JPH0634077B2 - Calibration device for wide range monitor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of use) The present invention relates to a calibration device for a wide range monitor that generates a calibration signal used for calibration of a wide range monitor.

(Prior Art) Conventionally, in order to measure the output of a nuclear reactor, a neutron flux level that is almost in a comparative relationship with the output is measured, and a value obtained by calibrating the level is used. Various neutron measuring devices have been made for use in it. However, the neutron flux level changes significantly with increasing reactor power. Therefore, even with a measuring device having a relatively wide measuring range, it was difficult to cover the entire range with one type of measuring instrument. Therefore, conventionally, a so-called wide-range monitor (wide-range reactor neutron flux monitor) is configured by combining two types of measuring instruments, and the wide-range monitor cannot measure with one conventional measuring instrument. A wide measurement range is continuously measured.

The wide-range monitor has a wide measurement range by two measurement methods having different principles such as a pulse counting method and a Campbell method. That is, the wide range monitor uses the pulse counting method in which the detected neutrons are individually measured as pulses in the neutron source region where the neutron flux density is relatively low. In the middle region where the neutron density is high and the detection pulse piles up, the Campbell method is used to measure the root mean square of fluctuations in the measured current due to fluctuations in the detection process.

(Problems to be Solved by the Invention) Even in such a wide range monitor, it is necessary to maintain the linearity between the reactor output and the measured value with high accuracy. For that purpose, the work of calibrating the wide range monitor prior to the actual measurement is indispensable and very important. However, the wide range monitor uses two measuring methods having different principles as described above. Therefore, in the calibration, different calibration signals from different calibration devices have to be switched and used because of different principles. That is, in the neutron source region, a signal obtained by FM-modulating a rectangular wave (pulse) was used as a calibration signal, and the magnitude of the frequency of the signal was made to correspond to the magnitude of the reactor output.
Further, in the intermediate region, a signal obtained by AM-modulating a sin wave is used as a calibration signal, and the amplitude of the signal is made to correspond to the variation of the fluctuation component corresponding to the variation of the reactor output. As described above, conventionally, two different calibration devices and different calibration signals are used, and therefore it is impossible to continuously calibrate the entire measurement range. For this reason, it was not possible to accurately calibrate the connecting portion between the two measurement areas, and it was not possible to continuously monitor the value of the period extending over these two areas. From a different point of view, generally, when a plurality of calibration devices are used, output characteristics such as output noise level and output impedance of the calibration devices often do not match. However, it is desirable that such output characteristics match. Further, from the viewpoint of easy maintenance, it is desired to calibrate using one calibration device without using a plurality of calibration devices.

The present invention has been made in view of the above, and its purpose is to:
It is an object of the present invention to provide a calibration device for a wide range monitor capable of continuously performing calibration for the entire measurement area of the wide range monitor.

[Structure of Invention]

(Means for Solving the Problem) A calibration device for a wide range monitor according to the present invention detects a reactor output in a neutron source region by a pulse counting method and a reactor output in an intermediate region by a Campbell method. In a calibration device for a wide range monitor that generates a calibration signal used for calibration, as the calibration signal, a pulse number change signal in which the number of pulses per unit time changes according to the reactor output of the neutron source region to be simulated, It is configured to have a calibration signal output unit that continuously outputs an amplitude root mean square value change signal whose amplitude root mean square value changes according to the reactor output in the intermediate region to be simulated.

(Operation) The reactor output in the neutron source region is simulated as a pulse number change signal in which the number of pulses per unit time changes according to the output. Further, the reactor output in the intermediate region is simulated by an amplitude root mean square value change signal in which the root mean square value of the amplitude changes according to the output. The pulse number change signal and the amplitude root mean square value change signal are continuously output as calibration signals from the calibration signal output means. So if you use that calibration signal,
Calibration work is continuously performed on the reactor power in the neutron source region and the intermediate region.

(Embodiment) FIG. 1 shows an example of a usage state of an embodiment of the present invention. In the figure, 1 is a wide range monitor calibration apparatus as an embodiment thereof, and 2 is a wide range monitor as a calibration target.

As is well known, the wide-range monitor 2 detects neutrons in a nuclear reactor with a detector 4, pre-amplifies the detection signal with a preamplifier 5, and then adds the detected signal to a post-signal processing circuit 6. The reactor output is detected by the output.

