JP2667034B2 - Power range neutron flux monitor of reactor - Google Patents

Description

Detailed description of the invention [Industrial application] The present invention is to measure the neutron flux in a nuclear reactor in a rated power operation state in a nuclear power plant or the like, The present invention relates to a power range neutron flux monitor of a reactor that generates a scram signal for shutting down a reactor by inserting a control rod when the average value of the flux becomes abnormally high.

[Conventional technology]

Generally, in a nuclear power plant or the like that requires high safety, an output area neutron flux monitor for monitoring the output of a nuclear reactor is provided. This kind of monitor is
Conventionally, most of them are analog type, but recently digitalized ones have been considered.

FIG. 5 is a diagram showing a configuration example of a conventional output area neutron flux monitor using an analog signal processing circuit.

In this power range neutron flux monitor, the individual neutron detection signals of a local power range monitor (LPRM) detector 1 for detecting the local power of the nuclear reactor are input to the LPRM signal input circuit 3 via the metal cable 2, and the neutrons are input there. After the detection signal is converted into a voltage signal and the detector sensitivity is corrected, it is input to the comparison circuit 4 to monitor the output of each LPRM detector 1. Also, each
The output of the LPRM signal input circuit 3 is input to an averaging circuit 5, where the calculation of the average output (APRM value) of the reactor is performed, and the calculation result is input to another comparison circuit 6. The comparison circuit 6 monitors the APRM value. That is, a threshold value is set in advance in the comparison circuit 6, and a scrum signal is generated when the average output of the reactor becomes abnormally high and the APRM value exceeds the threshold value. On the other hand, the flow rate detection signal of the differential pressure transmitter 7 for detecting the reactor recirculation flow rate is converted into a voltage signal by the recirculation flow rate signal input circuit 8 and then input to the arithmetic circuit 9 where it is set in the comparison circuit 6. A reference signal having a power threshold is generated, and the reference signal is output to the comparison circuit 6.
Further, the flow rate detection signal converted into the voltage signal by the recirculation flow rate signal input circuit 8 is input to the comparison circuit 10 and used for monitoring. The individual circuits that make up the system in this way are:
It is composed of a logic circuit and an analog signal processing circuit,
Continuous signal processing was performed.

On the other hand, in recent years, there has been an increasing demand for improved economic efficiency and safety in nuclear power plants, and there is a strong demand for improved maintainability due to higher functionality of equipment, cost reduction due to equipment miniaturization and cable reduction. As a result, digital signal processing devices and digital signal transmission using a microprocessor have been put to practical use.

FIG. 6 is a diagram showing a configuration example of a neutron flux monitor in an output area using a digital signal processing circuit. Reference numeral 11 shown in FIG. 1 denotes a CPU module for monitoring the reactor power. The CPU module 11 is connected to an LPRM signal input interface module (hereinafter, abbreviated as “LPRM signal input module”) 13 via a common data bus 12. Connected to the recirculation flow detection signal input interface module (hereinafter abbreviated as "flow signal input module") 14, the service signal interface module (hereinafter abbreviated as "service signal module") 15, and the digital signal output module 16 Have been. The LPRM signal input module 13 and the flow rate signal input module 14 receive safety-related signals used for scram determination, that is, neutron detection signals and flow rate detection signals.

The CPU module 11 controls the data bus 12 by sequentially reading out and executing the programs recorded in the memory 11-1 by the microprocessor 11-2, thereby controlling each signal from the LPRM signal input module 13 and the flow rate signal input module 14. And perform calculations related to scrum judgment, etc.
The result signal is output from the digital signal output module 16. The microprocessor 11-2 is connected to the data bus 12
It controls the other modules 15 connected to the device and performs signal transmission with external devices, processing of man-machine interfaces, and the like.

