JPH07225294A - Burnup measuring apparatus - Google Patents

Abstract

PURPOSE:To measure an accurately stable burnup even of a fuel is deviated from a detector by obtaining a distance from characteristics obtained previously by a test and count integrated values of two detectors, and operating to correct it to nonlinear characteristics. CONSTITUTION:Counters 3A, 3B output signals counted to be integrated from analog pulse signals of detectors 2A, 2B to correction operators 5a, 5b. A subtracter 4A decides necessity or not of a distance correcting operation of attenuation, positional deviation due to a shielding material from the signals of the counters 3A, 3B. When a difference of integrated counts NA, NB of the detectors 2A, 2B exceeds an allowable value, an amplitude of the counted value is decided, and its result is output to the operator 5. The operator 5 stores distances between a fuel 1 and the detectors 2A, 2B previously obtained by a test and count characteristics, operates based on input signals, and obtains a footing curve representing the distance between the detector and the fuel by an interior finishing method if N MIN<(NA+NB)/2<M MAX is satisfied. Thus, nonlinear characteristics are operated to be corrected to measure accurately stable burnup of the fuel 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a burnup measuring device for measuring the burnup of spent fuel that is transported from and received and stored in each nuclear power plant at a reprocessing facility that handles radioactive substances, and more particularly to a burnup measuring device. The present invention relates to a burnup measuring device capable of performing accurate and stable burnup measurement of fuel even if a displacement occurs between the detector and the detector.

[0002]

2. Description of the Related Art Generally, in reprocessing facilities that handle radioactive materials, burnup measuring devices are used to measure the burnup of spent fuel that is transported from each nuclear power plant for storage.

FIG. 6 is a block diagram showing a structural example of a conventional burnup measuring device of this type. In FIG. 6, the burnup measuring device comprises two detectors 2A, which are installed to face each other in order to measure neutrons emitted from the spent fuel 1.
2B and a measuring device 8 for measuring the burnup of the fuel 1 by processing the signals from the detectors 2A and 2B.

The measuring device 8 receives the analog pulse signals from the detectors 2A and 2B and counts and integrates (rates) within the measurement time.
And output counters 3A and 3B and the respective counters 3A and 3B
Calculator 6 for averaging and outputting the output signal from the calculator, and a display 7 for displaying the measurement result which is the output signal from the calculator 6.
Consists of.

In this case, the computing unit 6, as shown in the characteristic diagram of FIG. 7, has the values NA, which are counted by the counters 3A, 3B.
NB is averaged at (NA + NB) / 2 to correct the positional deviation between the fuel 1 and the detectors 2A and 2B.

By the way, in such a burnup measuring device, when the fuel 1 and the detectors 2A and 2B are misaligned with each other, as shown by the hyperbola in the characteristic diagram of FIG. Although it depends on the distance between 1 and each of the detectors 2A and 2B and the shielding material (water), the average correction is performed on the distance.

That is, since the count integrated values of the detectors 2A and 2B are simply averaged, the fuel 1
If the positional deviation between the detectors 2A and 2B exceeds a certain value, the measurement error increases because the relationship between the distance and the count value is non-linear as shown in the characteristic diagram of FIG. As a result, the burnup of the spent fuel 1 cannot be accurately measured.

[0008]

As described above, in the conventional burnup measuring apparatus, if the fuel and the detectors are misaligned, it is difficult to accurately measure the burnup of the fuel. There was a problem of becoming.

An object of the present invention is to correct the influence of the distance and the shielding material so that accurate and stable burnup measurement of the fuel can be performed even if there is a positional deviation between the fuel and each detector. To provide a simple burnup measuring device.

[0010]

In order to achieve the above object, in a burnup measuring apparatus for measuring burnup of spent fuel in a facility handling radioactive materials, first,
In the invention according to 1, the two detectors that are installed to face each other with the fuel containing the inspection object sandwiched therebetween and that measure the neutrons emitted from the fuel, and the output signals from the detectors are individually input, and count integration is performed. 2 counting means and a comparing and judging means for inputting and comparing output signals from the respective counting means, and judging whether or not there is a counting integration difference of a certain value or more between them, and a counting and judging means from the counting means. Two correction calculation means for individually inputting the output signal and the output signal from the comparison / determination means and performing a distance correction calculation due to the positional deviation between the fuel and each detector, and the output signal from each correction calculation means And arithmetic means for inputting and averaging, and output means for outputting an output signal from the arithmetic means.

