JP7060194B2 - Storage container for gamma ray measurement, gamma ray measuring device and gamma ray measuring method - Google Patents

Description

The present invention relates to a storage container for gamma ray measurement, a gamma ray measuring device, and a gamma ray measuring method.

Currently, various types of waste are generated due to the decommissioning of nuclear reactor facilities and nuclear fuel handling facilities and the repair of facilities. Of these wastes, those that may be contaminated by nuclear fuel are treated as "radioactive waste". This "radioactive waste" is stored in waste warehouses at each factory or business establishment until it is disposed of, and final disposal such as burial is carried out.

However, "radioactive waste" includes substances that are not actually contaminated by nuclear fuel and substances whose radioactive concentration of radioactive substances is extremely low and whose effects on humans can be ignored. Originally, such waste does not need to be treated as a radioactive substance if it is appropriately sorted and decontaminated.

For example, on the second page of Non-Patent Document 1, "Since the risk to human health caused by a certain radiation source can be ignored, it is not necessary to treat it as a radioactive substance, and the radiation source is treated from the system of regulations related to radiation protection. You may remove it. " And, among the substances that may be contaminated by radioactive substances, those whose radioactive concentration is extremely low and whose risk to human health can be ignored are "Act on the Regulation of Nuclear Source Material, Nuclear Fuel Material and Reactor". "And by performing sorting and decontamination treatment based on the procedures stipulated in the relevant ministry ordinance, it is called clearance so that it can be handled as a substance that does not need to be treated as a radioactive substance.

By implementing clearance for such waste, it is possible to dispose of these as general waste, so that not only the amount of radioactive waste is reduced, but also the waste after clearance is implemented. Will be available as a new resource.

Therefore, when the waste generated in the nuclear reactor facility or the nuclear fuel handling facility is to be buried or cleared, it is necessary to measure the radioactivity of the waste. As a method for measuring the radioactivity of waste, for example, there is a method for measuring alpha rays or a method for measuring gamma rays. In the case of the method of measuring alpha rays, since alpha rays are shielded even by a single sheet of paper, it is necessary to measure alpha rays for each item, which requires a huge amount of time. On the other hand, in the case of the method of measuring gamma rays, since gamma rays have a high penetrating ability that can be finally shielded by a lead plate having a thickness of about 10 cm, a certain amount of waste is packed in a container and gamma rays are emitted from the outside of the container. Can be measured. Therefore, the method of measuring gamma rays can measure the radioactivity of waste more efficiently than the method of measuring alpha rays.

Further, in Non-Patent Document 1, a 200 L drum can is used as a container for measuring gamma rays, a large amount of waste is packed in the drum, and the gamma ray of the waste is measured from the outside of the drum can with a dedicated passive gamma measuring device. Cases are disclosed.

In Non-Patent Document 1, when packing metal waste in a drum can and determining the clearance, it is rational to set the measurement unit handled in one measurement with the drum can to about 100 kg. ..

Furthermore, when calculating the radioactivity concentration of the target nuclei from the gamma ray measurement results, a calibration radiation source that has the same material and density as the object for which clearance is judged and whose radioactivity has been verified is placed in the drum can. A calibration test is performed using the sample (simulated clearance object), and the radioactivity concentration is calculated from the result of this calibration test, or the radioactivity concentration is calculated by simulation using the Monte Carlo method or the like. In this way, by uniformly packing the materials and densities of the objects to be judged to be packed in the drums and having similar contamination distribution and shape into the drums, the target nuclides are measured from the gamma ray measurement results. The amount of radioactivity can be calculated accurately.

Judgment method of clearance in uranium handling facility: 2010, Atomic Energy Society of Japan Standards Committee, February 20, 2012

However, if 100 kg of iron waste is packed in a 200 L drum, the specific gravity of iron is 7.7 g / cm ³ , so iron with a volume of about 13000 cm ³ (13 L) should be packed in a 200 L drum. become. Since iron waste is cut into a size that can be packed into a drum (for example, several hundred plates), it is very difficult and time-consuming to evenly pack a large amount of iron into a 200 L drum. waste. Even if it can be packed, a large amount of iron may collapse when moving the drum can or during measurement, and waste (measurement target) may collect at the bottom of the drum can.

Therefore, the present invention has been made in view of the above problems, and provides a storage container for gamma ray measurement, a gamma ray measuring device, and a gamma ray measuring method capable of accurately and efficiently measuring gamma rays emitted from a measurement object. With the goal.

