JP2006071397A - Control rod extraction monitoring method and device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control rod extraction monitoring method and a device capable of executing local output monitoring around a plurality of control rods with a short monitoring time difference and high simultaneity. <P>SOLUTION: In this control rod extraction monitoring device, a neutron flux in a nuclear reactor is measured in the output operation state by a plurality of neutron detectors 1-1-m to 1-n-m installed in the nuclear reactor, and a local output increase following an extraction operation of the control rods is monitored. The device has a constitution equipped with a monitoring means 11 for operating a local mean value of outputs from neutron detectors enclosing always each control rod regardless of selection or non-selection of the control rod to be an extraction object, selecting the local mean value of the outputs from the neutron detectors enclosing the pertinent control rods when a plurality of control rods are selected simultaneously and the extraction operation is performed, and executing extraction monitoring of the plurality of control rods simultaneously and respectively independently. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a control rod withdrawal monitoring method and apparatus for monitoring a local power increase due to withdrawal of a control rod in a boiling water reactor or the like.

  A large number of fuel assemblies are arranged in the reactor core, and control rods are regularly arranged between the fuel assemblies. These control rods control the fission chain reaction. In order to maintain the output of the nuclear reactor at a predetermined value, a predetermined control rod is pulled out from a large number of control rods. When the control rod is pulled out in this way, the chain reaction in the vicinity of the pulled out control rod increases and the output increases locally. If this increase in local output is too large, the operation of the nuclear reactor may be hindered. Therefore, the increase in local output caused by pulling out the control rod is monitored (see Patent Document 1).

  In the conventional control rod withdrawal monitoring device, when performing the control rod withdrawal operation, only the output signal of the neutron detector surrounding the control rod to be withdrawn is selected and averaged. In addition, in a control rod pull-out monitoring device configured with a conventional analog circuit, the output signals of 88 or 84 neutron detectors are individually input with a metal cable, and the neutron detector signal used for averaging is selected. The selection circuit is composed of multiple stages.

  Discrete semiconductors used in conventional analog circuits have not been highly integrated, so that many parts and space are required to construct a multistage selection circuit and an average calculation and monitoring circuit. For this reason, among the neutron detectors arranged as A level, B level, C level, and D level from the bottom in the height direction of the reactor, an A-system monitoring device that performs an average calculation of the A level and the C level, A convenient duplex system configuration using a B-system monitoring device that performs an average calculation of the B level and the D level has been adopted.

  Thereafter, a digital control rod pull-out monitoring device using a microprocessor for arithmetic processing was realized. In the digital control rod pull-out monitoring device, a plurality of neutron detector signals are received by multiplexed data transmission, and a neutron detector signal used for the average calculation is selected from the received data by arithmetic processing. In arithmetic processing using a microprocessor, functions are realized by sequentially executing the programs recorded in the memory, so that a multistage selection circuit for selecting the neutron detector signal is not required, and the apparatus can be miniaturized. Therefore, it is possible to adopt a complete duplex system configuration in which the same monitoring operation is performed in each of the A-system monitoring device and the B-system monitoring device.

The control rod pull-out monitoring logic is as follows. That is, each of the four neutron detector strings incorporated in four neutron detector strings (lower left, upper left, lower right, upper right) surrounding the selected control rod, and each of the neutron detector strings. Are selected two by two, and the average calculation of a total of eight neutron detector signals is performed to calculate the local average value. If this local average value is compared with the reactor average power, and the local average value before starting the control rod drawing is smaller than the reactor average power signal, the local average value is equivalent to the reactor average power signal. Multiply by setting various gains. When this value is used as the rod block value, this rod block value is compared with the alarm set value when pulling out the control rod, and if the rod block value becomes larger than the alarm set value, a signal to stop pulling out the control rod Outputs an alarm signal.
Japanese Patent Publication No. 8-10261

  Although the above-described digital control rod pull-out monitoring device has made it possible to monitor multiple control rod pull-outs, the digital control rod pull-out monitoring device uses a microprocessor and a program to output local outputs around each control rod. Since monitoring is executed sequentially, a difference occurs in the monitoring time of each local average output. However, when operating multiple control rods at the same time, high simultaneity is required to confirm that there are no spatial variations in reactor power.

