the step drive mode is determined when the effective multiplication factor Keff reaches 0.999 (point C). Specifically, when the effective multiplication factor reaches 0.999, the control rod automatic control device 100 operates within a predetermined time period based on that point (for example, retroactively from the point in time when the effective multiplication factor reaches 0.999). 50 seconds) is at least a second predetermined value (for example, within a predetermined range between the second predetermined value as the lower limit and an arbitrary upper limit), the block drive mode is activated. Switch to step drive mode.

On the other hand, when the effective multiplication factor reaches 0.999, the control rod automatic control device 100 operates within a predetermined period of time based on that point (for example, 50 seconds from the time when the effective multiplication factor reaches 0.999). ) is less than a second predetermined value (for example, less than a predetermined range between the second predetermined value as the lower limit value and an arbitrary upper limit value), continue the block drive mode. .

Note that the control rod automatic control device 100 monitors the rate of increase in the effective multiplication factor after that, and the rate of increase in neutrons within a predetermined period of time (for example, every second for 50 seconds retroactively from that time) is determined to be the second rate. When it becomes a predetermined value or more (for example, within a predetermined range between the second predetermined value as the lower limit and an arbitrary upper limit), the block drive mode is switched to the step drive mode.

Note that the predetermined value regarding the rate of increase in the effective multiplication factor used to determine switching to the step drive mode is set with reference to the typical rate of increase when performing a pull-out operation in the step drive mode during cold start-up.

The step drive mode is a drive mode in which the control rod is pulled out by the minimum operation unit amount (one notch for hydraulically driven control rods and one step for electrically driven control rods) in order to make minute reactivity adjustments possible. Yes (point C to point D). Note that the input reactivity per step, which is the minimum operation amount, is set to be, for example, 0.05% Δk or less.

Note that the control rod automatic control device 100 stops withdrawing the control rods when the rate of increase in the effective multiplication factor within a predetermined time exceeds a predetermined range during operation of each drive mode. Further, the control rod automatic control device 100 inserts the control rod if the rate of increase in the effective multiplication factor exceeds a predetermined range even after the withdrawal is stopped.

With this function, positive reactivity is imparted to the reactor, for example, when the xenon concentration decreases over time and positive reactivity is imparted, such as during high-temperature startup immediately after reactor shutdown. Even when the reactivity temperature coefficient is negative and the reactor water temperature decreases, the control rod automatic control device can perform appropriate control rod withdrawal operations.

Further, the control rod automatic control device 100 maintains the criticality state in the criticality maintenance mode after determining the criticality. That is, the control rod automatic control device 100 monitors the effective multiplication factor, pulls out the control rod when the degree of subcriticality exceeds a predetermined value, and inserts the control rod when the degree of supercriticality exceeds a predetermined value. Take control.

As described above, when making a subcritical reactor critical, if the effective multiplication factor of neutrons in the reactor core is small (the degree of subcriticality is large), the control rods are pulled out in high-speed drive mode and brought to criticality. If the control rods are close to each other, the control rods are withdrawn in approximately constant periods using block drive mode and step drive mode.

In this way, the control rod automatic control device 100 makes a switching decision between each drive mode by considering not only the value of the effective multiplication factor but also the rate of increase of neutrons within a predetermined time. As a result, the control rod automatic control system can prevent risks such as short periods even in situations where positive (or negative) reactivity is imparted due to transient changes in xenon concentration, such as during high-temperature startup immediately after reactor shutdown. It is possible to realize an optimal drive mode switching operation that is small and close to the shortest time control.

Further, the control rod automatic control device 100 can automatically maintain criticality by monitoring the effective multiplication factor even after determining criticality, thereby realizing labor saving in operation.

[Explanation of operation]
The processing executed by the control rod automatic control device 100 will be specifically described below.

FIG. 2 is a diagram showing a schematic configuration of the control rod automatic control device 100. As shown in the figure, a plurality of control rods 3 are arranged in a reactor core 2 within a reactor pressure vessel 1 to control the output of the reactor. Each control rod 3 is driven by a control rod drive mechanism 5 and a motor 6 that moves the control rod 3. Further, each control rod 3 is provided with a control rod position detector 8 . Further, a neutron flux detector 10 is arranged in the reactor core 2 to detect neutron flux at the time of reactor startup, and a value detected by the neutron flux detector 10 is monitored by a neutron flux monitor (SRNM) 4.