However, digital signal processing in the CPU module 11 implements various processing functions by sequentially executing programs corresponding to the individual processing contents, so that all processing is partially performed using common hardware. Will be For this reason, the function separation of the hardware is not clear as compared with the analog signal processing in which the hardware differs for each function, and there are many cases where hardware having different degrees of importance in safety coexist. Therefore, there is a possibility that a failure that has occurred in hardware with low safety importance may affect processing in hardware with higher safety importance. For example,
CPU module 11 (memory 11-1, microprocessor 11
-2), and the data bus 12 is used for all processes. For this reason, a failure occurs in any of the interface modules 3, 14, 15, and 16 connected to the data bus 12 to hinder the function of the data bus 12, or to stop the processing of the microprocessor 11-2. In such a case, the reactor power monitoring function may be impaired.

[Problems to be solved by the invention]

Therefore, in the conventional digital reactor power range neutron flux monitor, the safety system and the service system share the same data bus, microprocessor, and other hardware.
Failures occurring on hardware with lower safety significance may adversely affect signal processing with higher safety significance, and the amount of processing in the microprocessor will increase and signal processing speed will decrease. There was such a problem.

The present invention has been made in view of the above circumstances,
Reactors that can separate their functions according to the required degree of safety importance and improve signal reliability, improve safety, and increase data processing speed It is an object of the present invention to provide a neutron flux monitor in an output area.

[Means for Solving the Problems] In order to solve the above problems, the present invention solves the above problems by averaging the output signals of a plurality of neutron detectors installed in the reactor and calculating the reactor recirculation flow rate. In a reactor power range neutron flux monitor that performs a calculation to monitor a reactor average power in a rated output operating state, a first microprocessor that performs at least a calculation related to scrum signal processing, and other than not including the scrum signal processing To execute the operation related to the signal processing of
And a first data bus controlled by the first microprocessor, and an output signal of the neutron detector and the nuclear reactor which are connected to the first data bus as signals relating to the scrum signal processing. A first interface module for receiving a recirculation flow detection signal, a second data bus controlled by the second microprocessor, and connected to the second data bus and not directly related to the scrum signal processing; A second interface module to which signals are input, and two-way input / output ports respectively corresponding to the first microprocessor and the second microprocessor, wherein the first microprocessor and the second microprocessor have Data can be read and written independently of each other It has a structure and a memory.

[Action]

According to the present invention, by taking the above-mentioned means, the signals directly related to the scrum signal processing such as the neutron detection signal and the flow rate detection signal are input to the first interface module, and the first signal is transmitted via the first data bus. 1 and performs calculations related to signal processing with high safety importance such as scrum determination. On the other hand, other signals that do not include the neutron detection signal and the flow rate detection signal, that is, a signal relating to signal processing having a different degree of importance from the signal processing are input to the second interface module,
The data is taken into the second microprocessor via the second data bus and processed. Further, the first microprocessor and the second microprocessor transmit the calculation results of each other via the memory. Therefore, the signal processing function and the device are separated from each other according to the safety importance of the device to which the signal is input and the safety requirements for the signal processing. That can prevent the spread of the data to devices with high reliability and improve the reliability of the signal. In addition, the first microprocessor executes only high-priority processing, thereby increasing the data processing speed. Becomes

〔Example〕

 Hereinafter, examples of the present invention will be described.

FIG. 1 is a diagram showing a configuration of a neutron flux monitor in an output area according to a first embodiment of the present invention. This output region neutron flux monitor, the detection signals of neutron detectors installed at multiple locations in the reactor are input to the corresponding LPRM signal input module 20, and the flow rate signal that detects the recirculation flow rate of the reactor is also It is input to the flow signal input module 21. The LPRM signal input module 20 and the flow rate signal input module 21 are connected to the safety system side data bus 22. The data bus 22 is controlled by the safety-side CPU module 23. The scrum command signal output from the CPU module 23 is transmitted to the data bus 22
The CPU module 23 output from the digital signal output module 24 connected to the memory 23-1 stores a memory 23-1 in which a program describing a scrum signal processing function is stored.
And a microprocessor 23-2 for reading and executing the scrum signal processing program.

