JPH0882692A - Burnup measuring device - Google Patents

Abstract

PURPOSE: To exactly measure various γ-ray and more exactly calculate the burnup of spent fuel by checking the integrated count value of all energy channel output from a pulse height analyzer and controlling the insertion and withdrawal of absorber as to measure in optimum range of the γ-ray detector. CONSTITUTION: In the opening of a collimator 3, an absorber 9a and an absorber 9b having a larger shield attenuation rate are provided free of insertion and withdrawal. A controller 10 for controlling the insertion and withdrawal of each absorber 9a, 9b is provided. At the moment γ-ray of spent fuel 2 is measured, the integrated count value of all energy channel output from a pulse height analyzer 5 is checked and based on the result, the insertion and withdrawal of each absorber 9a, 9b is controlled 10. Thus, even in a high dose γ-ray field wherein a plurality of γ-ray species exist and in the case the γ-ray energy difference of the measuring object is large, the γ-ray from fuel 2 can be exactly detected in optimum range of a γ-ray detector 4 without miscounts.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a burnup measuring apparatus for measuring the burnup of spent fuel when it is transported from a radiation handling facility such as a nuclear power plant in a reprocessing facility and received and stored. Especially when there are multiple γ-ray nuclides and a high dose γ-ray dose field, and even when the γ-ray energy difference of the measurement target is large, the γ-rays are accurately measured and the spent fuel The present invention relates to a burnup measuring device capable of measuring burnup more accurately.

[0002]

2. Description of the Related Art Conventionally, burnup measuring devices have been used to measure the burnup of spent fuel when it is transported from a radiation handling facility such as a nuclear power plant in a reprocessing facility and received and stored. .

FIG. 5 is a block diagram showing a configuration example of a conventional burnup measuring device of this type. In FIG. 5, the burnup measuring device includes a collimator 3 having an opening for guiding the γ-rays emitted from the spent fuel 2 installed in the shield wall 1 to the outside of the shield wall 1, and the γ-rays guided by the collimator 3. The γ-ray detector 4 that detects and outputs the signal and the measuring device 8 that processes the signal output from the γ-ray detector 4.

Also, the measuring device 8 outputs the wave height for a preset time by performing the counting integration for each channel, which corresponds directly to the energy of each γ ray from the spent fuel 2 output from the γ ray detector 4. Analyzer 5 and wave height analyzer 5
For each energy channel output from each energy channel (corresponding to each γ-ray nuclide (cobalt, cesium, etc.)), the count value determined by the shape and opening area of the collimator 3 is corrected, and each energy channel is calculated. A computing unit 6 for calculating and outputting the burnup of the spent fuel 2 which is a corrected count value for each, and a display for displaying the burnup of the spent fuel 1 output from the computing unit 6 for each energy channel. 7 and 7.

By the way, in such burn-up measuring apparatus, for measuring the γ-rays of the spent fuel 2 installed in the shield wall 1, the counting range of the γ-ray detector 4 is set to the peak value of the energy of the γ-rays. Set proportionally (eg 5 for cobalt
V, 3 V for cesium, etc.), and to what extent and which nuclide was emitted.

However, when performing γ-ray measurement in a low-dose field, it is possible to measure γ-rays with a certain degree of accuracy, but it is possible to measure γ-rays in a high-dose field with a plurality of γ-ray nuclides. At the time of performing, counting count of the γ-ray detector 4 (phenomenon in which when the input count rate (γ dose rate) exceeds a certain value, a count value proportional to it is not output from the γ-ray detector 4), etc. Once generated, it becomes difficult to accurately measure γ-rays.

Further, even when the γ-ray energy difference of the measurement object is large, it becomes difficult to accurately measure the γ-ray. As a result, it becomes difficult to accurately measure the burnup of the spent fuel 2.

[0008]

As described above, in the conventional burnup measuring apparatus, in the case where there are a plurality of nuclides and a high dose γ-ray dose field, the γ-ray energy difference of the object to be measured is further large. In such cases, the γ-ray cannot be accurately measured, and as a result, it is difficult to accurately measure the burnup of the spent fuel.