Further, the neutron flux monitor 4 converts the output signal from the neutron flux detector 10, generates a neutron flux level signal and a period signal, and outputs them to the control rod operation calculation device 14. Further, the neutron flux monitor 4 outputs a neutron flux level signal to the reactivity meter 15. The reactivity meter 15 outputs an effective multiplication factor signal based on the acquired neutron flux level signal to the control rod operation calculation device 14.

Hereinafter, the control rod operation calculation device 14 of the control rod automatic control device 100, the control rod operation instruction device 13 that instructs the operation of the control rods, and the control rod drive control device 16 that manages the operation of the control rods execute the execution. The operation processing to be performed will be explained.

When the operator selects the critical proximity mode from the input device 12 of the control rod operation instruction device 13, the control rod operation calculation device 14 outputs the neutron flux level signal and period signal obtained from the neutron flux monitor 4, and the reactivity meter 15. Using the effective multiplication factor signal obtained from A determination process for determining the mode is performed. Further, the control rod operation calculation device 14 outputs a control rod operation permission signal and a drive mode signal indicating each determination result to the control rod operation instruction device 13.

The control rod operation instruction device 13 outputs the control rod operation permission signal and drive mode signal received from the control rod operation calculation device 14 to the control rod drive control device 16 as a control rod operation command and a drive mode signal, respectively. In addition, the control rod operation instruction device 13 uses these signals and control rod operation procedure data 9 inputted in advance to determine the location of the control rods 3 to be operated in the core 2 and the current withdrawal of the control rods. The position, the target control rod withdrawal position, the drive mode suitable for operation, and information as to whether or not the control rod 3 can be operated are displayed on the display device 11 to notify the operator.

The control rod drive control device 16 uses the control rod operation command and drive mode signal acquired from the control rod operation instruction device 13 and the control rod operation procedure data 9 to control the control rods to be operated from among more than 100 control rods. 3 is selected, and a withdrawal command or insertion command, control rod target position, etc. are transmitted to the motor drive control device 7 corresponding to the selected control rod 3.

The motor drive control device 7 responds to each control rod 3 based on the withdrawal command or insertion command obtained from the control rod drive control device 16, the value detected by the control rod position detector 8, and the control rod target position. The rotation speed of the motor 6 is controlled. In addition, when the control according to the withdrawal command or the insertion command is completed, or when the control rod 3 reaches the target position, the motor drive control device 7 sends a control completion signal indicating the completion of such control or when the control rod 3 reaches the target position. A target position arrival signal indicating that the position has been reached is output to the control rod drive control device 16.

When the control rod drive control device 16 receives a control completion signal or a target position arrival signal from the motor drive control device 7 corresponding to all the selected control rods 3, the control rod operation calculation device 14 and the control rod operation instruction device 13 and output these signals to. Upon receiving such a signal, the control rod operation calculation device 14 again performs the process of determining whether control rod operation is permitted or not, and the process of determining the drive mode for the next control rod operation, and indicates the determination results. A signal is output to the control rod operation instruction device 13.

With the above configuration, it is possible to realize control rod operation using the three drive modes described above.

Next, the details of the determination of whether control rod operation is permitted or not and the determination of the drive mode will be explained.

FIG. 3 is a flow diagram showing a process (algorithm) for determining permission/disapproval of control rod operation. Further, FIG. 4 is a flow diagram showing a determination process (algorithm) for determining a drive mode.

The process in FIG. 3 is started when the operator selects the critical proximity mode. The control rod operation calculation device 14 determines whether the initial setting process has been completed or not in step S001. Further, if the control rod operation calculation device 14 determines that the process has been performed (Yes in step S001), the process proceeds to step S002 and step S003, and if it determines that the process has not been completed (No in step S001). , performs initial settings (step S004). In the initial setting performed in step S004, firstly, the drive mode of the control rod 3 is set to high-speed drive mode, and secondly, the withdrawal permission signal of the control rod 3 is set to ON.