(1) One aspect of the present invention is a storage container for gamma ray measurement used for storing a plurality of measurement objects in an internal space and measuring gamma rays emitted from the measurement object, and the inside thereof. It has a dividing means for dividing the space into a plurality of regions in the vertical direction, and a storage means provided in each of the plurality of regions for accommodating the measurement object.
(2) In the aspect of (1) above, the sorting means may be connected to each other with the sorting means adjacent in the vertical direction.
(3) In the aspect of (1) or (2) above, the sorting means may be a partition wall or a partition wall having an opening.
(4) In any one of the above (1) to (3), the sorting means and the accommodating means may be integrally formed.
(5) Another aspect of the present invention is the gamma ray measuring device provided with the gamma ray measuring storage container according to any one of (1) to (4) above, which is the gamma ray measuring storage. It is equipped with a housing that surrounds the container and a gamma ray detector that detects gamma rays.
(6) Yet another aspect according to the present invention is a gamma ray measuring method for measuring gamma rays emitted from the measuring object using the gamma ray measuring device according to the above (5), wherein the measuring object is measured. Is accommodated in the accommodating means so that the weight difference between the plurality of regions is less than ± 20% with respect to the average value.
(7) In the embodiment of (6) above, using three or more of the gamma ray detectors, gamma rays emitted from the measurement object in the plurality of regions divided into the number of the gamma ray detectors or more are measured. You may.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a storage container for gamma ray measurement, a gamma ray measuring device, and a gamma ray measuring method capable of accurately and efficiently measuring gamma rays emitted from a measurement object.

It is a schematic sectional drawing which shows the gamma ray measuring apparatus provided with the storage container for gamma ray measuring which concerns on embodiment of this invention. It is explanatory drawing which shows the working procedure of the storage container for gamma ray measurement which concerns on embodiment of this invention. It is a top view and the side view which shows the classification means of the storage container for gamma ray measurement which concerns on embodiment of this invention. It is a plan view and a cross-sectional view which shows (a) modified example 1 and (b) modified example 2 of a classification means. 3 is a plan view and a cross-sectional view showing a modification 3 of the classification means and the accommodating means. It is a graph which shows the relationship between the weight difference between regions and the degree of influence on the gamma ray measurement result. It is a graph which shows the relationship between the number of regions and the degree of flattening of a measurement sensitivity.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In addition, the same element will be described with the same reference numerals throughout the description of the embodiment.

FIG. 1 is a schematic cross-sectional view showing a gamma ray measuring device 100 provided with a gamma ray measuring storage container 10 according to an embodiment of the present invention.
As shown in FIG. 1, the gamma ray measuring device 100 includes a housing 2 surrounding the gamma ray measuring storage container 10, a gamma ray detector 3 for detecting gamma rays, and a rotary table 4 on which the gamma ray measuring storage container 10 is placed. , Is equipped.

The housing 2 shields radiation coming from the outside of the gamma ray measuring device 100, and is provided so as to surround the gamma ray measuring storage container 10. That is, the housing 2 eliminates the influence of background radiation so that the gamma ray detector 3 can efficiently detect the gamma ray emitted from the measurement object T.

Further, the housing 2 has a square box shape in which an opening / closing door is formed on one surface such as the front surface, but is not particularly limited as long as it can surround the storage container 10 for gamma ray measurement, and may have a tubular box shape or the like. You may. The top surface, bottom surface, and side wall 2a of the housing 2 are formed to a desired thickness by using a material such as tungsten, lead, and iron that can shield radiation.

The gamma ray detector 3 measures the gamma ray emitted by the measurement object T housed in the gamma ray measurement storage container 10, and the sensitive portion 3a for detecting the gamma ray is located inside the housing 2. As the gamma ray detector 3, a Ge semiconductor detector or a NaI scintillation detector can be adopted, but the Ge semiconductor detector is preferable in terms of high resolution and low concentration quantitative measurement for each nucleus type. When used in a Ge semiconductor detector, it is preferable to install a tank for storing liquid nitrogen on the outside of the housing 2 or the like so that the gamma ray detector 3 can be cooled at the time of measurement.

Three gamma ray detectors 3 are arranged in the vertical direction of one side wall 2a of the housing 2, and the sensitive portion 3a of the gamma ray detector 3 is exposed inside the housing 2. It is provided so as to penetrate the side wall 2a of the housing 2.