Further, in the invention according to claim 2, two first detectors, which are installed so as to face each other with the fuel containing the inspection object sandwiched therebetween, for measuring neutrons emitted from the fuel, and each first detector, 1 second detector, which is installed to face the position orthogonal to the 1st detector, measures the neutrons emitted from the fuel, and the output signals from the 1st detector are individually input and the count integration is performed. Two first counting means, two second counting means for individually inputting and accumulating output signals from the second detector, and inputting output signals from each first counting means. Then, the first comparing and judging means for judging whether or not there is a counting integration difference of a certain value or more between them and the output signals from the respective second counting means are inputted and compared, and Second comparison and determination means for determining whether or not there is a count integration difference of a certain value or more between the two, and a first counting means Output signals from the first comparison determination means and the output signals from the first comparison and determination means are individually input, and two first correction calculations are performed to perform a distance correction calculation based on the positional deviation between the fuel and each first detector. Means, and the output signal from the second counting means and the output signal from the second comparing / determining means are individually input, and a distance correction calculation is performed based on a positional deviation between the fuel and each second detector. Two second correction calculation means, and a calculation means for selecting and averaging the output signals from the first or second correction calculation means based on the output signals from the comparison and determination means, and the calculation means. And output means for outputting the output signal from.

Here, in particular, as the calculation means, the output signal from each correction calculation means having a lower value of the count integration difference between the detectors is selected based on the output signal from each comparison determination means. I try to average them.

Further, in the invention according to claim 4, two first detectors which are installed to face each other with the fuel containing the inspection object interposed therebetween and which measure neutrons emitted from the fuel,
Two second detectors that are installed to face each other at a position orthogonal to the first detectors and measure neutrons emitted from the fuel, and output signals from the first detectors are individually input. Two first counting means for counting and accumulating, two second counting means for individually inputting and accumulating output signals from the second detector, and an output signal from each first counting means Is input and compared, and the first comparison / determination means for determining whether or not there is a difference in counting and integrating between them and a predetermined value and the output signals from the respective second counting means are input and compared. From the first or second counting means based on the output signals from the second comparison / determination means and the comparison / determination means, which determines whether or not there is a difference in counting and integrating between them. Selecting output means for selecting and outputting the output signal of, and an output signal from the selecting output means
Alternatively, two correction calculation means for individually inputting an output signal from the second comparison / determination means and performing a distance correction calculation due to a positional deviation between the fuel and each of the first and second detectors,
It comprises an arithmetic means for averaging the output signals from the respective correction arithmetic means, and an output means for outputting the output signal from the arithmetic means.

Here, in particular, as the selective output means,
Based on the output signal from each comparison / determination means, the output signal from each of the first or second counting means having the lower value of the count integration difference between the detectors is selected and output.

[0015]

Therefore, in the burnup measuring apparatus according to the first aspect of the present invention, first, the distance is calculated from the characteristic obtained by the test in advance and the count integrated value of each of the two detectors, and the correction calculation for the nonlinear characteristic is performed. By performing the above, accurate and stable burnup measurement can be performed even when a positional deviation occurs between the fuel and the two detectors installed facing each other.

Further, in the burnup measuring apparatus of the invention according to claim 2 or claim 4, it is installed so as to oppose a position where the difference between the integrated counts of the two first detectors is orthogonal to the first detector. By comparing the count integration difference of the two second detectors, the lower value is selected and the correction calculation for the above-mentioned non-linear characteristic is performed, the two detections installed facing the fuel are detected. Even if a positional deviation occurs with the vessel, it is possible to perform more accurate and stable burnup measurement.

[0017]

Embodiments of the present invention will now be described in detail with reference to the drawings. (First Embodiment) FIG. 1 is a block diagram showing a first embodiment of the burnup measuring apparatus according to the present invention, and the same elements as those in FIG. 6 are designated by the same reference numerals.

That is, the burnup measuring apparatus of this embodiment is
As shown in FIG. 1, two detectors 2A and 2B, two counters 3A and 3B, and subtractors 4A and 2 which are comparison / determination means.
Each of the correction calculators 5A and 5B, a calculator 6, and a measuring device 8 including a display 7 as an output means.

Here, the detectors 2A and 2B are installed so as to face each other with the fuel 1 containing the inspection object in between, and measure the neutrons emitted from the fuel 1. Also, the counter 3
A and 3B are for individually inputting output signals from the detectors 2A and 2B and counting and integrating them.

Further, the subtractor 4A includes the counters 3A and 3A.
The output signal from B is input and compared, and it is determined whether or not there is a difference in counting integration of a certain value or more between them.
On the other hand, the correction calculators 5A and 5B individually input the output signals from the counters 3A and 3B and the output signal from the subtractor 4A, respectively, depending on the positional deviation between the fuel 1 and the detectors 2A and 2B. The distance correction calculation is performed.

