Nuclear power plant output control system

Abstract

This invention provides a nuclear power plant output control system that enables the combustion of reactor core fuel to proceed as planned and facilitates the efficient use of reactor core fuel. [Solution] The nuclear power output control system 10 includes: a core fuel burnup calculation unit 11 that calculates the burnup of the core fuel from the detected local reactor output; a discrimination device 12 that compares the core fuel burnup signal from the core fuel burnup calculation unit 11 with the core fuel plan value and determines whether core fuel burnup adjustment is necessary from the deviation signal from the core fuel plan value; a control rod selection unit 14 that selects a control rod 9 to withdraw / insert when the deviation signal exceeds a predetermined value set in advance; and a control rod withdrawal / insertion command unit 15 that outputs a withdrawal / insertion command for the selected control rod 9 to the control rod operation monitoring device 8.

Description

Technical Field

[0001] The present invention relates to a nuclear power generation output control system that has functions of withdrawing / inserting control rods by electric drive and adjusting the recirculation flow rate in a nuclear reactor in order to adjust the reactor output during normal operation of a plant, and automatically performs the withdrawal / insertion of control rods or core flow rate adjustment according to a preset load pattern to control the output of the plant.

Background Art

[0002] In a nuclear power plant, based on the previous operation results, the control rod pattern and control rod operation procedure for the next cycle are planned in advance to achieve efficient combustion of core fuel and flattening of the output distribution. During reactor output operation, the operator withdraws / inserts the control rods according to the control rod operation procedure determined above.

[0003] For example, a method described in Patent Document 1 is known as a method for analyzing the axial output distribution of nuclear fuel. In Patent Document 1, it is described that when analyzing the axial output distribution of nuclear fuel, by considering the effect of local output distortion in a grid that bundles a plurality of cladding tubes, the axial output distribution can be obtained with high accuracy.

[0004] Also, a method described in Patent Document 2 is known as an automatic output adjustment method. In Patent Document 2, it is described that when the operator sets a target output or a target control rod pattern, an appropriate control rod operation procedure is automatically selected from N control rod operation procedures stored in the control rod operation procedure storage device, and the control rod is automatically operated according to the newly selected control rod operation procedure.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

[0006] However, while Patent Document 1 accurately determines the axial power distribution, it does not consider any measures to take if the combustion of the reactor core fuel does not proceed as planned. Furthermore, in the method described in Patent Document 2, although the control rods are operated automatically, if the combustion of the core fuel does not proceed as planned, the deviation in the core fuel burnup from the plan is not corrected during the same cycle, and operation continues with the core fuel burnup deviation, which may prevent efficient utilization of the core fuel. In other words, Patent Document 2 also does not consider how to deal with situations where the combustion of the core fuel does not proceed as planned.

[0007] Therefore, the present invention provides a nuclear power output control system that enables the combustion of core fuel to proceed as planned and enables the efficient utilization of core fuel. [Means for solving the problem]

[0008] To solve the above problems, the nuclear power output control system according to the present invention is characterized by comprising: a core fuel burnup calculation unit that calculates the burnup of the core fuel from the detected local reactor output; a discrimination device that compares the core fuel burnup signal from the core fuel burnup calculation unit with the core fuel plan value and determines whether or not core fuel burnup adjustment is necessary from the deviation signal from the core fuel plan value; a control rod selection unit that selects a control rod to withdraw / insert when the deviation signal exceeds a predetermined value set in advance; and a control rod withdrawal / insertion command unit that outputs a withdrawal / insertion command for the selected control rod to a control rod operation monitoring device. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a nuclear power output control system that enables the combustion of core fuel to proceed as planned and enables the efficient utilization of core fuel. Specifically, by correcting the deviation in core fuel burnup from the planned value during reactor power operation, it becomes possible to proceed with the burning of the core fuel as planned, thereby enabling the efficient use of core fuel. Other issues, configurations, and effects not mentioned above will be clarified by the following description of the embodiments. [Brief explanation of the drawing]

[0010] [Figure 1] This is a diagram of a nuclear power plant including a nuclear power output control system according to Embodiment 1 of the present invention. [Figure 2] Figure 1 is a block diagram of the nuclear power plant output control system. [Modes for carrying out the invention]

[0011] In this specification, boiling water reactors include conventional boiling water reactors (BWRs) equipped with recirculation pumps that forcibly circulate the cooling water within the reactor as a moderator, advanced boiling water reactors (ABWRs), economically simplified boiling water reactors (ESBWRs) that eliminate the need for recirculation pumps in BWRs and internal pumps in ABWRs by using a natural circulation system of cooling water via a chimney, and resource-renewable boiling water reactors (RBWRs). The following describes embodiments of the present invention using drawings, with an improved boiling water reactor (ABWR) as an example. [Examples]