The rotary table 4 mounts a storage container 10 for gamma ray measurement, and rotates the storage container 10 for gamma ray measurement at a predetermined angular velocity (rotational speed) when measuring gamma rays by the gamma ray detector 3. By measuring gamma rays while rotating the gamma ray measurement storage container 10, it is possible to make the measurement object T uniform in the circumferential direction of the gamma ray measurement storage container 10 and the radiation source uniform. This makes it possible to more accurately calculate the radioactivity concentration from the measured gamma rays. Further, instead of installing a plurality of gamma ray detectors 3 in the X-axis direction and the Y-axis direction, only by installing three gamma ray detectors 3 in the vertical direction, the object to be measured in the circumferential direction of the storage container 10 for gamma ray measurement. Measurements can be made assuming homogenization of T and homogenization of radiation sources.

Here, the measurement object T to be measured by the gamma ray measuring device 100 will be described. The measurement object T is a substance that may be contaminated with a radioactive substance, and is usually a solid. The measurement target T includes, for example, operation, repair, and modification in nuclear reactor facilities such as power generation reactors, experimental reactors, and research reactors, and nuclear fuel handling facilities such as nuclear fuel conversion facilities, nuclear fuel enrichment facilities, and nuclear fuel processing facilities. And waste materials such as equipment and buildings generated by decommissioning.

The measurement object T may have a high radioactivity concentration that is treated as a radioactive substance, or has a radioactivity concentration that is equal to or lower than the clearance level, which is a radioactivity concentration that is excluded from the treatment as a radioactive substance. May be.

Examples of the material of the object to be measured T include metals such as carbon steel, stainless steel, copper and aluminum, but the material is not particularly limited and may be concrete, plastic or the like. Further, among these, the higher the density of the material such as metal, the smaller the volume to be stored in the gamma ray measurement storage container 10, and it is difficult to uniformly pack the material so as not to collapse. The gamma ray measurement storage container 10 according to the above can be easily handled.

The shape of the object T to be measured includes a plate-like object, but is not particularly limited, and may be a simple shape such as a rod shape, a square shape, or a spherical surface, or a complicated shape having a protrusion and a curved surface. The large measurement object T that cannot be stored in the gamma ray measurement storage container 10 may be cut and shredded as necessary to have the same size and shape.

Next, the storage container 10 for gamma ray measurement will be described. FIG. 2 is an explanatory diagram showing a work procedure of the gamma ray measurement storage container 10 according to the embodiment of the present invention. FIG. 3 is a plan view and a side view showing the classification means 20 of the gamma ray measurement storage container 10 according to the embodiment of the present invention.

As shown in FIG. 2, the container body 11 of the gamma-ray measurement storage container 10 stores a plurality of measurement objects T in the internal space, and for example, has a strength capable of storing a total of about 100 kg of measurement objects T. Have. The container body 11 is preferably a bottomed cylinder and has a cylindrical box shape in which a disk-shaped lid 12 is ring-closed at the upper opening. For example, a 200 L drum can can be adopted. Drums are inexpensive, have desired strength, and have abundant transport jigs, and have good operability and transportability, such as being able to roll and move when empty.

The container main body 11 has a classification means 20 that divides (stages) the internal space into a plurality of regions Dn in the vertical direction. However, although n is an arbitrary integer of 1 and 2 or more, the number of gamma ray detectors 3 or more is preferable. In this embodiment, eight regions D1, D2 ... D8 are formed in order from the top. The sorting means 20 may be an eight-tiered sorting means 20 by stacking two four-tiered ones.

As shown in FIG. 3, the dividing means 20 has a disk-shaped partition wall 21 that divides a plurality of regions Dn, and a connecting member 22 that connects the partition walls 21. The partition wall 21 has an outer diameter slightly smaller than the inner diameter of the container body 11. That is, the plurality of regions Dn are in a state of communicating with each other when they are stored in the container main body 11 (see FIG. 1). The partition wall 21 may be, for example, one having an opening or one having a mesh shape. On the contrary, the partition wall 21 may have an outer diameter equal to the inner diameter of the container body 11 in order to divide the plurality of regions Dn into a state in which they do not communicate with each other.