The calibration apparatus 1 is for adding to such a wide range monitor 2 a calibration signal simulating the amount of neutrons according to the reactor output. The calibration device 1 is used by applying the calibration signal to the input side or the output side of the preamplifier 5 of the wide range monitor 2. The calibration device 1 has a controller 8. The controller 8 is configured to output a frequency setting signal S ₁ and an amplitude setting signal S ₂ according to the change when the output adjustment value is changed so as to simulate the reactor output.

The frequency setting signal S ₁ is applied to the oscillator circuit 9. When the applied frequency setting signal S ₁ is small, the oscillating circuit 9 outputs the pulse wave S ₃ having a constant amplitude and a long pulse width and cycle, and when the signal S ₁ is large, the pulse wave S ₃ is output. ₃ is output as a pulse having a constant amplitude and a short pulse width and a short period. The pulse wave (modulated signal) S ₃ from the oscillator circuit 9 is AM
It is applied to the modulation circuit 10, where it is AM-modulated by the amplitude signal (modulation signal) S ₄ from the reference voltage generator 11.

That is, the amplitude setting signal S ₂ from the controller 8 is applied to the reference voltage generator 11. The reference voltage generator 1
1 is configured to output the amplitude signal S ₄ as a large signal when the applied amplitude setting signal S ₂ is large, and output the amplitude signal S ₄ as a small signal when the signal S ₂ is small. . The amplitude signal S ₄ from the reference voltage generator 11 is applied to the AM modulation circuit 10. In the AM modulation circuit 10, the pulse wave S ₃ is AM-modulated according to the amplitude signal S ₄ . The AM modulation circuit 10
The calibration signal S ₅ output from the attenuator 12 is applied to the input side of the preamplifier 5 of the wide range monitor 2 or the attenuator 12 is used.
It is directly added to the output side of the preamplifier 5 without going through.

Next, when the output adjustment value is continuously changed in the controller 8, how the frequency setting signal S ₁ and the amplitude setting signal S ₂ output from the controller 8 change, and the AM modulation is caused by those changes. How the calibration signal S ₅ output from the circuit 10 changes will be described.

In conclusion, when the output adjustment value of the controller 8 is continuously changed, the calibration signal S whose frequency or amplitude continuously changes, as shown in FIG. 5, according to the change.
₅ is output from the AM modulation circuit 10. That is, the calibration signal S ₅ is output as an FM signal in the preceding stage where the output adjustment value of the controller 8 is smaller than the preset setting value (displacement point), while the output adjustment value from the controller 8 is the above setting value. The signal is output as an AM signal in the subsequent stage after passing. That is, the change in the reactor power is simulated by the frequency in the first half and by the amplitude in the second half.

That is, when the output adjustment value of the controller 8 is gradually increased within a range smaller than the set value, the frequency setting signal S ₁ is gradually increased from the controller 8.
And an amplitude setting signal S ₂ having a constant output is output. Since the frequency setting signal S ₁ is gradually increased, the oscillation circuit 9 outputs the pulse wave S ₃ whose pulse width and cycle are gradually shortened, that is, the frequency is increased.
It is added to the AM modulation circuit 10. On the other hand, the amplitude setting signal S
_{Since 2} is constant, the reference voltage generator 11 outputs the amplitude signal S ₄ having a constant magnitude, and the AM modulation circuit 10
Added to. In the AM modulation circuit 10, the amplitude of the pulse wave S ₃ is regulated to a constant value according to the magnitude of the amplitude signal S ₄ . As a result, from the AM modulation circuit 10,
The FM signal of the first half of the calibration signal S ₅ shown in FIG. 2 is output.

Further, when the output adjustment value of the controller 8 is gradually increased within a range larger than the above-mentioned set value, the controller 8 outputs the frequency setting signal S ₁ having a constant magnitude and the amplitude setting signal S ₂ gradually increasing. To be done. As a result, the oscillation circuit 9 outputs a pulse wave S ₃ having a constant pulse width and a constant period, and the reference voltage generator 11 outputs an amplitude signal S ₄ that gradually increases. In the AM modulation circuit 10, the amplitude of the pulse wave S ₃ having a constant cycle and pulse width is AM-modulated by the amplitude signal S ₄ of increasing magnitude, and the AM signal of the calibration signal S ₅ shown in FIG. Is output.

Although the case where the output adjustment value of the controller 8 is increased has been described above, the case where the output adjustment value is decreased is almost the same as the above except that the calibration signal changes opposite to the above.