The object of the present invention is to accurately obtain γ-rays even in the case where a plurality of γ-ray nuclides are present and a high-dose γ-ray dose field and the γ-ray energy difference of the measurement object is large. It is an object of the present invention to provide a burnup measuring device capable of measuring the burnup and measuring the burnup of spent fuel more accurately.

[0010]

In order to achieve the above-mentioned object, first, in the invention according to claim 1, combustion for measuring the burnup of spent fuel in a radiation handling facility installed in a shielding wall In the degree measuring device, a collimator provided on the shielding wall and having an opening that guides the γ rays emitted from the spent fuel to the outside of the shielding wall, and a γ ray detector that detects and outputs the γ rays guided by the collimator, A wave height analyzing means for outputting a count integration for each channel directly corresponding to the energy of each γ ray from the spent fuel outputted from the γ ray detector, and outputting each by the wave height analyzing means. Compensation calculation of the count value determined by the shape and opening area of the collimator is performed on the integrated count value of each energy channel, and the fuel count of the spent fuel that is the corrected count value of each energy channel is calculated. Computation means for calculating and outputting the degree of burntness, first shield attenuation means having a predetermined shield attenuation rate, which are respectively provided in the opening of the collimator so as to be insertable / withdrawable, and more than the first shield attenuation means. A second shield attenuation means having a large shield attenuation factor and an integrated count value for each energy channel output from the wave height analysis means are checked, and based on the check result, the count optimum range of the γ-ray detector is determined. And a control means for controlling insertion / extraction of the first and second shield attenuation means so as to measure.

In the invention according to claim 2, the burnup measuring device of the invention according to claim 1 is further provided with display means for displaying the burnup of the spent fuel output from the computing means.

Here, in particular, as the control means, the integrated count value for each energy channel output from the wave height analysis means is compared with the low area energy channel setting value and the high area energy channel setting value for each energy channel. 3 areas are selected, the integrated count value for each energy channel area is calculated from the shielding attenuation rate of the first and second shielding attenuation means, and the calculated value and the counting characteristic limit value of the γ-ray detector are I try to make comparisons.

As the control means, the integrated count value for each energy channel output from the wave height analysis means is compared with the low region energy channel set value and the high region energy channel set value to determine the 3 for each energy channel. A region is selected, the integrated count value for each energy channel region is calculated from the shielding attenuation rate of the first and second shielding attenuation means, and the calculated value is compared with the counting characteristic limit value of the γ-ray detector. , The minimum and maximum energy difference in each energy channel region is compared with its allowable value.

[0014]

Therefore, in the burnup measuring device of the present invention,
When measuring the γ-rays of the spent fuel, based on the check result of the integrated count value of each energy channel of the γ-rays from the spent fuel output from the γ-ray detector, the first and second shielding By inserting / pulling out the attenuator, it is possible to measure in the optimum counting range of the γ-ray detector.

In this case, in particular, the integrated count value for each energy channel output from the wave height analyzing means is compared with the low region energy channel set value and the high region energy channel set value to select three regions of each energy channel. By calculating the integrated count value for each energy channel region from the shielding attenuation rate of the first and second shielding attenuation means, and comparing the calculated value with the counting characteristic limit value of the γ-ray detector, Even in the case where there are a plurality of γ-ray nuclides and a high dose γ-ray dose field, accurate neutron measurement can be performed to more accurately measure the burnup of the spent fuel.

Further, the integrated count value for each energy channel output from the wave height analyzing means is compared with the low region energy channel set value and the high region energy channel set value to select three regions of each energy channel. The first and second integrated count values for each energy channel region
Calculated from the shielding attenuation rate of the shielding attenuation means, compare the calculated value with the limit value of the counting characteristics of the γ-ray detector, and compare the minimum and maximum energy difference in each energy channel region with its allowable value. By performing this, even when the γ-ray energy difference of the measurement target is large, accurate neutron measurement can be performed and the burnup of the spent fuel can be measured more accurately.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a block diagram showing a configuration example of a burnup measuring apparatus according to the present invention. The same elements as those in FIG. 5 are designated by the same reference numerals, and the description thereof will be omitted. Only different portions will be described here.

