JPS6012598B2 - In-core local power detection device - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to an in-reactor local power detection device, and in particular, to automatic sensitivity correction of local power detectors fixedly placed at various locations in a nuclear reactor core. The present invention relates to an in-core local power detection device suitable for use in

[Prior art]

In order to operate a nuclear power plant safely and economically, ``the status of the reactor and plant equipment must be accurately understood.

The main source of information in this case is the signal from a number of local power detectors that are fixedly arranged three-dimensionally at appropriate radial and axial positions in the reactor core. This signal is amplified by a local output amplifier and then transmitted to various indicators and recorders, and becomes an input signal to a safety protection circuit. However, the sensitivity of the local output detector gradually decreases as neutron irradiation progresses. Therefore, it is necessary to periodically detect the sensitivity of each in-core local power detector and correct the gain of the local power amplifier. Hereinafter, the operation for detecting the output of the standard neutron east detector, which will be described later, and the gain correction will be collectively referred to as a sensitivity test. Conventionally, this sensitivity test was manually performed periodically by an operator based on data collected by inserting and removing a standard neutron east detector into the reactor 0. Figure 1 explains a conventional example of output detection of a standard neutron east detector, where 1 is a reactor pressure vessel, 2 is a reactor D, 3 is a standard neutron east detector, and 4A to 4D are local output detectors. , 5 is a chamber tube, 6 is a standard neutron east detector driving wire 1, 7 is a standard neutron east detector driving device,
8 is a standard neutron east amplifier, 9 is a local output amplifier.
1 is an X-Y recorder for displaying the vertical neutron east distribution within the reactor core; 11 is a local power display device; and 12 is a safety protection system based on the local power.

FIG. 2 shows details of the local output amplifier 9.
is a variable resistor for gain adjustment. SO is the output signal of the local power amplifier 9 and must truly represent the neutron east at the location where the local power detector is installed.
When the time when sensitivity verification is required is reached, the standard neutron east detector driving device 7 is operated to move the standard neutron east detector 3 along the local output detectors 4A to 4D. By representing the output signal of 3 on the X axis and the position of the standard neutron east detector 3 in the direction of the bag on the Y axis,
The recorder 0 records the east distribution of neutrons in the koji direction of the reactor core. This operation is the operation for detecting the output of the standard neutron east detector 3. Sensitivity correction of the local output detectors 4A to Tortoise D is performed as follows.

A record of the amount Q of the X-Y recorder is taken to find the neutron east at the position where each local output detector 4A to 4D is present. It is necessary to adjust the gain adjustment variable resistor 13 of the local output amplifier 9 so that the value of neutron east obtained in this way matches the value output by the actual local output detector. For this adjustment, first, the signal value to be output by the corresponding local output amplifier 9 is determined based on the neutron east at the position where the local output detector is located, which is obtained from the output signal of the standard neutron flux detector 3. This time, the ratio of the signal value to be output and the output signal value before adjustment of the local output amplifier cost based on the output signal of the actual local output detector is multiplied by the current value from the shark main power supply before adjustment. Let be the new current value for the gain adjustment. The input side of the local output amplifier 9 is disconnected from the local output detector and connected to the shark positive power supply, and the output of the shark positive power supply is adjusted and the new current value obtained as described above is input to the local output amplifier 9. In this case, the gain adjustment variable resistor 13 is adjusted so that the signal value output by the local output amplifier 9 matches the signal value to be outputted as described above.This completes the sensitivity correction of the local output detector, and the “local output Switch the connection of the input end of the amplifier from the shark positive power supply to the local output detector.
For all of these, it takes a lot of effort to switch between the local output detector of the local output amplifier 9 and the shark positive power supply. Furthermore, ``During the sensitivity correction period, the connection between at least one local output detector and the local output amplifier is severed, so it becomes impossible to extract the output signal of that local output detector ~ Nuclear reactor Therefore, during the sensitivity correction period, the error in the reactor power obtained based on the output signal of the local power detector increases. [Object of the Invention] The present invention It is an object of the present invention to provide an in-reactor local power detection device which eliminates the above-mentioned drawbacks of the prior art, does not require a shark food source, and can reduce errors in reactor power measurements during the sensitivity correction period.