These partition walls 21 and the connecting member 22 (classifying means 20) are formed by using an appropriate material in consideration of material strength, gamma ray permeability, etc., but if cost is emphasized, wood may be used, but storage for gamma ray measurement is used. Since the container 10 may be used repeatedly, a material with a smooth surface is considered in consideration of durability such as weather resistance and corrosion resistance, resistance to scratches, resistance to contamination, and ease of decontamination at the time of contamination. In addition, thin or reticulated metal or plastic is preferable in consideration of reducing the influence of shielding during gamma ray measurement (conversely, ensuring the permeability of gamma ray).

The plurality of regions Dn divided by the classification means 20 are provided with accommodation means 30 for accommodating the measurement object T for each region Dn (see FIGS. 1 and 2). In the present embodiment, only one accommodating means 30 is provided for one region Dn, but a plurality of accommodating means 30 may be provided for one region Dn.

As shown in FIG. 2, the accommodating means 30 is a bottomed square tubular container 31, but is not limited to this, and may be cylindrical, dish, bowl-shaped, or the like. Further, the accommodating means 30 may have a lid 34 for closing the upper opening of the container 31. This is because the object T to be measured may have a high radioactivity concentration that is treated as a radioactive substance. Therefore, in consideration of safety, it can be said that the accommodating means 30 should be a closed space. However, the bottom portion and the side wall of the container 31 may have an opening or may have a mesh shape, as in the case of the sorting means 20.

The container 31 and the lid 34 (accommodation means 30) are formed by using a material such as metal, plastic, or wood. Wood may be used if cost is emphasized, but the storage container 10 for gamma ray measurement is repeated. Since it may be used, a material with a smooth surface is preferable, considering its durability such as weather resistance and corrosion resistance, resistance to scratches, resistance to contamination, and ease of decontamination at the time of contamination. In consideration of reducing the influence of shielding when measuring gamma rays (conversely, ensuring the permeability of gamma rays), thin or reticulated metals or plastics are preferable.

Next, modifications 1 to 3 of the classification means 20 and the accommodation means 30 will be described. FIG. 4 is a plan view and a cross-sectional view showing (a) modification 1 and (b) modification 2 of the classification means 120 and 220.
In the above embodiment, the classification means 20 and the accommodation means 30 are separate bodies, but in the classification means 120 of the modified example 1 and the classification means 220 of the modified example 2, the classification means 120 and 220 and the accommodating means 30 are used. It is integrally formed (by integral molding).

As shown in FIG. 4A, the sorting means 120 is a bottomed cylindrical container 121. In other words, the container 121 itself is the accommodating means 30. The container 121 can be stacked up and down like a sushi tub and a soba tub, and has a stepped bottom 122 so that the upper and lower containers 121 do not shift from each other. A lid (not shown) may be attached to the uppermost container 121.

On the other hand, as shown in FIG. 4B, the sorting means 220 is a bottomed square cylinder-shaped container 221, and the bottom portion 222 is formed in a disk shape. In other words, the container 221 itself is the accommodating means 30. This container 221 also has a stepped bottom 222 so that the upper and lower containers 221 do not shift from each other. Further, a lid (not shown) may be attached to the uppermost container 221.

Then, the sorting means 120, 220 in which a plurality of containers 121,221 are stacked may be integrated (collectively) with a connecting jig such as a number line so that the entire container does not collapse. The bottom portions 122, 222 and the side walls 123, 223 of the sorting means 120, 220 may have openings or may have a mesh shape, similarly to the sorting means 20.

Next, the classification means 320 and the accommodation means 330 of the modification 3 will be described. FIG. 5 is a plan view and a cross-sectional view showing a modification 3 of the dividing means 320 and the accommodating means 330.
As shown in FIG. 5, the dividing means 320 has a disk-shaped bottom plate 321, a vertical pillar 322 erected on the bottom plate 321 and a plurality of hooks 323 provided on the vertical pillar 322 at equal intervals. ing. On the other hand, the accommodating means 330 has a container 331 and a locked tool 332 provided in the container 331 and locked to the hook 323 of the sorting means 320.

In this case, the classification means 320 does not clearly divide the internal space of the storage container 10 for gamma ray measurement into a plurality of regions Dn, but the plurality of storage means 330 are provided by a plurality of hooks 323 provided at equal intervals. However, since they are arranged at equal intervals in the vertical direction and are not in a state of being arranged in the horizontal direction, the classification means 320 divides into a plurality of regions Dn in the vertical direction, and the accommodation means 330 includes a plurality of storage means 330. Each region Dn is provided.