In step S002 and step S003, the control rod operation calculation device 14 determines whether withdrawal of the control rod 3 is not permitted or permitted. Specifically, if (1-1) the control rod 3 is in operation and the period is less than or equal to a predetermined value (for example, 50 seconds), the control rod operation calculation device 14 (1-2) performs control rod operation in the high-speed drive mode. When the control rod 3 is stopped and the stop time of the control rod 3 is less than or equal to a predetermined value (for example, 10 seconds) or the period is less than or equal to a predetermined value (for example, 200 seconds), (1-3) block drive mode is selected. , the control rod 3 is stopped, and the stop time of the control rod is less than or equal to a predetermined value (e.g., 10 seconds), or the period is less than or equal to a predetermined value (e.g., 200 seconds), or the rate of increase in the effective multiplication factor is less than or equal to a predetermined value. If the value (for example, 0.01%Δk/s) or more, the control rod 3 is stopped in the step drive mode (1-4), and the stop time of the control rod is less than or equal to the predetermined value (for example, 10 seconds); Alternatively, if one of the following applies: the period is less than or equal to a predetermined value (e.g., 200 seconds), or the rate of increase in the effective multiplication factor is greater than or equal to a predetermined value (e.g., 0.0005%Δk/s), the control It is determined that withdrawal of the rod 3 is not permitted (step S002).

On the other hand, if (2-1) the control rod 3 is in operation and the period is a predetermined value (for example, 50 seconds) or more, the control rod operation calculation device 14 operates the control rod in the high-speed drive mode (2-2). 3 is stopped, the stop time of the control rod 3 is a predetermined value (for example, 10 seconds) or more, and the period is a predetermined value (for example, 200 seconds) or more, the control is performed in (2-3) block drive mode. The rod 3 is stopped, the stop time of the control rod 3 is a predetermined value (for example, 10 seconds) or more, the period is a predetermined value (for example, 200 seconds) or more, and the rate of increase in the effective multiplication factor is a predetermined value. (for example, 0.01% Δk/s) or less, (2-4) the control rod 3 is stopped in the step drive mode, and the stop time of the control rod 3 is greater than or equal to a predetermined value (for example, 10 seconds); And, when any one of the following applies, the period is greater than or equal to a predetermined value (e.g., 200 seconds) and the rate of increase in the effective multiplication factor is less than or equal to a predetermined value (e.g., 0.0005%Δk/s), the control is performed. A determination is made to permit withdrawal of the rod 3 (step S003).

When this process is completed, the control rod operation calculation device 14 performs a determination process to determine the drive mode shown in FIG. 4.

When the determination process for determining the drive mode shown in FIG. 4 is started, the control rod operation calculation device 14 determines the current drive mode (step S010). Specifically, the control rod operation calculation device 14 determines which drive mode is the current drive mode among the high-speed drive mode, block drive mode, and step drive mode.

If the current drive mode is determined to be the high-speed drive mode, the control rod operation calculation device 14 determines whether to switch to the block drive mode based on the effective multiplication factor. Specifically, the control rod operation calculation device 14 determines whether the effective multiplication factor Keff satisfies the following equation 2 (step S011), and if it is determined that it does not satisfy the following equation (No in step S011), the control rod operation calculation device 14 It is determined to continue the drive mode (step S014), and the processing of this flow ends. On the other hand, if it is determined that Equation 2 is satisfied (Yes in step S011), the control rod operation calculation device 14 temporarily outputs a signal disallowing withdrawal of the control rod 3 to the control rod operation instruction device 13 (step S011). S012), the process moves to step S013.

In step S013, the control rod operation calculation device 14 determines whether the rate of increase in the effective multiplication factor within a predetermined period of time (for example, 50 seconds retroactively from the time when the effective multiplication factor reaches 0.995) satisfies Equation 3 below. Determine whether or not. If it is determined that Equation 3 is satisfied (Yes in step S013), the control rod operation calculation device 14 determines to switch from the high-speed drive mode to the block drive mode (step S022), and ends the processing of this flow. . On the other hand, if it is determined that Equation 3 is not satisfied (No in step S013), the control rod operation calculation device 14 determines to continue the high-speed drive mode (step S014), and ends the processing of this flow.

