JP2931631B2 - Neutron flux measurement system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] [Field of Industrial Application] The present invention relates to a neutron flux measurement system capable of measuring a plateau characteristic which is a voltage application characteristic of a neutron detector.

[Conventional technology]

2. Description of the Related Art Conventionally, in nuclear power generation and the like, a high voltage for improving detection sensitivity is applied to a plurality of neutron detectors installed in a nuclear reactor, and detection signals of the respective neutron detectors are measured.
The neutron detectors used by applying a high voltage as described above each have a plateau characteristic. As shown in FIG. 3, this plateau characteristic shows that when the applied voltage is gradually increased under a constant neutron flux, the detection current rapidly increases up to a certain voltage, and from there, a voltage in a certain range It has a constant value. By using a neutron detector in a stable region where the value of the detection current is constant, the detector sensitivity is stabilized and a highly accurate measurement value can be obtained. Therefore, it is necessary for each of the plurality of neutron detectors installed in the reactor to measure this plateau characteristic.

The principle of measurement of the conventional plateau characteristic will be described with reference to FIG.

In FIG. 1, reference numeral 1 denotes a neutron detector. The detection signal of the neutron detector 1 is input to the (−) side input terminal of the amplifier 2. The output voltage of the variable high-voltage power supply 3 is applied to the (+) side input terminal of the amplifier 2. Amplifier 2 has feedback resistor R1
The detection signal is converted into a voltage signal by the
Output to The insulating amplifier 4 and the amplifier 2 are operated by the low voltage power supply 5 for the amplifier. The (+) side electrode of the variable high-voltage power supply 3 is connected to the common of the low-voltage power supply for amplifier 5, and the insulating amplifier 4 and the amplifier 2 operate based on the voltage of the variable high-voltage power supply 3.

The insulation amplifier 4 insulates the measurement channel side to which the voltage of the variable high-voltage power supply 3 is applied from the arithmetic processing side based on 0V. The output of this insulation amplifier 4 is an A / D converter 6
Is input to the computer 7 after the A / D conversion. Here, the detection signal of the neutron detector is calculated, and data on the output of the reactor is obtained.

FIG. 4 is a diagram showing a conventional neutron flux measurement system, which shows a configuration in which measurement of a plateau characteristic and measurement of a detection signal of a neutron detector are enabled in correspondence with a plurality of neutron detectors.

This neutron flux measurement system has a configuration in which a channel for measuring a detection signal of the neutron detector 1 and a channel for measuring plateau characteristics are integrated. That is, the high-voltage power supply 11 and the variable high-voltage power supply 12 are connected to the amplifiers 2 of the respective channels via the switches SW1. By switching the switch SW1 to the A-side terminal, a high voltage is applied to the channel from the high-voltage power supply 11, and by switching to the B-side terminal, the variable high-voltage power supply is switched.
12, a voltage that changes continuously is applied. The output of the isolation amplifier 4 of each channel is selected by the multiplexer 13 and A / D converted by the A / D converter 6.
Enter

In such a configuration, when normal neutron flux detection is performed, the switch SW1 is switched to the A-side terminal, and the detection signal of each channel is transmitted to the multiplexer 13 via the isolation amplifier 4.
To enter. When measuring the plateau characteristic of a specific neutron detector 1, the switch SW1 of the channel to which the detection signal of the neutron detector 1 is input is switched to the B-side terminal, and the variable high-voltage power supply 12 is changed to The plateau signal at that time is input to the multiplexer 13 via the isolation amplifier 4. The multiplexer 13 selects a predetermined insulation amplifier 4 from a plurality of insulation amplifiers 4 provided for each channel, inputs the output to the A / D converter 6, and outputs the output to the A / D converter 6. The output is input to the computer 7. The computer 7 executes processing relating to the plateau characteristic of the neutron detector 1 when the channel that has transmitted the input signal is performing plateau measurement, and performs processing related to the reactor output when performing normal neutron flux detection. Execute the process.

As described above, in the conventional neutron flux measurement system, the channel for measuring the plateau characteristic operates at a potential based on the voltage of the high-voltage variable power supply 12, and the other channels performing the neutron flux measurement use the voltage of the high-voltage power supply 11. Operates at the reference potential. Therefore, in order to operate each channel at a different voltage and operate the amplifier of each channel normally, a low-voltage power supply for amplifier 5 is required for each channel.

In addition, an insulating amplifier 4 is required for each channel in order to insulate each channel operating at the above-described voltage from the arithmetic processing side after the multiplexer 13 operating at 0 V as a potential. However, the low-voltage power supply for amplifier 5 and the insulated amplifier 4 are expensive and require a large installation space.

[Problems to be solved by the invention]

Therefore, the conventional neutron flux measurement system is a low-voltage power supply 5 for an amplifier that is expensive and requires a large installation space.
In addition, since the insulated amplifier 4 must be provided for each channel, there is a problem that the cost is high and the device becomes large.

The present invention has been made in view of the above circumstances,
It is an object of the present invention to provide a neutron flux measurement system which can easily measure a neutron flux and a plateau characteristic, and can reduce the cost and the size of the apparatus.