That is, the burnup measuring apparatus of this embodiment is
As shown in FIG. 1, in addition to FIG. 5, a first absorber 9a and a second absorber 9b which are shield attenuation means,
A controller 10 is added to the inside of the measuring device 8.

Here, the first absorber 9a is provided in the opening of the collimator 3 so as to be insertable / pullable, and has a predetermined shield attenuation rate for low energy as shown in the characteristic diagram of FIG. 2, for example. It is a thing.

The second absorber 9b is also provided in the opening of the collimator 3 so that it can be inserted / pulled out, and as shown in the characteristic diagram of FIG. 2, a shield for high energy larger than that of the first absorber 9a. It has an attenuation rate.

Further, the controller 10 includes the wave height analyzer 5
The integrated count value for each energy channel output from the first and second absorbers 9a and 9b is checked so that the integrated count value for each energy channel is checked and the counting optimum range of the γ-ray detector 4 is measured based on the check result. This is for controlling the insertion / withdrawal, outputting the contents of the insertion / withdrawal to the computing unit 6, and also outputting the counting start / end command to the wave height analyzer 5.

Next, the operation of the burnup measuring apparatus of this embodiment constructed as described above will be described with reference to the flow chart shown in FIG. In FIG. 1, as shown in FIG. 3, when the energy calibration has not been performed, the controller 10 instructs the insertion of the first absorber 9a and the second absorber 9b, and the command to start counting of the wave height analyzer 5. It is output respectively.

Then, in the wave height analyzer 5, the γ-ray detector 4
The analog pulse signal from is input to perform count integration within the measurement time, and as shown in FIG. 4, count integration is performed for each energy channel (corresponding to each γ-ray nuclide), and the integrated count value is calculated. It is output to the device 6 and the controller 10, respectively.

On the other hand, in the controller 10, as shown in FIG. 3, the energy check of the integrated count value for each energy channel from the wave height analyzer 5 is performed using the following equations (1) and (2). Thus, three regions of each energy channel are selected.

Ci ≦ Cs (1) Ci ≦ Co (2) Ci: All γ-ray nuclides (energy channel) analyzed by the wave height analyzer 5 Cs: Low region energy channel set value (for example, ¹³⁷ C
s) Co: High region energy channel setting value (eg ⁶⁰ C
o) Next, in the controller 10, as shown in FIG. 3, the integrated count value for each energy region is calculated using the following formula (3), and further, using the following formula (4), The count value for each energy region equal to or higher than the low region energy channel set value Cs is checked.

Mi = Σni × f (x) (3) mi: integrated count value for each energy region ni: integrated count value for each nuclide from the γ-ray detector 4 f (x): first, first Shielding attenuation rate of the two absorbers 9a and 9b mi ≦ ms (4) ms: Counting characteristic limit value of the γ-ray detector 4 In the controller 10, when the above equation (1) is satisfied, the first and second Command to select absorbers 9a and 9b,
When the formula (2) is satisfied and the formula (4) is not satisfied, a pullout selection command for the second absorber 9b is output, and when the formula (2) is not satisfied and the formula (4) is not satisfied, a pullout selection command for the second absorber 9b is output, and at the same time. The selection result is output to the arithmetic unit 6.

When the judgment result is other than the above, the first and second absorbers 9a and 9b remain inserted.
On the other hand, in the calculator 6, the output signals from the wave height analyzer 5 and the controller 10 are input, and using the following equation (5), the corrected count value for each γ-ray nuclide and the following (6 ) Is used to calculate the burnup of the spent fuel 2 for each energy channel.

Ni = ni × D × f (x) (5) Ni: Count value after correction for each γ-ray nuclide ni: Integrated count value for each γ-ray nuclide from the γ-ray detector 4 D: Corrected count value of collimator 3 M = ΣNi × E (6) M: Burnup degree of spent fuel 2 E: Burned degree conversion count value Then, according to the output signal from the computing unit 6 by the display unit 7, The burnup for each energy channel of the spent fuel 2 which is the measurement result is displayed.

