JPH0429085A - Neutron flux measurement system - Google Patents

Abstract

PURPOSE:To facilitate neutron flux and plateau characteristic measurement by performing the arbitrary plateau measurement by a plateau measurement channel connected through switches to respective plural neutron detectors and provided with a variable high voltage power supply. CONSTITUTION:When measuring the plateau characteristic of a neutron detector 1-1, a switch SW 2-1, to which the neutron detector 1-1 is connected, is switched to a terminal A side, and switches SW 2-2 to SW 2-4 of the other channels are switched to a B side. Next, the voltage of a variable power source 22 is set by a command from a calculator 38, and the characteristic data of the detector 1-1 in each voltages are inputted to an amplifier 21 of a plateau measurement channel 20 when changed successively. The amplifier 21 inputs a signal inputted to a (-)side input terminal to a multiplexer 35. On the other hand, the detection signals of the other detector 1-2 - 1-4, performing the neutron flux measurement, are inputted to the corresponding neutron flux measurement channel and the plateau multiplexer 35. The data from the neutron flux and the plateau measurement channel are taken out selectively by this multiplexer 35, and processed by the calculator 38.

Description

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

[Conventional technology]

Conventionally, in nuclear power generation, etc., a high voltage is applied to a plurality of neutron detectors installed in a nuclear reactor to increase detection sensitivity, and the detection signal of each neutron detector is measured. Each of the neutron detectors used by applying a high voltage in this manner has a plateau characteristic. This plateau characteristic is
As shown in Figure 3, when the applied voltage is increased as desired under a constant neutron flux, the detected current increases rapidly up to a certain voltage, and then remains at a constant value within a certain range of voltage. . By using a neutron detector in a stable region where the value of the detection current is constant, the sensitivity of the detector becomes stable and highly accurate measured values can be obtained. Therefore, it is necessary for each of the plurality of neutron detectors installed in the nuclear reactor to measure this plateau characteristic.

The conventional principle of measuring plateau characteristics will be explained with reference to FIG.

Reference numeral 1 shown in the figure is a neutron detector, and a detection signal of this neutron detector 1 is input to the (-) side input terminal of an amplifier 2. A variable high voltage power supply 3 is connected to the (+) side input terminal of this amplifier 2.
The output voltage of the amplifier 2 is applied to the feedback resistor R1.
The detection signal is returned to a voltage signal by the isolation amplifier 4.
Output to.

The isolated amplifier 4 and the amplifier 2 are connected to a low voltage power supply 5 for the amplifier.
Operates by. The common of this amplifier low-voltage power supply 5 is connected to the (+) side of the variable high-voltage power supply 3 as much as possible, and the isolated amplifier 4 and the amplifier 2ζ operate with the voltage of the variable high-voltage power supply 3 as a reference.

The isolation amplifier 4 isolates the measurement channel side to which the voltage of the variable high voltage power supply 3 is applied and the arithmetic processing side using OV as a reference. The output of this isolation amplifier 4 is A/D converted by an A/D converter 6 and then input to a computer 7. Here, the sweep signal of the neutron detector is calculated to obtain data regarding the output of the nuclear reactor.

Figure 4 shows a conventional neutron flux measurement system.
This figure shows a configuration that is compatible with multiple neutron detectors and enables measurement of plateau characteristics and detection signals of the neutron detectors.

This neutron flux measurement system has a configuration in which a channel for measuring the detection signal of the neutron detector 1 and a channel for measuring the plateau characteristic are integrated. That is, a high voltage power supply 11 and a variable high voltage power supply 12 are respectively connected to the amplifier 2 of each channel via the switch SWI.

By switching this switch SWI to the A side terminal, a high voltage is applied to the channel from the high voltage power supply 11, and by switching it to the B side terminal, a continuously changing voltage is applied by the variable high voltage power supply 12. Further, the output of the isolation amplifier 4 of each channel is selected by the multiplexer 13, returned by the A/D converter 6, and then input to the computer 7.

In such a configuration, when performing normal neutron flux detection, the switch sW1 is switched to the A side terminal and the detection signal of each channel is sent to the multiplexer 1 via the isolation amplifier 4.
Enter 3. In addition, when measuring the plateau characteristic of a specific neutron detector 1, switch the switch SWI of the channel to which the detection signal of the neutron detector 1 is manually inputted to the B side terminal, and vary the variable high voltage power supply 12. When the plateau signal is passed through the isolation amplifier 4 to the multiplexer 13
to use human power. The multiplexer 13 selects a predetermined isolation amplifier 4 from among the plurality of isolation amplifiers 4 provided for each channel, and inputs the output thereof to the A/D converter 6. The output of 6 is input to the computer 7.