The computing unit 6 is composed of the correction computing units 5A and 5A.
The output signal from B is input and averaged. Further, the display unit 7 displays the output signal from the arithmetic unit 6 which is the measurement result.

Next, the operation of the burnup measuring apparatus of the present embodiment constructed as described above will be described with reference to FIGS. 2 and 3. In FIG. 1, in the counters 3A and 3B, the analog pulse signals from the detectors 2A and 2B are input, and the signals accumulated and counted (rate) within the measurement time are corrected by the correction calculators 5A and 5B.
Is output to. That is, in the counters 3A and 3B, the analog signals from the detectors 2A and 2B are input and the count integrated value (rate) is calculated by the following formula.

[0023]

[Equation 1]

Ni: Accumulated count within the measuring time from the detector i ni: Counting rate from the detector i t: Measuring time On the other hand, in the subtractor 4A, the output signals from the counters 3A and 3B are compared, A determination is made as to whether or not the count integration difference is within a specified value, and the determination result is output to the correction calculators 5A and 5B.

That is, in the subtractor 4A, the counters 3A,
By inputting the output signal from 3B, it is determined whether or not the distance correction calculation for attenuation and positional deviation due to the shielding material (water) is performed as described below.

| NA-NB |> C (2) NA: Accumulated count of the detector 2A NB: Accumulated count of the detector 2B C: Allowable value When the above equation (2) is satisfied, the NA and NB values are satisfied. Is determined by the following formula (3), and the determination result is the correction calculator 5
It is output to A and 5B.

NA-NB> 0 (3) Further, in the correction calculators 5A and 5B, the distance between the fuel 1 and the detectors 2A and 2B obtained by a test in advance and the count characteristic (see FIG. 2). (Characteristics as shown) are stored, the output signals from the counters 3A and 3B and the subtractor 4A are input, and the calculation is performed as follows (the characteristic NMIN-NMAX in FIG. Included within this property).

(A) The determination result of the subtractor 4A is | NA-
When NB | <C, the calculation is performed by the following equation (4). Mi = Ni × D (4) Mi: Burnup obtained from detector i D: Conversion factor to burnup (b) When the judgment result of the subtractor 4A is NA-NB> + C, the following: The calculation is performed using the equations (5), (6), and (7).

(NA + NB) / 2 The average value is Mmin <(N
If A + NB) / 2 <Nmax, the footing curve of FIG. 2 is obtained by the interior method. P = f (L) (5) P: Attenuation correction coefficient of distance L L1: Distance obtained from NA in the characteristic diagram of FIG. 2 L2: Distance obtained from NB in the characteristic diagram of FIG. 2 L: | L1 − L2 | MA = Ni * (1-P) + D (6) MA: Burnup obtained from the detector 2A MB = Ni * (1 + P) * D (7) MB: Detector 2B When the judgment result in the burnup (c) subtractor 4A obtained from the above is NA-NB <-C, the above (6)
The calculation is performed by exchanging MA and MB in the equation (7).

On the other hand, in the arithmetic unit 6, the correction arithmetic units 5A, 5A
The output signal from B is input, the calculation is performed by the following equation (8), and the output signals from the correction calculators 5A and 5B are averaged.

S = (MA + MB) / 2 (8) Furthermore, the output signal from the calculator 6 which is the measurement result is displayed on the display 7 in real time.

As described above, the burnup measuring apparatus of this embodiment is installed so as to face each other with the fuel 1 containing the inspection object interposed therebetween, and the two detectors 2A for measuring the neutrons emitted from the fuel 1 , 2B and the output signals from the detectors 2A and 2B are individually input to perform counting integration, and the output signals from the two counters 3A and 3B and the respective counters 3A and 3B are input and compared, and , The output signals from the subtracters 4A and 3A and 3B and the output signal from the subtractor 4A are individually input to determine whether or not there is a counting integration difference of a certain value or more in the fuel 1 and each detector. Two correction calculators 5A and 5B for performing a distance correction calculation due to a positional deviation between 2A and 2B, and each correction calculator 5A,
An arithmetic unit 6 for inputting and averaging the output signal from 5B, and a display unit 7 for displaying the output signal from the arithmetic unit 6 which is a measurement result.
And a measuring device 8 composed of

Therefore, even if a positional deviation occurs between the two detectors 2A and 2B installed facing the fuel 1, the burnup of the fuel 1 can be measured accurately and stably. It will be possible.