As described above, the burnup measuring apparatus of this embodiment is provided on the shield wall 1, and has a collimator 3 having an opening for guiding the γ rays emitted from the spent fuel 2 to the outside of the shield wall 1, The γ-ray detector 4 that detects and outputs the γ-rays guided by the collimator 3 and the counting integration for each channel that directly corresponds to the energy of each γ-ray from the spent fuel 2 that is output from the γ-ray detector 4 The wave height analyzer 5 that outputs for a preset time and the integrated count value for each energy channel output from the wave height analyzer 5 are subjected to correction calculation of the count value determined from the shape and opening area of the collimator 3, An arithmetic unit 6 for calculating and outputting the burnup of the spent fuel 2 which is the corrected count value for each energy channel,
A first absorber 9 provided in the opening of the collimator 3 so as to be insertable / withdrawable and having a predetermined shield attenuation factor.
a and a second absorber 9b having a larger shield attenuation factor than the first absorber 9a, and the integrated count value for each energy channel output from the wave height analyzer 5 is checked, and based on the check result. Controller 1 for controlling insertion / extraction of first and second absorbers 9a, 9b so as to perform measurement in the optimum counting range of γ-ray detector 4.
It is composed of 0 and 0.

Therefore, when measuring the γ-rays of the spent fuel 1, based on the check result of the integrated count value for each energy channel of the γ-rays from the spent fuel 2 output from the γ-ray detector 4. , First and second absorbers 9a, 9b
Since it can be measured by inserting / pulling in, and measuring in the optimum counting range of the γ-ray detector 4, even when a plurality of γ-ray nuclides are present and a high dose γ-ray dose field is used,
It is possible to eliminate the counting of the line detector 4 and perform accurate neutron measurement to more accurately measure the burnup of the spent fuel 2.

That is, in the case of γ-ray measurement in a high dose field in which a plurality of γ-ray nuclides exist, there was a problem such as counting down of the γ-ray detector 4, but By performing the insertion / extraction control of the first and second absorbers 9a and 9b, accurate measurement can be performed by using the optimum range of the detector.

By installing an absorber even in a high-dose γ-ray dose field, it is possible to perform measurement in the counting optimum range in which the number of γ-ray detectors 4 to be counted is small, and the burnup of the spent fuel 2 can be accurately measured. Various measurements are possible.

The present invention is not limited to the above embodiment, but can be implemented in the same manner as described below. (A) As another embodiment of the present invention, as shown by the broken line portion in the flow chart of FIG. 3, after the energy channel 3 region is obtained by the equations (1) and (2), the controller 10
Therefore, the following absorber insertion / withdrawal control may be performed.

That is, when the expressions (2) and (7) are satisfied and the expression (4) is not satisfied, or when the expression (2) is satisfied and the following expression (7) is not satisfied, the second absorber 9b. Outputs a selection command for pull-out control of the
Also output.

The calculator 6 calculates the burnup of the spent fuel 2 by using the above equations (5) and (6). e ≦ | Cia−Cib | (7) e: Allowable value of minimum and maximum energy difference in each energy channel region Cia: Minimum energy in each energy channel region Cib: Maximum energy in each energy channel region (The example is shown in FIG. 4.) Therefore, in the burnup measuring apparatus of this embodiment, the wave height analyzer 5 is used.
By performing the absorber insertion / extraction control as described above on the basis of the integrated count value of each energy channel output from the output, even if the γ-ray energy difference of the measurement target is large, the corresponding γ-ray By selecting and installing an absorber whose energy count is in a range that is sufficiently satisfied, it is possible to measure γ-rays within a counting range that satisfies the corresponding γ-ray energies, and more accurately measure the burnup of the spent fuel 2. It becomes possible to measure.

(B) In the above embodiment, the case where the absorber is used as the shield attenuator has been described, but the present invention is not limited to this, and a filter can be used as the shield attenuator, and in this case, the same as the above. The effect can be obtained.