In the computer 7, when the channel that sent the input signal is performing plateau measurement, processing related to the plateau characteristics of the neutron detector 1 is executed, and when normal neutron flux detection is being performed, processing is performed regarding the plateau characteristics of the reactor output. □ Execute related processing.

In this way, in the conventional neutron flux measurement system, the channel that measures the plateau characteristic operates at a potential based on the voltage of the high voltage variable power supply 12, and the other channels that perform neutron flux measurement operate at a potential based on the voltage of the high voltage power supply 11. It operates at the reference potential. Therefore, each channel is operated at a different voltage,
In order to operate the amplifier of each channel normally, a low voltage power supply for the amplifier is required for each channel.

Furthermore, an isolation amplifier 4 is required for each channel in order to insulate each channel that operates with the above voltage from the arithmetic processing side after the multiplexer 13 that operates with Ov as a potential. However, the amplifier low voltage power supply 5 and the isolation amplifier 4 are expensive and require a large installation space.

[Problem to be solved by the invention]

Therefore, in the conventional neutron flux measurement system, each channel must be equipped with an amplifier low-voltage power supply 5 and an isolation amplifier 4, which are expensive and require a large installation space, resulting in high cost and large equipment. There was a problem of becoming

The present invention has been made in view of the above-mentioned circumstances, and enables easy measurement of neutron flux and plateau characteristics.
The object of the present invention is to provide a neutron flux measurement system that can reduce costs and downsize the device.

[Structure 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 so that each neutron detector In a neutron flux measurement system that measures an output detection signal and measures a plateau characteristic of an arbitrary neutron detector by applying a continuously changing voltage to the neutron detector, the plurality of neutron detectors A plateau measurement channel with a variable high-voltage power supply is connected to each of the neutron detectors via a switch, and the plateau measurement channel is used to measure the plateau of any neutron detector.

[Effect]

By taking the above measures, the present invention connects the neutron detector whose plateau characteristic is to be measured or a switch to the plateau measuring channel, and continuously changes the neutron detector from the plateau measuring channel. A voltage is applied, and the plateau signal of the neutron detector is guided to the plateau measurement channel and inputted to a subsequent measurement system such as a computer via the plateau measurement channel.

Therefore, the channel for detecting neutron flux and the channel for detecting plateau characteristics are separated, and the low-voltage power supply 5 for the amplifier and the isolation amplifier 4, which were required for each channel in the conventional system, are replaced by the channel for detecting neutron flux. The channel for detecting the plateau characteristic can be equipped with one for each channel, and the device can be made smaller and the cost can be reduced by reducing the number of antiques.

〔Example〕

Examples of the present invention will be described below.

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 a nuclear reactor are connected to a switch 5W.
2-1 to 5w2-4, one side is connected to an individual channel for normally measuring neutron flux (hereinafter referred to as "neutron flux measurement channel"), and the other side is connected to each neutron detector 11 to 5w2-4. Channel for measuring the plateau characteristics of 1-4 (hereinafter referred to as "plateau measurement channel") 2
Connected to 0. Each neutron flux measurement channel has an amplifier 31, the detection signal from the corresponding neutron detector 1 is input to (-) input terminals of this amplifier 31, and each neutron flux is input to (+) input terminals of the amplifier 31. An output voltage of a high voltage power supply 32 shared between the flux measurement channels is applied. Each amplifier 31 is provided with a feedback resistor R1, and the detection signal input to the amplifier 31 is converted into a voltage signal and appears at its output side by the feedback resistor R1. The output side of each amplifier 31 is connected to a multiplexer 33, respectively.

This multiplexer 33 sequentially selects signals input from each neutron flux measurement channel and outputs them to a plateau multiplexer 35 via a batch isolation amplifier 34. Note that the amplifier 31.degree. multiplexer 33. - bracket isolation amplifier 34. A photocoupler 36, which will be described later, is operated by the voltage of the high-voltage power supply 32 or a low-voltage power supply 37 applied to its common, and its operating voltage is the voltage of the high-voltage power supply 32.

On the other hand, in the plateau measurement channel 20, the output signal from any neutron detector 1 taken in via the switch SW2 is inputted to the (-) input terminals of the amplifier 21. The voltage of the variable high voltage power supply 22 is applied to the (+) input terminals of the amplifier 21.

This amplifier 21 is provided with a feedback resistor R2, and the signals input to the (-) input terminals of the amplifier 21 are converted into voltage signals by the feedback resistor R2 and appear on the output side. The output of amplifier 21 is applied to plateau multiplexer 35 via isolation amplifier 23. Note that the (+) side electrode of the variable high voltage power source 22 is connected to the common of the low voltage power source 24, and becomes the operating voltage of the amplifier 21 and the isolation amplifier 23.