  The present invention has been made to solve the above-described problems, and provides a control rod pull-out monitoring method and apparatus capable of monitoring local outputs around a plurality of control rods with a short time difference and high synchronism. Objective.

  In order to achieve the above-mentioned object, the invention of claim 1 is directed to a method for measuring a neutron flux in a nuclear power reactor in an output operation state by a plurality of neutron detectors installed in the nuclear reactor, and localizing the control rod with a pulling operation. Regardless of selection or non-selection of control rods to be pulled out, a local average value of neutron detector output surrounding each control rod is always calculated, and a plurality of control rods Are selected at the same time, and a monitoring means is provided to select a local average value of the outputs of the neutron detectors surrounding the corresponding control rod and simultaneously perform a plurality of control rod extraction monitoring independently. The configuration is as follows.

  A sixth aspect of the present invention is a control rod pull-out system in which a plurality of neutron detectors are installed in a nuclear reactor and a neutron flux in the reactor is measured in an output operation state to monitor a local output increase accompanying a control rod pull-out operation. In the monitoring method, the local average value of the output of the neutron detector that always surrounds each control rod is calculated regardless of the selection or non-selection of the control rod to be pulled out, and multiple control rods are selected at the same time to pull out , The local average value of the output of the neutron detector surrounding the corresponding control rod is selected, and the plurality of control rod pull-out monitoring logics are independently and simultaneously executed.

  According to the present invention, it is possible to provide a control rod pull-out monitoring method and apparatus capable of performing local output monitoring around a plurality of control rods with a short monitoring time difference and high synchronism.

In recent years, it has become possible to arbitrarily configure a circuit on a large-scale LSI. For example, there is an element called a field programmable logic array (FPGA).
The present invention provides a control rod pull-out monitoring method and apparatus capable of performing local output monitoring around a plurality of control rods with high simultaneity by simultaneously operating a plurality of circuits of the same logic configured using an FPGA.

Hereinafter, first to fifth embodiments of a control rod pull-out monitoring device according to the present invention will be described with reference to the drawings.
(First embodiment)
As shown in FIG. 1, the control rod pull-out monitoring apparatus according to the first embodiment of the present invention is operated by a plurality of neutron detectors 1-1-m to 1-nm installed in a nuclear reactor. In a control rod extraction monitoring device that measures the neutron flux in the reactor in the state and monitors the local power increase due to the control rod extraction operation, each control is always performed regardless of the selection or non-selection of the control rod to be extracted If the local average value of the neutron detector output surrounding the rod is calculated, and a plurality of control rods are selected at the same time and the extraction operation is performed, the local average value of the output of the neutron detector surrounding the corresponding control rod is calculated. It is the structure provided with the monitoring means 11 which selects and implements several control-rod pull-out monitoring each simultaneously independently.

  As shown in FIG. 1, the control rod pull-out monitoring device according to the first embodiment of the present invention outputs a plurality of neutron detectors 1-1-m to 1-nm and these neutron detectors. A plurality of signal conversion means 2-1 to 2-m for converting a part of the received signal and a plurality of data transmission means 3-1 to 3-m for transmitting neutron detector signals from the plurality of signal conversion means. And a monitoring means 11.

  The monitoring unit 11 includes a plurality of data receiving units 4-1 to 4-m that receive the output signals of the neutron detectors transmitted by the data transmission units 3-1 to 3-m, and the plurality of data receiving units 4- 1st data transfer means 6 which reads out each neutron detector signal from 1-4m, rearranges data in the order corresponding to each control rod block, and writes data in operation recording means 5, and operation recording A plurality of average calculation means 7-1 to 7-k for reading out the neutron detector signals used in the respective average calculations from the means 5 and calculating the local average value, and a control rod selection indicating a plurality of control rods to be extracted Control rod selection signal receiving means 9 for receiving signals and a plurality of local average outputs calculated by average calculating means 7-1 to 7-k and corresponding to control rod blocks specified by control rod selection signals, respectively. Local average of And a second data transfer means 10 to be outputted to the plurality of monitoring information display means 8-1 to 8-i.