[Constitution of the Invention] [Means for Solving the Problems] In order to solve the above problems, the present invention applies a high voltage to a plurality of neutron detectors installed in a nuclear reactor and applies a high voltage to each of the neutron detectors. In a neutron flux measurement system that measures a detection signal to be output and applies a continuously changing voltage to an arbitrary neutron detector to measure a plateau characteristic of the neutron detector, a plurality of neutron detectors are measured. A plurality of neutron flux measurement channels each connected via one end of a changeover switch, each having an amplifier and a feedback resistor, a common high-voltage power supply for supplying a high voltage to each of these neutron flux measurement channels, and a plurality of neutron detections One plateau measurement channel connected to the other end of the switch via the other end of the changeover switch and having an amplifier and a feedback resistor, and supplying a continuously varying voltage to the plateau measurement channel Those having a variable high voltage power supply that.

[Action]

According to the present invention, by taking the above measures, the neutron detector to be measured for the plateau characteristic is connected to the plateau measurement channel by the switch, and the neutron detector continuously changes from the plateau measurement channel to the neutron detector. The plateau signal of the neutron detector is guided to a plateau measurement channel, and is input to a subsequent measurement system such as a computer via the plateau measurement channel. Therefore, the channel for detecting the neutron flux and the channel for detecting the plateau characteristic are separated, and the low-voltage power supply for amplifier 5 required for each channel in the conventional system is used.
In addition, the configuration can be such that the isolation amplifier 4 is provided one each for the channel for detecting the neutron flux and the channel for detecting the plateau characteristic, so that the apparatus can be reduced in size and the number of parts can be reduced to reduce the cost. It is planned.

Furthermore, since a neutron measurement channel is provided for each neutron detector, and one plateau measurement channel shared by all neutron detectors is provided, even if a failure occurs in any one neutron measurement channel, By adjusting the variable high-voltage power supply to the same power supply as the high-voltage power supply of the neutron measurement channel, the function of the failed neutron measurement channel can be substituted for the plateau measurement channel, and the system can be operated without stopping.

〔Example〕

 Hereinafter, examples of the present invention will be described.

FIG. 1 is a diagram showing a neutron flux measurement system according to an embodiment of the present invention. In this measurement system, a plurality of neutron detectors 1-1 to 1-4 installed in the reactor are connected to one end (terminal B) of switches SW2-1 to SW2-4 as changeover switches.
On the other hand, is connected to individual channels for measuring the neutron flux (hereinafter referred to as “neutron flux measurement channel”) on the one hand, and each neutron detection via the other end (terminal A side) It is connected to a channel (hereinafter, referred to as a “plateau measurement channel”) 20 for measuring plateau characteristics of the devices 1-1 to 1-4. Each neutron flux measurement channel is
Each of the amplifiers 31 has a (−) input terminal to which a detection signal from the corresponding neutron detector 1 is input, and a (+) input terminal shared by the neutron flux measurement channels. The output voltage of the high voltage power supply 32 is applied. Each amplifier
The feedback resistor R1 is provided on the 31, and the detection signal input to the amplifier 31 is converted into a voltage signal at the output side by the feedback resistor R1 and appears. The output side of each amplifier 31 is connected to a multiplexer 33. The multiplexer 33 sequentially selects signals input from the respective neutron flux measurement channels and outputs the signals to the plateau multiplexer 35 via the collective insulation amplifier 34. Note that the amplifier 31, the multiplexer 3
3. The collective insulation amplifier 34 and a photocoupler 36 described later are operated by the low-voltage power supply 37 in which the voltage of the high-voltage power supply 32 is applied to its common, and the operation voltage is the voltage of the high-voltage power supply 32.

On the other hand, in the plateau measurement channel 20, an output signal from any neutron detector 1 which is taken in via the switch SW2 is input to the (-) side input terminal of the amplifier 21. The voltage of the variable high-voltage power supply 22 is applied to the (+) input terminal of the amplifier 21. The amplifier 21 is provided with a feedback resistor R2, and the signal input to the (−) input terminal of the amplifier 21 is converted into a voltage signal by the feedback resistor R2 and appears on the output side. The output of the amplifier 21 is input to the plateau multiplexer 35 via the isolation amplifier 23. The (+) side electrode of the variable high-voltage power supply 22 is connected to the common of the low-voltage power supply 24.
It becomes the operating voltage of the amplifier 21 and the insulation amplifier 23.

The plateau multiplexer 35 selects a neutron flux detection signal from the batch isolation amplifier 34 and a plateau measurement signal from the isolation amplifier 23, and outputs the selected signal to the A / D converter 37. The signals converted into digital signals by the A / D converter 37 are sequentially read into a computer 38. The computer 38 executes an operation relating to the reactor power on the signal from each neutron flux measurement channel, and executes a processing operation for detecting the plateau characteristic of the signal from the plateau measurement channel 20. The computer 38 adjusts the variable high-voltage power supply 22 and controls switching of the plateau multiplexer 35 according to the switching position of the switch SW2. Further, switching of the multiplexer 33 is controlled via the photocoupler 36.

