JPH01195394A - Output distribution adjusting device for nuclear reactor - Google Patents

Abstract

PURPOSE:To uniformly burn fuel to efficiently consume a fissionable material in fuel by operating the deviation between a target output and a detection output at each control rod position point in accordance with the target output distribution in the radial direction of a nuclear reactor and the signal of a neutron flux detector. CONSTITUTION:A computing element 6 selects a control rod, whose deviation between the target output and the detection output at each control rod position point in the nuclear reactor is maximum, as the output distribution adjusting control rod in accordance with a target output distribution 8 in the radial direction of the nuclear reactor, a detected neutron flux signal 11, and a detection control rod position signal 12 and outputs a detection output 15 and a target output 16 at the output distribution adjusting selected control rod point. Only when the deviation between these outputs exceeds a prescribed value, a signal is inputted to a control rod controller 20 by a signal limiter 19. A polarity discriminator 21 outputs a signal, which inserts or pulls out the output distribution adjusting selected control rod, to a control rod drive mechanism 3 in accordance with the deviation. Thus, a ratio of a maximum to a minimum of the output in the radial direction of the nuclear reactor is reduced to efficiently consume fuel.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an output control device for a nuclear power plant, and particularly to a nuclear reactor suitable for adjusting and maintaining the radial power distribution of the reactor to a target power distribution. The present invention relates to an output distribution adjustment device.

[Conventional technology]

A conventional device, as described in Japanese Patent Application Laid-Open No. 56-48585, is a device that adjusts the power distribution to a target value in the axial direction of the nuclear reactor.

[Problem to be solved by the invention]

The above conventional technology does not take into consideration the radial direction of the reactor, and the radial power distribution may be significantly different between the center and outer parts of the reactor, or the position of the control rod may be partially affected by new fuel. Depending on loading etc.

Output may vary depending on location.

If there is a large deviation in the radial output of a nuclear reactor, combustion will proceed in the fuel channels in areas with high output, while combustion will not proceed in fuel channels in areas with low output, resulting in a difference in fuel consumption. . If operation continues in this state for a long period of time, a large amount of unburned fissile material will remain in the fuel channel where the output was low even at the time of fuel removal, greatly reducing fuel economy. This will result in a lower level of performance.

An object of the present invention is to provide a power distribution adjustment device that reduces the difference in the amount of fissile material consumed in a fuel channel and burns fuel uniformly based on the distribution of radial output inside a nuclear reactor. be.

[Means to solve the problem]

The above object is achieved by the following method. That is,
The deviation between the target output and the detected output at each control rod position point is calculated from the reactor radial target output distribution set to uniformly burn the fuel and the neutron flux detector signal, and this deviation is the target output. The control rods are driven to adjust the reactor's radial power distribution to the target power distribution so that the distribution is within the tolerance range. At this time, in order to prevent the output of the entire reactor from changing due to the drive of the control rods, when the control rods are inserted, the control rods at the lowest output position are simultaneously withdrawn, and when the control rods are withdrawn, the control rods at the lowest output position are simultaneously withdrawn. Insert the control rods at the highest output position at the same time.

[Effect]

The target power distribution in the reactor radial direction is based on the fuel combustion plan, and sets an appropriate power distribution in order to uniformly burn the fuel and ensure a high burnup. Based on this target output distribution, the target output at each control rod position within the core is determined by a computing unit. In addition, this computing unit uses signals from a neutron detector.

The detected output at each control rod position point is determined using the same method as the target output. Based on this information, the calculator selects the control rod with the maximum deviation between the target output and the detected output, and
The target output and detected output are output to the control rod control device. If this deviation exceeds the permissible range with respect to the target output distribution, the control rod is driven so that the output falls within the permissible range of the target output distribution. But 1. If only the control rods are driven, the output of the entire reactor will fluctuate, so
When the control rods are driven in the insertion direction, the control rods inserted at the lowest protruding position are pulled out at the same time, and when the control rods are driven in the withdrawal direction, they are inserted at the same time. The control rods that are driven to compensate for the full power of the reactor are selected based on signals from control rod position detectors.

In addition, the reactivity value of the control rods that are driven to adjust the detected output within the range of the target output distribution is different from that of the control rods that are driven to compensate for the total output of the reactor. Therefore, even when driving the control rods for compensation, the computer outputs the target output and detected output to the control rod control device, and when either of the outputs falls within the allowable range by driving both control rods. , prohibiting both control rods from driving. While driving this control rod, the computing unit holds the control rod selection signal so that it does not change. Further, if the total output of the 1M child reactor changes by more than a certain value from the set value due to the drive of these control rods, the drive of the control rods is prohibited.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. FIG. 2 is an example of a schematic diagram when the method of the present invention is applied to a certain nuclear power plant.

This nuclear power plant has a reactor 1. Control rod 2° Control rod drive mechanism 3. Neutron detector 4. Control rod position detector5.
A control rod control device 7 is provided, and a detected neutron flux signal 11
．． Detection control rod position signal 12. The reactor radial target power distribution 82 selection control hold signal 14 is input to the reactor power distribution adjustment device 30, and the control rod control device 7 receives the signal from the reactor power distribution adjustment device 30 and the control rod drive switch 9. A control rod drive permission signal 29 from the control rod drive mechanism 3 outputs a control signal to the control rod drive mechanism 3 to drive the output control rod 2.