[0012] Figure 1 is a diagram of a nuclear power plant including a nuclear power output control system according to Embodiment 1 of the present invention. As shown in Figure 1, during normal operation of the nuclear power plant, the coolant is turned into steam by the heat generated by the nuclear fission reaction in the reactor core 2 within the reactor pressure vessel (reactor) 1. This steam is discharged from the reactor pressure vessel (reactor) 1 and sent to the turbine through the main steam piping 3. The steam flow rate into the turbine is adjusted by adjusting the opening of the turbine steam control valve 4 installed at the turbine inlet.

[0013] The electro-hydraulic pressure and load control device 6 consists of a pressure control unit that adjusts the opening of the turbine steam control valve 4 so that the reactor pressure remains constant, and a turbine speed control unit that adjusts the opening of the turbine steam control valve 4 in accordance with the turbine speed signal to control the turbine speed so that it remains constant. In the case of a boiling water reactor, reactor pressure control takes priority during normal operation unless the turbine speed increases significantly, and when turbine speed control is performed, the reactor pressure is controlled to remain constant by adjusting the opening of the bypass valve 5.

[0014] The reactor recirculation flow rate control device 7 is a device that controls the recirculation pump speed to adjust the recirculation flow rate of the cooling water in the reactor pressure vessel (reactor) 1, with the aim of controlling the nuclear fission reaction by the amount of voids in the cooling water within the reactor pressure vessel (reactor) 1. The reactor recirculation flow rate control device 7 has an automatic control mode that adjusts the recirculation pump speed according to the recirculation flow rate requirement value calculated based on the target value of the reactor output and the actual output signal.

[0015] The control rod operation monitoring device 8 is a device that controls the position of the control rods 9 either automatically or manually by the operator. There are two types of control rod insertion: a normal insertion operation used during normal operation and an emergency control rod insertion operation used in emergencies. The former is used when adjusting the reactor output during normal operation. The latter, on the other hand, is used as an electrically driven emergency insertion function as a backup for hydraulically driven control rod insertion operations such as scrams.

[0016] In this embodiment, the nuclear power output control system 10 is used to output commands to the control rod operation monitoring device 8 and the reactor recirculation flow rate control device 7 according to the burnup of the reactor core fuel.

[0017] Figure 2 is a block diagram of the nuclear power plant output control system shown in Figure 1. As shown in Figure 2, the nuclear power output control system 10 includes, for example, a core fuel burnup calculation unit 11 that calculates the burnup of the core fuel from the local reactor output (local reactor output signal) detected from a local power area monitor; a discrimination device 12 that compares the calculated core fuel burnup signal with the core fuel plan value and determines whether core fuel burnup adjustment is necessary from the deviation signal 17 (core fuel burnup deviation signal 17) from the core fuel plan value; a switch unit 13; a control rod selection unit 14 that, based on the signal from the discrimination device 12, turns on the switch unit 13, selects the control rod 9 to be withdrawn / inserted, and outputs a control rod withdrawal / insertion signal 19 to the control rod operation monitoring system; a control rod withdrawal / insertion command unit 15 that outputs a control rod withdrawal / insertion command 20 to the control rod operation monitoring device 8 for the control rod 9; and a reactor recirculation flow control automatic mode command unit 16 that outputs a reactor recirculation flow control automatic control mode command signal 18 to the reactor recirculation flow control device 7. Here, the core fuel burnup calculation unit 11, the discrimination device 12, the control rod selection unit 14, the control rod withdrawal / insertion command unit 15, and the reactor recirculation flow rate control automatic mode command unit 16 are implemented using, for example, a processor such as a CPU (not shown), a ROM for storing various programs, a RAM for temporarily storing data in the calculation process, and a storage device such as an external storage device. The processor such as the CPU reads and executes the various programs stored in the ROM, and stores the calculation results, which are the execution results, in the RAM or external storage device. The switch unit 13 is a normally-off type and may be either a software switch or a hardware switch.