That is, in the prior art, since the count integrated values of the detectors 2A and 2B were simply averaged, the positional deviation between the fuel 1 and the detectors 2A and 2B exceeds a certain value. Then, as shown in the characteristic diagram of FIG. 7, the relationship between the distance and the count value is non-linear, which causes a problem that the measurement error increases.
The positional deviation between the fuel 1 and the detectors 2A and 2B is shown in FIG.
As shown in the characteristic diagram, the distance L is calculated from the characteristic obtained by the test in advance and the count integrated value of each of the detectors 2A and 2B, and the correction calculation for the nonlinear characteristic is performed, so that the fuel 1 can be accurately and stable. It becomes possible to perform burnup measurement.

(Second Embodiment) FIG. 4 is a block diagram showing a second embodiment of the burnup measuring apparatus according to the present invention.
The same elements as those in FIG. 1 are designated by the same reference numerals.

That is, the burnup measuring apparatus of this embodiment is
As shown in FIG. 4, two first detectors 2A and 2B,
Two second detectors 2C, 2D, two first counters 3
A, 3B, two second counters 3C and 3D, a first subtractor 4A that is a first comparison and determination unit, a second subtractor 4B that is a second comparison and determination unit, a selector 4C, It is composed of two first correction calculators 5A and 5B, second correction calculators 5C and 5D, a calculator 6, and a measuring device 8 including a display 7 as an output means.

Here, the first detectors 2A and 2B are installed so as to face each other with the fuel 1 containing the inspection object sandwiched therebetween.
It measures the neutrons emitted from. The second detectors 2C and 2D are installed to face the first detectors 2A and 2B at right angles, and measure the neutrons emitted from the fuel 1.

Further, the first counters 3A and 3B are
The output signals from the detectors 2A and 2B are separately input and counted and integrated. Furthermore, the second counter 3C,
The 3D is for individually inputting output signals from the second detectors 2C and 2D and performing counting integration.

On the other hand, the first subtractor 4A inputs the output signals from the respective first counters 3A and 3B and compares them, and determines whether or not there is a difference in counting integration of a certain value or more between them. It is a judgment.

Further, the second subtractor 4B inputs the output signals from the respective second counters 3C and 3D and compares them, and judges whether or not there is a difference in counting integration of a certain value or more between them. It is a judgment.

Further, the selector 4C includes the subtractors 4A and 4A.
Based on the output signal from B, the first or second correction calculators 5A and 5B having the lower count integration difference between the detectors.
Alternatively, it outputs a signal for selecting the output signal from 5C and 5D.

On the other hand, the first correction calculators 5A and 5B are provided with the output signals from the first counters 3A and 3B and the first subtractor 4 respectively.
The output signal from A is individually input, and the distance correction calculation is performed by the positional deviation between the fuel 1 and each of the first detectors 2A and 2B.

The second correction calculators 5C and 5D are provided with the output signals from the second counters 3C and 3D and the second subtractor 4 respectively.
The output signal from B is individually input, and the distance correction calculation is performed based on the positional deviation between the fuel 1 and each of the second detectors 2C and 2D.

Further, the computing unit 6 is based on the output signal from the selector 4C, and the first or second correction computing unit 5 is provided.
The output signals from A, 5B or 5C, 5D are selected and averaged.

Furthermore, the display unit 7 displays the output signal from the arithmetic unit 6 which is the measurement result. next,
The operation of the burnup measuring apparatus of this embodiment configured as described above will be described with reference to FIGS. 2 and 3.

In FIG. 4, the first and second counters 3
In A, 3B and 3C, 3D, the analog pulse signals from the first and second detectors 2A, 2B and 2C, 2D are input, and the signal integrated by counting (rate) within the measurement time is the first signal.
And to the second correction calculators 5A, 5B and 5C, 5D, respectively.

That is, the first and second counters 3A,
In 3B, 3C and 3D, the first and second detectors 2
The analog integrated signals from A, 2B and 2C, 2D are input, and the count integrated value (rate) is calculated by the equation (1).

On the other hand, in the first and second subtractors 4A and 4B, the first and second counters 3A, 3B and 3 are used.
The output signals from C and 3D are compared, and it is determined whether or not the difference in counting and integrating is within a specified value.
And to the second correction calculators 5A, 5B and 5C, 5D, respectively.

That is, in the first and second subtractors 4A and 4B, the output signals from the first and second counters 3A, 3B and 3C, 3D are input, and the shielding material is expressed by the equation (2). A determination is made as to whether or not the distance correction calculation for the attenuation due to (water) and the positional deviation is performed.

When the equation (2) is established, the magnitude of the NA and NB values is discriminated by the equation (3), and the discrimination result is the first and second correction computing units 5A, 5B and 5C, 5.
It is output to D respectively.