FIG. 1 is a control block diagram showing an embodiment of the reactor power distribution adjusting device of the present invention. The computing unit 6 calculates the reactor radial target power distribution 8. Detected neutron flux signal 11. From the detection control head position signal 12, the control rod with the maximum deviation between the target output and the detected output at each control head position point in the reactor is selected as the control rod for power distribution adjustment, and the control rod is selected as the control rod for power distribution adjustment. A detection output 15 of the point and a target output 16 of the selected control rod point for output distribution adjustment are output. A signal is input to the control rod controller 20 only when the deviation between these two signals exceeds a predetermined value by the signal limiter 19. The polarity discriminator 21 outputs a signal for inserting or withdrawing the selected control rod for output distribution adjustment to the control rod drive mechanism 3 based on the deviation.

The signal from the control rod controller 20 is ANDed with the control rod drive permission signal 29 from the control rod drive switch 9 to output a control signal to the selected control rod drive mechanism 32 for power distribution adjustment.

Also, at this time, the control rod drive permission lamp 2 for power distribution adjustment
2 lights up, indicating that the drive conditions are met. This lamp is turned off when the deviation between the detected output and the target output decreases and the driving conditions are no longer satisfied (if limited by the signal controller 19).

On the other hand, in order to prevent the output of the entire reactor from fluctuating when the selected control rod for output distribution adjustment is driven, the arithmetic unit 6 uses the polarity discrimination signal 29 from the polarity discriminator 21 to select the selected control rod for output adjustment. In the case of insertion, the control rod at the lowest output position, and in the case of withdrawal, the control rod at the highest output position is selected as the control rod for reactor power compensation, and the selected control rod for reactor power compensation is selected. The detection output 17 of the point and the target output 18 of the selected control rod point for reactor output compensation are output. At this time 1
A signal limiter 19 is provided so that the control rod cannot be driven when the output at the selected control rod point is within an allowable range with respect to the target output.

If the signal is restricted as a result, the signal from the reactor power compensation control selection switch 31 will select the next lowest output position or the highest output position after the previously selected control rod. At this time, if the selected control rod for reactor power compensation satisfies the drive permission, the selected control rod drive permission lamp 23 for reactor power compensation lights up. In the reactor power compensation selection control rod drive mechanism 33, the polarity inverter 24 is used to drive the control rods in the opposite direction to the drive direction of the power distribution adjustment selection control rods.
Input the signal. In addition, the selection control rods for both of these are
The configuration is such that when either one stops, the other one also stops.

Furthermore, even if the overall reactor output fluctuates, if the deviation between the reactor total output signal 25 and the reactor total output set value 26 exceeds a predetermined value, a control rod drive prohibition signal 34 is output. to prohibit the control rod from driving.

Figure 3 shows 1M calf radial target power distribution 8, power distribution fluctuation tolerance 28, and actual reactor radial direction power distribution 2
By using the above method, the actual reactor radial power distribution 27 can be adjusted to within the variation tolerance range 28 of the reactor radial target power distribution 8. .

According to this embodiment, based on the fuel combustion plan, the output in the reactor radial direction is set to It is possible to adjust it within the allowable range, and by uniformly burning the fuel, the fissile material in the fuel can be effectively consumed, and a great effect on reducing fuel costs can be expected.

〔Effect of the invention〕

According to the present invention, the core of the nuclear reactor, the outer layer, or
It is possible to reduce the ratio between the maximum and minimum radial power of the reactor caused by the position of control rods, the loading of new fuel, etc., which allows the fuel to burn evenly and efficiently consumes the fissile material in the fuel. I can do it.

[Brief explanation of the drawing]

FIG. 1 is a control block diagram of an embodiment of the present invention. FIG. 2 is a block diagram showing an example in which the present invention is applied to a nuclear couplant, and FIG. 3 is a diagram showing an example of the target power distribution in the reactor radial direction and the actual power distribution in the reactor radial direction. DESCRIPTION OF SYMBOLS 1... Nuclear reactor, 2... Control rod, 3... Control rod drive mechanism, 4... Neutron detector, 5... Control rod position detector.

Claims (1)

[Claims] 1. In a nuclear power plant including a control rod that adjusts the output of the reactor, a drive mechanism for the control rod, a position detector for the control rod, and a neutron detector, the target power distribution in the reactor radial direction and the detected neutron flux signal , using the detected control rod position,
A first calculation that selects the control rod at the position where the deviation is maximum based on the deviation between the target output and the detected output at the position of each of the control rods in the reactor core, and outputs the detected output and the target output. a controller that drives the control rod so as to suppress the deviation between the detected output and the target output within an allowable range; and a controller that is inserted at a position with the lowest output or a position with the highest output depending on the driving direction of the control rod. a second computing unit for selecting the control rods in the control rod; means for simultaneously driving the two control rods selected by the first computing unit and the second computing unit; output setting for the reactor; A nuclear reactor power distribution adjustment device, characterized in that it is provided with means for stopping the driving of the control rods when the detected total reactor power exceeds a permissible range.