Then, when the output adjustment value of the controller 8 is continuously increased or decreased beyond the set value (displacement point), the FM signal and the AM signal are continuous without interruption as shown in FIG. A calibration signal S ₅ is obtained. Therefore, as illustrated in FIG. 3, by using the calibration signal S ₅ , the output (pulse signal count value) of the wide range monitor for the measurement range across the neutron source region and the intermediate region in the reactor output can be obtained. The calibration can be done continuously.

FIG. 4 (a) shows how the frequency and the square of the amplitude of the calibration signal S ₅ change before and after the output adjustment value of the controller 8 exceeds the set value. As can be seen from FIG. 7A, regarding the frequency of the calibration signal S ₅ , the frequency gradually changes before exceeding the above set value, but remains constant after exceeding the set value. As for the square of the amplitude of the calibration signal S ₅ , the square keeps a constant value before exceeding the set value and gradually changes after exceeding the set value.

FIG. 4 (b) shows a calibration signal S ₅₀ different from the above. That is, in the calibration signal S ₅₀ , the square of the amplitude is not constant before the set value but changes gently, and the frequency changes gently after the set value. Therefore, before and after the set value, there is a region A in which both the square of the amplitude and the frequency change. Such a calibration signal S ₅₀ is a closer approximation of the neutron output from a real nuclear reactor. Therefore, more proper calibration becomes possible.

The calibration signals S ₅ and S ₅₀ shown in FIGS.
The set value of can be adjusted by the controller 8 of FIG. That is, the setting value of the output adjustment signal of the controller 8 can be changed so that the frequency setting signal (S ₁ ) changes and the amplitude setting signal (S ₂ ) remains constant, and the frequency setting signal (S ₁ ) remains constant and amplitude. It is possible to adjust the output adjustment signal value at which the state of change of the setting signal (S ₂ ) is switched.

In the above-described embodiment, as shown in FIG. 2, a calibration signal S ₅ having a rectangular wave is used, but the waveform is not particularly limited. For example, Sin wave, triangular pulse, exponential function pulse, etc. Can also be used. FIG. 5 shows an example of the calibration signal S ₅₁ formed using the exponential function type pulse. As can be seen from FIG. 5, as the calibration signal, the number of pulses is proportional to the reactor output in the neutron source region, and the square of the pulse amplitude is proportional to the reactor output in the intermediate region. . further,
In the intermediate region, the root mean square value of the pulse amplitude need only be proportional to the reactor power, so instead of changing the pulse amplitude, change the pulse width or change the pulse amplitude and pulse amplitude. It is also possible to change both widths.

〔The invention's effect〕

According to the present invention, since the signal simulating the reactor output in the neutron source region and the signal simulating the reactor output in the intermediate region are continuously output, the calibration of the wide range monitor is performed even if the calibration is performed. Can be continuously performed even if the calibration spans the above two areas, and thus the calibration of the period spanning the two areas can be easily performed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a usage state of an embodiment of the present invention, FIG. 2 is a waveform diagram showing an example of a calibration signal output from the embodiment, and FIG. 4 is a diagram showing an example of calibration of a wide range monitor according to an embodiment, FIGS. 4 (a) and 4 (b) are diagrams showing squares of frequency and amplitude of different calibration signals, and FIG. 5 is another example of calibration signals. It is a waveform diagram showing. 1 ...... calibration device, 2 ...... wide-range monitor, 8 ...... controller, 9 ...... oscillating circuit, 10 ...... AM modulation circuit, 11 ...... reference voltage generator, 12 ...... attenuator, _{S 1} ...... frequency setting Signal, S ₂ ... Amplitude number setting signal, S ₃ ... Pulse wave, S ₄ ... Amplitude signal, S ₅ ... Calibration signal.

Claims (1)

[Claims] 1. A calibration device for a wide range monitor for generating a calibration signal used for calibrating a wide range monitor for detecting a reactor output in a neutron source region by a pulse counting method and detecting a reactor output in an intermediate region by a Campbell method. In the above, as the calibration signal, a pulse number change signal in which the number of pulses per unit time changes in accordance with the reactor output in the neutron source region to be simulated, and the square of the amplitude in accordance with the reactor output in the intermediate region to be simulated. A calibration device for a wide range monitor, comprising a calibration signal output means for continuously outputting an amplitude root mean square value change signal whose average value changes.