[Summary of the Invention] The present invention is characterized by a means for storing a predetermined first correction coefficient corresponding to a first signal that is an output signal of an amplifier paired with a local output detector; means for calculating the product of the first signal and a first correction coefficient corresponding to the first signal; and means for calculating a second correction coefficient based on the second signal that is the output of the standard neutron east detector and the output signal of the multiplication means. and means for storing the obtained second correction coefficient as the first correction coefficient in place of the corresponding first correction coefficient stored in the storage means.

[Embodiments of the invention]

According to the embodiment of the invention, the gain of the local power amplifier 9 shown in FIG. 2 is fixed.

Multipliers for sensitivity correction are prepared for all local output detectors. Normally, the true local output is obtained by multiplying the output of the local output detector by this constant. The constant of this local power detector is obtained based on a comparison between the output signal of the standard neutron east detector 3 inserted into the reactor core and the output signal of the local power detector. First, we will discuss the normal local output detection operation.

In Fig. 3, 9 is a local output amplifier, and i4 is a scanner.
, 15 is an analog-to-digital converter, 17 is a storage device, 8 is a digital-to-analog converter, 9 is a scanner, 28 is a hold circuit, 111 is a local output display device, 381 is a This is a scanner control device.The scanner control device 30 and storage device 17 have an automatic terminal A and a manual terminal M. From this, the coordinates of the detector are given.The output signal of the local output detector is transmitted to the local output amplifier 9. is input and amplified.

The output signals of the local output amplifiers 9 are sequentially input to the scanner 14, and then sequentially converted into digital quantities. More can be obtained.
) will be destroyed. Thereafter, the output signal of the digital multiplier 16 is converted into an analog quantity in a digital-to-analog converter, and held in a hold circuit 20 prepared for each local output detector via a scanner 19.
Then, it is displayed on the display device 11. It is also used as data for the safety protection system 12. This hold circuit 20
The value of is updated every scanning cycle. Incidentally, the local output detectors are arranged three-dimensionally as shown in FIGS. 4a and 4b. Therefore, the storage device 17 stores the numbering of iik in each axis direction and the gain constant N(
i, i, k) are stored as shown in FIG.
FIG. 6 is a flowchart for explaining the procedure of this normal local output detection operation. First off (i, j,
k)=(1,1,1) The output of the local output amplifier 9 is amplified based on the output of the local output detector So(1,1,1
). The analog-to-digital converter 15 converts this into a digital quantity. So(1,
A predetermined gain N(1, 1) corresponding to
1,1) from the storage device 17, and the digital multiplier 16 multiplies So(1,1,1) by N(1,1,1) to obtain S2(1,1,1). S2 (1, 1, 1) is converted into an analog quantity by the digital-to-analog converter 18 and held by the hold circuit 20. Next, the same operation is performed for the coordinates (1, 1, 2) with k=2. When k = 4 (in this example, there are 4 in the k direction as shown in Figure 4b), set 1 = 2 and do the same for the coordinates (1, 2, 1), sequentially all local output detectors. Let's go about it. As described above, normal local output detection operations are performed to obtain data for display or input to the safety system 12.

For example, the reactor output is determined based on the values held in all the hold circuits 20 and used for monitoring the reactor output and controlling the reactor operation. This local output detection operation is performed at predetermined intervals or whenever data is required. Next, sensitivity correction in this embodiment will be described.