  In the control rod pull-out monitoring device of the present embodiment configured as described above, the local average outputs of the respective control rod blocks are always calculated in parallel in the average calculation means 7-1 to 7-k, and as a result, Are sequentially output to the monitoring information display means 8-1 to 8-i, and the processing in the monitoring information display means 8-1 to 8-i is also performed in parallel.

  According to the present embodiment, since the pull-out monitoring of a plurality of control rods is processed simultaneously in parallel, the control rod pull-out monitoring device that can perform local output monitoring around a plurality of control rods with a short monitoring time difference and high synchronism is provided. Can be provided. In addition, by making the number of monitoring information display means 8-1 to 8-i equal to that of the average calculation means 7-1 to 7-k, the local power around each control rod is constantly monitored with high simultaneity throughout the entire reactor. can do.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. The same components as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted.
In the control rod pull-out monitoring apparatus according to the second embodiment of the present invention, the first data transfer means 6 collects output signal data of all neutron detectors involved in each control rod into the calculation recording means 5. This is a writing configuration.

  The most devised point in the present invention is the first data transfer means 6. FIG. 2 shows an example of the function of the first data transfer means 6 in a straight line with the block removed. As described above, the first data transfer means 6 reads the individual neutron detector signals from the plurality of data receiving means 4-1 to 4-m, and rearranges the data in the order corresponding to each control rod block. It has a function of writing data to the arithmetic recording means 5. This function is shown in FIG. 2 by linearly connecting the storage elements A-1, B-4 to H21 and LL-1-A to RU-1-C of the data receiving means 4-1 to 4-8 and the recording means 5 for calculation. It is shown by connecting with.

  In the case of a boiling water reactor with 1.1 million kW output, there are 172 neutron detectors for monitoring the power operating area installed in the reactor, and four neutron detectors are installed in one assembly of four each. It is installed in 43 places. One detector assembly is called a string. In the neutron detectors 1-1-1 to 1-mn connected to the plurality of signal conversion means 2-1 to 2-m, each signal conversion means 2-1 to 2-m covers the entire core equally. It is distributed to do. Therefore, since it is necessary to collect signals from neutron detectors arranged around a specific control rod in order to perform control rod pull-out monitoring, neutron detector signals from all the data receiving means 4-1 to 4-m are collected. It is necessary to collect one by one.

  In order to realize this, the first data transfer means 6 records the read source address and the write destination address of the neutron detector signal in the address recording means 12 as shown in FIG. 3, and sequentially based on this address information. Perform data transfer.

  One neutron detector located in the reactor center can be located in the lower left, upper left, lower right, and upper right positions for four different adjacent control rod blocks. When four write destination addresses are set and the average calculation means 7-1 to 7-k read a maximum of eight neutron detector signals used for the average calculation, the eight data are collected from one memory block. The data is written in the calculation recording means 5 so that it can be read.

  According to the present embodiment, when calculating the average value of the neutron detector signals arranged around each control rod block, the neutron detector signals used in the respective average calculations can be read at once.

(Third embodiment)
In the control rod pull-out monitoring apparatus according to the third embodiment of the present invention, each of the calculation recording means 5 has a memory address corresponding to each lattice point of a grid of grids that includes the whole reactor inside, and The lattice point corresponds to the position of the neutron detector, the address of the signal of the neutron detector located at the predetermined position with respect to the predetermined control rod is specified, and the address of the signal of the neutron detector at the other position is the position of the predetermined position. It is specified by adding or subtracting a certain value to the address of the signal of the neutron detector, and the average calculation means 7-1 to 7-k are configured to read out the neutron detector signal from each address and perform the average calculation.

  In the second embodiment, the first data transfer means 6 needs to transfer one neutron detector signal four times. As shown in FIG. 4, each lattice of square lattices covering the whole reactor is used. A single control rod when the lattice points are numbered sequentially by making the point correspond to the neutron detector string position and treating the point where the string does not actually exist so that there is a virtual string. The relative difference in the numbers of the four strings surrounding the block can be made constant. For example, if a 9 by 9 grid (9 × 9) grid is set and numbered sequentially from the upper left to the right, if the upper left string number is n, the upper right string number is n + 1, the lower left string is n + 9, the right Below, the relationship n + 10 is maintained throughout the core.