As yet another modification, the classification means 20 of the above embodiment and the accommodating means 30 may be connected and integrated by a fixing means such as an adhesive or a bolt.

Finally, an example of a measurement method for measuring gamma rays emitted from the measurement object T by using the gamma ray measuring device 100 will be described.

First, in the preparatory work for the plurality of measurement objects T, the waste generated in the reactor facility or the nuclear fuel handling facility, which may be contaminated by radioactive substances, is cut into a size that can be stored in the storage means 30. Then, sort by type such as material and shape so that the total measurement unit is about 100 kg. Even if the object T to be measured cannot be accommodated in the accommodating means 30, the size is such that the area Dn of the dividing means 20 in which the accommodating means 30 is installed does not interfere with (invade) the area Dn of the other dividing means 20. No problem.

Next, as shown in FIG. 2, the plurality of measurement objects T are accommodated in each of the plurality of accommodating means 30. For example, when the shapes of the measurement objects T are all strip-shaped, as shown in FIG. 1, the orientation of the strip-shaped measurement objects T is appropriately changed so that the adjacent measurement objects T overlap. The work of packing the object T to be measured into the accommodating means 30 is performed so that the degree does not differ greatly.

Then, the accommodating means 30 accommodating the measurement object T is prepared according to the number of stages of the dividing means 20. At this time, it is advisable to pack the measurement target T so that the difference in weight between the plurality of accommodating means 30 does not become large. At this time, it is desirable that there is no weight difference between the accommodating means 30 in each of the plurality of regions Dn, but even if there is a weight difference, if it is less than ± 20% of the average value, it is significant for the gamma ray measurement result. It is known to have no effect (details will be described later).

After that, these plurality of accommodating means 30 are placed on all the partition walls 21 of the dividing means 20. Further, after that, the sorting means 20 is housed in the internal space of the container body 11, the lid 12 is closed, and the storage container 10 for gamma ray measurement is used.

Finally, the gamma ray measurement storage container 10 is placed on the rotary table 4 so that the axis of the gamma ray measurement storage container 10 coincides with the center of the rotary table 4 of the gamma ray measurement device 100. Then, with the storage container 10 for gamma ray measurement surrounded by the housing 2, the gamma ray detector 3 measures the gamma ray emitted from the object T to be measured while rotating the rotary table 4 at a predetermined angular velocity.

In this way, the gamma ray measuring device 100 provided with the gamma ray measuring storage container 10 is used to collectively measure the gamma ray of the plurality of measurement objects T.

Here, the influence of the weight difference X of the measurement object T housed in the plurality of regions Dn on the gamma ray measurement result will be described. FIG. 6 is a graph showing the relationship between the weight difference X of the region Dn and the degree of influence F on the gamma ray measurement result.
The degree of influence F uses the storage container 10 for gamma ray measurement divided into eight regions Dn, and the total weight of the measurement object T is divided by the number of regions Dn in the four central regions D3 to D6. The weight difference X (%) is stored more than the average value A, and the weight difference X is stored less in the four upper and lower regions D1, D2 and D3, D6, and the weight difference X is 0% to 99. The gamma ray is measured by three gamma ray detectors 3 provided in the vertical direction, the average value of the gamma ray measurement value is calculated, and the average value of the gamma ray measurement value when the weight difference X is 0% is used. Obtained by comparison.

As shown in FIG. 6, when the weight difference X between the regions Dn is less than ± 20% with respect to the mean value A, it can be seen that the gamma ray measurement result hardly changes. When the weight difference X was 20%, 40%, and 60%, the influence degrees F were −0.1%, −1.6%, and −5.7%, respectively.

As described above, the storage container 10 for gamma ray measurement according to the embodiment of the present invention stores a plurality of measurement objects T in the internal space, and gamma ray measurement used for measuring gamma rays emitted from the measurement object T. The storage container 10 is a storage means 20, 120, 220, 320 for vertically dividing the internal space into a plurality of regions Dn, and a storage means provided in each of the plurality of regions Dn to accommodate the measurement object T. It has 30,330 and. As a result, the storage container 10 for gamma ray measurement can store a plurality of measurement objects T in each of a plurality of regions Dn whose internal space is vertically divided, so that uneven distribution in the axial direction is reduced and uniformity is achieved. Since the measurement sensitivity is increased, the measurement sensitivity is flattened and gamma rays can be measured accurately and efficiently.