Further, when it is determined in step S10 that the current drive mode is the block drive mode, the control rod operation calculation device 14 determines whether the effective multiplication factor Keff satisfies the following equation 4 (step S021). If it is determined that Equation 4 is not satisfied (No in step S021), it is determined to continue the block drive mode (step S022), and the processing of this flow ends.

On the other hand, if it is determined that Equation 4 is satisfied (Yes in step S021), the control rod operation calculation device 14 performs a criticality determination (step S031). Specifically, the control rod operation calculation device 14 measures the duration of the period after the control rod stops being 200 seconds or less, and when the elapsed time exceeds 120 seconds and satisfies Equation 5 below, It is determined that criticality has been reached.

If the control rod operation calculation device 14 determines that criticality has been reached (Yes in step S031), it determines to switch the drive mode to criticality maintenance mode (step S034), and ends the process of this flow. At this time, the control rod operation calculation device 14 notifies the operator via the display device 11 that criticality has been reached.

On the other hand, if it is determined that criticality has not been reached (No in step S031), the control rod operation calculation device 14 operates within a predetermined period of time (for example, 50 seconds from the time when the effective multiplication factor reaches 0.999). ) is determined whether the rate of increase in the effective multiplication factor satisfies Equation 6 below (step S032). If it is determined that Equation 6 is satisfied (Yes in step S032), the control rod operation calculation device 14 determines to switch from the block drive mode to the step drive mode (step S033), and ends the processing of this flow. . On the other hand, if it is determined that Equation 6 is not satisfied (No in step S032), the control rod operation calculation device 14 determines to continue the block drive mode (step S022), and ends the processing of this flow.

Further, if it is determined in step S010 that the current drive mode is the step drive mode, the control rod operation calculation device 14 performs the criticality determination in step S031 described above. Note that the processes from step S031 to step S034 are the same as described above, so detailed explanations will be omitted.

Note that when the current drive mode is the criticality maintenance mode, the control rod operation calculation device 14 does not perform the processing shown in FIGS. and perform the specified processing. Specifically, the control rod operation calculation device 14 determines whether or not Equation 7 or Equation 8 is satisfied, and if Equation 7 or Equation 8 is satisfied, it is determined to insert the control rod 3, and if Equation 8 is satisfied, the control rod 3 is inserted. Decide to pull out stick 3. That is, the control rod operation calculation device 14 performs control to insert the control rod 3 when the effective multiplication factor of neutrons exceeds the critical value of 1.000, and to withdraw the control rod 3 when it becomes less than 1.000.

In addition, the control rod operation calculation device 14 uses the determination result of the control rod operation permission/disapproval determination process shown in FIG. 3 and the determination process result of the drive mode determination process shown in FIG. The information is sent to the device 13.

Note that when the drive mode determined in the process of FIG. 4 is one of the high-speed drive mode, block drive mode, and step drive mode, the control rod operation calculation device 14 executes the series of processes shown in FIGS. 3 and 4. Execute periodically (eg, every second).

According to such an automatic control rod control device, the start-up time of a nuclear reactor can be shortened by switching the control rod drive mode at a more appropriate timing. That is, according to the control rod automatic control device, operations at the time of reactor startup can be optimized and automated, so startup time can be shortened and the load on operators can be reduced. In addition, the control rod automatic control device determines control rod operation and drive mode switching based on the value of the effective multiplication factor and its change over time, thereby reducing startup time even during high-temperature startup immediately after reactor shutdown. Optimal control rod operation is possible from this perspective.

FIG. 5 is a diagram showing an example of the hardware configuration of the control rod operation calculation device 14, the control rod operation instruction device 13, and the control rod drive control device 16. As shown in the figure, each of these devices includes at least a calculation device 210, a main storage device 220, an auxiliary storage device 230, a communication device 240, and a bus 250 that electrically connects each of these devices. are doing.