Next, the operation of the present embodiment configured as described above will be described. For example, when measuring the plateau characteristic of the neutron detector 1-1, the switch SW2-1 to which the neutron detector 1-1 is connected is switched to the terminal A, and the switches SW2-2 to SW2- of other channels are switched. 4 switches to the B side. As a result, the voltage of the variable high-voltage power supply 22 is applied to the neutron detector 1-1, and the voltage of the high-voltage power supply 32 is applied to the other neutron detectors 1-2 to 1-4.

Next, according to a command from the computer 38, the voltage of the variable high-voltage power supply 22 is set, and characteristic data of the neutron detector 1-1 at each voltage when continuously changed is supplied to the amplifier 21 of the plateau measurement channel 20. input. Since the amplifier 21 operates at the same voltage as the voltage of the variable high-voltage power supply 22, only the signal input to the (-) side input terminal is converted into a voltage signal by the feedback resistor R2,
Enter 35. On the other hand, the detection signals of the other neutron detectors 1-2 to 1-4 performing the neutron flux measurement are respectively input to the corresponding neutron flux measurement channels, converted into voltage signals and input to the multiplexer 33, and further integrated. Isolation amplifier 34
To the plateau multiplexer 35.

In the plateau multiplexer 35, the data from the neutron flux measurement channel and the data from the plateau measurement channel are selectively extracted, and the computer 3 outputs the data through the A / D converter 37.
Read in 8. The computer 38 sequentially reads the data from each neutron flux measurement channel, processes the data of the channel connected to the plateau measurement channel so as to bypass the plateau multiplexer 35, and passes the plateau multiplexer 35 to the plateau measurement channel side. Collect data. As described above, the measurement of the neutron flux and the measurement of the plateau characteristic for the neutron detector are performed.

As described above, according to the present embodiment, the conventional isolation amplifier provided for each channel for measuring the plateau characteristic,
It is only necessary to provide one low-voltage power supply for the amplifier in one of the plurality of neutron flux measurement channels and one in the plateau measurement channel 20, so that expensive parts can be reduced, cost can be reduced, and the size of the apparatus can be reduced. It is possible to save space.

When a part of the channel for performing the normal neutron flux measurement, for example, one or both of the amplifier 31 and the feedback resistor R1 fails, the switch SW2 of the channel is used.
By moving the variable high-voltage power supply 22 to the same voltage as the high-voltage power supply 32,
It can be operated without stopping the system.

Further, when a portion of the predetermined neutron flux measurement channel that operates at the same potential as the high-voltage power supply 32 fails, a signal input to that channel is guided to the plateau measurement channel, and the plateau measurement channel is set in the same manner as the neutron flux measurement channel. By operating, the system can be operated without stopping.

In the above embodiment, the case where the number of the neutron detectors 1 is four has been described as an example. However, the number of the neutron detectors is not limited to this, and can be increased or decreased according to a request for the system.

[Effects of the Invention] As described in detail above, according to the present invention, it is possible to provide a neutron flux measurement system that can easily perform neutron flux measurement and plateau characteristic measurement, and that can reduce costs and downsize the apparatus. .

Further, since a neutron measurement channel having an amplifier and a feedback resistance for each neutron detector and a plateau measurement channel are provided independently of each other, even if a failure occurs in any one of the neutron measurement channels, The neutron measurement channel that failed for the plateau measurement channel by connecting the plateau measurement channel to the neutron measurement device of the channel via the changeover switch and adjusting the variable high-voltage power supply to the same power supply as the high-voltage power supply of the neutron measurement channel Function can be substituted. Therefore, the operation can be performed without stopping the system, and the reliability of the entire system can be improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a neutron flux measurement system according to an embodiment of the present invention, FIG. 2 is a diagram for explaining the principle of measurement of plateau characteristics, FIG. 3 is a diagram showing plateau characteristics, and FIG. 1 is a configuration diagram of a neutron flux measurement system. 1 ... neutron detector, 20 ... plateau measurement channel, 2
1,31 ... amplifier, 22 ... high voltage variable power supply, 23 ... insulated amplifier, 24,37 ... low voltage power supply, 33 ... multiplexer, 3
4… General isolation amplifier, 35… Plateau multiplexer, 36… Photocoupler, 37… A / D converter, 38… Calculator.

Claims (1)

(57) [Claims] A high voltage is applied to a plurality of neutron detectors installed in a nuclear reactor to measure a detection signal output from each of the neutron detectors. In a neutron flux measurement system for measuring a plateau characteristic of a neutron detector by applying a changing voltage, a plurality of neutron detectors are connected to each of the plurality of neutron detectors via one end of a changeover switch, each of which has an amplifier and a feedback resistor. A neutron flux measurement channel, a common high-voltage power supply for supplying the high voltage to each of these neutron flux measurement channels, connected to each of the plurality of neutron detectors via the other end of the changeover switch, an amplifier and A plateau measurement channel having a feedback resistance, and a variable high-voltage power supply for supplying the continuously changing voltage to the plateau measurement channel. Neutron flux measurement system.