Since the object T to be measured is accommodated in each of the plurality of accommodating means 30, 330, even if the load collapses, it does not collapse significantly because of the limited space of the accommodating means 30, 330. The measurement object T is not unevenly distributed at the lowermost portion of the gamma ray measurement storage container 10, and does not affect the weight difference of each region Dn. Therefore, the uneven distribution in the axial direction is reduced and the uniformity is improved, so that the measurement sensitivity is flattened and the gamma ray can be measured accurately.

In addition, the storage container 10 for gamma ray measurement can uniformly store the plurality of measurement objects T even when the total volume is small, so that the gamma rays can be stored according to the type, size, shape, etc. of the measurement objects T. There is no need to change the design of the measurement storage container 10. Further, even if the measurement object T has a low radioactivity concentration equal to or lower than the clearance level, the influence of the attenuation effect due to shielding can be reduced, so that gamma rays can be accurately measured.

In the embodiment, the sorting means 20, 120, 220 are connected to each other with the sorting means 20, 120, 220 adjacent in the vertical direction. As a result, the plurality of measurement objects T are stored in the container body 11 of the gamma ray measurement storage container 10 in a small number of times, so that the efficiency of the measurement work can be improved.

In the embodiment, the sorting means 20 is a partition wall 21 or a partition wall 21 having an opening. Thereby, if the partitioning means 20 is the partition wall 21, a closed space can be formed, and if the partitioning means 20 is the partition wall 21 having an opening, the weight of the storage container 10 for gamma ray measurement can be reduced, and the measurement can be performed. Work efficiency can be improved.

In the embodiment, the sorting means 120 and 220 and the accommodating means 30 are integrally formed. As a result, it is not necessary to transship the plurality of accommodating means 30 to the dividing means 120 and 220, so that the efficiency of the measurement work can be improved.

The gamma ray measuring device 100 of the embodiment includes a gamma ray measuring storage container 10, a housing 2 surrounding the gamma ray measuring storage container 10, and a gamma ray detector 3 for detecting gamma rays. As a result, a plurality of measurement objects T can be collectively stored in the gamma ray measurement storage container 10, and gamma ray measurement can be performed collectively (at once). Further, since the storage container 10 for gamma ray measurement is surrounded by the housing 2 of the gamma ray measuring device 100 to measure gamma rays, the influence of background radiation can be eliminated.

Further, when the gamma ray measuring device 100 includes the rotary table 4, the gamma ray measuring object T is uniformly measured by measuring the gamma ray while rotating the gamma ray measuring storage container 10 about the axis. It is possible to make the radiation source uniform.

In the gamma ray measuring method of the embodiment, the object T to be measured is accommodated in the accommodating means 30, 330 so that the weight difference between the plurality of regions Dn is less than ± 20% with respect to the average value. As a result, the gamma ray can be measured accurately because the measurement object T is uniformly arranged in the internal space of the gamma ray measurement storage container 10 in consideration of the weight of each region Dn in which the measurement object T is stored. can.

(Transformed form)
In the above embodiment, the number of gamma ray detectors 3 is 3, but the number is not limited to this. It is preferable that at least two or more gamma ray detectors 3 are provided in order to perform the measurement in the axial direction. However, for example, for a NaI scintillation detector having a sensitive portion 3a over a wide range in the axial direction, even one can be measured over a wide range in the axial direction, so that the number is not necessarily two or more. .. Further, when the gamma ray measuring device 100 does not have the rotary table 4 and the gamma ray is measured in a fixed state without rotating the gamma ray measuring storage container 10, the gamma ray detector 3 is the gamma ray measuring storage container 10. A total of two pairs, one in the X-axis direction and one in the Y-axis direction, may be provided around the center (note that the axis direction of the gamma-ray measurement storage container 10 is the Z-axis direction).

By the way, as the number of gamma ray detectors 3 increases, the gamma ray measurement sensitivity can be flattened and the measurement accuracy increases, but on the other hand, the cost increases and maintenance becomes complicated. Therefore, the number and arrangement of the gamma ray detectors 3 may be determined in consideration of the accuracy of the radioactivity concentration, the cost, and the like. For example, when measuring a gamma ray measuring storage container 10 formed of a drum can or the like having a height of about 80 cm by using a gamma ray measuring device 100 provided with three gamma ray detectors 3 as in the above embodiment, in the axial direction. It can be said that this is an example of a device system suitable for measuring three points, upper, middle and lower.