On the other hand, a service signal module 25 for transmitting and receiving data to and from a service external device is connected to a service data bus 26. The data bus 26 is controlled by the service system side CPU module 27. This CPU module 27
A memory 27-1 in which a program describing other functions in the output area neutron flux monitor other than the scrum signal processing function is stored, and a microprocessor 27-2 which reads out and executes the program from the memory 27-1 Consists of

Further, in the monitor of the present embodiment, one of the two-directional input / output ports is connected to the safety system CPU module 23, the other is connected to the service system CPU module 27, and each of the CPU modules 23 and 27 is connected to each other. A two-port RAM 28 for independently writing and reading data is provided.

Next, the operation of the present embodiment configured as described above will be described.

The microprocessor 23-2 on the safety side has a memory 23-1.
The scrum signal processing program is read from and executed at high speed, the data bus 22 is controlled, and the LPRM signal is input from the LPRM signal input module 20 connected to the data bus 22 to calculate the average output of the reactor. . On the other hand, a flow rate signal relating to the recirculation flow rate is input from the flow rate signal input module 21 to calculate a threshold value which is a reference for scram determination. Then, when the average output becomes abnormally high and exceeds the threshold value, the data bus 22 is controlled to quickly output a scrum signal from the output module 24 connected to the data bus 22. Further, the operation result of the microprocessor 23-2 is sequentially stored in the two-port memory 28.

On the other hand, the microprocessor 27-2 on the service side has a memory.
Execute the program recorded in 27-1 and execute 2 ports
The signal processing results of the microprocessor 23-2 on the safety side are input from the RAM 28 to perform monitoring other than the scrum monitoring, and these results are controlled from the service signal module 25 connected to the data bus 26 to external devices. Outputs a signal or inputs a signal from an external device. Thus, input / output of signals with external devices and a man-machine interface function are performed.

As described above, in the present embodiment, the microprocessors 23-2 and 27-2 mounted on the CPU modules 23 and 27 have different degrees of safety importance required by reading and executing different programs. Performs signal processing, and each microprocessor 23-2, 27-2 has a separate data bus.
The control section controls the interface modules connected to the data buses 22 and 26 to perform the required processing. In addition, data can be written to and read from the two-port RAM 28 independently of each other from the two directions of the two microprocessors connected thereto.

Therefore, according to the present embodiment as described above, the LPRM signal input module 12, the flow rate signal input module 21, the data bus 22, the CPU module 23, the digital signal output module 2
The device related to scrum determination such as 4 and the service-related devices such as the service signal module 25, the data bus 26, and the CPU module 27 are separated, and the microprocessor 23-2 and 27-2 are separated by two.
Since the configuration is such that the connection is made by the port RAM 28, on the one hand, safety-critical processing relating to scrum determination can be performed, and on the other hand, sophisticated and complicated signal processing that improves the operability of the apparatus can be performed. As a result, the two microprocessors 23-2 and 27-2 for the safety system and the normal system can be operated independently and asynchronously without interfering with each other, and the burden on the microprocessors 23-2 and 27-2 is increased. Can be reduced, and the data processing speed can be increased. Further, since the data buses 22 and 26 are physically separated from each other, it is possible to prevent a failure occurring on one data bus from spreading to the other data bus, thereby improving the reliability of the processing signal function. Can be improved,
Safety can be improved.

Next, a second embodiment of the present invention will be described with reference to FIG.