[0037]

As described above, according to the present invention, in the burnup measuring device for measuring the burnup of the spent fuel in the radiation handling facility installed in the shield wall, the burnup measuring device is provided on the shield wall and is used. The collimator with an opening that guides the γ-rays emitted from the spent fuel to the outside of the shielding wall, the γ-ray detector that detects and outputs the γ-rays guided by the collimator, and the spent fuel output from the γ-ray detector Of the collimator for the accumulated count value for each energy channel output by the wave height analysis means, which outputs the count integration for each channel directly corresponding to the energy of each γ ray for a preset time. A calculation means for correcting the count value determined from the shape and opening area, calculating and outputting the burnup of the spent fuel, which is the corrected count value for each energy channel, and A first member that is inserted / withdrawn in the opening of the meter and has a predetermined shielding attenuation factor.
And the second shielding attenuation means having a greater shielding attenuation rate than the first shielding attenuation means, and the integrated count value for each energy channel output from the wave height analyzing means is checked. Since the control means for controlling the insertion / extraction of the first and second shielding / attenuating means is provided so as to measure in the optimum counting range of the γ-ray detector based on the check result, a plurality of γ-ray nuclides are provided. Even in the case of a high dose γ-ray dose field, and even if the γ-ray energy difference of the measurement target is large, the γ-rays can be accurately measured to improve the burnup of the spent fuel more accurately. A burnup measuring device capable of measuring can be provided.

[Brief description of drawings]

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

FIG. 2 shows first and second burnup measuring devices of the same embodiment.
FIG. 6 is a diagram showing an example of the shielding attenuation characteristics of the absorber of FIG.

FIG. 3 is a flow chart for explaining the operation of the burnup measuring device according to the present invention.

FIG. 4 is a conceptual diagram for explaining an example of a relationship between an energy channel and an integrated count value in the burnup measuring apparatus of the same embodiment.

FIG. 5 is a block diagram showing a configuration example of a conventional burnup measuring device.

[Explanation of symbols]

1 ... Shielding wall, 2 ... Spent fuel, 3 ... Collimator, 4 ...
γ-ray detector, 5 ... Wave height analyzer, 6 ... Operator, 7 ... Display, 8 ... Measuring device, 9a ... First absorber, 9b ... Second absorber, 10 ... Controller.

Claims (4)

[Claims] 1. A burnup measuring device for measuring the burnup of spent fuel in a radiation handling facility installed in a shield wall, wherein gamma rays emitted from the spent fuel are provided in the shield wall. A collimator having an opening leading to the outside of the shielding wall, and γ for detecting and outputting γ rays guided by the collimator
Ray detector and each γ from the spent fuel output from the γ ray detector
Wave height analysis means for performing counting integration for each channel directly corresponding to line energy for a preset time, and a shape of the collimator for integrated count values for each energy channel output from the wave height analysis means. -Computation means for performing a correction calculation of the count value determined from the opening area, calculating and outputting the burnup of the spent fuel, which is the corrected count value for each energy channel, and inserting / pulling in / out the opening of the collimator. First shield attenuator having a predetermined shield attenuator, second shield attenuator having a shield attenuator larger than the first shield attenuator, and output from the wave height analyzer. Check the accumulated count value for each energy channel, and based on the check result, in the optimum counting range of the γ-ray detector. Wherein to measure first, insertion / control means for controlling the withdrawal, burnup measuring apparatus characterized in that it comprises a second shielding attenuation means. 2. The burnup measuring device according to claim 1, further comprising display means for displaying a burnup for each energy channel of the spent fuel output from the computing means. Burnup measuring device. 3. The control means, the integrated count value for each energy channel output from the wave height analysis means,
3 for each energy channel compared to the low and high region energy channel settings
A region is selected, an integrated count value for each energy channel region is calculated from the shielding attenuation rate of the first and second shielding attenuation means, and the calculated value and the counting characteristic limit value of the γ-ray detector The burnup measuring device according to claim 1 or 2, wherein the comparison is performed. 4. The control means, the integrated count value for each energy channel output from the wave height analysis means,
3 for each energy channel compared to the low and high region energy channel settings
A region is selected, an integrated count value for each energy channel region is calculated from the shielding attenuation rate of the first and second shielding attenuation means, and the calculated value and the counting characteristic limit value of the γ-ray detector are calculated. The burnup measuring device according to claim 1 or 2, wherein the comparison is made to compare the minimum and maximum energy difference in each of the energy channel regions with an allowable value thereof.