In addition, the first and second correction calculators 5A,
In 5B, 5C, and 5D, the distance between the fuel 1 and the first and second detectors 2A, 2B and 2C, 2D, which were previously obtained by the test, and the counting characteristics (characteristics as shown in FIG. 2) were measured. Memorize and store the first and second counters 3A, 3B and 3C, 3D, and the first and second counters.
The output signals from the subtracters 4A and 4B are input, and the calculation is performed by the equations (4), (5), and (6).

On the other hand, in the selector 4C, on the basis of the output signals from the first and second subtractors 4A and 4B, the first or the second one of the lower count integration difference between the detectors is obtained. A signal for selecting the output signal from the correction calculator 5A, 5B or 5C, 5D is output.

That is, in the selector 4C, the selection is made by the following equation (9), and the result is output to the arithmetic unit 6 as a signal indicating whether or not the equation (9) is satisfied. | NA-NB |-| NC-ND |> ... (9) Further, in the arithmetic unit 6, each of the first and second correction arithmetic units is based on the establishment / non-establishment signal from the selector 4C. 5A, 5
The output signal from B or 5C, 5D is selected, and the operation is performed by the equation (8) or the following equation (10),
The first or second correction calculator 5A, 5B or 5C,
The output signal from 5D is averaged.

S = (MC + MD) / 2 (10) Further, the display device 7 displays the output signal from the calculator 6 as a measurement result in real time.

As described above, the burnup measuring apparatus of this embodiment is installed so as to face each other with the fuel 1 containing the inspection object interposed therebetween, and measures the neutrons emitted from the fuel 1 by the first detector 2A. , 2B, and second detectors 2C, 2D, which are installed facing each other at a position orthogonal to the first detectors 2A, 2B, and measure neutrons emitted from the fuel 1, and a first detector 2
A first counter 3A, 3B for individually inputting and accumulating output signals from A and 2B, and a second counter 3 for individually accumulating and accumulating output signals from second detectors 2C, 2D.
C, 3D, a first subtractor 4A for inputting and comparing output signals from the respective first counters 3A, 3B, and determining whether or not there is a difference in counting integration of a certain value or more between them. A second subtractor 4B, each subtractor 4A, which receives and compares the output signals from each of the second counters 3C and 3D and determines whether or not there is a difference in counting and integration between the two, which is equal to or greater than a certain value. , 4B, a signal for selecting an output signal from each of the first or second correction calculators 5A, 5B or 5C, 5D having the lower count integration difference between the detectors, based on the output signal from each detector. Selector 4C for outputting
The output signals from the first counters 3A and 3B and the output signal from the first subtractor 4A are individually input, and the fuel 1 and each first
Output signals from the first correction calculators 5A and 5B and the second counters 3C and 3D, which perform distance correction calculation due to the positional deviation between the detectors 2A and 2B, and the outputs from the second subtractor 4B. Signals are input individually and fuel 1 and each second detector 2
Based on the output signals from the second correction calculators 5C and 5D and the selector 4C that perform the distance correction calculation based on the positional deviation between C and 2D, the first or second correction calculators 5A and 5A
The measuring device 8 includes a computing unit 6 for selecting and averaging the output signals from B or 5C and 5D, and a measuring device 8 including a display unit 7 for displaying the output signal from the computing unit 6 which is a measurement result.

Therefore, the two first and second detectors 2A, 2B and 2C, 2D installed to face the fuel 1
Even if a positional deviation occurs between the fuel cell and the fuel cell, the burnup of the fuel 1 can be measured accurately and stably.

That is, in the prior art, since the count integrated value of each of the first and second detectors 2A, 2B and 2C, 2D was simply averaged, the fuel 1 and each detector 2A, 2B and If the positional deviation between 2C and 2D exceeds a certain value, the relationship between the distance and the count value is non-linear, as shown in the characteristic diagram of FIG. On the other hand, in the present embodiment, the positional deviation between the fuel 1 and each of the detectors 2A, 2B and 2C, 2D is obtained by a test in advance as shown in the characteristic diagram of FIG. 2A, 2B and 2C, 2
By obtaining the distance L from each count integrated value of D and performing the correction calculation for the nonlinear characteristic, it is possible to measure the burnup of the fuel 1 accurately and stably.

Further, the difference between the counts of the two first detectors 2A and 2B and the two second detectors 2C and 2C, which are installed so as to face each other at a position orthogonal to the first detectors 2A and 2B, Since the 2D count integration difference is compared and the lower value is selected to perform the correction calculation for the non-linear characteristic, the fuel 1
Two first and second detectors 2 installed facing each other
Even if a displacement occurs between A, 2B and 2C, 2D, it is possible to perform more accurate and stable burnup measurement.