In the output region neutron flux monitor of the second embodiment, the first CPU module 30 for determining the output of a scrum signal outputs a plurality of LPRM signal input modules 32, a flow rate signal input module 33, and a scrum signal via the data bus 31. A digital signal output module 34 is connected. The CPU module 30 has a memory 30-1 in which a program related to scrum determination is stored as a function requiring high reliability.
A microprocessor 30-2 for calling a predetermined program from the memory 30-1 and executing a function requiring high reliability at high speed; and a microprocessor 30-2.
Is input via one input / output port.
And a port RAM 30-3. The program for the scrum determination stored in the memory 30-1 of the CPU module 30 is the input processing function of each LPRM signal directly related to the scrum signal generation processing, and the reactor power percentage conversion value of each LPRM signal ( LPRM percent value) conversion processing function, LPRM percent value average arithmetic processing function, conversion processing function from average value of LPRM percent value to reactor average output power percentage value (APRM percent value), and recirculation Flow signal input processing function, conversion processing function to convert recirculation flow rate signal to percentage, function to calculate reference value for scrum condition judgment using recirculation flow signal, and APRM percentage using reference value for scrum condition judgment It consists of a value monitoring function and a scrum signal output processing function.

On the other hand, CPU module 3 that performs processing other than scrum determination
5 is a data bus 3 which is separated from the data bus 31
6 via display module 37, external data transmission module
38, and a digital signal input module 39. The CPU module 35 includes a memory 35-1 in which various programs without a scrum monitoring function are stored, and a microprocessor 35-2 which reads a predetermined program from the memory 35-1 and executes the function. Have been. The program stored in the memory 35-1 of the CPU module 35 has functions other than the above scrum monitoring,
For example, an APRM high value alarm to stop the pulling of the control rod before reaching the scrum condition and a monitoring function such as a low value alarm to detect when each signal is not processed normally, an output including each alarm output signal Among the functions of the output area neutron flux monitor such as the input / output function of signals between the area neutron flux monitor and an external device and the man-machine interface function, the processing functions are not included in the memory 30-1.

Further, in this embodiment, the microprocessor 35-2 for monitoring other than the scrum signal monitoring is connected to the other input / output port of the two-port RAM 30-3 provided in the CPU module 30 for monitoring the scrum signal via the data bus 36. It is connected. Thus, the microprocessor 30-2 and the microprocessor 35-2 can read and write the contents stored in the two-port RAM 30-3 independently of each other.

Next, the operation of the second embodiment configured as described above will be described.

For example, six or seven LPRM detector signals are input to each LPRM signal input module 32 as a multiplexed digital signal, and the total eight LPRM signal input modules 32
Signals from 52 LPRM detectors are input. The microprocessor 30-2 for monitoring the scrum signal has a memory 30-1.
From the LPRM signal input module 32 to control the data transmission of the data bus 31 and input the detection signals of the 52 LPRM detectors.
Perform conversion processing to RM percentage value. The average operation of the LPRM percentage value obtained by this operation is performed, and the APRM
The value is calculated, and further converted to an APRM percentage value. On the other hand, the flow rate signal is input from the flow rate signal input module 33 by controlling the data transmission of the data bus 31, and the percentage conversion of the recirculation flow rate signal is performed. Then, an operation for obtaining a reference value for scrum determination is performed using the value obtained by this conversion, and the APRM percentage value is monitored based on the reference value. When the APRM percentage value becomes larger than the reference value, the data transmission of the data bus 31 is controlled to output a scrum signal from the signal output module. On the other hand, the microprocessor 30-2 writes the input signal and the signal processing result into the two-port RAM 30-3 on the CPU module 30.

In the other CPU module 35, the microprocessor 35-2 reads and executes the program from the memory 35-1, controls the data transmission on the data bus 36, and controls the data transmission on the data bus side port of the two-port RAM 30-3. The signal input by the processor 30-2 and the signal processing result are read out asynchronously independently of the operation of the microprocessor 30-2. Then, the soundness of each LPRM signal is checked from the data thus read. For example, checking transmission errors, monitoring high and low values for individual LPRM percentage values, monitoring high and low values for APRM percentage values, and the like. The microprocessor 35-2, together with such a check, calculates a comparison value for monitoring the APRM percentage value, and compares the calculation result and the check result with a signal input from the microprocessor 30-2 and a signal processing result thereof. In addition, the data is output to the display module 37 and the external data transmission module 38 connected to the data bus 36. The microprocessor 35-2 writes the data input from the external data transmission module 38 and the digital signal input module 39 together with the comparison value for monitoring the APRM percentage value from the data bus 36 to the 2-port RAM 30-3 on the CPU module 30. Microprocessor 30
-2.