[0018] In this embodiment, the core fuel burnup calculation unit 11 calculates the burnup of the core fuel by receiving the local reactor output (local reactor output signal) from the local output region monitor disposed in the reactor pressure vessel (reactor) 1. The discrimination device 12 compares the core fuel burnup calculated by the core fuel burnup calculation unit 11 with the core fuel planned value, and when the deviation 17 from the core fuel planned value becomes equal to or greater than a predetermined value set in advance, it determines that adjustment of the core fuel burnup is necessary and turns on the switch unit 13 (sets it to the on state). The control rod selection unit 14 selects the control rod 9 to be withdrawn / inserted around the core fuel and outputs a withdrawal / insertion control rod signal 19 to the control rod operation monitoring device 8. Further, the control rod withdrawal / insertion command unit 15 outputs a control rod withdrawal / insertion command signal 20 to the control rod operation monitoring device 8. Further, the reactor recirculation flow rate control automatic mode command unit 16 outputs a reactor recirculation flow rate control automatic control mode command signal 18 to the reactor recirculation flow rate control device 7. Thereby, even if the reactor output fluctuates due to the withdrawal / insertion of the control rod 9, the reactor recirculation flow rate control device 7 can adjust the recirculation flow rate (core flow rate) to correct the reactor output before the withdrawal / insertion of the control rod 9. Here, the adjustment of the core fuel burnup obtains an adjustment amount based on the deviation 17 between the burnup of the core fuel calculated by the core fuel burnup calculation unit 11 and the core fuel planned value. However, it is not limited to this, and the adjustment amount may be stored in advance in a table, function, graph, etc. in a DB not shown, and a configuration that refers to it may be adopted.

[0019] For example, when there is core fuel whose core fuel burnup has progressed more than planned, an insertion command signal for the control rod 9 around the core fuel is output to the control rod operation monitoring device 8, and the control rod operation monitoring device 8 performs an insertion operation of the control rod 9, whereby the reactor output around the control rod 9 decreases, and it becomes possible to suppress the burnup of the core fuel. Further, since a reactor recirculation flow rate control automatic control mode command signal 18 is output to the reactor recirculation flow rate control device 7 simultaneously with the insertion command signal for the control rod 9 to the control rod operation monitoring device 8, the reactor recirculation flow rate control device 7 increases the core flow rate in response to the decrease in the reactor output due to the insertion of the control rod 9 and corrects it to the reactor output before the insertion of the control rod 9. Thereby, while adjusting the core fuel burnup, it becomes possible to operate the reactor with a constant output.

[0020] According to the present embodiment as described above, it is possible to provide a nuclear power generation output control system that enables the combustion of the core fuel to proceed as planned and enables efficient utilization of the core fuel. Note that the present invention is not limited to the above-described embodiments, and various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Also, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, or replace a part of the configuration of each embodiment with the configuration of another embodiment.

Explanation of Reference Numerals

[0021] 1... Reactor pressure vessel (reactor) 2... Core 3... Main steam pipe 4... Turbine steam control valve 5... Bypass valve 6... Electro-hydraulic pressure / load control device 7... Reactor recirculation flow rate control device 8... Control rod operation monitoring device 9... Control rod 10... Nuclear power generation output control system 11... Core fuel burnup calculation unit 12... Discrimination device 13... Switch unit 14... Control rod selection unit 15... Control rod withdrawal / insertion command unit 16... Reactor recirculation flow rate control automatic mode command unit 17... Core fuel burnup deviation signal 18... Reactor recirculation flow rate control automatic control mode command signal 19... Withdrawal / insertion control rod signal 20... Control rod withdrawal / insertion command signal

Claims

1. A nuclear power output control system for controlling the output of a boiling water reactor, A core fuel burnup calculation unit that calculates the burnup of core fuel from the detected local reactor power, A discrimination device that compares the core fuel burnup signal from the core fuel burnup calculation unit with the core fuel plan value and determines whether core fuel burnup adjustment is necessary from the deviation signal from the core fuel plan value, A control rod selection unit selects a control rod to withdraw / insert when the deviation signal exceeds a predetermined value set in advance. A nuclear power plant output control system characterized by comprising: a control rod withdrawal / insertion command unit that outputs a withdrawal / insertion command for a selected control rod to a control rod operation monitoring device.

2. A nuclear power output control system according to claim 1, A nuclear power plant output control system characterized by having a switch unit that turns on when the deviation signal exceeds a predetermined value set in advance, and activates the control rod selection unit and the control rod withdrawal / insertion command unit.

3. A nuclear power output control system according to claim 2, A nuclear power plant output control system characterized by having an automatic reactor recirculation flow control command unit that adjusts the core flow rate and corrects the reactor output in response to fluctuations in reactor output caused by the withdrawal / insertion of the control rods.

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