(Third Embodiment) FIG. 5 is a block diagram showing a third embodiment of the burnup measuring apparatus according to the present invention.
The same elements as those in FIGS. 1 and 4 are designated by the same reference numerals.

That is, the burnup measuring apparatus of this embodiment is
As shown in FIG. 5, two first detectors 2A and 2B,
Two second detectors 2C, 2D, two first counters 3
A, 3B, two second counters 3C and 3D, a first subtractor 4A that is a first comparison and determination unit, a second subtractor 4B that is a second comparison and determination unit, a selector 4C, Selective output device 9,
It is composed of two correction calculators 5A and 5B, a calculator 6, and a measuring device 8 including a display 7 which is an output means.

Here, the first detectors 2A and 2B are installed so as to face each other with the fuel 1 containing the inspection object interposed therebetween.
It measures the neutrons emitted from. The second detectors 2C and 2D are installed to face the first detectors 2A and 2B at right angles, and measure the neutrons emitted from the fuel 1.

Furthermore, the first counters 3A and 3B are
The output signals from the detectors 2A and 2B are separately input and counted and integrated. Furthermore, the second counter 3C,
The 3D is for individually inputting output signals from the second detectors 2C and 2D and performing counting integration.

On the other hand, the first subtractor 4A inputs the output signals from the respective first counters 3A and 3B and compares them, and determines whether or not there is a count integration difference of a certain value or more between them. It is a judgment.

Further, the second subtractor 4B inputs the output signals from the respective second counters 3C and 3D and compares them, and determines whether or not there is a difference in counting integration of a certain value or more between them. It is a judgment.

Further, the selector 4C includes the subtractors 4A and 4A.
Based on the output signal from B, a signal for selecting the output signal from the first or second counter 3A, 3B or 3C, 3D having the lower count integration difference between the detectors is output. To do.

On the other hand, the selection output unit 9 is based on the output signal from the selection unit 4C, and the first or second counter 3A,
The output signals from 3B or 3C and 3D are selected and output.

Further, the correction calculators 5A and 5B individually input the output signals from the selective output device 9 and the output signals from the first and second subtractors 4A and 4B, and the fuel 1 and each of the first The distance correction calculation is performed by the positional deviation between the detectors 2A and 2B or the second detectors 2C and 2D.

Further, the computing unit 6 includes the correction computing units 5A,
The output signal from 5B is averaged. Furthermore, the display 7 displays the output signal from the calculator 6 which is the measurement result.

Next, the operation of the burnup measuring apparatus of this embodiment constructed as described above will be explained. In FIG.
In the first and second counters 3A, 3B and 3C, 3D, the first and second detectors 2A, 2B and 2C, 2
The analog pulse signal from D is input, and signals obtained by counting and integrating (rate) within the measurement time are output to the first and second subtractors 4A and 4B, respectively.

That is, the first and second counters 3A,
In 3B, 3C and 3D, the first and second detectors 2
The analog integrated signals from A, 2B and 2C, 2D are input, and the count integrated value (rate) is calculated by the equation (1).

On the other hand, in the first and second subtractors 4A and 4B, the first and second counters 3A, 3B and 3 are used.
The output signals from C and 3D are compared with each other, it is determined whether or not the difference in counting integration is within a specified value, and the determination result is output to each selector 4C.

That is, in the first and second subtractors 4A and 4B, the output signals from the first and second counters 3A, 3B and 3C, 3D are input, and the shielding material is expressed by the equation (2). A determination is made as to whether or not the distance correction calculation for the attenuation due to (water) and the positional deviation is performed.

When the equation (2) is established, the magnitude of the NA and NB values is discriminated by the equation (3), and the discrimination result is output to the selector 4C. Further, in the selector 4C, based on the output signals from the first and second subtractors 4A and 4B, the first or second counter 3A having the lower count integration difference between the detectors. , 3B or 3C, 3D
A signal for selecting the output signal from is output.

That is, in the selector 4C, the selection is made according to the equation (9), and the result is output to the selection output device 9 as a signal indicating whether or not the equation (9) is satisfied. On the other hand, in the selection output device 9, based on the output signal from the selector 4C, from the first or second counter 3A, 3B or 3C, 3D having the lower count integration difference between the detectors. Output signal is selected and output to the correction calculators 5A and 5B, respectively.

Further, in the correction calculators 5A and 5B, the distance between the fuel 1 obtained in advance by the test and each of the first or second detectors 2A, 2B or 2C, 2D and the count characteristics (see FIG. 2). (Characteristic as shown) is stored and the first or second counter 3A from the selective output device 9 is stored.
3B or 3C, 3D and the first and second subtractors 4A, 4
Input the output signal from B, and use the equations (4) and (5).
The calculation is performed by the formula and the formula (6).