The arithmetic device 210 is, for example, a CPU (Central Processing Unit). The main storage device 220 is a volatile or nonvolatile memory such as a RAM (Random Access Memory) or a ROM (Read Only Memory). The auxiliary storage device 230 is, for example, an HDD (Hard Disk Drive) or an SSD (Solid State Drive). The communication device 240 is a NIC (Network Interface Card) for connecting to a predetermined network that communicably connects each device.

The control rod operation calculation device 14, the control rod operation instruction device 13, and the control rod drive control device 16 execute predetermined operations according to a program that causes the calculation device 210 to perform processing. This program is stored in the main storage device 220 or the auxiliary storage device 230, and when the program is executed, it is loaded onto the main storage device 220 and executed by the arithmetic unit 210. Furthermore, information communication between each device is performed via the communication device 240.

Further, each of the above-described configurations of the control rod operation calculation device 14, the control rod operation instruction device 13, and the control rod drive control device 16 may be realized by hardware, for example, by designing with an integrated circuit.

Further, the present invention is not limited to the above-described embodiments and modifications, but includes various modifications within the scope of the same technical idea. For example, the embodiments described above are described in detail to explain the present invention in an easy-to-understand manner, and the present invention is not necessarily limited to having all the configurations described. Furthermore, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace a part of the configuration of each embodiment with other configurations.

Further, in the above description, the control lines and information lines are those considered necessary for the explanation, and not all control lines and information lines are necessarily shown in the product. In reality, almost all configurations can be considered to be interconnected.

100... Control rod automatic control device, 1... Reactor pressure vessel, 2... Reactor core, 3... Control rod, 4... Neutron flux monitor, 5... Control rod drive mechanism, 6 ...Motor, 7.Motor drive control device, 8.Control rod position detector, 9.Control rod operation procedure data, 10.Neutron flux detector, 11.Display device, 12... Input device, 13... Control rod operation instruction device, 14... Control rod operation calculation device, 15... Reactivity meter, 16... Control rod drive control device, 210... Calculation Device, 220... Main storage device, 230... Auxiliary storage device, 240... Communication device, 250... Bus

Claims (15)