In FIG. 3, 8 is a standard neutron east amplifier, 15 is an analog-to-digital converter, and 21 is a comparator for comparing the outputs of the analog-to-digital converter 15 and the digital multiplier 16. The comparison calculation bag layer 21 is a comparison timing ST taken out from the standard neutron east detector driving device 7.
'Based on this, the standard neutron east detector 3 is the local output detector 4.
Input the respective outputs when they are in the same location and compare them. S is a contact that is closed only during verification. The multiplier before correction stored in the storage device 17 is N(j,i
, k), the corrected multiplier obtained by the comparator 21 is N
'(i, i, k), the output of the local amplifier 9 based on the output of the local output detector S, and the output of the standard neutron east detector S,,N
The output of the local output detector corrected by (i, i, k) and N' (i, i, k) is set to S2 and S. First, S
, is considered to be a true local output, so it must be equal to S2'' or S, and the following relationship holds true.

S,=S2'=S. ×N'...
{11N'=kishu Also, S2 is expressed by the following equation.

S2=S.

×N...'3' By the way, if we substitute So into the t21 formula from the relationship in the '3} formula, we get [
Equation 2' can also be expressed using N. N' Miyuki X
N... [41 As mentioned above, in short, N
' can be expressed as a function of S.

■ and N′(j, j, k) given by formula [4} is N(
i, i, k) to be newly stored in the storage device 17.

FIG. 3 is an example diagram when using the t4} formula, and the ninth
The figure is an example diagram when using the relationship of equation (2). Note that when making corrections, the logic judgment device 22
The following logical judgment is made for N'(i, j, k) input from 1. First, the core configuration of a nuclear reactor is symmetrical about the center, and the local outputs at symmetrical positions are almost the same.

Therefore, before performing the correction process, in order to correct the value for the position (i, i), it is necessary to correct Also refer to the value of
The difference between the four must be within the limit value. Second, since the sensitivity of the local power detector is inevitably reduced by neutron east irradiation, N'(i, j, k) must be greater than N(i, j, k).

Third, the degree of sensitivity reduction is determined by neutron radiation and irradiation time, and the functional relationship is known as the characteristic of local output detectors.

Since the value of neutron east is known as the output signal So, t
The ratio of N'(i, 19k) to N(i, j, k) must be appropriate in relation to the previous verification period. 7th
The procedure for output detection of the standard neutron east detector when using formula ■ is shown in Figure 8. This is done by inserting the East detector 3 into the core 2 (coordinate k direction in Figure 4) ~ Standard neutron East amplifier 8 that amplifies the output of the standard neutron East detector 3 when closest to the local output detector 4 The output signal S, (i, i, k) is taken in.

S, (i, i, k) to analog-to-digital converter 15
Convert to digital quantity by On the other hand, Scanner Ichiyoku 4
The output signal So(i, i, k) of the local output amplifier 9 amplified by the local output detector 4 at t is taken in. The multiplier N (5, js k) corresponding to the position coordinates of this local output detector is called from the storage device IT, and the digital multiplier turtle 6 calculates the
(i, j, k) to obtain the output S2 (is i?k). S2 (i, i, k) is held by the hold circuit 20' respectively. This is performed on the output detector.As shown in FIG.
From (i, car, k) and the multiplier N (i, i, k), a new multiplier N' (i, i, k) is determined using the 'three-choice formula'. Next, as described above, the logic judgment device 22 checks whether the multiplier N' is a proper value. If it is recognized as appropriate, N(i, j,
k) is rewritten as N'(i, i, k). This operation is performed for all local output detectors. logical judgment device 2
For those found to be abnormal in the check in step 2, an abnormality display is performed. That is, since it is displayed when there is an abnormality in the local power detector, the presence or absence of an abnormality in that detector can be ascertained when correcting the sensitivity of the local power detector. According to the present embodiment described above, the decrease in sensitivity of the local output detector is corrected by the comparator 21 using the output signal of the local output amplifier 9, so there is no need to adjust the gain of the amplifier for the local output.