On the other hand, the computing unit 6 performs the computation according to the equation (8) or the equation (10), and each correction computing unit 5
The output signals from A and 5B are averaged. Further, on the display 7, the output signal from the calculator 6 which is the measurement result is displayed in real time.

As described above, the burnup measuring apparatus of this embodiment is installed so as to face each other with the fuel 1 containing the inspection object in between, and the first detector 2A for measuring the neutrons emitted from the fuel 1 is detected. , 2B, and second detectors 2C, 2D, which are installed facing each other at a position orthogonal to the first detectors 2A, 2B, and measure neutrons emitted from the fuel 1, and a first detector 2
A first counter 3A, 3B for individually inputting and accumulating output signals from A and 2B, and a second counter 3 for individually accumulating and accumulating output signals from second detectors 2C, 2D.
C, 3D, a first subtractor 4A for inputting and comparing output signals from the respective first counters 3A, 3B, and determining whether or not there is a difference in counting integration of a certain value or more between them. A second subtractor 4B, each subtractor 4A, which receives and compares the output signals from each of the second counters 3C and 3D and determines whether or not there is a difference in counting and integration between the two, which is equal to or greater than a certain value. , 4B, based on the output signal from each of the detectors, a signal for selecting the output signal from each of the first or second counters 3A, 3B or 3C, 3D having the lower value of the counting integration difference between the detectors. Selector 4C for outputting, Selective output device 9 for selecting and outputting the output signal from each of the first or second counters 3A, 3B or 3C, 3D based on the output signal from the selector 4C, selective output The output signal from the output device 9 and the output signals from the first and second subtractors 4A and 4B are individually input, From the correction calculators 5A and 5B and the correction calculators 5A and 5B, which perform distance correction calculation due to the positional deviation between the charge 1 and the first detectors 2A and 2B or the second detectors 2C and 2D. An arithmetic unit 6 for averaging the output signals,
The measuring device 8 comprises a display 7 for displaying the output signal from the arithmetic unit 6 as the measurement result.

Therefore, the two first and second detectors 2A, 2B and 2C, 2D installed to face the fuel 1
Even if a positional deviation occurs between the fuel cell and the fuel cell, the burnup of the fuel 1 can be measured accurately and stably.

That is, in the prior art, since the count integrated value of each of the first and second detectors 2A, 2B and 2C, 2D was simply averaged, fuel 1 and each detector 2A, 2B and If the positional deviation between 2C and 2D exceeds a certain value, the relationship between the distance and the count value is non-linear, as shown in the characteristic diagram of FIG. On the other hand, in the present embodiment, the positional deviation between the fuel 1 and each of the detectors 2A, 2B and 2C, 2D is obtained by a test in advance as shown in the characteristic diagram of FIG. 2A, 2B and 2C, 2
By obtaining the distance L from each count integrated value of D and performing the correction calculation for the nonlinear characteristic, it is possible to measure the burnup of the fuel 1 accurately and stably.

Further, the difference between the integrated counts of the two first detectors 2A and 2B and the two second detectors 2C and 2C, which are installed facing each other at a position orthogonal to the first detectors 2A and 2B, Since the 2D count integration difference is compared and the lower value is selected to perform the correction calculation for the non-linear characteristic, the fuel 1
Two first and second detectors 2 installed facing each other
Even if a displacement occurs between A, 2B and 2C, 2D, it is possible to perform more accurate and stable burnup measurement.

The present invention is not limited to the above embodiments, but can be implemented in the same manner as described below. (A) In each of the above embodiments, the case where a display device for displaying the measurement result is used as the output means for outputting the measurement result has been described. However, the output means for outputting the measurement result is not limited to this. Alternatively, a printer for printing the measurement result may be used.

(B) In each of the above-mentioned embodiments, both the display device for displaying the measurement result and the printing device for printing the measurement result may be used as the output means for outputting the measurement result.

[0083]

As described above, according to the present invention, the influence of the distance and the shielding material is corrected, and even if the fuel is misaligned with each detector, the fuel is accurately and stably burned. A burnup measuring device capable of performing burnup measurement can be provided.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of a burnup measuring apparatus according to the present invention.

FIG. 2 is a characteristic diagram showing an example of a relationship between each detector, a fuel distance, and a count value in the burnup measuring apparatus of the embodiment.

FIG. 3 is a flowchart for explaining the operation of the burnup measuring apparatus according to the embodiment.