The plateau multiplexer 35 selects the neutron flux detection signal from the isolation amplifier 34 and the 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 calculator 38 performs calculations related to reactor power on the signals from each neutron flux measurement channel, and performs processing calculations on the signal from the plateau measurement channel 20 to detect its plateau characteristics. Further, 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. Furthermore, switching of the multiplexer 33 is controlled via the photocoupler 36.

Next, the operation of this embodiment configured in this manner will be explained. For example, when measuring the plateau characteristic of the neutron detector 1-1, switch the switch 5W2-1 to which the neutron detector 1-1 is connected to the terminal A side, and switch the switches 5W2-2 to 5W2- of the other channels to the terminal A side. 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 other neutron detectors 1-2 to 1-
4 is applied with the voltage of the high voltage power supply 32.

Next, according to a command from the computer 38, the variable high voltage power supply 22
The characteristic data of the neutron detector 1-1 at each voltage when continuously changed is input to the amplifier 21 of the plateau measurement channel 20. Since this amplifier 21 operates at the same voltage as the variable high voltage power supply 22, (-
) Only the signal input to the sub-input terminal is converted into a voltage signal by the feedback resistor R2, and is input to the plateau multiplexer 35 via the isolation amplifier 23. On the other hand, the detection signals of the other neutron detectors 1-2 to 1-4 that are performing neutron flux measurements are input to the corresponding neutron flux measurement channels, converted to voltage signals, input to the multiplexer 33, and further integrated. The plateau multiplexer 35 is powered through the isolation amplifier 34.

In the plateau multiplexer 35, data from the neutron flux measurement channel and data from the plateau measurement channel are selectively taken out and read into the computer 38 via the A/D converter 37.

The computer 38 sequentially reads the data from each neutron flux measurement channel, processes the data of the channels connected to the plateau measurement channel by bypassing it, moves the plateau multiplexer 35 to the plateau measurement channel side, and calculates the plateau characteristic. Collect and collect data. As described above, neutron flux measurement and plateau characteristic measurement for a specific neutron detector are performed.

As described above, according to the present embodiment, an isolated amplifier and a low voltage power supply for the amplifier, which were conventionally provided for each channel for measuring plateau characteristics, are replaced with one for each of the plurality of neutron flux measurement channels and one for the plateau measurement channel 20. Only one device is required for each device, which reduces the number of expensive parts and reduces costs.Moreover, the device can be made smaller, saving space.

In addition, a part 1 of the channel where normal neutron flux measurement is performed, for example, an amplifier 31. If one or both of the feedback resistors R1 fails, the switch S of that channel
By turning W2 toward the plateau measurement channel 20 side and setting the variable high voltage power supply 22 to the same voltage as the high voltage power supply 32, the system can be operated without stopping.

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

In addition, although the said Example demonstrated the case where the number of neutron detectors 1 was four, the number of neutron detectors is not limited to this, and can be increased or decreased according to the requirements for the system.

[Effects of the Invention] As detailed above, according to the present invention, it is possible to provide a neutron flux measurement system that can easily measure neutron flux and plateau characteristics, and can reduce costs and downsize the device. .

[Brief explanation of drawings]

Figure 1 is a configuration diagram of a neutron flux measurement system according to an embodiment of the present invention, Figure 2 is a diagram for explaining the measurement principle of plateau characteristics, Figure 3 is a diagram showing plateau characteristics, and Figure 4 is a conventional diagram. FIG. 1 is a configuration diagram of a neutron flux measurement system. DESCRIPTION OF SYMBOLS 1... Neutron detector, 20... Plateau measurement channel, 21.31... Amplifier, 22... High voltage variable power supply, 23... Isolation amplifier, 24.37... Low voltage power supply, 33... Multiplexer, 34... General isolation amplifier, 5... Plateau multiplexer, 6... Photocoupler, 7... A/D converter, 8... Computer.

Claims (1)

[Claims] A high voltage is applied to a plurality of neutron detectors installed in a nuclear reactor, a detection signal output from each neutron detector is measured, and a continuous signal is applied to any neutron detector. A neutron flux measurement system that measures plateau characteristics of a neutron detector by applying a voltage that changes to the neutron flux, comprising: a plateau measurement channel connected to each of the plurality of neutron detectors via a switch and having a variable high voltage power supply; A neutron flux measurement system characterized by measuring the plateau characteristics of an arbitrary neutron detector using this plateau measurement channel.