Further, regarding the region Dn, it is preferable that the number of regions Dn is large from the viewpoint of flattening the measurement sensitivity. On the other hand, in terms of operation such as stuffing work and maintenance, it is preferable that the number of regions Dn is small. However, when the number of regions Dn is smaller than the number of gamma ray detectors 3 in the axial direction, flattening of the measurement sensitivity cannot be expected.

Therefore, as an example, in the gamma ray measuring device 100 having three gamma ray detectors 3, the number of regions Dn was changed, and the influence of the number of regions Dn on the measurement sensitivity of gamma rays was evaluated. The degree R of the flattening of the measurement sensitivity is the average value of the gamma ray measurement values when the measurement object T is spread and stored on average in the region Dn for each of the plurality of regions Dn, and the plurality of regions Dn. Each of the above was obtained by using the difference from the average value of the gamma ray measurement values when the measurement object T was unevenly distributed and stored downward. The evaluation result is shown in FIG. From FIG. 7, it can be seen that when the number of regions Dn is less than the number of gamma ray detectors 3, that is, when the number is less than 3, the degree R of flattening of the measurement sensitivity is poor. That is, by dividing the gamma ray measurement storage container 10 into a plurality of regions Dn by the number of gamma ray detectors 3 or more, flattening of the measurement sensitivity can be expected.

Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications and variations are made within the scope of the gist of the present invention described in the claims. It can be changed.

2 Housing, 2a Side wall 3 Gamma ray detector, 3a Sensitive part 4 Rotating table 10 Gamma ray measurement storage container, 11 Container body, 12 Lid 20 Separation means, 21 Bulk partition, 22 Connecting member 30 Storage means, 31 Container, 34 Lid 100 Gamma ray measuring device 120 Sorting means, 121 container, 122 bottom, 123 side wall 220 sorting means, 221 container, 222 bottom, 223 side wall 320 sorting means, 321 bottom plate, 322 vertical column, 323 hook 330 accommodating means, 331 container, 332 Locked tool Dn area T Measurement target

Claims (7)

A storage container for gamma ray measurement used for storing a plurality of measurement objects in an internal space and measuring gamma rays emitted from the measurement objects.
A partitioning means for dividing the internal space into a plurality of regions adjacent in the vertical direction, and
It has one or a plurality of accommodating means provided in each of the plurality of regions and accommodating the object to be measured.
The storage container for gamma ray measurement is characterized in that the storage means is a bottomed container separate from the classification means. A storage container for gamma ray measurement used for storing a plurality of measurement objects in an internal space and measuring gamma rays emitted from the measurement objects.
It has a dividing means for dividing the internal space into a plurality of regions adjacent in the vertical direction.
The sorting means is a plurality of bottomed containers stacked in the vertical direction .
The upper opening of the bottomed container on the lower side is closed at the bottom of the bottomed container stacked on the upper side.
A storage container for gamma ray measurement. The storage container for gamma ray measurement according to claim 1 or 2, wherein the classification means has a partition wall or an opening. A storage container for gamma ray measurement used for storing a plurality of measurement objects in an internal space and measuring gamma rays emitted from the measurement objects.
A partitioning means for dividing the internal space into a plurality of regions adjacent in the vertical direction, and
Each of the plurality of areas is provided with a storage means for accommodating the object to be measured.
The sorting means has a vertical column in which a plurality of hooks are provided in the vertical direction.
The storage container for gamma ray measurement is characterized in that the storage means is a container having a locked tool that is locked to the hook. The storage container for gamma ray measurement according to any one of claims 1 to 4,
The housing surrounding the storage container for gamma ray measurement and
A gamma ray measuring device including a gamma ray detector for detecting gamma rays. A gamma ray measuring method for measuring gamma rays emitted from the measurement object using the gamma ray measuring device according to claim 5.
When claim 5 cites any one of claims 1 to 3,
The object to be measured is housed in the bottomed container so that the weight difference between the plurality of regions is less than ± 20% with respect to the average value.
If claim 5 cites claim 4,
A gamma-ray measuring method comprising accommodating an object to be measured in the accommodating means so that the weight difference between the plurality of regions is less than ± 20% with respect to the average value. The sixth aspect of claim 6, wherein three or more gamma ray detectors are used to measure gamma rays emitted from the measurement object in the plurality of regions divided into the number of the gamma ray detectors or more. Gamma ray measurement method.

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