  When the first data transfer means 6 writes one neutron detector signal to the calculation recording means 5, the data is written at one address corresponding to the square lattice, and the average calculation means 7-1-7. -K designates one (for example, upper left) address corresponding to the corresponding control rod block when data is read out, and the neutron detector signal is also obtained from addresses +1, +9, +10 with respect to the address. All neutron detector signals used for averaging are obtained by reading.

  According to the present embodiment, the time for transferring the neutron detector signal from the data receiving means 4-1 to 4-m to the operation recording means 5 is shortened, and the monitoring is simultaneously performed when a plurality of control rods are pulled out. Can be increased.

(Fourth embodiment)
In the control rod pull-out monitoring apparatus according to the fourth embodiment of the present invention, the data receiving means 4-1 to 4-m, the operation recording means 5 and the first data transfer means 6 are integrated into the third data. This third data transfer means comprises a transfer means, and the recording means 5 has different addresses on the data writing side and the data reading side, and is arranged in the periphery of each control rod block from the reading side. The address is given so that the signal of the neutron detector can be read continuously.

  In this embodiment, as shown in FIG. 5, the data receiving means 4-1 to 4-m, the operation recording means 5 and the data transfer means 6 are integrated into the data transmitting means 3-1 to 3-m. The address when data is received is different from the address when the average arithmetic means 7-1 to 7-k read data, and when the average arithmetic means 7-1 to 7-k read data, the respective controls Addresses are assigned to the individual recording areas so that the signals of the neutron detectors arranged around the bar block can be read out by the method shown in the third embodiment.

  According to the present embodiment, the time for transferring the neutron detector signal from the data receiving means 4-1 to 4-m to the operation recording means 5 is omitted, and the monitoring is simultaneous when a plurality of control rods are pulled out. Can be further enhanced.

(Fifth embodiment)
The control rod pull-out monitoring device of the fifth embodiment of the present invention does not include the first data transfer means 6, and the data receiving means 4-1 to 4-m receive the output signal of the neutron detector. In this configuration, four addresses corresponding to the four control rods surrounding the neutron detector are generated and the output signal of the neutron detector is written in the operation recording means 5.

  In this embodiment, when the data receiving means 4-1 to 4-m receive data, four addresses are automatically generated and the data is written in the calculation recording means 5. At this time, in the lattice space shown in FIG. 4 in the third embodiment, the address intervals corresponding to the upper left, upper right, lower left, and lower right control rod blocks as viewed from the neutron detector strings are set to the upper left. +1, +8, and +9, respectively. In this case, the data receiving means 4-1 to 4-m may be used as direct data input means for the average calculating means 7-1 to 7-k. Alternatively, an address is automatically generated when data is transferred from the data receiving means 4-1 to 4-m to the calculation recording means 5, and the calculation recording means 5 is replaced with the average calculation means 7-1 to 7-. It is good also as a direct data input means of each k.

  Also according to the present embodiment, the time for transferring the neutron detector signal from the data receiving means 4-1 to 4-m to the operation recording means 5 is shortened, and the simultaneity of monitoring when a plurality of control rods are pulled out is reduced. Can be increased.

The block diagram which shows the structure of the control-rod extraction monitoring apparatus of the 1st Embodiment of this invention. The block diagram which shows the function of a 1st data transfer means in the control-rod pull-out monitoring apparatus of the 2nd Embodiment of this invention. The block diagram which shows the relationship between the read-out address of a neutron detector signal, and a write-in address in the control-rod extraction monitoring apparatus of the 2nd Embodiment of this invention. The arrangement | positioning figure which shows the control-rod position and neutron detector string position of a nuclear reactor in the control-rod extraction monitoring apparatus of the 3rd Embodiment of this invention. The block which shows the recording means for calculation made into the structure from which the address when data is received from a data transmission means and the address when an average calculating means reads data in the control rod drawing-out monitoring apparatus of the 4th Embodiment of this invention differs Figure.