As described above, according to the second embodiment, the microprocessor connected to the data bus 31 includes only the modules 32, 33, and 34 for inputting and outputting signals necessary for scrum signal processing.
30-2 is dedicated to scram signal processing, and data is transmitted to and from the other microprocessor 35-2 via the 2-port RAM 30-3 in the same module. 30−
2 is completely independent of the operation of the modules connected to the microprocessor 35-2 and the data bus 36 which are not directly related to the scrum signal processing, and the scrum signal processing can be performed regardless of whether the operation of these modules is good or defective. it can. As a result, the amount of hardware involved in the scrum signal processing can be reduced, and the reliability of the scrum signal processing function can be improved. For example, even if a failure occurs in one of the modules connected to the data bus 36 and the operation of the microprocessor 35-2 becomes abnormal, the microprocessor 30-2 which performs the scrum signal processing has no influence. Therefore, it is possible to monitor the average power of the reactor normally. On the other hand, in the microprocessor 35-2, various functions such as data transmission with an external device and a man-machine interface can be performed without affecting the scrum signal processing function, thereby realizing high functions.

The present invention is not limited to the first and second embodiments. For example, as shown in FIG. 3, a 2-port RAM 40 is provided as a single module, and each CPU module
30 and 35 may be connected to one input / output port and the other input / output port of the two-port RAM 40 via the mutually connected data buses 31 and 36, respectively. Further, as shown in FIG. 4, a configuration in which a 2-port RAM 50 is mounted on the CPU module 35 side can be adopted.
RAM for one CPU module 30 and the other CPU module 35
And the operations of both are made independent from each other, the same operation and effect as in the first and second embodiments can be obtained.

[Effects of the Invention] As described above in detail, according to the present invention, the functions thereof are separated according to the required degree of safety importance, thereby improving the reliability of the signal and improving the safety. Can be
Further, it is possible to provide a neutron flux monitor in a power region of a nuclear reactor, which can increase a data processing speed.

[Brief description of the drawings]

1 is a block diagram of the first embodiment, FIG. 2 is a block diagram of the second embodiment, FIGS. 3 and 4 are block diagrams of a modification in which the arrangement position of the two-port RAM is changed, and FIG. FIG. 6 is a configuration diagram of an analog output area neutron flux monitor, and FIG. 6 is a configuration diagram of a digital output area neutron flux monitor. 20 …… LPRM signal input module, 21 …… Recirculation flow rate input module, 22,26 …… Data bus, 23,27 …… CPU module, 24 …… Digital signal output module, 25 …… Common system signal module, 28 ...... Two-port RAM.

Claims (1)

(57) [Claims] Claim: What is claimed is: 1. A reactor for monitoring an average reactor output in a rated output operation state by performing an average calculation of output signals of a plurality of neutron detectors installed in the reactor and a reactor recirculation flow rate. In the output area neutron flux monitor, a first microprocessor that performs at least an operation related to scram signal processing, a second microprocessor that performs an operation related to other signal processing not including the scrum signal processing, and the first microprocessor A first data bus controlled by a processor and at least an output signal of the neutron detector and a detection signal of the reactor recirculation flow rate are input as signals related to the scram signal processing connected to the first data bus. A first interface module; a second data bus controlled by the second microprocessor; A second interface module connected to a second data bus for inputting a signal not directly related to the scrum signal processing, and bidirectional input / output corresponding to the first microprocessor and the second microprocessor, respectively. A neutron flux monitor for an output region of a nuclear reactor, comprising: a memory having a port, wherein the first microprocessor and the second microprocessor can independently read and write data.