Further, during sensitivity correction, there is no need to switch the connection of the input end of the local output amplifier 9 between the local output detector and the shark positive power supply. Therefore, the effort of the operator is significantly reduced.
Naturally, this embodiment does not require a positive power supply.In addition, in this embodiment, even during correction, the output signal of each local output detector does not disappear like in the conventional example, Therefore, since the reactor output can be obtained based on the output signals of all local output detectors, it is possible to obtain the reactor output with less error even during the correction period. Although not explicitly shown in the example, by automating the operation of inserting the standard neutron east detector into the reactor core, the effect of reducing operator labor becomes even more significant.In addition, the validity of the correction is checked by logical judgment. Therefore, there is no risk of accidental detonation.
Although this is a case of digital processing, for example, the circuit shown in FIG. 3 can also be constructed from an analog circuit.

However, in this case, the device itself would be larger.Also, in Figure 3, the multiplication results are converted to analog quantities and held in analog format, and an analog display device is used, but it is not possible to store them as digital signals. ``A digital display or a CRT display may be used.

Furthermore, there is also another embodiment of the present invention as shown in FIG.

That is, FIG. 9 shows a circuit constructed based on the above-mentioned formula {2}, and N〆 is calculated from So and S. Figure Q and Figure 1 are flowcharts for explaining the operation of the embodiment of Figure 9.

I believe that the detailed explanation can be easily inferred from the flow diagrams of FIGS. 7 and 8, so the explanation will be omitted here. [Effects of the Invention] According to the present invention, there is no need for a shark positive power supply, and there is no need to simulate switching between the local power amplifier, the local output detector, and the shark positive power supply during sensitivity correction.

Therefore, the effort required by the operator when correcting the sensitivity of the local power detector is significantly reduced. In addition, ``Even during the sensitivity correction period, the output signals of all local power detectors do not disappear, so the error in the obtained reactor power is reduced.

[Brief explanation of drawings]

Figure 1 is a diagram explaining the configuration of the local output device and standard neutron east detector installed in the reactor, Figure 2 is a configuration diagram of the amplifier for the subordinate local output detector, and Figure 3 is a diagram explaining the configuration of the local output detector installed in the reactor. FIG. 4 is a system diagram showing an embodiment of the present invention in which the sensitivity of the local power detector is corrected by using the local power detector. FIG. 5 is an explanatory diagram showing the storage of the sensitivity correction multiplier, and FIG. Diagram T is a flow diagram showing the procedure for collecting data for multiplier correction using a standard neutron east detector, and Figure 8 shows the procedure for correcting the stored multiplier based on the collected data. Figure 9 is a system diagram of another embodiment of the present invention, and Figures io and 11 are flow diagrams showing the operation of the embodiment shown in Figure 9. Pressure vessel, 2...Reactor core, 3...
・Standard neutron east detector, Kame A~4D...W local output detector, 7...Standard neutron east detector drive device, 8...
・Standard neutron east amplifier ~ 9...Local output amplifier,
12... Safety protection system, ]4... Scanner, 1
5...Analog-digital converter, 16...
Digital multiplier, 17...Storage device, box 8...
- Digital to analog converter, 20...Hold circuit, 21... Comparison calculation device, 22...Logic judgment device. Ta'tuta 2
Shape hair 3 figures many 4 figures many S figures many 6 figures many 7 figures many 8 figures hair? Kanta 10 diagram world li map

Claims (1)

[Claims] 1. A plurality of local output detectors installed in a nuclear reactor, and a plurality of amplifiers that input output signals of the local output detectors that form pairs with each of the local output detectors. , an in-reactor local power detection device having a standard neutron flux detector inserted into the reactor, storing a predetermined first correction coefficient corresponding to a first signal that is an output signal of each of the amplifiers; means for calculating the product of the first signal and the first correction coefficient corresponding to the first signal; and a second signal that is the output of the standard neutron flux detector and the output signal of the multiplication means. and means for storing the obtained second correction coefficient as a first correction coefficient in place of the corresponding first correction coefficient stored in the storage means. An in-core local power detection device characterized by: