JPH0441315B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a wide range monitoring device that measures about 10 digits of neutron flux level from the neutron source region to the intermediate region of a nuclear reactor with one neutron flux detector. Regarding improvements.

[Technical background of the invention]

Conventional water nuclear instrumentation system (BWR)
The reactor was controlled by measuring the neutron flux level using two neutron flux detectors. In other words, based on the detection signal from the neutron flux detector, the neutron flux level in the neutron source region is measured by the neutron source region monitor (hereinafter referred to as SRM), and the neutron flux level in the intermediate region is measured by the intermediate region monitor (hereinafter referred to as IRM). Was.

Figure 1 shows the configuration diagram of the SRM system, and this SRM1
0 is based on the logarithmic counting method, in which the detection signal amplified by the preamplifier A1 is sent from the SRM neutron flux detector D1 that detects neutron flux to the logarithmic counting rate measuring circuit 12 through the disc discriminator 11. The logarithmic count rate measurement circuit 12 converts the pulse count rate into a logarithmic count signal for logarithmic indication and outputs it to the outside, and the period meter 13 determines the rising rate of the neutron flux level and outputs the period signal. The unit 14 monitors the level change of the logarithmic counting signal and outputs the SRM trip signal when an abnormal operation occurs.

On the other hand, Figure 2 shows the configuration diagram of the IRM system.
The IRM20 performs measurements based on the Campbell measurement method, and specifically uses a linear range switching method to perform range switching, and detects signals sent from the IRM neutron flux detector D2 via the preamplifier A2. The signal is amplified or attenuated according to its level in the amplification/attenuation circuit 21 and then sent to the root mean square circuit 2.
2, and outputs the signal averaged by the root mean square circuit 22 to the outside, while the trip unit 23 monitors the level of the signal from the root mean square circuit 22 and outputs the IRM trip signal in the event of an abnormal operation. It is. Here, preamp A2
The gain of the amplification/attenuation circuit section 21 is switched by the operator operating the range selection switch 24, and a gain switching signal corresponding to this range is output from the gain switching logic circuit 25 to the preamplifier A2 and the amplification/attenuation circuit 21. Been,
It changes depending on the range. In addition,
In addition to the function of measuring the power level of the reactor by measuring the neutron flux level, the IRM 20 also has the function of protecting the reactor from becoming excessively fast.

By the way, conventionally, the SRM system and
There is a wide range monitor device WRM that incorporates the functions of the IRM system into one device and monitors the neutron flux level with a single neutron flux detector. There are two methods: one that combines the two, and one that uses the logarithmic Campbell measurement method in both areas.

[Problems with background technology]

In the WRM configured as described above, especially the IRM system that adopts the linear range switching method, a trip circuit is provided for each range. The system is configured to output a reactor shutdown (scram) signal if the reactor does not follow this. For this reason, although it is possible to measure the reactor output level with high accuracy, it is difficult to switch ranges that follow the reactor output level, and if the operator is inexperienced, there is a risk of the reactor being shut down. .

Furthermore, when measurements are made based on the logarithmic Campbell measurement method, a period meter is used to monitor the rate at which the power level of the reactor increases. This type of logarithmic canvel measurement method allows the output level of the furnace to be treated as a single output and eliminates the need for range switching; however, compared to the linear canvel method, it is less accurate in accurately measuring changes in the output level. was inferior.

[Purpose of the invention]

The present invention was made based on the above circumstances, and
Switching ranges in the IRM system does not cause operational errors, and furthermore, range switching can be performed in automatic mode or manual mode, and neutron flux levels can be measured using the Campbell method and logarithmic Campbell measurement method. The purpose of the present invention is to provide a wide range monitoring device that can perform measurements based on both measurement methods.

[Summary of the invention]

The present invention includes a neutron source area monitor unit, which monitors the neutron flux level from the neutron source area to the intermediate area of the nuclear reactor.
Measurement is performed by an intermediate region monitor section and a wide range monitor section, and the output as a wide range monitor device is measured by a switching output means that switches and outputs the output of the neutron source region monitor section and the wide range monitor section, and the intermediate region monitor section. The intermediate region is divided into a plurality of ranges, and a range control means for outputting a range switching signal for switching between the ranges, and a manual mode and automatic mode switching means are provided, and the range is divided into a plurality of ranges corresponding to the neutron flux level in the intermediate region monitor section. When switching to manual mode, the switching means bypasses the trip monitoring function in the wide range monitor section, and when switching to automatic mode, the switching means bypasses the trip monitoring function in the intermediate range monitor section to measure the neutron flux level. It is a range monitor device.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to FIGS. 3 to 5. FIG. 3 is a block diagram of a wide range monitor device according to the present invention. Third
In the figure, the WRM neutron flux detector Det detects the neutron flux from the neutron source region of the nuclear reactor (not shown) to the intermediate region, and sends the detection signal to the preamplifier A.
neutron source monitor section 40, intermediate region monitor section 50, and logarithmic chamber section 60 of WRM30
This is what is output to.

The neutron source monitor section 40 has the function of the SRM system shown in FIG.

The intermediate region monitor section 50 has a function as an IRM system shown in FIG. 2, and includes an amplification/attenuation section 51,
Root mean square circuit 52, trip circuit 53, range selection switch 54, and gain switching logic circuit 5
It consists of 5.

The logarithmic Campbell section 60 is a measurement circuit based on the logarithmic Campbell measurement method, and specifically,
A bandpass amplifier 61 amplifies the detection signal from the WRM neutron flux detector Det for each band, and the detection signal amplified by the bandpass amplifier 61 is converted into a signal indicating an effective value and then logarithmically converted. and a logarithmic effective value calculation section 62 that outputs a Campbell signal to an output section 70.

Further, the output unit 70 is a neutron source area monitor unit 40
By switching and outputting the logarithmic counting signal and the logarithmic Canvel signal from the Logarithmic Canvel section 60, it covers the measurement of the neutron flux level from the neutron source region to the intermediate region, and together with the Logarithmic Canvel section 60 constitutes a wide range monitor section. .
This output section 70 includes a signal selection circuit 71,
It is composed of a period meter 72 and a trip unit 73, and the signal selection unit 71 selects the logarithmic count signal and logarithmic canvel signal from the neutron source area monitor unit 40 and the logarithmic canvel unit 60 by the output switching signal P1 from the range control unit 80. The signal is switched and outputted to the outside as the output signal _Wput of the wide range monitor section 30, and also outputted to the period meter 72 and trip section 73. Period total 72
The trip unit 73 determines the rising rate of the neutron flux level and outputs the period signal, and the trip unit 73 monitors the signals from the period meter 72 and the signal selection unit 71 and outputs the WRM trip signal in the event of abnormal operation. be.

Furthermore, this device is provided with the range control section 80, a mode changeover switch 81 for switching between automatic mode and manual mode, and switches 82 and 83 that operate in conjunction with this mode changeover switch 81, as switching means. When the mode selector switch 81 is switched to the M1 end, the preamplifier A and the amplification/attenuation section 5
The mode is a manual mode in which the gain of 1 is switched by the operator, and when the gain is switched to the M2 end, the mode is an automatic mode in which the gain of the preamplifier A is varied by the range switching signal P2 from the range control section 80. The switch 82 is for sending an INHIBIT signal to the trip section 53 when the mode is set to automatic, and the switch 83 is for sending an INHIBIT signal to the trip section 53 when the mode is set to the manual mode.
This is to send an INHIBIT signal to 3.

The range control section 80 compares the level of the output signal W _put from the signal selection section 71 with a plurality of predetermined reference levels, and determines that the output signal W _put as the wide range monitor section 70 is equal to or higher than the predetermined reference level. It outputs an output switching signal P1 for switching from a logarithmic counting signal to a logarithmic Campbell signal to the signal selection section 71 when the signal becomes low, and also outputs a gain switching signal P2 for switching the gain of the preamplifier A to the mode switching switch 81. Specifically, the fourth
As shown in the figure, a plurality of comparators 80a-1 to 80a-
n, range logic circuit 80b, resistance R ₁ ~ _{R o+1}
It is composed of a resistor array 80c consisting of. These comparators 80a-1 to 80a-n have output signals
A reference level signal from the resistor string 80c is input together with Wout, and these comparators 80a-1 to 80a
a-n is the value of each range when the level of the output signal Wout exceeds the reference level as shown in Figure 5.
The range switching signal P2 for each of L1 to L6 is outputted through the range logic circuit 80b, and is comprised of a comparator with hysteresis, such as a Schmitt trigger circuit, to eliminate fluctuations in the range when switching ranges. And this range switching signal
P2 is sent to preamplifier A via mode selector switch 81 to change the gain of preamplifier A when mode selector switch 81 is set to automatic mode M2.

Next, the operation of the apparatus configured as described above will be explained. First, a case will be described in which the mode changeover switch 81 is set to manual mode. Assume that the reactor is in a critical state and in the neutron source region. The neutron flux in this state is detected by the WRM neutron flux detector Det, and the detection signal is
Sent to 0. This detection signal is sent through the discriminator 41 to the logarithmic count rate measuring circuit 42, where it is converted into a logarithmic count signal of a pulse count rate for logarithmic indication and sent to the neutron source area monitor section. ₄₀ and output to the trip section 43. This trip section 43 outputs the SRM trip signal when an abnormal operation occurs while monitoring the level change of the logarithmic count signal.

The logarithmic count signal passes through the selection circuit 71 and becomes the output signal W _put of the wide range monitor section. That is, this logarithmic count signal is compared with a predetermined reference level by the range control unit 80, but since the level is still low, the signal selection unit 71 selects the logarithmic count signal from the neutron source area monitor unit 40. Output. Then, based on this logarithmic count signal, the rate of increase in the neutron flux level is determined by the period meter 72, and the period signal is output.

Here, since it is the manual mode, the INHIBIT signal INH is sent to the trip section 73 via the switch 83.
is input, and this trip section 73 is configured not to output a WRM trip signal.

As the neutron flux level of the reactor increases and enters the intermediate region, measurements thereof are performed by the intermediate region monitor section 50 and the logarithmic-camber section 60. Therefore, in the intermediate region monitor section 50, the operator sequentially operates the range changeover switch 54 in accordance with the increase in the neutron flux level. As a result, the gains of the preamplifier A and the amplification/attenuation section 51 change in accordance with the neutron flux level. These preamplifier A and amplification/attenuation section 5
The detection signal that has passed through 1 is input to the root mean square circuit 52. This root mean square circuit 52 calculates the root mean square of the detection signal and outputs an output signal _Iput from the intermediate area monitor section 50.
At the same time, it is output to the trip section 53. The trip unit 53 monitors the level change of the signal from the root mean square circuit 52, and outputs an IRM trip signal when an abnormal operation occurs.

On the other hand, in the logarithmic Campbell section 60,
The detection signal from the WRM neutron flux detector Det passes through the bandpass amplifier 61 to the logarithmic effective value calculation unit 6
The logarithmic effective value calculation unit 62 converts the signal into a signal representing an effective value, and further logarithmically transforms this signal and outputs it to the signal selection unit 71 as a logarithmic Campbell signal.

Here, the range control section 80 outputs the switching signal P1 to the signal selection section 71 since the level of the output signal _Wput has become equal to or higher than the predetermined reference level. Thereby, the signal selection section 71 switches to the logarithmic Canvel signal from the logarithmic Canvel section 60 and outputs it. Then, the period meter 72 determines the rate of increase in the neutron flux level based on the logarithmic Campbell signal.

Next, a case will be described in which the mode changeover switch 81 is set to automatic mode. When the reactor is in the neutron source region, the detection signal from the WRM neutron flux detector Det is converted into a logarithmic count signal and output to the signal selection section 71 in the neutron source region monitor section 40 in the same manner as described above. This logarithmic count signal becomes the output signal W _put , and the period total is 7.
2, the rate of increase in the neutron flux level is determined.

Now suppose that the neutron flux level increases and the reactor enters the intermediate region. Then, the range control section 80
outputs a signal switching signal to the signal selection section 71, which causes the signal selection section 71 to pass the logarithmic Campbell signal. Furthermore, the range control unit 80
The level of the output signal W _put is compared with the reference level. That is, the output signal _Wput and the reference level signal for each range from the resistor array 80c are input to each of the comparators 80a-1 to 80a-n. As shown in FIG. 5, each time the level of the output signal _Wput from these comparators 80a-1 to 80a-n increases, the range switching signal P2 is switched to the range logic circuit 80b.
Output via . This range switching signal P2 is then sent to the preamplifier A via the mode switching switch 81. As a result, preamplifier A
The gains of are set sequentially as the neutron flux level increases.

As a result, in the intermediate region, the gain of the preamplifier A is changed by the range switching signal P2 from the range control section 80, and the neutron flux level is measured based on the detection signal passing through the preamplifier A. That is, the detection signal is sent to the logarithmic canvas section 60 through the preamplifier A, and in the logarithmic canvas section 60, it is converted into a logarithmic canvas signal and sent to the signal selection section 71 in the same manner as described above. The rate of increase in the neutron flux level is determined by the period meter 72, and the rate of increase in the neutron flux level is determined by the period meter 72.
The level change of the logarithmic Campbell signal is monitored.

Here, since the trip section 53 is in automatic mode, the INHIBIT signal INH is inputted through the switch 82, and the IRM trip signal is not outputted.

In this way, this device is provided with a manual mode/automatic mode changeover switch 81, which prohibits the output of the WRM trip signal from the trip section 73 in the manual mode, and inhibits the range switching from the range control section 80 in the automatic mode. The gain of preamplifier A is switched and set using signal P2, and the output of the IRM trip signal from trip unit 53 is prohibited to measure the neutron flux level.
It can be operated as a system, and by outputting the output signal W _put as a single output as a wide range monitor section, the period meter 72 can perform period measurements over the region from the neutron source region to the intermediate region. be able to. Also,
In the case of manual mode, the scram monitoring output to the reactor system by the trip unit 73 and period meter 72 of the wide range monitor unit is not required, so the INHIBIT signal is sent to prohibit the output of the trip signal, and the automatic mode In this case, the intermediate area monitor section 5
The output of the trip signal from the trip unit 53 of 0 is prohibited. This allows operation and monitoring of the equipment and the safety monitoring of the reactor output in both the manual mode and automatic mode, which are the same as conventional functions.

In addition, by switching to automatic mode, the gain of preamplifier A can be changed automatically, and the output of the reactor can be automatically monitored. This eliminates the possibility that switching cannot be performed in sequence, and operation errors during driving can be prevented. Since the range control section 80 compares a predetermined reference level with the level of the signal from the signal selection section 71 and outputs a switching signal, the gain of the preamplifier A can be set to the optimum value. Accurate measurements can be made.

Furthermore, although the logarithmic Campbell measurement method does not allow highly accurate measurements, the intermediate range monitor section 50 that employs a linear range switching method is provided, so changes in the furnace output level can be adjusted according to the measurement requirements. Can be measured in detail.

In addition, by switching the mode changeover switch 81, the automatic mode and manual mode can be selected according to the measurement requirements, providing great flexibility.

Note that the present invention is not limited to the above embodiment. In the above embodiment, the range control unit 80 controls the switching of the range in the intermediate range monitor unit 50.
However, such a range control section 90 may be provided in the intermediate area monitor section 50 as shown in FIG. 6, and the level of the output signal _Iput of this monitor section 50 may be monitored. . In this case, the range control section 90 switches the gain of the preamplifier A so that the level of the output signal _Iput falls within a predetermined level range.

〔Effect of the invention〕

According to the present invention, a mode changeover switch is provided for switching between manual mode and automatic mode, and in the manual mode, the trip monitoring of the wide range monitor section is bypassed, and in the case of the automatic mode, the trip monitoring of the intermediate range monitor section is bypassed. So,
In addition to not causing any operational errors when changing ranges in IRM, ranges can be changed in automatic mode and manual mode, and the neutron flux level is determined based on both the Campbell method and the logarithmic Campbell measurement method. It is possible to provide a wide range monitoring device that can perform measurements.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a conventional neutron source region monitor, FIG. 2 is a configuration diagram of a conventional intermediate region monitor, FIG. 3 is a configuration diagram showing an embodiment of a wide range monitor device according to the present invention, and FIG. 4 5 is a diagram for explaining the operation of the range control unit shown in FIG. 4, and FIG. 6 is a configuration diagram showing a modification of the device. . 30... wide range monitor device, 40... neutron source area monitor unit, 50... intermediate area monitor unit, 54... range changeover switch, 60... logarithmic canvas unit, 61... band pass amplifier, 62
... Logarithmic effective value calculation section, 71 ... Signal selection section, 7
2...Period total, 73...Trip section, 80...
... Range control section, 81 ... Mode changeover switch,
82, 83...Switch, Det...WRM neutron flux detector.

Claims (1)

[Claims] 1. A neutron source area monitor that measures the neutron flux level in the neutron source area based on a detection signal from a neutron flux detector in a wide range monitor device that monitors the neutron flux level from the neutron source area to the intermediate area of a nuclear reactor. an intermediate region monitor section that divides the intermediate region into a plurality of ranges and measures a neutron flux level based on the detection signal amplified with a gain set according to each level;
Consists of a logarithmic-cavel section that calculates the neutron flux level from the detection signal based on the log-camber method, and an output section that switches and outputs the output signal from the logarithmic-cavel section and the output signal from the neutron source area monitor section. Gain switching in the wide range monitor unit and the intermediate area monitor unit is set to automatic mode or manual mode, and in the case of the automatic mode, the trip monitoring function in the intermediate area monitor unit is bypassed, and in the case of the manual mode, generates a plurality of reference voltages using a switching means that bypasses the trip monitoring function in the wide range monitor section and a plurality of resistors connected in series to a power supply of a predetermined voltage, and connects these reference voltages to the wide range monitor section. an output switching signal for instructing whether to output either the output of the logarithmic-camber section or the neutron source region monitor section from the output section of the wide range monitor section based on the output of the wide range monitor section; and the gain 1. A wide range monitor device comprising: range control means for outputting a gain switching signal for instructing switching settings.