FIG. 4 is a block diagram showing a second embodiment of the burnup measuring apparatus according to the present invention.

FIG. 5 is a block diagram showing a third embodiment of the burnup measuring device according to the present invention.

FIG. 6 is a block diagram showing a configuration example of a conventional burnup measuring device.

FIG. 7 is a characteristic diagram showing an example of a relationship between each detector, a fuel distance, and a count value in a conventional burnup measuring device.

[Explanation of symbols]

1 ... Fuel, 2A, 2B ... Detector (first detector), 3
A, 3B ... Counter (first counter), 4A ... Subtractor (first subtractor), 5A, 5B ... Correction calculator (first correction calculator), 6 ... Calculator, 7 ... Display Vessel, 8 ... Measuring device, 2
C, 2D ... second detector, 3C, 3D ... second counter,
4B ... Second subtractor, 4C ... selector, 9 ... selection output device.

Claims (5)

[Claims] 1. A burnup measuring device for measuring the burnup of a spent fuel in a facility handling radioactive substances, which is installed so as to face each other with a fuel containing a test object interposed therebetween, and measures neutrons emitted from the fuel. And two counting means for individually inputting output signals from the detectors and performing counting integration, and for inputting and comparing output signals from each of the counting means, a constant value is maintained between them. Comparing and determining means for determining whether or not there is a counting integration difference equal to or more than a value, the output signal from the counting means and the output signal from the comparison and determining means are individually input, and the fuel and each detector are Two correction calculation means for performing a distance correction calculation due to a positional shift between them, a calculation means for inputting and averaging output signals from the correction calculation means, and an output means for outputting an output signal from the calculation means Comprising, Burnup measuring apparatus characterized. 2. A burnup measuring device for measuring the burnup of a spent fuel in a facility handling radioactive substances, which is installed so as to face each other with a fuel containing a test object interposed therebetween, and measures neutrons emitted from the fuel. Two first detectors, two second detectors that are installed to face each of the first detectors at a position orthogonal to each other, and measure neutrons emitted from the fuel; Two first counting means for individually inputting output signals from the first detector and counting and integrating, and two second counting means for individually inputting output signals from the second detector and counting and integrating. Counting means, and a first comparison / determination means for determining whether or not there is a count integration difference of a predetermined value or more between the input signals output from the first counting means and comparison. The output signals from each of the second counting means are input and compared, and the two are counted between the two. A second comparison / determination means for determining whether or not there is a counting integration difference equal to or larger than a fixed value, an output signal from the first counting means and an output signal from the first comparison / determination means are individually input. , Two first correction calculation means for performing a distance correction calculation based on a positional deviation between the fuel and each first detector, an output signal from the second counting means and the second comparison determination The output signals from the means are individually input, and two second correction calculation means for performing distance correction calculation based on the positional deviation between the fuel and each second detector; The output signal from each of the first or second correction operation means based on the output signal of 1., and an output means for outputting the output signal from the operation means. A burnup measuring device characterized by being formed. 3. The calculating means is based on an output signal from each of the comparing / determining means, and is output from each of the first or second correction calculating means having a lower count integration difference between the detectors. The burnup measuring device according to claim 2, wherein the output signals are selected and averaged. 4. A burnup measuring device for measuring the burnup of a spent fuel in a facility handling radioactive substances, which is installed to face each other with a fuel containing a test object interposed therebetween, and measures neutrons emitted from the fuel. Two first detectors, two second detectors that are installed to face each of the first detectors at a position orthogonal to each other, and measure neutrons emitted from the fuel; Two first counting means for individually inputting output signals from the first detector for counting and integrating, and two second counting means for individually inputting output signals from the second detector for counting and integrating. Counting means, and a first comparison / determination means for determining whether or not there is a count integration difference of a predetermined value or more between the input signals output from the first counting means and comparison. The output signals from each of the second counting means are input and compared, and the two are counted between the two. Based on the output signals from the second comparison / determination means and the comparison / determination means for determining whether or not there is a counting integration difference that is equal to or more than a fixed value, the output signal from each of the first or second counting means is output. Select output means for selecting and outputting, output signal from the select output means and the first or second
Output signals from the comparison / determination means are individually input, and two correction calculation means for performing distance correction calculation based on the positional deviation between the fuel and each of the first and second detectors, and each of the corrections A burnup measuring device comprising: a calculating means for averaging output signals from the calculating means; and an output means for outputting an output signal from the calculating means. 5. The selection output means is based on an output signal from each of the comparison / determination means, and outputs from each of the first or second counting means having a lower value of the count integration difference between the detectors. The burnup measuring device according to claim 2, wherein the output signal is selected and output.