A high-speed drive mode in which control rods in the core of a nuclear reactor are operated at high speed; and a block drive mode in which the control rods are operated in blocks defined in the withdrawal direction of the control rods so that the input reactivity is approximately equal. and a step drive mode in which the control rod is operated one step at a time, which is the minimum unit operation amount of the control rod,
An automatic control rod control device characterized in that the switching of the drive mode and the operation of the control rod are performed based on a value of an effective multiplication factor of neutrons and a tendency of increase/decrease in the effective multiplication factor of neutrons within a predetermined time. . The control rod automatic control device according to claim 1,
While operating the control rod in the high-speed drive mode, the effective multiplication factor of neutrons reaches a first predetermined value, and the tendency of increase/decrease in the effective multiplication factor of neutrons within the predetermined time reaches a second predetermined value. When the lower limit is within a predetermined range, switching from the high-speed drive mode to the block drive mode;
While operating the control rod in the high-speed drive mode, the effective multiplication factor of neutrons reaches the first predetermined value, and the increase/decrease trend of the effective multiplication factor of neutrons within the predetermined time is the second predetermined value. An automatic control rod control device characterized in that the high-speed drive mode is continued when the value is less than a predetermined range with a lower limit. The control rod automatic control device according to claim 1,
While operating the control rod in the block drive mode, the effective multiplication factor of neutrons reaches a third predetermined value, and the tendency of increase/decrease in the effective multiplication factor of neutrons within the predetermined time reaches a fourth predetermined value. When the lower limit is within a predetermined range, switching from the block drive mode to the step drive mode;
While operating the control rod in the block drive mode, the effective multiplication factor of neutrons reaches the third predetermined value, and the increase/decrease trend of the effective multiplication factor of neutrons within the predetermined time is the fourth predetermined value. An automatic control rod control device characterized in that the block drive mode is continued when the value is less than a predetermined range with a lower limit. The control rod automatic control device according to claim 3,
While operating the control rod in the step drive mode, if the tendency of increase/decrease in the effective multiplication factor of neutrons within the predetermined time becomes less than a predetermined range with the fourth predetermined value as the lower limit, the control rod is changed from the step drive mode to the block. A control rod automatic control device characterized by switching to a drive mode. The control rod automatic control device according to claim 1,
While operating the control rod in each of the drive modes, if the increasing tendency of the effective multiplication factor of neutrons within the predetermined time exceeds a predetermined range, the withdrawal of the control rod is stopped; An automatic control rod control device characterized in that the control rod is inserted if the increasing tendency of the effective multiplication factor continues to exceed a predetermined range . The control rod automatic control device according to claim 1,
After reaching criticality, when the effective multiplication factor of neutrons is larger than the fifth predetermined value, the control rod is inserted, and when the effective multiplication factor of neutrons is smaller than the fifth predetermined value, the control rod is withdrawn. A control rod automatic control device characterized by: The control rod automatic control device according to claim 1,
the control rod is in operation;
If the period, which is the furnace cycle, is less than or equal to the sixth predetermined value,
A control rod automatic control device characterized in that withdrawal of the control rod is not permitted. The control rod automatic control device according to claim 1,
the control rod is stopped in the high-speed drive mode;
The stop time of the control rod is equal to or less than a seventh predetermined value, or
If the period, which is the furnace cycle, is less than or equal to the eighth predetermined value,
A control rod automatic control device characterized in that withdrawal of the control rod is not permitted. The control rod automatic control device according to claim 1,
the control rod is stopped in the block drive mode;
The stop time of the control rod is equal to or less than a seventh predetermined value, or
The period, which is the furnace cycle, is equal to or less than the eighth predetermined value, or
When the rate of increase in the effective multiplication factor is equal to or higher than a ninth predetermined value,
A control rod automatic control device characterized in that withdrawal of the control rod is not permitted. The control rod automatic control device according to claim 1,
the control rod is stopped in the step drive mode;
The stop time of the control rod is equal to or less than a seventh predetermined value, or
The period, which is the furnace cycle, is equal to or less than the eighth predetermined value, or
When the rate of increase in the effective multiplication factor is greater than or equal to a tenth predetermined value,
A control rod automatic control device characterized in that withdrawal of the control rod is not permitted. The control rod automatic control device according to claim 7,
the control rod is in operation;
If the period is equal to or greater than the sixth predetermined value,
A control rod automatic control device, characterized in that the control rod is allowed to be withdrawn. The control rod automatic control device according to claim 8,
the control rod is stopped in the high-speed drive mode;
The stop time of the control rod is equal to or greater than the seventh predetermined value, and
When the period is equal to or greater than the eighth predetermined value,
A control rod automatic control device, characterized in that the control rod is allowed to be withdrawn. The control rod automatic control device according to claim 9,
the control rod is stopped in the block drive mode;
The stop time of the control rod is equal to or greater than the seventh predetermined value, and
the period is greater than or equal to the eighth predetermined value, and
When the rate of increase in the effective multiplication factor is equal to or less than the ninth predetermined value,
A control rod automatic control device, characterized in that the control rod is allowed to be withdrawn. The control rod automatic control device according to claim 10,
the control rod is stopped in the step drive mode;
The stop time of the control rod is equal to or greater than the seventh predetermined value, and
the period is greater than or equal to the eighth predetermined value, and
When the rate of increase in the effective multiplication factor is equal to or less than the tenth predetermined value,
A control rod automatic control device, characterized in that the control rod is allowed to be withdrawn. A control rod automatic control method performed by a control rod automatic control device, comprising:
The control rod automatic control device includes:
A high-speed drive mode in which control rods in the core of a nuclear reactor are operated at high speed; and a block drive mode in which the control rods are operated in blocks defined in the withdrawal direction of the control rods so that the input reactivity is approximately equal. and a step drive mode in which the control rod is operated one step at a time, which is a minimum unit operation amount of the control rod;
In the operation step,
A control rod automatic control method characterized in that the switching of the drive mode and the operation of the control rod are performed based on a value of an effective multiplication factor of neutrons and an increase/decrease tendency of the effective multiplication factor of neutrons within a predetermined time. .

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