Explanation of symbols

1-1-m to 1-nm ... Neutron detector, 2-1 to 2-m ... Signal conversion means, 3-1 to 3-m ... Data transmission means, 4-1 to 4-m ... Data reception Means 5: Recording means for calculation, 6: First data transfer means, 7-1 to 7-k: Average calculation means, 8-1 to 8-i: Monitoring information display means, 9: Bar selection signal reception Means, 10 ... second data transfer means, 11 ... monitoring means, 12 ... address recording means.

Claims (7)

  In the control rod extraction monitoring device, which measures the neutron flux in the reactor in the power operation state by a plurality of neutron detectors installed in the reactor and monitors the local power increase due to the control rod extraction operation, the object to be extracted Applicable when the local average value of the neutron detector output that always surrounds each control rod is calculated regardless of the selection or non-selection of the control rod, and multiple control rods are selected at the same time to perform the extraction operation A control rod pull-out monitoring device comprising: monitoring means for selecting a local average value of the outputs of the neutron detectors surrounding the control rod to perform and simultaneously performing a plurality of control rod pull-out monitoring independently.   The monitoring means includes a plurality of data receiving means for receiving the output signals of the plurality of neutron detectors transmitted by the plurality of data transmitting means, and reading out the individual neutron detector signals from the plurality of data receiving means. First data transfer means for rearranging data in the order corresponding to the control rods and writing the data to the operation recording means, and reading out the neutron detector signals used in the respective average operations from the operation recording means to obtain a local average A plurality of average calculation means for performing value calculation, a control rod selection signal receiving means for receiving a control rod selection signal indicating a plurality of control rods to be pulled out, and a plurality of local average outputs calculated by the plurality of average calculation means And second data transfer means for outputting local average values corresponding to control rods specified by the control rod selection signal to a plurality of monitoring information display means Control rod withdrawal monitoring apparatus according to claim 1, characterized in that it comprises.   3. The control rod pull-out monitoring apparatus according to claim 2, wherein the first data transfer means collectively writes the output signal data of all neutron detectors involved in each control rod into the calculation recording means.   The monitoring means receives the output signals of the plurality of neutron detectors transmitted by the plurality of data transmission means, and has four control rods corresponding to the four control rods surrounding the neutron detector that has received the output signals. A plurality of data receiving means for generating an address and writing the output signal of the neutron detector to the calculation recording means, and reading out the neutron detector signals used in the respective average calculations from the calculation recording means to calculate the local average value A plurality of average calculation means, a control rod selection signal receiving means for receiving a control rod selection signal indicating a plurality of control rods to be pulled out, and a plurality of local average outputs calculated by the plurality of average calculation means The second data transfer means for outputting the respective local average values corresponding to the control rods specified by the control rod selection signal to a plurality of monitoring information display means Control rod withdrawal monitoring apparatus according to claim 1, characterized in that it comprises and.   The calculation recording means has a memory address corresponding to each grid point of a grid of grids that encloses the entire nuclear reactor inside, and each grid point corresponds to a neutron detector position, and has a predetermined control rod. On the other hand, the address of the signal of the neutron detector located at the predetermined position is specified, and the address of the signal of the neutron detector at the other position is specified by adding or subtracting a certain value to the address of the signal of the neutron detector at the predetermined position. 5. The control rod pull-out monitoring apparatus according to claim 2, wherein the average calculation means reads the neutron detector signal from each address and performs an average calculation.   The data receiving means, the calculation recording means, and the first data transfer means are integrated to form a third data transfer means. The third data transfer means includes a data writing side and a data reading side. The address is given so that the signals from the neutron detectors arranged in the periphery of each control rod can be read out continuously from the readout side. Or the control rod pull-out monitoring device according to 4. In the control rod extraction monitoring method, which installs multiple neutron detectors in the reactor and measures the neutron flux in the reactor in the power operation state to monitor the local power increase due to the control rod extraction operation, Applicable when the local average value of the output of the neutron detector that always surrounds each control rod is calculated regardless of the selection or non-selection of the control rods, and multiple control rods are selected at the same time to perform the extraction operation A control rod extraction monitoring method, wherein a local average value of outputs of neutron detectors surrounding a control rod to be selected is selected and the plurality of control rod extraction monitorings are performed independently and simultaneously.

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